A differentiable dynamic modeling approach to integrated motion planning and actuator physical design for mobile manipulators

Abstract

This paper investigates the differentiable dynamic modeling of mobile manipulators to facilitate efficient motion planning and physical design of actuators, where the actuator design is parameterized by physically meaningful motor geometry parameters. The proposed differentiable modeling comprises two major components. First, the dynamic model of the mobile manipulator is derived, which differs from the state-of-the-art in two aspects: (1) the model parameters, including magnetic flux, link mass, inertia, and center-of-mass, are represented as analytical functions of actuator design parameters; (2) the dynamic coupling between the base and the manipulator is captured. Second, the state and control constraints, such as maximum angular velocity and torque capacity, are established as analytical functions of actuator design parameters. This paper further showcases two typical use cases of the proposed differentiable modeling work: integrated locomotion and manipulation planning; simultaneous actuator design and motion planning. Numerical experiments demonstrate the effectiveness of differentiable modeling. That is, for motion planning, it can effectively reduce computation time as well as result in shorter task completion time and lower energy consumption, compared with an established sequential motion planning approach. Furthermore, actuator design and motion planning can be jointly optimized toward higher performance.