Adaptive-Interaction-Based Online Reconfiguration of Cable-Driven Parallel Robots

With continuously increasing requirements for physical human-robot interaction (pHRI), cable-driven parallel robots (CDPRs) have emerged as outstanding systems for its implementation due to the sufficient motion workspace and inherent cable flexibility. In particular, their modular structure facilitates straightforward reconfiguration. Inspired by this, this paper aims to enhance the dynamic characteristics of CDPRs during pHRI through online reconfiguration, so as to achieve the interaction performance improvement based on human intent. A novel metric, the mixed interaction wrench margin (MIWM), is first proposed to determine the optimal reconfiguration. This metric is devised by integrating the interaction force characteristics with CDPR inherent workspace properties, while explicitly considering the leading role of human intent. Subsequently, an adaptive-interaction-based reconfiguration strategy is established that the configuration can be arbitrarily changed by cable anchors, enabling compliant and adaptive pHRI. Informed by the actual interaction frequency, the strategy implements an asynchronous adjustment with different periods for configuration change and platform movement to achieve online optimization for reconfiguration. Finally, simulations and experiments conducted on different CDPR configurations with multiple pHRI tasks indicate that this strategy provides humans with more freedom, allowing them to exert more casual interaction forces, receive a quicker interactive response, and operate in a larger workspace.