Active wheel speed control to avoid lifting the swingarms in rocker-bogie suspension

Rocker-bogie is kind of suspension system where wheels from each side of the vehicle are connected with swingarm on the rotary axle. Both levers are connected with a differential mechanism. If the vehicle has not had turnable wheels and turns only using the velocity or heading difference of each side or the object, then increased traction on the most loaded wheels causes lifting of the swingarms in opposing directions. This situation is undesirable because it leads to the high inclination of the vehicle's body and threatens to fall over. This article shows the way of active adjusting each wheel's speed to avoid swingarms lifting. Presented algorithm increases or decreases the angular velocity of selected wheels depending on the robot's rotation speed, acceleration, and traction. Parameters are calculated from the velocity of swingarm lift angle changes compared to the vehicle's relative rotation speed. Theoretical description presents the geometry of vehicle suspension, used sensors, and wheels speed control circuitry. The algorithm is implemented on an existing vehicle, and experimental part contains a comparison of behavior with and without active control on different surfaces.