binsfeld

TorqueTrak Revolution Instrument – Periodic Maintenance & Calibration

The torque & power measurement system from Binsfeld Engineering consists of two main items, the strain gage sensor plus the TorqueTrak Revolution instrument.

Strain Gage Sensor - Measure Torque.

Part # CEA-06-250US-350: http://www.vishay.com/company/brands/measurements-group/guide/500/gages/250us.htm

Full-Bridge configuration, 350 ohms. Use one piece per shaft.

TorqueTrak Revolution System: http://www.binsfeld.com/ttrevolution.cfm

User's Manual: http://www.binsfeld.com/manuals/TTRevolution.pdf

Specifications: http://www.binsfeld.com/tt_revolution_spec_sheet.pdf

Periodic Maintenance:

There really is no recommended periodic maintenance, except perhaps for the occasional clean-up or wipe-down.

The strain gage installation can remain valid for years. Checking the Zero Reference and the Shunt Calibration, described below, is the best method for checking the strain gage. If and when the Torque output signal seems to drift, it may be time for a new strain gage installation. See Strain Gage Adhesive in the Reliability section, next page.

Periodic Calibration Check:

1. Check the Zero Reference (Torque) output signal.

The Zero Reference should remain the same from one shaft operation to the next. With the shaft stopped and with Zero Torque on the shaft, check the Torque output signal (milliamp.) This current output signal is the “Zero Reference”. The strain gage plus TorqueTrak Revolution instrument should always return to the same Zero Reference. Actually, the system should always return to nearly the same Zero Reference. It is not unusual to have residual torque/strain on the shaft, from one shaft operation to the next, resulting in slight deviations in the Zero Reference output signal.

2. Check the Shunt Calibration.

The TorqueTrak Revolution instrument has a built-in Shunt Calibration feature for easy calibration check anytime.

Shunt Calibration Resistor: 174.825K ohm. Precision: ±0.1%. Very stable.

The Shunt Calibration Switch applies a 0.1% precision resistor right at the strain gage termination, across –EXC and

–SEN terminals, simulating real strain/torque on the shaft of 250 microstrain. For our standard TorqueTrak Revolution instrument, the Full Scale strain input is ±500 microstrain. So, the Shunt Calibration resistor simulates precisely 50% full scale strain/torque.

Torque Sensitivity = Torque Input per Current Output.

a. Know the Full Scale Torque, 500 microstrain, of your particular shaft. See Accuracy & Calibration section.

b. Apply the Shunt Calibration Switch, located inside the Master Control Unit (control box.)

Shunt Calibration Switch On means Torque Input = 250 microstrain, 50% full scale torque.

c. Observe the Torque current output signal.

At factory settings, Shunt-on minus Shunt-off equals 4.0mA. Check and verify system calibration anytime simply by actuating the Shunt Calibration Switch. This should yield a repeatable value each time, 50% of full scale torque. Please see the Accuracy & Calibration section or the User's Manual for more information.

If the Zero Reference remains consistent and the Shunt Calibration Switch yields a consistent output signal, then the entire Torque & Power Measurement system remains calibrated.

Reliability:

Typically, the strain gage will be bonded to the shaft using the standard cyanoacrylate adhesive, M-Bond 200. For best reliability, the strain gage should then be protected against environmental conditions using the protective coating, M‑Coat J. Strain Gages and accessories are supplied by Vishay Micro-Measurements Company in Raleigh, NC.

The weakest link in the entire measurement system may be the M-Bond 200 adhesive used to bond the strain gages to the shaft. M‑Bond 200 can remain valid for years. Still, the adhesive may be the first thing to fail.

Checking the strain gage:

a. Check the Zero Reference (Torque) output signal.

b. Check the Shunt Calibration. Shunt Calibration Switch is built into the TorqueTrak Revolution instrument.

If the Zero Reference remains consistent and the Shunt Calibration Switch yields a consistent output signal, then the entire Torque & Power Measurement system remains calibrated.

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The alternative to M-Bond 200 adhesive is an epoxy adhesive, M-Bond AE-10. A comparison is shown below.

M-Bond 200 adhesive: http://www.vishay.com/brands/measurements_group/guide/a110/acc/mb200.htm

For routine experimental stress analysis applications under temperate environmental conditions, M-Bond 200 adhesive is ordinarily the best choice. This adhesive is very easy to handle, and cures almost instantly to produce an essentially creep-free, fatigue-resistant bond, with elongation capabilities of five percent or more. The user should note that the performance of the adhesive can be degraded by the effects of time, humidity conditions, elevated temperature, and moisture absorption. Because of the latter effect, strain gage installations should always be covered with a suitable protective coating (M-Coat J.) When necessitated by more rigorous test requirements and/or environmental conditions, consideration should be given to one of the epoxy adhesives.

Positive: Easy installation. No clamping required. One-minute cure time. Can remain valid for years.

Negative: Adhesive may degrade over time.

M-Bond AE-10 adhesive: http://www.vishay.com/brands/measurements_group/guide/a110/acc/mbae10.htm

Two-component, 100% solids epoxy system for general-purpose stress analysis. Transparent, medium viscosity. A cure time as low as six hours at +75°F (+24°C) may be used. For maximum elongation, bonding surface must be rough.

Positive: This epoxy adhesive is considered a “permanent” adhesive that will not degrade over time.

Negative: +75°F temperature and 20 psi clamping pressure are required during the minimum cure time of six hours.

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Protective Coating for strain gage.

Part # M-Coat J: http://www.vishay.com/company/brands/measurements-group/guide/ib/b147/147index.htm

A two-part polysulfide liquid polymer compound for environmental protection of strain gage installations. When fully cured, it forms a rubber-like covering that provides an effective barrier against water and many other fluids. The tough coating also protects installations from mechanical damage.

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Suggestions for Fail-Safe precautions:

a. Install a backup strain gage on each shaft to save time in the event the strain gage must be switched out quickly.

b. Consider epoxy adhesive vs. M-Bond 200 (cyanoacrylate) adhesive for the strain gage.

c. Have a spare TorqueTrak Revolution instrument on hand to save time in the event the instrument must be switched out quickly. Delivery leadtime of a replacement instrument is 4-6 weeks.

