Speedometer Calibration

Speedometers are commonly divided into mechanical or electronic types. A cable enclosing a rotating, flexible shaft is fixed to mechanical speedometers to furnish the input signal. The rotating shaft is coupled with a permanent magnet in the speedometer. It turns at a speed relative to that of the vehicle. Electromagnetic forces deliver the torque to ricochet the needle.

At the time of calibration, the magnetization of the fixed magnet in the meter is altered until the exact deflection is acquired. An automated speedometer calibration technique includes a calibrated supplier to produce input signals for the speedometer. It also incorporates a sensing method to exactly establish the deflection of the needle, and entails a control scheme to modify the limits that manage the torque and sets off the needle to deflect.

The most complicated factor is the sensing system that reads needle deflection. The most commonly applied sensing method for this use is a camera, an image acquisition board, and image processing software that explores the image for the needle.

The system offers an output in respect to the angle of deflection from the commencement point, or immediately as speed in miles per hour (mph) or kilometers per hour (kmph). The speedometers vary in form, kinds of graduations, needle patterns, dial background designs, and nonlinear dial graduations. As a sequel to this, mapping between the deflection angle and the equivalent speed is not linear.

The mechanical speedometers pulsate in the fixture when exposed to major electromagnetic forces at the time of calibration. Hence, there was a major necessity to produce image-processing software that endured rotations and offsets in the meter image because of the effective movements between the meter and the camera.

In several of the assembly areas, companies often resort to minor batch work where diverse speedometer versions are created in the same day. This implies that the time to alter the system from one type of meter setup to another must be small.