“MobileRobot” — Development of an Omnidirectional Manipulator for a Mobile Robot Welding Facility with a Demo Application of Mobile Welding

The goal of this project is the development of a mobile robot consisting of an omnidirectional mobile platform and a robot arm that work together as a team. The two robots will work simultaneously to perform one continuous movement. Usage areas are measurement and processing task like sanding, performing (spray) paint jobs, welding or validating parts.

Assembly of the planed mobile robot consisting of an omnidirectional platform and a robot arm

In contrast to existing solutions the omnidirectional platform and the robot arm do form one kinematic system or chain, that allows for simultaneous use of all available axis concurrently. Existing systems use their platforms only to move the arm between points where the arm works solely on its own. This project seeks to integrate the motion control of the six degrees of freedom of the arm with the three degrees of freedom of the platform. The integration of both systems at a control level allows for more flexibility on the robot’s movement. A given task can be handled in multiple ways and the possible work area is substantially expanded. Given constraints like time vs. energy efficiency and stability regarding the handling weight, an optimal trajectory can be selected. Additionally external factors like obstacles can be avoided while the Tool Center Point (TCP) does not deviating from the planned trajectory.

Through real-time synchronization of the platform and the arm, the processing task of a large workpiece can be performed alongside the trajectory of the platform. The absolute position of the platform is established using laser range finders, while the TCP (of the arm) tracks the relative position to the workpiece to be processed. To reduce the vibration of the platform two drive-steering modules connected through the platform are used. A drive-steering module consists of two individual wheels that are turning around a common central leading axle. This project also investigates how the kinematic constraints imposed by the drive-steering modules need to be considered by the motion planning and controlling layers of the mobile robot’s software.

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