Underactuation Design for Tendon-driven Hands via Optimization of Mechanically Realizable Manifolds in Posture and Torque Spaces

A Tendon-Driven Robot Gripper With Passively Switchable Underactuated Surface and its Physics Simulation Based Parameter Optimization

“…Similarly to [17], they sampled multiple joint configurations, but the contact points were also optimized by adjusting the link thickness. In the work by Chen et al [19], the optimization problem was to shape the Mechanically Realizable Manifold to the desired synergy. They used multi-staged dual-layer optimization, which employs QP to solve the inner layer and CMA-ES [21] for the outer layer.…”

“…For the extension, we did not set the spring properties as optimized variables but fixed them as a constant with 0.1 Nm/rad stiffness and π/6 pretension. In [19], the pulley radii were optimized for the post-contact torque and the extension springs were optimized in the second layer for the pre-contact motion. In our case, the pre-contact motion is regulated by the parallel link stopper mechanism therefore the extension spring properties and the flexion pulley radii are redundant.…”

“…One major limitation of the proposed optimization framework is the computation time: the 72 hours of computation time is around two orders larger than the 45 minutes in [19]. Its proportion in the total design period, though, is small compared with other hardware-related processes.…”

“…Given the basic structure of a hand, deciding the design parameters such as the geometric property of the links and the actuation parameters of the joints is also a challenging problem. While there are a variety of successful works on the optimization of underactuated grippers [16], [17], [18], [19], most works consider the static equilibrium of the grasp wrench. The exception is the work by Chen et al [19],…”

“…While there are a variety of successful works on the optimization of underactuated grippers [16], [17], [18], [19], most works consider the static equilibrium of the grasp wrench. The exception is the work by Chen et al [19],…”