ACCURACY & CALIBRATION, Torque:

Using the TorqueTrak Revolution telemetry system, you can expect Accuracy better than ±1.0% Full Scale. Accuracy is a function of two primary elements - proper installation of the strain gage and accurate determination of the "Sensitivity" of the system. The entire "system" includes the shaft, the strain gage and the TorqueTrak Revolution system. "Sensitivity" is expressed in terms of Torque-Input per Current-Output. The Input-Output relationship is linear all throughout the elastic range of the shaft material. Shown below are some methods for determining Sensitivity and checking Calibration.

1. The most precise method for determining Sensitivity of the system is a true mechanical calibration, sometimes called a Deadweight Test, where a known torque (a known force/weight on a known moment-arm) is applied to the shaft. Example: 100 pounds weight on a 1-foot moment-arm equals 100 foot-pounds "known Torque-Input." Observe the Current-Output of the TorqueTrak Revolution system. Sensitivity of the entire system is equal to the Torque-Input per Current-Output. Take two or more points of reference using different known Torque-Input values as confirmation of the "Sensitivity" value determined.

The known moment arm should be affixed to the shaft using a clamp or perhaps by bolting onto a flange. The length of the moment arm should be measured accurately from the axis of the shaft to the point of applied force/weight. The known force/weight could be calibrated weights free-hanging from the arm, in which case the moment arm would be the horizontal dimension. Or the known force could be applied using a calibrated torque wrench. On large shafts the known force could be applied using a crane or a jack and measured with a calibrated load cell. Very Important: The applied force and the moment arm must be perpendicular to each other.

Be Careful! The applied force and the moment arm must be perpendicular to each other. Be careful with your measurements, especially if the moment arm drops when free hanging weight is applied. In this case, the length of the moment arm becomes shorter in the dimension perpendicular to the weight/force.

2. You can use the Full Scale Torque calculator at our web site: http://www.binsfeld.com/rev-nom-tq.cfm

The upper calculator on this page can be used to determine the Full Scale Torque range, based on shaft characteristics. For best accuracy, enter precise values* for all the inputs - Shaft Diameter, Gage Factor, Modulus of Elasticity and Poisson Ratio. Then, "Calculate Full Scale Torque." The resultant "Full Scale Torque" corresponds to 500 microstrain on the shaft defined. The input range of Zero-to-Full Scale Torque corresponds to the nominal "factory setting" output signal range of 12-20 mA. At the factory setting, Sensitivity = Full Scale Torque / 8 mA.

* Shaft Diameter has a major influence in the Sensitivity calculation – a precise value should be used. Gage Factor is supplied with the package of strain gages. Modulus of Elasticity and Poisson Ratio were probably recorded by the shaft manufacturer, but it may be difficult to recover those values. Using nominal values for Modulus of Elasticity and Poisson Ratio introduces an uncertainty of perhaps ±3% Full Scale. This is not to say that using nominal values introduces error, because the true shaft characteristics may be exactly equal to the nominal values used.

The bottom Calculator on this page can be used to determine the "RPM Factor" switch setting that will relate Torque on the Shaft to Power. "Full Scale Torque" is the value calculated above and it corresponds to the full scale torque output signal, 20 mA at factory settings. "Power Full Scale" is the Power value you choose to correspond to the full scale power output signal, 20mA at factory settings. Please see the User's Manual for more explanation.

… continued …

ACCURACY & CALIBRATION, Torque, continued:

3. The Shunt Calibration Switch, built into the TorqueTrak Revolution Master Control Unit, is a very useful tool.

Shunt Calibration Resistor, Value: 174.825K ohm. Precision: ±0.1%. Thin film construction, very stable over temperature.

The Shunt Calibration Switch applies a 0.1% precision resistor right at the strain gage termination, across –EXC and –SEN terminals, simulating real strain/torque on the shaft of 250 microstrain, assuming a balanced 350 ohm full-bridge strain gage. For our standard system the Full Scale strain input is ±500 microstrain, so the Shunt Calibration resistor simulates precisely 50% full scale strain/torque. If there is a Zero Offset, an imbalance in the 350 ohm strain gage after installation, the simulated 250 microstrain will likewise be affected.

Torque Sensitivity = Torque Input per Current Output.

a. Know the Full Scale Torque, 500 microstrain, of your particular shaft.

b. Apply the Shunt Calibration Switch, located inside the Master Control Unit (control box.)

Shunt Calibration Switch On means Torque Input = 250 microstrain, 50% full scale torque.

c. Observe the Torque current output signal.

At factory settings, Shunt-on minus Shunt-off equals 4.0mA. Check and verify system calibration anytime simply by actuating the Shunt Calibration Switch. This should yield a repeatable value each time, 50% of full scale torque. Please see the User's Manual for more information.

Torque/Strain Calculator plus Shunt Resistor Calculator: http://www.binsfeld.com/SCforHS.cfm

The upper calculator on this page can be used to determine the strain, in units of "microstrain" (microinches/inch), that results from a known torque (deadweight) on a defined shaft (diameter, etc.) The lower calculator can be used to determine the shunt resistance value that relates to a known strain, as determined in the upper calculator. You can also use this lower calculator in the event the strain gage is out of balance – change the 350 ohm Gage Resistance value to the true gage value and then back-calculate the effect the 174.825K ohm shunt resistor will have.

Limited Warranty:

Binsfeld Engineering Inc. warrants that its products will be free from defective material and workmanship for a period of one year from the date of delivery to the original purchaser and that its products will conform to specifications and standards published by Binsfeld Engineering Inc. Upon evaluation by Binsfeld Engineering Inc., any product found to be defective will be replaced or repaired at the sole discretion of Binsfeld Engineering Inc. Our warranty is limited to the foregoing, and does not apply to fuses, paint, or any equipment, which in Binsfeld Engineering’s sole opinion has been subject to misuse, alteration, or abnormal conditions of operation or handling.

