DYNAMIC MODELING AND CONTROL OF QUADRUPED ROBOT WITH COMPLIANT LEGS

Abstract

Quadruped robots o er better maneuverability over wheeled mobile robots. They provide a better balance between the stability and the speed with reduced constructional complexity in comparison to other legged robots like bipeds and hexapods. These are the few reasons which have attracted researchers to explore various research aspects pertaining to quadruped robot. Prior dynamic analysis plays an important role for development of control laws for quadruped locomotion. Thus an e cient dynamic model is must for the study of quadruped robot. Here, a three dimensional dynamic model of a quadruped has been developed using the bond graph technique which can be interfaced with various controller models. This model contains a detailed sub-model for telescopic compliant legs. Developed bond graph model is validated through experiment results. The versatility of the model is demonstrated by performance measures of locomotion parameters. It is of practical importance to move the leg tips in a desired trajectory in order to achieve speci c objectives such as to avoid obstacles, minimize energy consumption and reduce locomotion time. This thesis, also discusses quadruped's locomotion control in the workspace through a control scheme in which the leg forward motion is controlled in the workspace while the body forward motion is controlled by providing the required e ort directly to the joint actuators. In order to generate faster locomotion while balancing the entire robot body, posture control is an important issue. Posture disturbance in the case of quadruped robot takes place because of uneven terrain, dynamic walk, heavy weight of jointed legs and compliance in the legs. Here, rst of all conceptualization for the posture control has been developed and then revolute prismatic manipulator and rack pinion device are discussed in detail to control the body inclination. Finally, the posture control of dynamic gait like trot and pace are performed using rack-pinion device. In addition to control, safety and reliability are the other critical issues in any automotive system design. Quadruped robots are meant to work in hazardous environment. Sensor and actuator faults are more likely to occur when the robot is put to work in such xix an environment. Thus, fault tolerant control and recon guration is an emerging eld of research for quadruped robot. Here, attempt is made to explore this area also. Joint failures are of two types: Free swinging failure and locked joint failure. Here, both kind of joint failures are considered and fault tolerant and recon guration strategies are suggested for the same. Also, sensor fault accommodation through sensor redundancy is proposed.