Impedance Modulation for Negotiating Control Authority in a Haptic Shared Control Paradigm

Communication and cooperation among team members can be enhanced significantly with physical interaction. Successful collaboration requires the integration of the individual partners' intentions into a shared action plan, which may involve a continuous negotiation of intentions and roles. This paper presents an adaptive haptic shared control framework wherein a human driver and an automation system are physically connected through a motorized steering wheel. By virtue of haptic feedback, the driver and automation system can monitor each other actions and can still intuitively express their control intentions. The objective of this paper is to develop a systematic model for an automation system that can vary its impedance such that the control authority can transit between the two agents intuitively and smoothly. To this end, we defined a cost function that not only ensures the safety of the collaborative task but also takes account of the assistive behavior of the automation system. We employed a predictive controller based on modified least square to modulate the automation system impedance such that the cost function is optimized. The results demonstrate the significance of the proposed approach for negotiating the control authority, specifically when humans and automation are in a non-cooperative mode. Furthermore, the performance of the adaptive haptic shared control is compared with the traditional fixed automation impedance haptic shared control paradigm.