Robotic systems are crucial in modern manufacturing. Complex assembly tasks require the collaboration of multiple robots. Their orchestration is challenging due to tight tolerances and precision requirements. In this work, we set up two Franka Panda robots performing a peg-in-hole insertion task of 1 mm clearance. We structure the control system hierarchically, planning the robots’ feedback-based trajectories with a central policy trained with reinforcement learning. These trajectories are executed by a low-level impedance controller on each robot. To enhance training convergence, we use reverse curriculum learning, novel for such a two-armed control task, iteratively structured with a minimum requirements and fine-tuning phase. We incorporate domain randomization, varying initial joint configurations of the task for generalization of the applicability. After training, we test the system in a simulation, discovering the impact of curriculum parameters on the emerging process time and its variance. Finally, we transfer the trained model to the real-world, resulting in a small decrease in task duration. Comparing our approach to classical path planning and control shows a decrease in process time, but higher robustness towards calibration errors.

Robotic systems are crucial in modern manufacturing. Complex assembly tasks require the collaboration of multiple robots. Their orchestration is challenging due to tight tolerances and precision requirements. In this work we set up two Franka Panda robots performing a peg-in-hole insertion task. We structure the control system hierarchically, planning the robots’s trajectories feedback-based with a central policy trained with reinforcement learning. These trajectories are executed by a low-level impedance controller on each robot. To enhance training convergence, we use reverse curriculum learning incorporating domain randomization, varying initial configurations of the task. After training, we test the system in a simulation, studying the impact of curriculum parameters on emerging process characteristics like process time and variance. Finally, we transfer the trained model to a real-world setup, comparing results with simulation as well as classical path planning and control approaches.

This paper presents a concept for integrating geometrictolerance analysis into system simulations using FunctionalMock-up Units (FMUs). While various methods and tools fortolerance analysis exist in the mechanical domain, there iscurrently no standardized or widely established approachfor their integration into multi-domain system simulation.This work proposes a structured FMU interface based on theFunctional Mock-up Interface (FMI) standard, enabling amodular and reusable representation of tolerance behaviour.The concept is demonstrated in a case study, in which anFMU for static tolerance calculation was implemented andsuccessfully verified against a commercial analysis tool.Furthermore, the use of the FMU with FMUGym illustrates thepotential of the FMI ecosystem to flexibly combinetolerance models with other simulation environments andanalysis methods.The results demonstrate that FMUs can provide a suitableand tool-independent interface for integrating geometricaltolerance effects into system-level simulations andmodel-based engineering processes.