Design and Experimental Validation of Two Cam-Based Force Regulation Mechanisms

This paper presents the design and experimental validation of two force regulation mechanisms (FRMs) containing a translational cam and a rotational cam, respectively. With the friction-considered profile identification method (FCPIM) to define the cam and through the squeezing between the cam and the spring-supported slider, the FRMs can passively output the desired force over the designed displacement. Under the premise of that the friction coefficient can be accurately obtained, the friction-considered design principle will be significant for the realization of FRMs in actual applications since it is no longer necessary to achieve high accuracy by pursuing the frictionless condition. Hence, the conventional materials and mechanical parts can be directly used to assemble the FRMs without sacrificing the force regulating accuracy. We are highly interested in the actual experimental behavior of the proposed FRMs under the friction-considered condition. Then, prototypes of the two FRMs capable of outputting multiple types of forces including in zero-stiffness, positive and negative stiffness are specially designed, fabricated, and tested quasi-statically. The experimental results verify the correctness of FCPIM since they agree with the design objective well. Meanwhile, the effectiveness of the FCPIM is proved as the errors of the experimental results considering friction is much lower than those ignoring friction. The experiments also show that the noise phenomenon in the testing curves that may affect the judgment of test accuracy can be highly degraded by using more stable and controllable loading tools, which is helpful for future research.