Modeling, Kinematic Analysis, Gait, and Trajectory Generation for Quadruped Robot

A quadruped robot is an underactuated system. In the case of underactuated systems, the degree of freedom of the system is less than that of the actuators provided for the motion. So, the body movement needs to be controlled indirectly by defining proper trajectory, gait, and contact parameters. In this paper, the quadruped robot is modeled using design software, and the complete robot is specified using a unified robot description format. The body movement of the quadruped depends on the foot trajectory and the gait pattern to be implemented. This paper defines a mixed gait pattern to study its impact on body motion. The gait defined combines the advantages of trot and static gait. D-H convention is used to define the axis for joints. Simulations are carried out in MATLAB–Simulink. Kinematic equations are designed for the leg system and the body of the quadruped. Kinematic analysis is used to generate joint-space trajectories from task-space trajectories. The inverse kinematic solver available in the Robotics System Toolbox creates joint-space trajectories. Simulations are performed using these joint-space trajectories. The simulations are performed to observe the body motion. The plot of the body’s translation and rotation concerning time suggests that the gait has been executed with stable body movement. The iterative simulation defines contact parameter values to perform a stable gait with stable body movement.