Parallel Force Feedback Device Design with Constant Jacobian Matrix and Net Weight Fully Balanced

Abstract Haptic devices offer realistic and intuitive feedback to operators, and achieving higher accuracy and transparency has been a prominent research focus in this field. However, it is inevitable to encounter errors in real-time force or position calculations, which can have adverse effects on the accuracy of the equipment. This paper presents the design of a parallel mechanism that incorporates a constant force and position mapping relationship based on the type synthesis of the constant Jacobian matrix. Specifically, the mechanism maintains a fixed direction of force applied to the operating platform by the drive pair, which is mounted on the fixed platform in each limb, irrespective of position changes. This unique feature enables the mechanism to achieve complete net weight balance. The implementation method is detailed in this article, which involves adding appropriate counterweights to achieve balance between the weight of the connecting rod and the overall gravity of the operating platform. Furthermore, the optimization of structural parameters helps to improve the performance of the developed prototype. The proposed design scheme not only addresses the fundamental reduction of errors caused by real-time force and position mapping solving but also enhances operational transparency. Finally, simulation and experimental tests are conducted to validate the proposed theory.