Ackermann Drive
VolksBots usually are differential wheeled robots; they change direction of movement by varying rotation speed of their left and right driving units. An alternative is to implement an Ackermann steering unit (A-steering unit) which was invented in 1816 by Rudolph Ackermann.
A-steering is based on different steering angles for left and right wheels of a steering axis. In automotive implementations this is realized by dedicated mechanics shown by the picture on the right side. The steering angle (also called Ackermann Angle) for each wheel depends on dimensions of the vehicle (wheelbase, track-width, wheel distance to steering centre).
In VolksBot we did not apply a mechanical A-steering unit, we used distinct steering drives for left and right steering wheels instead. The calculation of Ackermann angles is done in software by taking robot dimensions as input parameters. This enhances flexibility in robot dimensioning and additionally supports higher steering angles.
In order to achieve reasonable driving behavior with great steering angles, we placed the robot driving units also on the steering wheels.
Our solution on the base of Volksbotelements consists of:
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