| With the expansion of human activities and increasing complexity of the future combat environments,researchers have paid more and more attention to smart composite ground mobile robot.Faced with a complex work environment,the drawbacks of traditional single-drive mode ground mobile robots are obvious.To meet the practice requirements,a variety of multi-drive hybrid mobile robots have been developed in recent years.This paper develops a new type of wheel-tracked mobile robot for the uses of battlefield reconnaissance and postwar cleanup in the future combat environment.Firstly,mechanical property is an important indicator to evaluate the performance of ground mobile robot.Therefore,semi-physical simulation tests are carried on based on the first generation of physical prototype.ADAMS is used to establish the seven-degree-of-freedom vehicle dynamics model of the mobile robot.A time-domain activation model of C-level random road surface is derived based on the filtering white noise method of stationary Gaussian random process.Considering the coherence function of the left and right wheel’s inputs and the time lag between the front and rear wheel’s inputs,the random road surface is modeled as a time domain model in SIMULINK,and regarded as the activation function of the kinetic model in ADAMS.The ride comfort of the mobile robot is analyzed by means of joint simulation in ADAMS & MATLAB.Dynamic differential equations of the mobile robot in wheeled model and crawler-type are yielded respectively,and transformed into forms of state space equations according to D’Alembert’s principles.In addition,the dynamic model of the mobile robot in crawler-type is established in SIMULINK and vibratility is discussed further because of the hysteresis characteristics of the inputs between crawler wheels.Secondly,unlike conventional mobile robot,the mobile robot proposed in the paper is featured with both wheels and crawler.To flexibly switch its drive mechanism,a good performance of the switching mechanism is important to ensure its efficiency and stability.In order to analyze and check the mechanical characteristics of the switching mechanism in different working conditions,simulation results are used as the inputs of the switching mechanism in simulation tests.Finally,based on SIMULINK dynamics model and MATLAB co-simulation,Genetic Algorithm is utilized to optimize a multi-objective parameters function of the robot’s suspension system.The result shows that,the ride comfort of the mobile robot can be improved to a certain degree after optimizing its parameters.Especially,after a slight decrease in the dynamic load of the tires,the effects of optimization are obvious,specifically,the comprehensive acceleration parameter is decreased by 17.19% and the suspension dynamic deflection parameter is decreased by 4.34%.The conclusions are of great significance to the theoretical research and optimization of composite mobile robot. |
