How to reduce the impedance for pHRI: Admittance control or underactuation?

Many applications of physical human–robot interaction (pHRI) seek to minimize the impedance felt by the operator. For large-scale operations, such as industrial material handling, two architectures have been proposed. The first uses a rigid robotic manipulator with force sensing and an admittance controller, such as the class of Intelligent Assist Devices (IADs). The second utilizes an underactuated macro-mini manipulator system, such as the uMan Assist Device. Given an application with a large payload, which of these two systems can offer the lowest inertia interaction? This work analyzes the effective inertia experienced by the operator in each of the systems. It compares the conditions under which each provides the lightest manipulation, conditions that depend on the payload as well as the frequency of manipulation. The results are validated on a large overhead robotic system configured alternatively in each of the configurations. [ABSTRACT FROM AUTHOR]