A Minimum-Energy Control Approach for Redundant Mobile Manipulators in Physical Human-Robot Interaction Applications

Abstract

Research on mobile manipulation systems that physically interact with humans has expanded rapidly in recent years, opening the way to tasks which could not be performed using fixed-base manipulators. Within this context, developing suitable control methodologies is essential since mobile manipulators introduce additional degrees of freedom, making the design of control approaches more challenging and more prone to performance optimization. This paper proposes a control approach for a mobile manipulator, composed of a mobile base equipped with a robotic arm mounted on the top, with the objective of minimizing the overall kinetic energy stored in the whole-body mobile manipulator in physical human-robot interaction applications. The approach is experimentally tested with reference to a peg-in-hole task, and the results demonstrate that the proposed approach reduces the overall kinetic energy stored in the whole-body robotic system and improves the system performance compared with the benchmark method.

Figures (7)

• Figure 1: (a) Considered mobile manipulator and (b) an example of Human/Mobile Manipulator cooperative task.
• Figure 2: Architecture for physical interaction between a human operator and a mobile manipulator through a virtual admittance model.
• Figure 3: Power-Oriented Graph (POG) representation of the virtual admittance model, showing the energetic port of the interaction between the human operator and the admittance model to generate the desired end-effector twist $\boldsymbol{v}_d$.
• Figure 4: Experimental test scenario, consisting in performing a peg-in-hole task with respect to the holes encircled in red.
• Figure 5: Results in terms of average energy $\bar{E}$, average human force $\bar{F}_h$, average execution velocity $\bar{v}$, final displacement $x_f$ and execution time $T_f$ for the executions of each of the 27 users using the three control approaches.