This warranty is exclusive and in lieu of all other warranties, expressed or implied, including but not limited to any implied warranty of merchantability or fitness for a particular purpose or use. Binsfeld Engineering Inc. will not be liable for any special, indirect, incidental or consequential damages or loss, whether in contract, tort, or otherwise.

NOTE (USA only): Some states do not allow limitation of implied warranties, or the exclusion of incidental or consequential damages so the above limitations or exclusions may not apply to you. This warranty gives you specific legal rights and you may have other rights which vary from state to state.

Aluminum Welding

Application Summary
To gain greater fuel efficiency, auto makers are incorporating lighter components into their new car designs. Manufacturers are increasingly interested in fabricating auto components from aluminum, which are much lighter than the same components made out of steel. The problem is that the manufacturing techniques developed for steel are not always suited to work in aluminum, and therefore new manufacturing techniques need to be developed.

That’s why researchers at a major auto manufacturer are investigating better ways to optimize the welding of aluminum performed by robots. The quality of the weld is a function of several factors such as the arc frequency and magnitude, the distance from the welder tip to the aluminum, and the thickness of the aluminum being welded. In order to quantify these variables, the researchers mounted sensors on the welding apparatus.

Potential Solution
The first system considered as a data acquisition solution was a 12-bit digital storage oscilloscope (DSO) with custom signal conditioning and low pass filtering. However, this solution was expensive – typically a 12-bit DSO costs about $10,000. Furthermore, it would have required custom programming. Since researchers did not consider themselves programmers, developing the skills needed to program the test system would have been time intensive.

IOtech’s Solution
The researchers selected IOtech’s WaveBook^™ PC-based data acquisition system for their application. The analog signals were conditioned by an IOtech WBK13A^™ signal conditioning card. The 8-channel programmable card provides low-pass filtering and simultaneous sample and hold functions in order to correlate channels and eliminate the highest frequency. The IOtech system was chosen for its ability to record a large amount of data to the PC’s hard drive in real time. This feature allowed the engineers to examine long welds. Another feature that the researchers found attractive was the system’s included WaveView^™ Out-of-the-Box^™ software. WaveView allowed them to set up their application quickly and easily without programming. PostView^™ software, which was also included, let them review the data immediately after the test to verify if the test was valid.

A major automaker selected the WaveBook system for research on aluminum welding.

Testing Manufacturing Equipment

Application Summary
Because today’s new high-efficiency engines demand engine parts made to tighter tolerances than ever before, the parts in turn require even more precise equipment to make them. A company that manufactures equipment for engine component production (i.e. pistons, crank shafts, valves) for the OEM market needed a way to analyze and improve the precision of its equipment. For this type of machinery, vibration dampening is critical to the quality of the manufactured part, so engineers needed to measure the effects of various dampening techniques. Another critical area is uneven or excessive pressure during stamping, which would ruin both the die and the parts. Accelerometers and strain gages were mounted in the appropriate places on the equipment.

Potential Solutions
At first, the machinery manufacturer considered using a digital storage oscilloscope (DSO) with an external signal conditioner. This approach was rejected as being too bulky and difficult to program. The engineers also considered using a plug-in board data acquisition system with a desktop PC, but it lacked the portability that the engineers needed to move the system around the machinery.

IOtech’s Solution
The engineers selected IOtech’s WaveBook^™ data acquisition system for their application. To measure vibration, the system included a WBK14^™ eight-channel dynamic signal conditioning module. To measure strain, the system included a WBK15^™ multi-purpose isolated signal conditioning module which accepts any combination of up to eight 5B modules.

The speed and flexibility of the WaveBook system allowed the engineers to use one system for both strain and vibration applications. The WaveBook provided the high sample rates needed for vibration work across multiple channels, plus several channels used for strain measurements. Because the system was compact (the system has the same footprint as a notebook PC), it was easy to carry onto the factory floor or to ship to a customer. Furthermore, the WaveBook attaches to a PC using a common parallel-port connection, allowing it to be easily attached to any PC, such as the PC at a customer site. DASYLab^™ software, also available from IOtech, was selected for its FFT capability and ease of set-up.

The WaveBook data acquisition system aided engineers in the design of machinery
for engine component manufacturers.

In-Vehicle Seat Suspension Testing

A manufacturer of vibration and shock control products needed to develop a seat suspension system that would maximize the comfort and safety of operators of heavy-duty, on- and off-road construction equipment. This required the manufacturer’s engineers to conduct in-vehicle development and testing. This in-vehicle testing required a lightweight, portable data acquisition system capable of displaying data in real-time. The engineers chose IOtech’s DaqBook, a portable data acquisition system that fits neatly beneath a notebook PC.

Performance Criteria
Because of space limitations in the testing environment, the engineers decided to employ a notebook PC in their data acquisition system. Since an AC power source was not readily available, the fully configured system had to be able to draw sufficient power from its own battery or from a standard car battery. The selected data acquisition system needed to provide a sampling rate and resolution high enough for a vibration application, as well as voltage outputs that could be used to adjust the seat’s suspension. Furthermore, it had to be able to withstand the hostile environment in which heavy-duty over-the-road trucks and off-highway construction equipment generally operate.

IOtech's Solution
IOtech’s DaqBook met all of these performance criteria. The DaqBook is a portable data acquisition system that can be connected to a notebook PC via a standard or enhanced parallel port. In addition to meeting all of the required performance specifications, the DaqBook was easy to set up and use.

The DaqBook ships with Windows-based setup, acquisition, and data-display applications, and drivers for third-party graphical acquisition packages. The DaqBook also provides Windows drivers, which allowed the engineers to write their own data acquisition software.

Application Summary
Each seat under test required a controllable fluid damper adjusted for the particular vehicle model in which it would be used. During the tests, which were conducted on an outdoor test track that duplicated common road conditions for heavy-duty trucks and construction equipment, the seats were secured in either a test stand or a test vehicle. The design engineers configured the test setup by connecting the notebook PC and the DaqBook to a sensor, the controllable fluid damper, and the seat’s air-spring suspension mechanism. The controllable fluid damper was then attached to the air spring suspension. A proprietary interface was used for power and signal conditioning. In order to electronically adjust the damping characteristics of each fluid damper, the data acquisition system needed to be able to acquire data in real time. A closed control loop, in which the DaqBook generated an electrical output based on the acquired vibration data, was used to adjust the controllable fluid damper.

