Internally-Balanced Displacement-Force Converter for Stepless Control of Spring Deformation Compensated by Cam With Variable Pressure Angle
Tori Shimizu, Kenjiro Tadakuma, Masahiro Watanabe, Eri Takane, Masashi Konyo, Satoshi Tadokoro
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.
BibTeX
@inproceedings{ral2021_internallybalanc,
title = {Internally-Balanced Displacement-Force Converter for Stepless Control of Spring Deformation Compensated by Cam With Variable Pressure Angle},
author = {Tori Shimizu and Kenjiro Tadakuma and Masahiro Watanabe and Eri Takane and Masashi Konyo and Satoshi Tadokoro},
booktitle = {RA-L 2021},
year = {2021}
}