Design methodology for workspace adjustment of industrial robot arms using a long end-effector: implementation in a dishwashing robot system

System integrators (SIers) design and build robotic systems by integrating robotic arms with peripheral devices to perform tasks within specific operational environments. In this context, the reachable workspace of a robot arm is a fundamental constraint in the system design. To ensure a sufficiently large workspace, integrators often resort to large-scale robot arms or multiarm configurations, even when handling lightweight objects. However, these choices inevitably increase the system costs and impose stricter installation constraints. To avoid such over-specification, this study utilizes an existing small-scale robot arm and introduces a long end-effector (LEE) as a design variable for the workspace adjustment. We propose a system-level design methodology that extends the effective workspace through the geometric configuration of the end-effector (EE) rather than by increasing the size or complexity of the arm itself. First, we analyzed the robot arm specifications from major manufacturers to systematically summarize the constraints regarding reachable workspaces and installation conditions. Next, based on a kinematic model, we present a method for determining the link length and mounting angle to satisfy the task workspace requirements. To validate the effectiveness of this approach, we developed a prototype system for a dishwashing task in a restaurant’s kitchen. We demonstrated that a small robot arm equipped with an LEE can successfully execute the required motion sequences. The key contribution of this study is the provision of a system-integration-oriented design guideline that satisfies workspace requirements without relying on larger robot arms or increased degrees of freedom.