Research Projects

Pneumatically actuated soft grippers are used in various applications, such as fruit-picking, vegetable-picking, and egg-picking/placing. These grippers have varying end-effectors based on the shape and size of the objects to be picked and placed. Most existing grippers are designed using heuristic methods or hand-designed, which depend on the designers' experience and expertise. To design grippers for real-world applications, a systematic approach is needed. This proposal aims to provide a topology optimization approach to design such grippers. Topology optimization (TO) is a computational design tool that determines the optimum material layout of a design problem by extremizing an objective subjected to given constraints. The design domain is generally parameterized using finite elements, each assigned a design variable $\rho \in [0,\,1]$ and typically has two phases (solid/void). Pneumatic loads are design-dependent, posing unique challenges such as identifying the boundary to apply the pneumatic load, converting the fluidic pressure field into consistent nodal loads, and effectively evaluating load sensitivities. These challenges become more pronounced when designing soft robots with pneumatic loads. Soft grippers experience finite deformation when gripping some objects and come into contact modes with objects. In a typical TO setting, elements/regions with low stiffness are prone to significant deformation/excessive distortion or inversion, stalling topology optimization progress due to numerical instabilities arising from localized large deformations. This proposal aims to include large deformation mechanisms within the TO setting for designing pneumatic-actuated gripper mechanisms while considering the loads' design-dependent nature.