Robotic joints mimic human knees and grip 3× more weight efficiently

Engineers at Harvard have developed a novel method for designing robotic joints that closely mimic the human knee by using rolling contact joints—pairs of curved surfaces that roll and slide against each other, connected with flexible elements. This design approach optimizes the shape of each joint component based on the specific forces and tasks it must perform, enabling the joint to direct energy efficiently. As a result, robots can use smaller actuators and simpler control systems, improving overall efficiency. In tests, a knee-like joint designed with this method corrected misalignment by 99 percent compared to standard joints, and a two-finger robotic gripper using these optimized joints could hold over three times the weight of a conventional gripper for the same actuator input. The innovation stems from efforts to enhance soft robotic grippers, combining rigid links with flexible joints to emulate human limb mechanics. Unlike traditional rolling contact joints that use simple circular surfaces, the Harvard team’s method creates irregular shapes tailored to follow specific trajectories and force transmission ratios, allowing joints to