Non-contact high speed monitoring of wheel motion in vehicle dynamics testing
WheelWatch is built around a high-resolution high speed digital camera consisting of a high resolution CMOS sensor, an integrated high performance flash and an image analysis processor. The digital camera features offers extremely short shutter speeds of just a few micro-seconds that are necessary for long duration tests. The high quality camera also ensures the system is robust and stable over time.
It provides data at a frequency of 490Hz, ideal for studying and optimizing static and dynamic chassis parameters. Measurements are controlled automatically and may be collected over long periods of time. The triggering function ensures that multiple sensors are fully synchronized.
The camera can be mounted at a distance of less than 500 mm from the fender. The camera processor uses TCP/IP protocol to communicate with the laptop computer which controls the system. The computer is placed in the test vehicle. The vehicle 12 Volt power system provides power during the test drive.
For the measurement of wheel movements, one camera for each wheel is mounted so that the wheel as well as part of the surrounding fender is visible. Special optical targets applied to the fender define the vehicle coordinate system. A lightweight carbon fiber wheel adapter is fixed to the wheel.
The position of the camera does not have to be stable as WheelWatch recalculates its position continuously using the reference targets on the vehicle fender. The wheel movement measurements are always provided in the vehicle coordinate system. Movements of the camera or camera mount do not influence measurement results, making the system inherently more stable than competing systems.
The driver manually triggers the beginning and end of a measurement session. No other interaction with WheelWatch is required. The high speed camera collects wheel measurements at a rate of up to 490 times per second.
The image processor analyzes the digital images in real time and passes the measurement values to the notebook computer. Wheel target positions and target trajectories are available shortly after the image acquisition. In addition, WheelWatch computes all six degrees of freedom of the wheel in the vehicle coordinate system.
- Vehicle dynamics testing without mechanical connection between sensor and wheel
- Self-referencing to vehicle coordinate system in real time
- Very short setup time
- Complete capturing of wheel motion in 6DoF
- Measurements on a moving vehicle or on test station
- Simultaneous measurement of all wheels and of the engine is possible
- Expandable for other dynamic measurement tasks
- Unlimited acquisition time
- Realtime data transfer via CANBus/Ethernet
- Simple synchronisation with 3rd party sensors
- Combinable with wheel force transducers (on request)
- Rugged against sun exposure/different light conditions
- WheelWatch basic system
- Per axle 2 MoveInspect HF cameras and 2 CFK wheel adapters
- Mounting frame
- Accessory set including targets, syncbox for 1 - 4 cameras and controlling computer with WheelWatch software
|Type of camera||High-speed CMOS camera|
|Resolution||1,280 x 1,024 pixels|
|Max. acquisition frequency||500 Hz|
|Exposure time||10 µs|
|Lens||High-performance lens, f=10 mm, minimal distortion|
|Flash||High-performance LED ring light, 10 µs|
|Data transmission||TCP / IP|
|Synchronization||Digital time stamp, Master/slave mode, Clock/Enable In/Out (TTL / 20 mA Loop)|
|Power supply||Test drive: 12 V vehicle power system; Test station: 90- 240 V|
|Weight||< 500 g|
|Targets||ANCO on retro reflective film High Gain 7610|
|Test drive||Notebook (Microsoft© Windows© 7 and 10 (64 Bit))|
|Test station||Notebook or Desktop (Microsoft© Windows© 7 and 10 (64 Bit))|
- Camera calibration
- Axle calibration
- Determination of reference points
- Transformation in vehicle coordinate system
- Calculation of axle and wheel parameters
- Data transfer via data file, analog or digital (TCP/CANBus)
|Position accuracy||± 0.1 mm|
|Angular accuracy||± 0.015 °|
|Measurement volume||1,000 mm x 1,000 mm x 500 mm|
|Distance camera/wheel adapter||Approx. 0.5 m|
|Measurement range (track - camber)||± 45°|
|Spin angle range||unlimited|
|Acquisition frequence||up to 500 Hz|
|Realtime data transfer||> 200 Hz|