Safe Expeditious Whole-Body Control of Mobile Manipulators for Collision Avoidance

Abstract: In the control task of mobile manipulators (MMs), achieving efficient and agile obstacle avoidance in dynamic environments is challenging. In this letter, we present a safe expeditious whole-body (SEWB) control for MMs that ensures both external and internal collision-free. Firstly, control barrier functions (CBFs) are employed for an MM to establish initial safety constraints. Moreover, to resolve the pseudo-equilibrium problem of CBFs and improve avoidance agility, we propose a novel approach called adaptive cyclic inequality (ACI). ACI comprehensively considers obstacles, nominal control to generate directional constraints for MM. Then, we combine CBF and ACI to decompose safety constraints. Considering all these constraints, we formulate a quadratic programming (QP) as our primary optimization. In the QP cost function, we account for the motion accuracy differences between the base and manipulator, as well as obstacle influences, to achieve simultaneous whole-body motion. We validate the effectiveness of our SEWB control in avoiding collision and reaching target points through simulations and real-world experiments, particularly in challenging scenarios that involve fast-moving obstacles. SEWB has been proven to achieve whole-body collision-free and improve avoidance agility.