To conduct the test, the engineers electronically tuned the fluid damper to the structure (either a test stand or vehicle) to which it was attached. The DaqBook received an analog signal input from the sensor, which was attached to the seat, indicating the position of the seat. This analog signal was sent to the notebook PC via the DaqBook’s A/D converter. The notebook PC used this signal to determine the seat’s gross motion and vibration. This motion was then reduced by varying the current (via the DaqBook’s D/A converters) through the electronically controlled damper, which in turn leveled the seat’s air spring suspension so that the seat provided the best operator support. The seat’s air spring suspension was also adjusted directly by the DaqBook’s 24 general-purpose digital I/O lines.

Conclusion
The tests conducted using IOtech’s DaqBook portable data acquisition system proved very effective. The semi-active seat suspension system that the DaqBook helped to develop is currently in use in many heavy-duty, off-road trucks and in construction equipment. The vibration- and shock-control product manufacturer foresees additional applications in equipment and vehicles used in aerospace, agriculture, construction, logging, mining, and transportation.

In-Vehicle Brake Testing on Trucks

A major original-equipment manufacturer (OEM) of truck braking systems requires a portable data acquisition system that enables the verification of lab tests in the field. Such in-vehicle road tests are critical to developing quality systems that conform to federal transportation specifications. They are also useful for assisting customers in diagnosing system issues.

Application Summary
As a supplier for the major truck manufacturers, the brake OEM is often called on-site to verify that its brake systems meet federal and contract specifications and to help truck manufacturers troubleshoot problems. To facilitate such troubleshooting, the OEM typically equips the truck braking systems under test with strategically positioned pressure transducers, which measure everything from pedal pressure and individual cylinder pressure to pressure differentials among axles. In addition, the OEM obtains data on pressure waveforms and timing and evaluates it to assure even, adequate braking at all times.

Initially, the brake manufacturer's field-test system consisted of a “luggable” lunch-box-style computer, equipped with a plug-in data acquisition board. However, this solution was bulky, difficult to transport to test sites, and awkward to operate within the tight confines of an eighteen-wheeler truck cab. In addition, as the brake manufacturer refined its testing requirements and improved the dynamics of its brake systems, the board’s 100-kHz A/D conversion rate was insufficient for the task. Another drawback of the original field-test system was its dependence on the luggable computer. Because field-testing is often performed on very short notice, test engineers were reluctant to use the luggable computer for lab applications, since there was no assurance that they would be able to complete lab tests without interruption. Consequently, use of the luggable computer was in effect confined to field-testing, which proved a drain on the test department's limited computer resources.

Potential Solution
The brake manufacturer first evaluated several high-speed boards as replacements for the original field-test system. However, while these would have eliminated the technical limitations of the original system, they would not have addressed the practical difficulties and space problems associated with using a luggable computer or a notebook PC equipped with a docking station.

IOtech’s Solution
The brake manufacturer selected IOtech's WaveBook for its replacement field-test system. The manufacturer chose the WaveBook in part because its compact 8.5” x 11” x 1.375” size matches the typical form factor of notebook PCs, the manufacturer's preferred portable computer platform. The WaveBook’s 125 Ksample/s per channel sampling rate—10 times faster than the original system's—was a further factor, as it addressed the manufacturer's fears regarding system obsolescence if faster sampling rates are required. The brake manufacturer was impressed as well by the WaveBook's expandability, which permits the addition of pressure transducers as necessary.

Another strong point was the WaveBook's ability to be powered by a variety of sources. Because the unit can operate from any 10 to 30 VDC source or from an included AC power adapter, it is ideal for both the manufacturer’s in-vehicle truck tests and lab tests.

Connectivity also figured in the manufacturer’s selection of the WaveBook for its new in-field brake test system. The WaveBook’s eight BNC inputs simplify system hook-up, eliminating the need for special cabling.

Finally, the brake manufacturer was pleased with the WaveBook’s ability to operate from either a notebook or desktop PC. This enables its simple connection to virtually any available computer, making it easier for test personnel to get maximal use from limited computer resources.

Conclusion
The WaveBook’s high-speed sampling, convenient BNC inputs, DC operability, and light weight make it a unique portable solution. Also, because it is external to the controlling computer, it is ideal for field-service applications, where system flexibility and expandability are often important issues.

Airbag Testing

In contrast to other automotive safety features such as seat belts, which can be periodically checked for proper operating condition, in-vehicle airbags may be stored unchecked for years before being used. Because lives depend upon airbag systems being ready to deploy in an instant, rigorous airbag testing is critical.

Application Summary
One of the most important components of an airbag system is the ignitor, which generates the explosion that forces the airbag out of its storage compartment when a specific amount of force is applied to a vehicle. This simple device must operate flawlessly. If the triggering mechanism detects the force improperly, the airbag can falsely deploy or fail to deploy; if the trigger is late in responding, the airbag fails to prevent potential injury. A leading manufacturer of airbag ignitors ensures that its ignitors work properly by having research engineers examine the ignitor’s response time and trigger detection mechanism during the unit’s design and test phase.

Until recently, the engineers subjected ignitor designs only to laboratory tests, which they measured with a digital storage oscilloscope (DSO). For most of these tests, the engineers connected a DSO to a desktop PC via its RS-232 port so that they could store, analyze, and report their data in a third-party data acquisition software package running on the PC. For tests that required multiple data channels, the engineers found that the DSO had limited memory depth and input channels. To circumvent the input-channel limitation, the engineers linked multiple DSOs together. Besides being a costly and awkward solution, the daisy-chained DSOs could not provide simultaneous triggering. Furthermore, the engineers had difficulty correlating the data acquired from the DSOs.

