Research On Walking Attitude Control Of Multi-legged Robot

For the complex environments such as coastal,shoal and water-land junctions,it is necessary to develop a kind of multi-legged robot with the capability of carrying out offshore defense,investigation,communication,rescue,etc.In this paper,through the study of the functional bionic and structural bionic of sea crab,an multi-legged robot is developed which can walk on land,crawl on the seabed.The robot has the ability of moving autonomously in complex unstructured terrain,with strong environmental adaptability and movement stability.The purpose of this research is to design an multi-legged robot with the omni-directional motion ability.The whole structure of the robot are designed based on the prototype of sea crab.The series-parallel hybrid walking leg is developed with five-bar linkage mechanism.Aiming at the flexibility of the robot,the structure optimization of the walking leg is carried out.The walking leg is divided into two series of mechanical arm.The D-H method is adopted for analyzing the positive and inverse kinematics of the walking leg and the working space,and then the kinematics is verified,which lay the foundation for the attitude feedback control strategy and the motion planning.In this paper,a motion control method based on the Central Pattern Generator(CPG)is used to simulate the movement of the robot.The improved nonlinear differential equation is adopted as the oscillator model of the rhythm signal.The stability and uniqueness of the limit cycle of the oscillator model are analyzed,and then using the method of independent parameter the simulation study of CPG model properties is completed.A CPG control network model is set up,which takes one Hopf oscillator as the controller for each leg.In order to enhance the environmental adaptability of the robot,the typical waveform gait is investigated.The transition of typical waveform gait is realized by changing the connection mode of weight matrix,and the feasibility of this method is validated with simulation.A new biological control method is proposed for the walking stability of the robot in complex environment.By using the combination method of high-order curve and straight line to plan the leg-end trajectory of the robot.The approximate full fourier series of the ideal trajectory of the full leg is developed,which can facilitate the movement of the robot State regulation and gait transformation.An adaptive controller is designed to make the CPG unit integrate the attitude feedback signal and realize closed-loop control of the robot's posture,so as to restrain the perturbation of the external environment to the robot and improve the motion performance of the multi-legged robot.The virtual prototype is built,and the co-simulation is conducted,to verify the validity of the attitude feedback control strategy.The results show that the oscillation of the robot in the slope is weakened and the slipping problem is restrained.The prototype of multi-legged robot is developed,and the experiment platform of robot is built.By going straight,turning and climbing experiment,the motion capacity of the robot in to verify the robot in complex terrain and the effectiveness of the attitude feedback adjustment strategy are verified,thereby improving the environment adaptability of the robot.The experimental results show that under the action of the control strategy,the robot has good walking performance and environmental adaptability.