Internally-Balanced Displacement-Force Converter for Stepless Control of Spring Deformation Compensated by Cam with Variable Pressure Angle

Research output: Contribution to journalArticlepeer-review

Abstract

The force required to drive a mechanism can be compensated by adding an equivalent load in the opposite direction. By reversing the input and output of the load compensation, we proposed the concept of a displacement-force converter that enables the deformation of the elastic element to be controlled steplessly by a minimal external force. Its principle was proved in our previous study, but challenges arose owing to the use of a wire and pulley. Here, we introduce a new compensation method using a noncircular cam that generates a compensation torque due to the contact force from the follower, which is split in the tangential direction of the cam by the pressure angle varying at rotation. Using a prototype for proof of concept, the maximum control force required for the extension of the spring was successfully reduced by 23.2%. Furthermore, uniform forces were obtained between extension and compression so that the difference between them decreased from 543% to 49% relative to compression. Thus, actuators and current supplies requiring less power could be selected. Moreover, the prototype model was incorporated into a variable stiffness mechanism of a soft robotic gripper as a wire tensioner to show the expandability of the displacement-force converter.

Original languageEnglish
JournalIEEE Robotics and Automation Letters
DOIs
Publication statusAccepted/In press - 2021

Keywords

  • -Actuation and Joint Mechanisms
  • Force
  • Force Control
  • Mathematical model
  • Mechanism Design
  • Prototypes
  • Pulleys
  • Springs
  • Torque
  • Wires

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Biomedical Engineering
  • Human-Computer Interaction
  • Mechanical Engineering
  • Computer Vision and Pattern Recognition
  • Computer Science Applications
  • Control and Optimization
  • Artificial Intelligence

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