AICON Wheel Watch

Non-contact high speed monitoring of wheel motion in vehicle dynamics testing

  • on a moving vehicle or in a test station
  • measuring of wheel clearance
  • accurate measurement of all wheel parameters including track, camber inclination, spring travel, and steering angle 
  • simultaneous monitoring of several wheels or axles

Description

WheelWatch - Functional principle

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 500mm (20 in) 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.

Workflow

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.

Technical Data

System components:

  • MoveInspect 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

System parameters: 

Position accuracy: 
X, Y, Z
± 0.1 mm
Angular accuracy ± 0,015°
Measurement volume 1,000 mm x 1,000 mm x 500 mm 
(40“ x 40“ x 20“)
Distance camera /wheel adapter approx. 0.5 m (20“)
Measurement range (track/camber) ± 45°
Spin angle range unlimited
Max. acquisition frequency 500 Hz

Wheel adapter: 

Material carbon fiber
Diameter 400 mm (16”)
Weight < 500 g
Targets ANCO on retro reflective film High Gain 7610

Camera: 

Type of camera High speed CMOS camera (MoveInspect HF)
Resolution 1280 x 1024 pixels
Max. afrequency 500 Hz
Exposure time 10 µs - 100 µs
Lens High performance lens, f=10 mm, minimal distortion
Flash High performance LED ring light, 10-100 μs
Data transmission TCP/IP
Synchronization Digital time stamp / Master/slave mode, Clock / Enable IN/OUT (TTL o. 20 mA Loop)
Power supply Test drive: 12 Volt vehicle power system; test station: 90 - 240 Volt

Software: 

  • camera calibration
  • axle calibration
  • determination of reference points
  • transformation in vehicle coordinate system 
  • data transfer via data file, analog or digital (TCP/IP)
  • calculation of axle and wheel parameters

Controlling computer: 

Test drive Notebook (Microsoft ® Windows ® 7 (64 Bit))
Test station Desktop computer (Microsoft ®
Windows ® 7 (64 Bit))

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