Development of an Inertially-Actuated Passive Dynamic Technique to Enable Single-Step Climbing by Wheeled Robots
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A solution to these problems is a novel, passive dynamic system that is inertially excited by the motion of the robot to allow the robot to rotate on each axle and â hopâ over the step. The system that was investigated for this project is a sliding mass-spring that shifts forward and backward based on the acceleration of the base robot. With high acceleration, the mass is pushed towards the rear wheel from an inertial force and compresses a spring that creates a moment on the body to induce rotation. This torque can cause the robot to â pop a wheelieâ , lifting its front wheels off the ground. To pull the rear wheels up, the inertial force from a large deceleration of the robot shifts the mass forward and extends a spring. These effects result in a moment acting in the opposite direction that can rotate the robot on its front axle and pull the rear wheels up. By coordinating the acceleration and deceleration of the robot, the front wheels can lift over a step and the rear wheels can be pulled up afterward â both actions being a product of inertial actuation. This passive system does not need additional actuators or direct control of the sliding mass, so it can be more durable over a robotâ s lifetime. Other advantages of this system are that the design is simple, cost-effective, and can be adjusted and retrofit to a different wheeled robot in the future with little effort.
By deriving the equations of motion of this inertially actuated sliding mass, the dynamics show how design parameters of the system can be tuned to better optimize the overall step-climbing process. A computer simulation was created to visualize the robotic step-climbing process and demonstrate the effects of changing design parameters. An implementation of this sliding mass system was added to a wheeled robot, and the results from experiments were compared to simulated trials. This research has shown that an inertially actuated sliding mass can effectively enable a wheeled robot to climb a step that was previously impassable and that the system can be tuned for other wheeled robots using an understanding of the system dynamics.
- Masters Theses