Harnessing Elastic Energy to Transfer Reciprocating Actuation into Rotary Motion

TL;DR

This paper introduces a method to convert reciprocating actuation into rotary motion by using elastic energy in linkages, overcoming torque transmission issues near kinematic singularities, with potential applications in small-scale engines and robotics.

Contribution

The paper presents a theoretical model and experimental validation for using elastic energy to improve force transmission in four-bar mechanisms near singularities.

Findings

Model accurately predicts force transmission behavior.

Prototype demonstrates effective reciprocating to rotary conversion.

Approach enables design of singularity-robust rotary devices.

Abstract

The ability to convert reciprocating, i.e., alternating, actuation into rotary motion using linkages is hindered fundamentally by their poor torque transmission capability around kinematic singularity configurations. Here, we harness the elastic potential energy of a linear spring attached to the coupler link of four-bar mechanisms to manipulate force transmission around the kinematic singularities. We developed a theoretical model to explore the parameter space for proper force transmission in slider-crank and rocker-crank four-bar kinematics. Finally, we verified the proposed model and methodology by building and testing a macro-scale prototype of a slider-crank mechanism. We expect this approach to enable the development of small-scale rotary engines and robotic devices with closed kinematic chains dealing with serial kinematic singularities, such as linkages and parallel manipulators.