Optimal control simulations of two-finger grasps

• Published in: Mechanism and machine theory Vol. 167; p. 104508
• Main Authors: Phutane, Uday, Roller, Michael, Leyendecker, Sigrid
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.01.2022
• Subjects: Contact mechanics; Grasping; Hybrid sequential program; Optimal control; Structure preserving integrator; Hybrid sequential program; Optimal control; Grasping; Contact mechanics; Structure preserving integrator
• ISSN: 0094-114X
• DOI: 10.1016/j.mechmachtheory.2021.104508

Grasping is a complex human activity performed with readiness through a complicated mechanical system as an end effector, i.e. the human hand. Here, we apply a direct transcription method of discrete mechanics and optimal control with constraints (DMOCC) to reproduce human-level grasping of an object with a three-dimensional model of the hand, actuated through joint control torques. The equations of motions describing the hand dynamics are derived from a discrete variational principle based on a discrete action functional, which gives the time integrator structure-preserving properties. The grasping action is achieved through a series of constraints, which generate a hybrid dynamical system with a given switching sequence and unknown switching times. To determine a favourable trajectory for grasping action, we solve an optimal control problem (OCP) with different physiological objectives subject to discrete Euler–Lagrange equations, boundary conditions and path constraints. •Hybrid dynamical system is presented to execute grasping optimal control simulations.•Modular setup to perform simulations for different grasps.•Comparison of grasp behaviour across a variety of objectives.•Simplified expressions for grasp matrix and hand Jacobian have been derived.