| Due to the particularity of the working environment,various ships will inevitably produce various fluctuations during their voyage on the ocean.Hydraulically-driven legged robot with their high power to weight ratio,adaptability to harsh environments and fearlessness of task execution,can be used on ships for dangerous area patrol,precision cargo handling and other high-intensity work.This requires high stability of its operation.In order to realize the stable and reliable movement of the robot,it is necessary for each leg of the robot to maintain accurate control of the contact force of the foot end on the basis of certain flexibility.The contact force control algorithm with hydraulic control inner ring as the core and impedance control outer ring is an effective control method to achieve the above requirements.However,the current contact force control algorithm only has a high control effect in light load and small inertia scenario.In view of the poor application effect of traditional contact force control methods in hydraulically driven legged robot,an innovative contact force controller based on multi-joint novel impedance structure is proposed.Moreover,aiming at the problem of poor working condition applicability caused by single parameter,fuzzy control is used to carry out optimization research.It mainly includes:(1)Mathematical modeling for the lightweight bionic quadruped robot designed by the team.According to the mechanical structure of each part of the robot,the kinematics,statics and the dynamics models are built respectively,and the corresponding relationships between the displacement and output force of the hydraulic drive unit and the angular displacement and torque of each moving joint are deduced respectively,which provide the control basis for the realization of the control algorithm in the following chapters.(2)A contact force control algorithm based on novel impedance structure is proposed.The impedance control principle based on position/force of robot leg are analyzed and established respectively.A contact force control algorithm is proposed by combining the indirect adaptive algorithm.Then,the principle of the novel impedance structure is analyzed,and the control algorithm of the foot end contact force based on the novel impedance structure is proposed,and the corresponding simulation model is built.Finally,MATLAB/Simulink is used to simulate the control effect of contact force.(3)Fuzzy control algorithm is proposed to optimize the problem of poor practicability in working conditions.The fuzzy controllers are set up specifically,and the contact force control combining with fuzzy adaptive algorithm is proposed to optimize the problem of poor applicability of control parameters in working conditions.In addition,MATLAB/Simulink and Fuzzy toolbox are used to simulate various working conditions of the proposed control principle,and the optimization effect of the algorithm is verified.(4)The single leg experimental platform of the legged robot and the ground simulation platform are used for experimental verification.When the ground position is fixed and the ground position is changed,the effectiveness of the contact force control algorithm based on the novel impedance structure and the ground position identification effect are verified respectively.The optimization effect of contact force control based on fuzzy-adaptive algorithm is verified under the same working condition. |
