Virtual Validation of Power and Force Limiting Setups in Human-Robot-Collaboration

Abstract

Industrial applications with physical human-robot-interaction that rely on the application principal “Power and force limiting” require to verify the biomechanical load acting on the operator during a contact to ensure compliance with applicable standards. The related force and pressure measurements can only be carried out after a specific application is built up. Existing approaches to determine the biomechanical load range from simulations over setups with crash test dummies or biofidel measurement devices to studies with humans. Studies with humans are suited to define thresholds for biomechanical loads but not to verify them on a real application. To some extent, dynamic simulations can estimate the biomechanical load in unconstrained contact situations but are limited in case of constrained contacts. To fill this gap related to constrained contacts we propose a comprehensive approach for the planning of Power and force limiting in this paper. After giving an overview over existing testbeds for collision testing in human-robot-interaction, a new testbed setup is proposed as well as an approach to utilize the generated data to create benefits for end users of the tested robots. With this approach the collision-force and -pressure during a contact are estimated based on information that are available before the application is built up. An expert system gives advice to the user how to modify the application to meet design requirements and ensure operator safety. The proposed approach relies on an advanced testbed, which is able to reproduce representative contact situations between a human and a test-robot by varying the parameters: contact position and direction, velocity at the contact point, end-effector weight, collision surface and affected human body part. The testbed is implemented prototypically to investigate the feasibility of the approach. The biomechanical loads of reproduced contact situations are measured using a state-of-the-art biofidel measurement device and stored in a database, where they can be used to estimate the force and pressure of planned applications and create instructions to influence a desired application parameter.