Research On Bilateral Operation Of Hexapod Robot Based On Haptic Force Feedback

Hexapod robot compared to other types of mobile robots,it has a wider application prospect in the fields of disaster relief,engineering exploration,supplies transportation,and so on.This is mainly due to the stability of hexapod robot in its high load state and the motion ability to deal with the extreme environment.Therefore,it attracts the attention of many experts and scholars.At present,the key problem for the researchers is that the autonomous control algorithm developed for the hexapod robot can not be used in the complex and changeable real-world situation.On the other hand,if every degree of freedom of the hexapod robot are controlled completely by the operator,it will increase the work burden for the operator.In view of this,when the hexapod robot subject to various working conditions,it is considered an effective way to solve this problem by developing the operation system.The abilities of human perception are integrated into the control loop for improveing the controllability and adaptability of the hexapod robot.Aiming at how to achieve a stable and efficient bilateral operation of hexapod robot subject to flat terrain.Then,the structure of hexapod robot is analyzed.Considering the workspace between the master and slave is mismatch,the coordination between the master`s position and the slave`s velocity is adopted here.On the basis,a semi-autonomous control mode is proposed,and the motion algorithm is planned in the underlying control unit of the hexapod robot.Meanwhile,the control law of the bilateral operation system is designed by tracking the difference between the expected velocity and the actual velocity,and the difference is fed back to the operator in the form of haptic force.The reasonable range of the parameters of control law are guaranteed by the passivity theory.Finally,the semi-physical simulation platform is developed,which composed of the virtual simulation models developed based on the Vortex dynamic engine and a Novint Falcon haptic interface.Experiments of the system demonstrate the proposed semi-autonomous bilateral operation of the hexapod robot is effective subject to flat terrain,and the system is stable with a good tracking performance.In view of the operation problem of hexapod robot subject to soft terrain,the interaction mechanism in the process of dynamic contact between the robot foot and the flexible ground is researched.When a hexapod robot is walking on the soft terrain,the slippage between the flexible foot and the deformable ground is easy to happen.The environment termination,which can be regarded a nonpassivity system,will inject the extra energy into the slave system.Therefore,this dissertation analyses the potential active of environment system based on the foot-terrain interaction mechanics models in the normal and the tangential directions.Then,a time-domain passivity control(TDPC)is proposed to compensate for the loss of velocity,which caused by the foot slip,so as to ensure the bilateral operation system of hexapod robot subject to soft terrain is passivity.Based on the existing semi-physical simulation platform,the designed operation method is verified.It is proved that the proposed control method can improve the continuous tracking performance of the operation system.In view of the multidimensional operation problem of hexapod robot subject to rough terrain,a two dimensional operation method based on semi-autonomous control is proposed to regulate the velocity and attitude of body cooperatively.The leg spring-damping model is step up,and the uneven foot-terrain interface may cause the body`s fluctuation.Therefore,this dissertation proposes a coordinated constraint force distribution method based on deformation,and analysis the foot force distribution solutions in the underlying control unit.Then,actual force of the feet can dynamically track target force on the basis of impedance control.According to the virtual suspension model,the bilateral controller of attitude-level operation subsystem is designed.Then,the stability and transparency of the subsystem are proven by the passivity theory.The expansion of MMSS mode on the previous semi-physical simulation operation platform is implemented.It is verified that the proposed bilateral operation method of hexapod robot subject to rough terrain can ensure the stable tracking performance in the process of the omnidirectional motion and the attitude fluctuation compensation.The operator can also have a better perception for the motion state of hexapod robot and the environmental force acting on the robot body in these two operation dimensions,respectively.In obstacle terrain,the dissertation proposes a bilateral operation method for regulating the translation of trunk and the displacement of the manipulable leg coordinately,which can ensure the stability magrgin of the trunk and improve the ability of hexapod robot to interact with the environment.At this point,the robot`s leg can be regarded as a series manipulator,and the translational motion of the trunk is equivalent to the parallel platform.The coupling relationship of the trunk and the manipulable leg is analyzed.Then,the kinematic model of the whole robot and the dynamic model of the manipulable leg coupled with the trunk are established.Next,the control schemes of the body-level and the leg-level subsystem are designed.In order to eliminate the influence of coupling action on the trunk translation,the control law parameters are designed by absolutely stability criterion.Additionally,in order to compensate for the influence of the unmeasurable operation force and parametric uncertainties on the whole closed-loop control,a modified four-channel(4-CH)control architecture based on nonlinear force observer and adaptive robust controller is designed for the leg-level subsystem.Experiments of the proposed method and controllers can guarantee the stable bilateral operation of hexapod robot subject to unstructured environment,improving the tracking accuracy of the system while having a good force transparency.In general,according to the different terrain conitions and task requirements,different type and targeted bilateral operation systems of hexapod robot are designed respectively.The research results of this dissertation can be widely used for the control tasks of hexapod robot in high risk and complex scenarios,which is of theorectical guiding significance and practical values.