Load-Based Variable Transmission Mechanism for Robotic Applications

TL;DR

This paper introduces a passive load-based variable transmission mechanism for robots that automatically adjusts torque transmission using a spring and linkage, improving efficiency and adaptability without extra actuators.

Contribution

The novel LBVT mechanism passively adapts transmission ratio based on load, reducing complexity and enhancing robotic actuation efficiency.

Findings

Achieves up to 40% increase in transmission ratio at torque thresholds.

Demonstrates autonomous torque amplification when force exceeds 18 N.

Reduces system complexity by eliminating additional actuators.

Abstract

This paper presents a Load-Based Variable Transmission (LBVT) mechanism designed to enhance robotic actuation by dynamically adjusting the transmission ratio in response to external torque demands. Unlike existing variable transmission systems that require additional actuators for active control, the proposed LBVT mechanism leverages a pre-tensioned spring and a four-bar linkage to passively modify the transmission ratio, thereby reducing the complexity of robot joint actuation systems. The effectiveness of the LBVT mechanism is evaluated through simulation-based analyses. The results confirm that the system achieves up to a 40 percent increase in transmission ratio upon reaching a predefined torque threshold, effectively amplifying joint torque when required without additional actuation. Furthermore, the simulations demonstrate a torque amplification effect triggered when the applied force exceeds 18 N, highlighting the system ability to autonomously respond to varying load conditions. This research contributes to the development of lightweight, efficient, and adaptive transmission systems for robotic applications, particularly in legged robots where dynamic torque adaptation is critical.