Potential Solutions
The engineers evaluated two PC-based data acquisition solutions. They first considered a rack-mounted system. Although the engineers considered this solution preferable to daisy-chaining DSOs, they eventually decided against it because it was not sufficiently portable for in-vehicle testing. The second solution was a 1-MHz A/D plug-in board, which the engineers planned to install in an industrial-grade, rugged “luggable” PC. However, this option was still too large and heavy for their requirements.

IOtech’s Solution
The engineers chose IOtech’s WaveBook portable 1-MHz digitizer because it offered them the necessary speed, size, and ruggedness for this application. The engineers liked its light-weight, all metal construction and its ability to receive power from either an AC source for laboratory testing or from a DC source such as a cigarette lighter for in-vehicle testing. In addition, the engineers find that the WaveBook’s ability to work with most notebook and desktop PCs – a big plus over plug-in boards.

Other WaveBook features influenced the engineers’ decision. The unit’s BNC connectors permit them to save time and money by enabling them to re-use the BNC cables that they used with their DSOs. The WaveBook’s wide-ranging software support allowed them to use the same third-party data acquisition software, sparing them the need to learn a new software package. They were also impressed by the WaveBook’s multi-channel triggering, which eliminates false captures and quickly displays the data of interest, reducing the time needed for post-analysis data reduction and shortening the time required to generate reports.

Conclusion
The WaveBook 1-MHz digitizer is an ideal substitute for DSOs in many electro-mechanical applications. It provides the speed and channel expansion required for many applications, and because it links directly to the computer via a parallel port or PCMCIA slot, it can be connected to most computers.

Electric Car Battery Testing

An electric utility company was interested in using electric vehicles for its meter readers and other customer service personnel. In order to determine the feasibility of this idea, engineers needed to evaluate the vehicle’s operating parameters during operation and measure what effect they would have on its electrical requirements. In other words, they needed to determine how long the batteries would be able to power the vehicle under normal operating conditions.

Application Summary
After an electrical propulsion system was installed in a small pickup truck, the engineers began to research methods for increasing the truck’s operating efficiency and its operating range between battery chargings. Some initial possibilities they considered were: solar panels to extend the battery life, regenerative braking to recover kinetic energy, lighter plastic components replacing the heavier stock vehicle components, and low-resistance tires. All of these methods would extend the range of the vehicle; however, the relative merits of each needed to be quantified so that the value of each modification in terms of performance could be compared to the cost of its implementation. To obtain this data, the vehicle’s operation needed to be measured both before and after each modification.

To make the measurements, the researchers needed a data acquisition system able to meet a demanding set of performance criteria. These criteria included portability, operability from a battery, ability to accommodate mixed analog signals, a high channel count, and expandability. The system needed to run unattended after a relatively simple setup procedure. Furthermore, the system’s sampling rate, resolution, accuracy, and data transfer speed needed to be sufficient.

IOtech’s Solution
The data acquisition system that best met these criteria was IOtech’s PC-based DaqBook data acquisition system. The DaqBook system was equipped with IOtech’s thermocouple card and universal voltage and current card. The thermocouple card provided auto zero, cold-junction compensation, and programmable gain for a variety of temperature measurements. The signal conditioning card accommodated analog signals from transducers placed on the vehicle to measure voltage, current, temperature, and other variables. The data acquisition was controlled by a notebook PC using a custom software program; the PC’s hard drive provided data storage.

The DaqBook data acquisition system provided the accuracy needed to capture even the most rapidly changing variables. It also provided sufficient channels in the form of 8 differential or 16 single-ended analog inputs, plus many additional output and digital input channels. Expandable to 256 analog-input channels, the DaqBook system was capable of multiplexing all channels with individual gains for each channel.

The DaqBook’s rugged metal enclosure is roughly the same form factor (8 1/2” x 11” x 1 3/8”) as the notebook PC, as is the optional expansion card enclosure and battery pack. The system was installed behind the driver’s seat, and combined with the PC, weighed no more than 35 pounds, of which 15 pounds was mounting hardware.

Data Acquisition System Measurements
Battery charge and discharge characteristics were perhaps the most important variables measured on the electric vehicle, which used 20 six-volt lead/acid batteries connected in series to drive a 120 VDC motor. A voltage divider was used to scale down the aggregate voltage to 5 VDC for input into the data acquisition system. A clamp-on current sensor measured battery charge and discharge current, up to a maximum of 400A. The sensor output was set up for ±5 VDC for 500A full-scale current flow in either direction. Voltage and current were also measured on a 12 VDC accessory battery used to operate windshield wipers and lights.

To help determine the effects of charge and discharge characteristics on the batteries, temperatures were measured in various locations. Thermocouple probes were installed in selected cells to measure electrolyte temperatures inside the front and rear battery assemblies. Flush mount thermocouples measured the batteries’ casing temperatures. Other temperature measurements included a flush mount thermocouple on the drive motor, and a thermocouple probe in the bed of the truck for ambient air temperature.

Charge/discharge data was correlated with truck loading. Although the truck load itself was virtually constant, terrain affected both motor load and speed. Terrain was measured with an inclinometer installed behind the truck’s seat in the center of the cab. The output was scaled 0 to 3.6 VDC for 0 to 360° of rotation (incline). Vehicle speed was measured by attaching a pulse generator to the speedometer cable. The DaqBook data acquisition system’s counter timer created the appropriate speed scale. The output from an electronic tachometer connected to the motor was used in a similar fashion to obtain motor speed.

Conclusion
Using a single portable PC-based data acquisition system, the researchers quickly and easily acquired many channels of data of mixed signal types. IOtech’s DaqBook data acquisition system worked so well that the utility is considering alternative uses for it. One use would be to add a GPS (Global Positioning Satellite) system that would determine the vehicle’s coordinates and those of its proposed destination. This information, combined with terrain data and battery-charge data, would allow the driver to decide whether the truck could make a trip of a certain distance on its current charge.

Military Vehicle Off-Road Testing

Military and civilian drivers with a wide range of driving skills are using sport-utility and multi-purpose vehicles in extreme off-road environments. To assure vehicle quality, vehicle manufacturers are adopting portable PC-based data acquisition systems to perform innovative field tests.

