Speed consensus control for a parallel six-wheel-legged robot on uneven terrain

Wheel-legged robots suffer from the disturbances arising from the inconsistent of the wheel's speed and the external environments while driving over the uneven terrain, which may impair the smoothness of driving, or even fail in moving over the terrain. In this study, a speed consensus control (SCC) method that combines the distributed consensus algorithm (DCA) with the linear active disturbance rejection control (LADRC) is proposed to enhance the smoothness of the wheel-legged robot while traversing the uneven terrain. Firstly, the DCA is employed to reach a consensus amongst the speeds of the robot's body and each wheel which are regarded as a multi-agent system. Furthermore, the LADRC is applied to attenuate the disturbances arising from the model uncertainty and the unknown environments and to precisely track each wheel's desired speed obtained by the DCA. Finally, a series of simulations and experiments are conducted on a parallel six-wheel-legged robot (i.e., BIT-NAZAII) to validate the proposed method.