This paper presents fault tolerant control through reconfiguration of a four legged walking robot. It is assumed that the walking robot motion is in sagittal plane and it follows the bounding gait. The bond graph model of walking robot in sagittal plane is developed. A novel and simple attitude control device based on the motion of the moving appendage is proposed. The bond graph model of the system is used to generate the Analytical Redundancy Relations (ARRs) which are then evaluated with actual measurements to generate residuals. These residuals are used to perform structural fault isolation. Once the fault list is updated in the equipment availability database, an automaton selects the best option to reconfigure the system such that the given control objectives are achieved. The developed methodology is validated by considering the joint actuator failure.

This paper presents fault accommodation through the reconfiguration of a four legged (quadruped) walking robot. It is assumed that the walking robot is moving using a bounding gait. A bond graph model to represent the robot's locomotion in the sagittal plane is developed. A novel and simple attitude control device based on a moving appendage is proposed. This appendage device serves as redundant hardware and is activated only when the robot experiences a locked joint failure. The bond graph model of the system is used to generate the analytical redundancy relations which are then evaluated with actual measurements to generate residuals. These residuals are used to perform structural fault isolation. Once the fault list is updated in the equipment availability database, an automaton selects the best option to reconfigure the system such that the given control objectives are achieved. The developed methodology is validated by considering the failure of a joint's actuator.

In this paper, the issue of control of impact forces generated during the interaction between the hopping robot toe and the ground while landing has been considered. The force thus generated can damage the robot altogether. With the objective to control these impact forces, impedance control strategy has been applied to the hopping robot system. The dynamics pertaining to the impact between robot toe and ground has been modeled as in case of a ball bouncing on the ground. Bond Graph theory has been used for the modeling of the hopping robot system. Simulation results show that impact forces generated during the landing has been controlled to a specified limiting value. This model and the corresponding analysis can be further extended for understanding the dynamics involved in continuous hopping of robot with constant height and velocity control.

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