Application Summary
The maker of a popular multiple-purpose military vehicle learned that some inexperienced operators were not maneuvering vehicles through obstacles correctly, causing tremendous stress on driveline components. In rare situations, the drivers compromised performance by putting excessive torque on transmissions, transfer cases, and differentials. To better understand this phenomenon, the manufacturer’s engineering team needed to identify the combined effects of engine torque, speed, and controlled brake activation on components during the worst possible operating scenarios. This would require simultaneous, multiple-channel data acquisition during torturous field testing.

Potential Solution
Initially, the engineers used traditional measurement equipment, such as dedicated instruments and rack-mounted systems. This equipment had major drawbacks. Only a few of the bulky instruments fit inside the vehicle’s cabin, and tests had to be repeated numerous times to capture readings. Once the data was gathered, the measurements were put through exhaustive calculations to evaluate vehicle performance. The process was costly, time-consuming, and it compromised data accuracy.

IOtech’s Solution
After considering their options, the engineers decided to use a portable PC-based system that easily mounted inside the vehicle’s cabin on the center console during field tests. At the heart of this compact system was IOtech’s WaveBook, a 1-MHz system designed for high-speed, multi-channel data acquisition. The WaveBook included IOtech’s WaveView™ Out-of-the-Box™ software, which allowed engineers to take measurements without the complicated setup and programming often associated with typical data acquisition programs.

The WaveBook system transferred data to a notebook computer. This combination allowed up to two full days of measurements to be saved to disk or the PC’s hard drive. Using an IOtech WBK10 8-channel analog expansion module and a WBK15 8-channel multi-purpose isolated signal conditioning module, the WaveBook acquired data from 16 sensors attached to various vehicle components.

Speed sensors were easily mounted to front and rear propshafts and halfshafts, and four transducers were attached to brake lines to collect pressure readings. Measuring torque on front and rear propshafts and all four halfshafts presented a challenge. Because shafts move during testing, traditional wired sensors were not an option. To solve the problem, the engineers custom-fit the shafts with non-contact, wireless sensors. These sensors were supported by small 9V-battery-powered transmitters that sent readings to a receiver/signal conditioner mounted in the vehicle’s cabin.

With the system in place, engineers put the vehicle through a host of field applications designed to challenge the transmission, transfer case, and differential. During field tests, the vehicle made its way through water and mud up to 28-inches deep, VW-Bug-sized snow piles, and bumpy terrain that often limited it to two-wheel ground contact. For skid-torque testing, the vehicle was nudged against a concrete wall, and the vehicle’s gas pedal was depressed until all wheels started to skid. In all, these tests generated more abuse than most off-road vehicles will ever have to endure.

With the acquired data, test conditions were replicated in a lab by mounting the vehicle on a bed-plate and four electric absorption dynamometers (one for each wheel). Loads for each dynamometer were controlled individually to replicate exact field conditions. The WaveBook was used to validate conditions and to further evaluate performance. Using analytical software, engineers conducted real-time, post-experiment analysis to make direct correlations between test data and component performance. Engineers used their findings to make the driveline components “user-proof.”

Conclusion
The WaveBook’s performance capabilities, compact size, and mobility helped engineers to quickly accomplish field tests that would have been impossible with dedicated test-and-measurement instruments only a few years ago. As the manufacturer’s director of product assurance put it, “With traditional equipment, there were many exhausting steps to acquiring measurements. We had to wait days, even weeks, for results. Now, with portable PC-based systems, data collection is easy and results are instantaneous.”

Truck Turbocharger Testing

To meet quality standards and shorten design times, vehicle equipment manufacturers are evaluating new components with portable PC-based data acquisition systems. These PC-based systems provided more mobility, higher performance and often cost less than traditional test-and-measurement instruments. As a result, manufacturers are designing better components while saving time and money.

Application Summary
A leading truck engine manufacturer set out to test a new diesel-engine turbocharger. During testing, engineers needed to record high-frequency oscillations at the turbocharger’s inlet as the truck operated in demanding environments, such as sweltering heat and metal-chilling cold.

To accurately gather the turbocharger’s performance data, the engineers needed a multichannel test-and-measurement system that was capable of providing high resolution, signal conditioning, and noise isolation — all for a reasonable cost. This demanding test criteria eliminated the possibility of using traditional off-the-shelf equipment.

Potential Solution
Initially, the engineering team attempted to monitor the turbocharger manually by having an engineer listen to the oscillations by ear. This method was very inaccurate.

Searching for a new test method, the team reviewed proposals from system integrators. Unfortunately, the proposed systems consisted of several bulky instruments with limited performance capabilities and expensive price tags, ranging from $25,000 to $50,000. In need of a better solution, the engineers began researching portable PC-based data acquisition systems.

IOtech’s Solution
Research led the team to IOtech’s DaqBook^®, a portable PC-based data acquisition system. The DaqBook was matched with signal conditioning cards housed in a DBK10 expansion module: a DBK7 frequency input card, a DBK15 universal current/voltage input card, and a DBK16 strain-gage card. The system was powered by a DBK30A battery module, adding to the system’s mobility.

The system was compact and easy to install. The DaqBook and its modules each matched the typical form factor of a notebook PC and were stacked and secured on top of each other. The total system weighed less than 20 lbs., making it easy to mount inside the truck’s cab, and the its convenient installation eliminated the set-up problems associated with the larger integrated instruments.

Once installed, the system received signals from various strain gages, piezoelectric transducers and thermocouples, collecting nearly 20 channels of data from the turbocharger and other engine components. The DaqBook provided the accuracy needed to measure rapidly changing variables, and the system’s digital output transferred the data to the PC through the PC’s parallel port.

The measurements were viewed in real time on the PC’s screen, giving the engineers a clear picture of how the turbocharger was performing during the field tests.

Running data acquisition software, the system gave the engineers the ability to specify A/D settings, such as the channel sequence, sample rate, and display frame length. The system also gave them the ability to create virtual instruments on the PC’s screen. The system’s digital-meter feature made it easy to read average real-time values, while the strip-chart recorder function was useful for trending.

