| In modern society,people's demands for the performance of mobile robots are more and more inclined to mobility,efficiency and adaptability.The commonly used moving ways of mobile robot are wheeled,tracked and leg-foot.The wheeled mobile robot has the advantages of fast moving speed and high energy efficiency,but its terrain adaptability is poor,so it can only work in the flat ground.Due to the contact area with the ground is so large,the tracked mobile robot has improved its adaptability to the terrain,but its efficiency of energy utilization and mobility are significantly reduced.In the past decade,leg-foot robots with rapid development have outstanding performance in complex terrain environment,but slow moving speed and low energy efficiency are always difficult to break through.Under this background,more and more people pay attention to the leg-wheeled mobile robot,which combines the advantages of wheeled and legged robots.Using the form of two wheels can maximize the efficiency of energy utilization and mobility,because of the leg structure,the robot has a qualitative improvement in the ability to adapt to complex terrain environment.Based on the analysis of the expected motion performance of the two leg-wheeled robot,a series of motion control algorithms are proposed based on the kinematic and dynamic models,and verified by virtual prototype simulation in Webots environment.The main research contents are as follows:1.The two leg-wheeled robot is equivalent to a two wheel inverted pendulum system with variable mass center height,and the change of mass center height is realized by leg motion.The kinematic and dynamic models of the two wheel inverted pendulum system and the leg system are established respectively,the mass center distribution of each component is calculated,the Jacobian matrix of the leg mechanism is derived,and the motion space of the driving wheel center relative to the body is analyzed,which is the machine Human motion planning and control has laid a good foundation2.The motion of the two legged wheeled robot can be decoupled into the motion and steering motion in the sagittal plane,and the motion control in the sagittal plane can be divided into the balance control and the speed control;the balance controller based on T-S fuzzy model,the speed controller based on mamdni fuzzy model and the steering controller based on the segmented PD algorithm are designed respectively;the virtual two legged wheeled robot is constructed in webots environment The simulation results show that the control algorithm is effective3.In this paper,a position control algorithm based on the trajectory planning of foot end is designed for the two legged wheeled robot to cross the obstacle and limit the height of the obstacle through the height of the metamorphic center.For the jumping obstacle of the ground,an impedance control algorithm based on the trajectory of foot end and an active compliance control algorithm based on the virtual model are designed for the three-stage motion planning of the robot:squat,take-off and fall In the webots environment,the obstacle surmounting ability and the convergence and robustness of the control algorithm are verified by simulation.4.The two legged wheeled robot is a kind of under actuated and unstable robot,which is easy to topple.According to the direction of dumping and the physical structure of the robot,it can be divided into forward dumping,backward dumping and lateral dumping.Due to the lack of roll joints.In this paper,the two legged wheeled robot only has the fall recovery ability to overcome the first two kinds of toppling.The fall recovery control algorithm is also decoupled for the control of wheels and legs.Position control algorithm and plane motion control algorithm based on foot end trajectory planning are adopted respectively,and the feasibility of the algorithm is verified by implementation.Finally,the paper summarizes the research results and shortcomings,and looks forward to the next step. |
PDF Full Text Request