Topology Optimization for a Rigid-Compliant Hybrid Constant Force Gripper

Abstract

Grippers are essential components in robotic systems, particularly for tasks involving object grasping and manipulation. A constant force gripper provides the advantage of generating a nearly constant output force over a range of input loads without relying on sensors or control, which significantly reduces cost and system complexity. In this article, a topology optimization model is proposed for the design of a constant force gripper, which can simultaneously optimize both rigid links and material distribution. The combination of rigid links and deformable material is expected to reduce the low preload stroke, enabling the gripper to reach the constant force stroke rapidly and thereby improving operational efficiency. To develop the topology optimization model, rigid links and material distribution are represented by state and density variables, respectively, with the constant force behavior as the objective function. To implement a numerically efficient gradient-based algorithm, the sensitivity of the objective function with respect to the densities of all elements and the states of all links is derived. The experimental result shows the preload stroke of the gripper is 2.2 mm, and the constant force stroke reaches 6.4 mm. The preload stroke of the gripper is reduced by 85.33% compared with the fully compliant constant force gripper.