For post-acquisition analysis, software enabled important data to be identified with the PC cursor and then bookmarked to annotate specific points. As engineers placed markers on specific waveforms, corresponding data values were automatically sent to a compatible spreadsheet program. This eliminated manual entries for customized reports and data plots.

The DaqBook proved to be extremely valuable to the engineering team. The system was able to gather numerous types of data from a variety of transducers in ways that no other test-and-measurement system was capable of doing. As a result of the testing, the engineers were able to quickly make adjustments to the turbocharger’s design, improving its quality and shortening its time to market.

Because the DaqBook system was so effective during turbocharger testing, the manufacturer’s engineering team continues to use the DaqBook system for several other component tests.

Conclusion
The DaqBook system provided the analog-to-digital (A/D) conversion, signal conditioning, performance flexibility, and portability required to thoroughly evaluate the turbocharger during field tests. The system’s low cost, ease of setup, portability, and high performance continue to make it an ideal solution for an endless number of vehicle field tests.

Vehicle Crash Testing

A leading original equipment manufacturer (OEM) of automobile and truck air-bag systems required an in-vehicle data acquisition system to verify crash test results. Crash testing is critical to developing reliable air-bag systems that conform to federal transportation specifications.

Application Summary
When attached to fereromagnetic material, the magnetostrictive sensor emits a signal with an amplitude in the millivolt range. When the ferromagnetic material experiences a stress, as it would during a vehicle crash, the material’s magnetization changes and the output of the sensor changes. Because shock waves travel well through the vehicle’s metal frame, the sensor can detect impacts from any direction that occur at a distance from the sensor.

To test the reaction time of the sensor, the OEM installs air-bag systems into vehicles and subjects them to simulated crash tests. Engineers perform many crash tests at different speeds and angles to acquire test data.

Because the beginning of the crash contains the most critical events, the engineers look to discover the precise time at which the crash occurred (time zero), and how long it took for the sensor to detect the crash. Data is collected in the 0.5s to 1s interval immediately following impact, an acquisition period which produces approximately 50,000 to 100,000 data points.

Potential Solution
The air-bag manufacturer evaluated several data acquisition systems that would quickly and easily collect the data from a high-speed vehicle crash; however, these systems were not able to withstand the g forces involved in a crash and did not meet the OEM’s sampling requirement.

IOtech’s Solution
Ultimately, the air-bag manufacturer selected IOtech’s LogBook/300^™ stand-alone data acquisition system, which provided the convenience of a PC-based system without exposing the PC to potentially damaging forces. The LogBook/300’s removable PC-Card (PCMCIA) permitted the data to be transferred to a benchtop PC. The card’s non-volatile storage of up to 250 million samples was adequate for the sizable files of data, acquired at a rate of 100K samples/s with a resolution of 16 bits.

Two essential requirements for the data acquisition system were portability and ability to withstand the g forces encountered in a high-speed crash test. To perform a test, company technicians mounted the compact LogBook/300 chassis in the test vehicle, using twisted pair cable to connect the system to a terminal board located four to six feet away. The terminal board, in turn, was connected to the air-bag system’s magnetostrictive sensor and an impact trigger switch.

The air-bag manufacturer was impressed by the LogBook/300 system’s trigger programability. Contact switches or tapes placed in the test vehicle’s impact area supplied the trigger signal. When the trigger signal came from a simple switch, the company’s engineers easily programmed the LogBook/300 to trigger on the switch closure signal — often a TTL compatible signal. IOtech’s LogBook/300 was configured to sample the magnetostrictive sensor at 100 kHz for 1 second after it was triggered by the impact trigger switch.

Moreover, the air-bag manufacturer was pleased with the LogBook/300’s 20 Mbyte memory storage PC-Card. After each test, technicians remove the card from the data acquisition system, insert it into the lab’s laptop computer, and quickly and easily upload the data for analysis with their analysis software of choice. LogView^™ Out-of-the-Box^™ software, a graphical data acquisition package included with the LogBook/300 system, provided an easy means to configure the application on the lab PC, without programming.

Another compelling reason for choosing the LogBook/300 was the ease of use of LogView, the included application software. The OEM needed a data logging software package that was flexible and powerful, yet did not require the help of programmers or software integrators. LogView met all of their requirements by providing a simple interface for setting up channel acquisition parameters while providing sophisticated features such as multiple sample rates, calculated channels, and dynamic outputs.

Conclusion
The LogBook/300 data acquisition system and included LogView software provides flexible triggering, low cost, and ease of use. With removable PC-card memory, the stand-alone LogBook/300 system can operate without an attached PC in the test platform. What’s more, the system’s extensive signal conditioning options for strain gages, thermocouples, accelerometers, and other signal types — combined with an optional control terminal for triggering and reviewing acquired data — make it an effective solution that outperforms other test and measurement instruments.

In-Vehicle Temperature Testing

Automobile owners expect their vehicles to operate reliably wherever they are driven, whether in the desert or in the arctic. Therefore it is imperative that automobile manufacturers verify the temperature operating ranges of components in a prototypical automobile in its final stage before production.

Application Summary
An automobile manufacturer needed to road test a new model of vehicle in extreme temperatures and collect engine performance data. Researchers planned road tests in Arizona and Alaska, in ambient temperatures ranging from -30^o to +55^oC (-22^o to +131^oF). To measure the prototype’s performance, test engineers needed to instrument six automobiles for more than 70 temperature measurements of each engine and its components including oil, coolant, engine-control unit, alternator, and other OEM parts.

Potential Solution
Previously, the automobile manufacturer utilized a DAT recorder that required a time-consuming effort to convert a digital tape to a workable computer file for data evaluation. In addition to being difficult to work with, the DAT recorder was bulky and prohibitively expensive for outfitting six cars.

IOtech’s Solution
To conduct the on-the-road tests, the manufacturer needed a data acquisition system able to meet a demanding set of performance criteria. These criteria included portability, operability from a battery, ability to accommodate and filter thermocouple signals, and a high-channel count. The system needed to run unattended by way of a simple setup process, followed by an easy download of the data to a laptop PC.

