WheelView Operation

Operation:                                    

The WheelView®system is installed under the rail in a stable  and relatively tangent track position. However, by design the system has a high tolerance for vertical (and horizontal) displacements of the rail that may occur due to heavy carloads and track repairs.

Remote Train Presence Sensors

Once a sensor (see figure) detects an incoming train, certain system components such as lasers are activated and the shutters are opened. Sensors are usually located 10-50 yards away from the system installation site. For system protection, dragging equipment detectors may be installed at appropriate locations.

Triggering Sensors

Imaging devices are actually triggered by train wheels. Once activated, an image of each wheel is captured using at least two cameras. All sensors (see figure) are designed specifically for railroad applications and are heavy duty industrial grade. The triggering system is designed to be insensitive to both train speed and its direction.

 

 Automatic Equipment Identification (AEI)

After every wheel is processed, its ID, i.e. the car it belongs to (Car ID) and its position in that car (e.g. R1 or L4), must be determined. This information is later used to identify every wheel in the database. This is accomplished using an Automatic Equipment Identification (AEI) system. The AEI is an essential part of the system. Using AEI, every wheel in the fleet is identified and traced for as long as that wheel is in service. This allows a user to track data on a single wheel as far back in time as data is retained.

Image Acquisition and Processing

At least two images are taken of every wheel, one from tread side and the other from the flange. The flange side image is used to determine the flange position, and to measure a complete end-to-end profile of the wheel. This section of the profile is used to measure rim thickness and determine tracking position.

 

The tread side image is used to measure the remaining part of the profile and also determines the wheel diameter.    

After both images are processed in sub-pixel accuracy, the tread and flange parts of the profile are reconstructed to generate a complete end-to-end profile of the wheel (shown below). Additionally, both cameras view the tread part of the wheel. The redundant measurement of   this       

critical part of the profile is used to improve the measurement accuracy of the profile.

Typical images from both cameras are shown above.

 

Parameter Measurement:

Measured parameter are defined as shown in the figure as follows:

1- Flghgt is the Flange Height and is measured as the difference in height of point C (Tape line) and point F (flange top point)

2- Flgthk is width (thickness) of the flange, and is measured as the horizontal distance between point D and line AB.

3- Flgslp is slope of the flange, and is measured as the horizontal distance between E and D.

4- Trdhw is the tread hollow along wheel tread, measured as the difference of the maximum and minimum of the tread surface height.

5- Trdthk (Rt)is rim (tread) thickness that is the difference in height of point C (Tape line) and point A (End of rim pint).

6- Dm (wheel diameter) is measured as the wheel diameter at tapeline, point C.