This paper presents the design, development, modeling and control of a biomimetic multi degree of freedom compliant locomotive mechanism that can follow a prescribed trajectory. Locomotive motion in nature is achieved by the peristaltic movement of body segments of crawling animals or the legged motion by completing a gait cycle. Compliant mechanisms transfer the input displacement, force or torque from one point to another point through the large deformation of its flexible links or hinges as same approach is implemented in nature. Since compliant mechanisms can be designed as a single piece, it reduces the number of parts required to build the system, reduces the friction, increases performance and accuracy. A compliant mechanism incorporates either a flexible link or flexure hinge to achieve desired output motion. Flexure hinges replaces the revolute joints and provides more degrees of freedom compared to conventionally designed rigid body mechanisms. If the flexural pivot is so small compared to the connected rigid body segments, then the flexure is assumed to be small length flexure.  The research objective of this study is the design of a high mobility and flexible planar locomotive mechanism incorporating large deflecting compliant hinges. The actuation is realized using both servo motors and contactless electromagnetic forces. Mechanism is consisted of five sliding carts, rail, 3D-printed supplementary pieces to house motors and pins. Carts are connected by monolithically designed two arm links joined by a large deflecting flexure. Four servo motors are mounted on the both ends of the mechanism. Since sliding carts are identical, forward motion is achieved by changing the friction of carts through the connecting pins. Dynamical model is created in Matlab Simulink using D’Alembert’s principle, pseudo rigid body modeling (PRBM), vector closure-loop equations and kinematic constraints. To robustly control the position of the mechanism, first its nonlinear dynamics replaced with a family of linear time invariant  systems which have parameter uncertainty. Then a robust controller is designed based on the Quantitative Feedback Theory (QFT) for the desired robust tracking and stability bounds. QFT is one of the most powerful robust control techniques which can take into account both phase and magnitude information of the system and enables the designer to minimize the cost of feedback by clearly observing the design constraints through robust performance bounds. Finally, the performance of the designed controller is validated though nonlinear simulations using the nonlinear dynamics of the mechanism. It has been shown that the mechanism can consistently track the desired inputs both in frequency and time domains.   


Design of a Compliant Based Biomimetic Planar Locomotive Mechanism

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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