IOtech’s LogBook/300^™ stand-alone data acquisition system was chosen for the thermocouple application because it was cost effective, equipped to measure many thermocouples, fit easily in the car’s front seat, and provided quick download via a memory PC-Card (PCMCIA) and included LogView^™ Out-of-the-Box^™ software.

Technicians glued or taped thermocouples to engine components, or sealed them into engine pipes, and ran the thermocouples to a single position in the front seat where they were screwed into the terminals of the LogBook/300 data acquisition system. The LogBook/300 was powered via a DBK34A^™ DC uninterruptable power supply attached to the cigarette lighter. The DBK34A supplied necessary power to the LogBook/300 during power sags caused primarily by engine cranking. The LogBook/300 measured more than 70 channels at the rate of 1 Ksample/s.

To accommodate the thermocouple signals, the manufacturer used the DBK84^™ signal conditioning option. Six DBK84 modules expanded the system to up to 84 channels of thermocouple inputs. Noise reduction averaging was employed in the software setup to eliminate the noise induced by the automobile into the thermocouples. After averaging channels, stability was within 0.05^oC even in the electrically noisy engine compartment.

The researchers were also pleased with the LogBook/300’s optional LBK1^™ handheld terminal that allowed remote monitoring and control of the LogBook/300 while the car was on the road.

After each test, technicians removed the 20-Mbyte memory PC-Card (PCMCIA) from the LogBook/300 and quickly and easily transferred the data to a laptop PC. LogView Out-of-the-Box™ software, included with the LogBook/300, served as a simple method to graphically view the data and save it to disk, for later analysis using any post-acquisition analysis package including Microsoft Excel.

Conclusion
With nonvolatile storage of up to 250 million samples and a removable PC-Card memory, the LogBook/300 data acquisition system provided a low-cost-per-channel and easy-to-use solution. The system’s extensive signal conditioning options for many signal types including thermocouples, combined with an optional control terminal for triggering and reviewing required data, made it an effective tool for researchers measuring temperatures in the field.

The Logbook/300 collected on-the-road data that verified that the engine and its components operate according to expectations at extreme temperatures and that there are no unexpected problems: a mission critical to ensuring that the car will operate under all driving conditions satisfactorily.

Turbocharger Testing

Turbochargers are one of many products manufactured in the war against pollution. Automotive manufacturers, government agencies, and environmental organizations concerned with pollution from automobile and truck exhaust rely on turbochargers to reduce harmful emissions by increasing air intake to a vehicle’s engine. To verify that vehicles equipped with turbochargers meet these requirements, on- and off-road testing is required.

Application Summary
A leading manufacturer of turbochargers and other anti-pollution products must verify that their electronically activated turbocharger (called a “supercharger”) more effectively reduces harmful emissions by activating faster than other turbocharger products. The manufacturer’s supercharger mounts in the vehicle’s intake line; when pressure is applied to the pedal, a trigger switch causes the supercharger’s built-in wheel to spin immediately, generating pressure to the intake, thereby improving fuel burn, engine power, and a reduction in emissions. The elimination of this lag time — normally spent waiting for a turbocharger’s wheel to spin up to speed and generate pressure to the intake — leads to the supercharger’s superiority.

The engineers test their supercharger in a two-part investigation. First it is tested on a laboratory dynamometer, where the supercharger is installed into a typical vehicle and measured for current, engine rpm, manifold pressure, motor speed, horsepower, and torque. Later, the vehicle is removed from the lab and taken on a road test where the same parameters are measured under normal driving conditions. Engineers directly compare the supercharged vehicle’s performance results to the same vehicle operating with the supercharger turned off.

The researchers needed a PC-based data acquisition system to monitor, record, and analyze their supercharger’s performance. To be effective, the data acquisition system has to be mobile, powered by the vehicle battery, and withstand the vibration associated with road testing.

IOtech’s Solution
The manufacturer evaluated a number of systems, and selected IOtech’s LogBook/300™ stand-alone data acquisition system. Their research required storage of 10-Mbyte data files that were too large for the typical memory sizes available with comparably priced data acquisition systems.

The manufacturer was impressed with the data acquisition system’s capability to store large data files generated by their research. The LogBook/300 uses removable PC-Card memory (PCMCIA), allowing researchers to use a 20-Mbyte memory storage PC-Card. More importantly, the manufacturer liked the system’s signal conditioning options and included LogView™ Out-of-the-Box™ graphical data acquisition software, which gave them the ability to view real-time data with no programming required.

The engineers also appreciated the LogBook/300’s compact size (11” x 8.5” x 1.75”), the same form factor as a notebook PC, which allowed the system to fit easily under the front seat of the test vehicle.

The researchers measured current, engine rpm, manifold pressure, motor speed, horsepower, and torque by way of sensors installed on the engine and wired to the data acquisition system located inside the vehicle. All connections were zip tied and secured with epoxy to avoid contact with moving parts.

Several signal conditioning options expanded the capability of the LogBook/300 system: IOtech’s DBK7™ frequency input card provided 4 channels of frequency measurement capability; the DBK83™ thermocouple input card provided 14 channels of highly accurate thermocouple measurements plus automatic cold-junction compensation; the DBK11A™ provided researchers with convenient screw terminals for signal connection; and the DBK34A™ provided backup power to the LogBook/300 system in case the vehicle’s battery voltage dropped.

After each test was completed, engineers removed the PC-Card from the LogBook/300, inserted it into a laptop computer, and reviewed the data with included PostView™ software, a post-acquisition viewing package included with LogView™ software. Using PostView™, the engineers were able to display and scroll data from files that were too large to evaluate using Microsoft Excel.

Conclusion
Mobile and easy to use, the Logbook/300 data acquisition system from IOtech provides a high-performance solution to researchers testing in the lab and in the field. The system’s extensive signal conditioning options make it an effective solution that outperforms other groups of test and measurement instruments in its price range. With nonvolatile storage of up to 250 million samples via removable PC-Card memory, the Logbook/300 is a compact solution for portable data collection that makes it an effective alternative to more expensive stand-alone data acquisition systems.