Knee-Inspired Hinge Absorbs Longitudinal Impacts to Enhance Robot-Environment Interaction Safety
Lianxin Yang, Xinyan Li, Tianyu Zhao, Zhihua Zhao
AI summary
Problem
Rigid robotic joints transmit high longitudinal impact forces during collisions and locomotion, compromising safety. Replicating the natural longitudinal compliance of biological joints like the knee within traditional mechanical frameworks remains structurally complex and unstable.
Approach
The authors integrated a custom-shaped buffer mechanism with elastic elements into a standard mechanical hinge, transforming axial compression into amplified rotational deformation of springs and rubber bands to create tailorable impact-absorbing stiffness.
Key results
- Designed a conformal buffer structure that converts longitudinal compression into controlled sleeve rotation
- Achieved tailorable high-static-low-dynamic stiffness by combining preloaded torsion springs and rubber bands
- Demonstrated reduced transmitted acceleration to the robot body in drop tests
- Lowered ground reaction forces in a biped walking robot to improve interaction safety
Why it matters
Enables direct integration of impact-absorbing compliance into existing robotic systems, exoskeletons, and prostheses for safer human-environment interaction.
Abstract
As robots integrate into human society, ensuring safe robot-environment interaction, particularly in the event of col- lisions, has emerged as a growing design priority. A promising solution is introducing proper compliance into existing rigid robots, akin to musculoskeletal systems, to absorb impacts in various directions. However, mimicking longitudinal compliance seen in biological joints to absorb compressive impacts along limbs, such as the role of cartilages like menisci, remains a challenge shad- owed by the complexity of joint architecture. Here, exploring and adapting the elastic longitudinal movement structure of knee, we incorporated traditional mechanical hinges with a compact buffer structure to enable both simple rotational motion and effective longitudinal impact absorption. Under longitudinal loading, the buffer structure functions as a mechanism transmitting the limited compression to amplified deformations of elastic elements, thus producing resistance against load. The resistive load-displacement relationship is tailorable by tuning diverse elastic components, allowing for a high-static-low-dynamic stiffness to improve energy absorption efficiency. Drop tests and walking robot demonstrations confirm that the proposed knee-inspired hinge not only mitigates acceleration transmitted to the robot’s main body but also reduces ground reaction forces, thereby improving robot-environment in- teractionsafety.Thisworkhighlightsthedesignparadigmofadapt- ing natural solutions to mechanical systems, and holds potential for direct integration into diverse robots, exoskeletons, and prostheses.