Kinematic Modeling and Control Design of a Novel Single-Rail Parallel Arm * *This work was partially supported by The Norwegian Centre for International Cooperation in Education (SIU) and The Research Council of Norway (RCN)

This paper presents a novel 3-DoF parallel robot arm designed for use in applications that demand a high number of densely mounted manipulators with overlapping workspaces. The presented arm, which is mounted on a single rail, has such a workspace that allows the mechanism to reach outside the transverse footprint of its rail. Neighboring arms may therefore have overlapping workspaces on both sides and can be placed very close together, a property that is usually not found in parallel robots. The workspace of the arm in the direction of the rail is only limited by the length of the rail itself, and can therefore be made arbitrarily long. This makes the arm a light-weight alternative to traditional gantry systems. The main motivation is to increase the number of arms that can be mounted on a restricted area compared to conventional robots. The arm is applied to the agricultural domain where we show that it is well suited for tasks like robotic weeding and harvesting, i.e., cases where a high number of arms working in parallel is beneficial and can increase efficiency of the operations substantially. A kinematic analysis of the arm in terms of workspace and singularities is presented.