Characteristic Research And Simulation Analysis Of A Three-Link Bionic Kangaroo Leg Suspension

The vehicle suspension system can effectively buffer or isolate the vibration and impact of uneven pavements,and plays an important role in improving the vehicle's ride comfort and drive safety.With the rapid development of the automotive industry,traditional suspension systems cannot meet people's needs for high-performance suspensions due to functional and cost constraints.Therefore,the development of new suspension structures has become an urgent issue.It is found that the kangaroo's rapid response,stable and low energy consumption characteristics in motion are highly consistent with the performance requirements of high-performance suspensions.Therefore,from the perspective of bionics,the structure and function of kangaroo leg are analyzed and extracted,and constructed a three-link bionic kangaroo leg suspension with equal bone proportion.The performance of the suspension and the comfort of the vehicle are studied by the theoretical modeling and simulation methods.The main study contents of this paper are as follows:1)The deficiencies and constraints of the traditional suspension systems development are summarized and analyzed through consulting relevant literatures,and it is found that the existed suspensions and design methods are difficult to meet the demand for high-performance suspensions.In order to solve this problem,based on the movement characteristics of kangaroo legs,a bionic design solution for suspension has been proposed and a three-link bionic kangaroo leg suspension with equal bone proportion has been design.2)The dynamic model of the three-link bionic kangaroo leg suspension is established by the Lagrange's Equations Method.It is found that the model parameters have strong coupling and nonlinear,and it is difficult to solve them by analytical methods.Therefore,the characteristics of the three-link bionic kangaroo leg suspension are studied and analyzed by numerical simulation method.3)The kinematic model of the three-link bionic kangaroo leg suspension is derived by D-H method and matrix multiplicative inverses method,the positions and postures of the suspension in the static balance,stretch limit and compression limit are solved by combining the forward and the inverse kinematic equations,the movement characteristics of the kangaroo leg and so on.4)According to the vehicle suspension design method,combined with the structure and motion characteristics of the kangaroo leg,the system parameters(such as the stiffness,damping,sprung mass and so on)of the three-link bionic kangaroo leg suspension are determined,and the simulation model is established in ADAMS.5)In MATLAB,impact and random pavements(class A,B,C and D)at speeds of 30km/h,40km/h,50km/h,60km/h,70km/h,90km/h and 120km/h have been generated and input into the ADAMS model of the three-link bionic kangaroo leg suspension,the performance research and vehicle comfort analysis are performed.It is found that,(1)the performance parameters of the suspension such as body vertical acceleration,tire dynamic displacement,suspension deflection and body height are all within a reasonable range,indicating that the rationality structural design and parameters selection;(2)the RMS values of the body vertical acceleration and its transmissibility are distributed in the value range of 0.08?1.42m/s~2 and 1?2.8%,showing that the suspension can effectively buffer and isolate the impact from the pavement surface and express good ride comfort;(3)the RMS transmissibility values of body vertical acceleration and tire dynamic displacement distribute centrally and change steadily under the pavement condition of medium-high speed,indicating that the suspension is stable and has good performance under the pavement condition of medium-high speed;(4)the influence of road level on ride comfort is greater than that of vehicle speed;(5)the weighted acceleration RMS values are within the comfort range as a whole.However,the comfort on the class D pavement at a speed of 60km/h is poor,indicating that the suspension has well vehicle comfort in most road conditions,but there is still room for further optimization;(6)the suspension's damping effect on convex impact pavement can reach 66%,showing that the suspension has good impact resistance.6)The frequency response of the three-link bionic kangaroo leg suspension is studied by means of Swept Frequency Method.The results show that the first resonance frequency of the three-link bionic kangaroo leg suspension is about1.1Hz,which avoids the sensitive frequency range of human body.7)Based on the polynomial fitting principle,the data obtained from the Lagrangian dynamic model and the simulation model is fitted and compared.The results show that the theoretical data and simulation data have good consistency.In summary,the proposed three-link bionic kangaroo leg suspension can effectively buffer and isolate the vibration and impact of the pavement,the suspension system shows good performance and ride comfort,which also verify the rationality and effectiveness of the three-link bionic kangaroo leg suspension design.