Proxy-based Guidance Virtual Fixtures with Orientation Constraints

In applications of physical human-robot interaction, robots pose a potential risk to human safety. A virtual fixture is used to ensure the safety of human operators by restricting the robot's behavior, which assists operators in moving the robot along a desired path. In this paper, we propose a novel and practical guidance virtual fixture based on a virtual proxy. By designing the dynamics of the proxy and connecting it to the robot using a viscoelastic linkage model, the robot's end-effector position can be constrained within pipeline and conical geometries. In addition, the end-effector orientation of the robot can also be constrained within a specific range to comply with ergonomics. The conducted experiment validated the effectiveness and convenience of the proposed control scheme in path tracking tasks by evaluating it involving several subjects and a Franka Emika Panda robot.