Stewart-Platform Six-DoF Haptic Joystick with Force-Feedback via Cartesian Wrench Compensation

This paper presents the development of a novel six-degree-of-freedom (DoF) force-feedback (FF) joystick, which is designed for controlling large mobile manipulators. We first present the joystick design based on a compact Stewart-platform mechanism to generate motion in all translational and rotational DoF. A computationally efficient closed-form inverse-kinematics formulation is derived, and the necessary forward-kinematics solution is presented. The forward-kinematics solver is implemented on an Arduino-class microcontroller, demonstrating that the approach is suitable for embedded real-time operation. In addition, FF is provided in each DoF to support the operator during manipulation. With our novel compensation scheme, the nonlinearities of the parallel mechanism are addressed to achieve a linear force-displacement characteristic, improving operator comfort. Finally, the proposed joystick is integrated into a human-in-the-loop simulator, and a control mapping is implemented exemplarily. Initial tests demonstrate the approach is feasible and suggest broad utility for future applications.