| The study of service robots in indoor environment has always been a hot issue in robot fields.As an important part of the service robot,mobile underpan can determine the ideal movement function,and can also affect the control performance.Good mechanical structure design is beneficial to realize the various motion law,and it can also improve the ability to adapt to the environment.Therefore,it is of great theoretical significance and application value to investigate the design theory and analysis of the locomotion mechanism.The main contents in this paper are as follows:(1)The selection of movement mechanism of underpan is proposed.The driving force under typical conditions is calculated.Based on the static stability,moving stability,driving force to cross obstacle and turn,a multi-objective optimization model for wheel layout is established and the optimal solution is derived by Genetic Algorithm.The driving motor is selected.(2)The characteristics of the existing mobile underpants and the vehicle independent suspensions are summarized,respectively.Aiming at design requirements of the mobile underpan,independent transverse-arm suspension and trailing-arm suspension are put forward.The basic structures and the crossing obstacle principle are introduced.The calculation method of spring stiffness in the suspension is put forward.The spring design of transverse-arm suspension is finished.And spring shock absorber of the trailing-arm suspension is determined.(3)The mapping relationship of the mobile underpan in the global and local coordinate systems is analyzed.The forward and inverse kinematics models of the two-wheeled differential mobile mechanism are established.The kinematic constraint of mobile underpan is analyzed.The forward dynamic model of mobile underpan is derived by Lagrangian equation,and the inverse dynamic model based on drive wheel angular velocity is obtained according to forward kinematics and dynamic model.(4)Based on ADAMS virtual prototyping technology,the simulation analysis on acceleration and turn movement of mobile underpan are analyzed,which validates the correctness of the kinematic model and the dynamics model.Assuming the factors of centroid angle,ground contact force and drive torque as evaluation indicators,the motion simulation on mobile underpan with two types of suspension and optimization are carried out.The results show that the mobile underpan with transverse-arm suspension is better than that with trailing-arm suspension.(5)Taking the mobile underpan with transverse-arm suspension as the prototype design,the process and assembly of the prototype are finished. |
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