Path Following Controller for Differentially Driven Planar Robots with Limited Torques and Uncertain and Changing Dynamics

Abstract

This paper presents a path following controller that is suitable for asymmetrical planar robots with significant mass and limited motor torques. The controller is resistant against environmental forces, and inaccurate estimates of robot's inertia, by estimating their effects with Unscented Kalman Filter. The controller outputs wheel torque commands which take in account the motor torque limits and given relative priority of internal control elements. The method presented is thoroughly explained and the simulation results demonstrate the performance of the controller.

Obstacle Avoidance with Kinetic Energy Buffer

“…If that is not the case, the equations (1-5) need to be modified. Examples how to calculate wheel forces for robots with an asymmetrical mass distribution are found for example in [9].…”

“…The acceleration twist could be realized with some torque control method like [9], but motor controllers often accept only velocity values. In such a case, the new desired wheel velocities can be calculated with 𝜔 𝑤1,𝑡+1 = 𝜔 𝑤1,𝑡 + 𝛥𝑡(𝑎 𝑐 − 𝑦 𝑤1 𝛷 𝑐 )/𝑅 𝑤1 , 𝜔 𝑤2,𝑡+1 = 𝜔 𝑤2,𝑡 + 𝛥𝑡(𝑎 𝑐 − 𝑦 𝑤2 𝛷 𝑐 )/𝑅 𝑤2 , where 𝜔 𝑤𝑛,𝑡 is the current rotational velocity of wheel n and 𝛥𝑡 is the control cycle length.…”