Performance Analysis And Optimization Of Quadruped Bionic Horse Rehabilitation Robot Driven By Cam Linkage Mechanism

Bionic rehabilitation robots are a hot spot in robotic bionic research today,and the development of a bionic equine quadruped robot is of great significance for the popularization of equine therapy.In this paper,based on the combination of emerging equine therapy,bionics and mechanics,a quadrupedal bionic horse rehabilitation robot driven by an equal-width double-arc cam linkage mechanism is proposed,which is important for realizing equine therapy application and promotion.The paper firstly introduces the configuration of the quadrupedal bionic horse robot and establishes the kinematic model using the loop vector method for kinematic analysis.As the driven equal-width double-arc cam,its abrupt change in radius of curvature has an important impact on the performance of the mechanism.In order to optimize the influence produced by the sudden change of the radius of curvature of the equal-width double-arc cam,a direct-acting flat-bottom equal-width double-arc cam mechanism model is selected as the research object.A Bezier curve-based variable speed drive law for the cam mechanism is proposed,and a variable speed drive is adopted to significantly improve the performance of the cam mechanism.The results show that the motion characteristic value(AV)max is reduced by 11.63% on average,and the sharp jump is reduced by 15.36% on average.This method provides a new idea for improving the motion performance of similar cam mechanisms.To address the complex problem of parameter relationships affecting the foot-end trajectory of the quadrupedal bionic horse robot,this paper uses a sensitivity analysis method to analyze the effects of changes in each structural parameter on the foot-end trajectory,so as to obtain the key structural parameters with high sensitivity to the robot performance,and obtain 8 main parameters out of 36 parameters for the subsequent optimization of the foot-end trajectory.A multi-objective optimization model with the foot-end trajectory performance index as the main objective was established.Constraints such as structural constraints,motion feasible domain conditions,and pressure angle requirements are considered.The support phase trajectory based on the composite cycloid form is adopted as the optimization objective.The more ideal mechanism parameters are obtained by the intelligent optimization-seeking method.In the study,the trajectory of the foot end of the bionic horse was improved by optimization to make its body movement more in line with the needs of actual rehabilitation.In the study,the three-dimensional model of the single-legged system of the four-legged bionic horse was established,and ADAMS simulation was performed to compare and analyze with the theoretical calculation results;and the overall model of the four-legged bionic horse was established to verify the trajectory of the bionic horse body mass movement.The prototype model of the single-legged walking system was tested and the foot-end trajectories were compared with the design results and the simulation results.It is verified that the bionic horse model and the optimization design process are correct.In this paper,the structural parameters of the complex cam-link combination mechanism are optimized with the foot-end trajectory of the four-legged square bionic horse robot as the optimization target,and the related ideas provide a reference for the solution of similar problems.