Stair Climbing Performance in Claw Mode and Control Strategy in Wheel Mode for Claw-Wheel Transformable Robot
Date Issued
2016
Date
2016
Author(s)
Pan, Li-Han
Abstract
This thesis develops the Claw-Wheel transformable robot that enhances the stair climbing performance in claw mode and maneuverability in wheel mode. The concept follows the Claw-Wheel transformable structure as the research group before, and focus on the innovation and improvement of the hardware and software. The improvement of the transformation mechanism simplifies the transformation process, which just lifts the front body up and lay the front body down to the ground, and forms the claws or composite wheels; the process would not be much affected by the rough terrain. After analyzes the geometric specification and stair climbing performance of the robot striding two steps in last version, this research develops the robot with extended body length for striding three steps. Thus, the relative position of the mass of center to the support polygon is changed, and the stability of stair climbing is more enhanced. Besides, the difference of the required torques between the front and rear motors could be narrowed down and more balanced. In the movement of the wheel mode, the driving wheels are formed with the claws in stance and claws in flight; the claws in stance are controlled by the speed control for following the speed of movement and radius of gyration in differential drive, and the claws in flight are controlled by the angle-tracking control for forming the driving wheels. Finally, the switching control strategy with yaw feedback make the robot track the desired orientation more correctly. In the simulation of stair climbing performance, the robot striding three steps has better climbing performance than striding two steps. In the simulation of differential drive, the movement of speed and radius of gyration are set, and the angular velocities and period ratio of the claws in stance can be computed. The experiment of the claw mode transforming to wheel mode verifies the feasibility of transformation process, and the process is more simplified than before. In the experiment of the stair climbing, the robot climbs the stairs more steadily under the stair climbing strategy. In the experiment of the differential drive, after adding the yaw feedback, the robot tracks the desired yaw angle more accurately, and reduces the errors of the expected path.
Subjects
Hybrid robot
Transformable robot
Mobile robot
Stair climbing
Differential drive
Type
thesis
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