Study of Orientation Control for a Wheeled Jumping Robot in the Flight Phase of Motion

The work studies the flight phase (a part of jumping motion) of a jumping robot. The robot consists of the body with wheeled base and a jump booster module installed in the body. The jump booster module allows the robot to accelerate in a given direction up to a predetermined speed, allowing to control the velocity of the robot at the moment when it breaks contact with the supporting surface. The goal of this study is to develop a control system for the robot’s wheels, allowing to use their inertial properties to control the robot orientation at the moment of landing. This is achieved by controlling the wheels’ orientation throughout the duration of the motion. The goal of controlling the orientation of the robot at the moment of landing is to be able to land on all four wheels and avoid tipping over. The paper studies the supporting surfaces (from which the robot jumps and to which the robot lands) described by piecewise linear functions, including a horizontal and slopped linear sub-functions. In this work, four types of supporting surfaces were distinguished, which the distinction based on the slope of the mentioned about sub-function. Another varying parameter is the point where two sub-functions connect. For the purpose of this study a kinematic and dynamic model of the robot were developed, and a control system design was proposed. The proposed control system includes a trajectory planner that allows to plan the robot’s motion resulting in the desired orientation of the robot’s body at the moment of landing. This problem was formulated as an optimization problem. Simulation results showed the dependencies between the three supporting surface parameters (two angles describing linear sub-functions and the point where the sub-functions intersect) and the duration of the robot flight, the achieved velocities of the robot’s wheels and required motor torques. The influence of those parameters on the maximal and minimal values of the wheels’ angular velocities achieved during the flight were demonstrated. This could be used in designing this type of robots, in particular it could help to set specifications for the robot’s wheel motors.