Truck builder tests wheels "on-the-road"
Greg Reed, Technical Editor -- Test & Measurement World, 10/1/2004
Simulations can be powerful engineering tools, but the best place to gather data on product performance is still in the real world. Yet, sophisticated test equipment is frequently unable to withstand the physical punishment involved in real-world testing.
One Chinese truck builder, First Automotive Works (FAW), recently required a test system that would
 |
| A technician from FAW adjusts a wheel-force sensor. Courtesy of FAW. |
FAW contracted with RS Technologies (www.rstechltd.com) and CAESAR DataSystems (www.caesar-datasystems.com), both of Farmington Hills, MI, to build a test system that is sensitive enough to deliver useful information and tough enough to function reliably on the road. RS Technologies and CAESAR needed to blend mechanical and electronic engineering skills in a unified system capable of data capture and analysis.
"It was apparent from the beginning that the system would have to combine high-accuracy measurement, data recording, and data analysis in a single package that fully integrated the sensors, electronics, and software," said Ralph Shoberg of RS Technologies. It also had to be modular to cover the range of vehicles that FAW wanted to be able to test and analyze.
Self-contained assemblyThe system that was supplied to FAW was a self-contained wheel-sensor assembly machined from one piece of titanium. It measures three components of road load force and three components of torque.
All sensing elements and signal-conditioning electronics are housed in the unified wheel assembly that attaches by bolts directly on to the test vehicle. Data-acquisition hardware and software are carried onboard the vehicle.
RS Technologies designed the wheel-force transducer (WFT) that measures the forces acting on the wheel assembly. The WFT design includes a proprietary one-piece sensor section that is rugged yet provides sensitive readings.
CAESAR Datasystems developed the computer-aided data-acquisition (CADA) hardware and software that perform onboard signal conditioning, shunt calibration, angular position resolution, and signal transmission. The key is a transducer interface unit (TIU) that is fully integrated into the data-acquisition system, providing for dynamic force, torque, and position communication between the wheel sensor and the CADA system.
Rack-mounted hardware and a laptop loaded with the necessary communication, data-analysis, and data-storage software is supplied with the system. Moreover, the unified test system can be installed and set up with only 10 wheel revolutions and in less than 10 min per wheel.
FAW purchased two units for testing on medium-sized trucks and two units for heavy trucks. Initial testing commenced at the test track in Changchun, Kirin, a province near Manchuria. Since then, road profiling has logged thousands of miles traveling to the south of China over all road surfaces under vastly differing weather conditions with heavily loaded trucks.
