Mechanism Analysis On Lower-mobility Parallel Mechanism For Energy-regenerative Suspension System

The energy-regenerative suspension(ERS)is a new type of the regenerative suspension system(RSS),which can be replaced the traditional shock absorber damper.The ERS not only can reduce the vibration of the vehicle body and also can be converted the suspension vibration energy into the electrical energy.It is an effective means of the vehicle energy saving and emission reduction.Aiming at resolving the low efficiency,and simplifying the structure and increasing the support rigidity of the traditional energy-regenerative suspension,a novel lower-mobility parallel mechanism energy-regenerative suspension(LPMERS)is designed.The LPMERS can be converted the vertical motion from the vehicle suspension into rotary motion.In view of the lower-mobility parallel mechanism(LPM),the degree of freedom(DOF)for the(LPM)is analyzed based on the screw theory.Then according to the branched chain constraints,the inverse and forward kinematics constraint equations are deduced using the position transformation formula and the descent Newton iteration method respectively.The mathematical model of the velocity and acceleration for the LPM is established,which is based on the first and the second order influence coefficient method separately.Lately,the evaluation index of the reachable workspace for the LMP is defined.Finally,the speed analyses for the links were also carried out by the spatial projection approach.And the general expressions of the three unit system rotation(TUS)period were obtained,and extending it to the general analytical expression of the moving base with the positive N shape.And then,discusses the feasibility numbers of the positive shape edge N?? and N?0.On the basis of the TUS,a possible variable structure motion(VSM)of the LPM is proposed.The analysis results indicate that the designs of this VSM mechanism not only consider the displacement coupling,but also we should consider the influence of the speed on the elastic deformation of the link.In order to obtain the constraint reaction and anti-torque of the LMP in a certain position,using the dismantle-splitting method to analyze the constraining force for the each part of the LMP,the static equilibrium equations(SEE)are set up.And a generalized coordinate system based on the SEE is founded.Then the Jacobian matrix of the mechanism is derived and the stiffness mapping matrix(SMM)between the operating force and the execution platform of the LMP is established respectively.The evaluation index is defined on the basis of the SMM and the correlation between the mechanism parameters and the evaluation index are discussed.Based on Lagrange methods,the dynamic equations of the parallel manipulator and the energy-regenerative suspension were established.The feasibility of the LMP was analyzed by the numerical examples and the simulation of the kinematics and dynamics were carried out by ADAMS software.The comparison results show that the LMP can transform the vertical vibration of the suspension into the rotary motion of the motor,and it is feasible and effective.Meanwhile,the dynamics also indicates that the LMP system has the advantages of the maximum stiffness,the quick response and the high conversion efficiency.Also,the research works of this paper have significance for the energy-regenerative suspension reference.