Assessment of force control for surface finishing – an experimental comparison between Universal Robots UR10e and FerRobotics active contact flange

Abstract

Robotic surface treatment is already broadly used in the manufacturing industry because it guarantees repeatable high-quality surfaces at short production time. Such a robotic solution, with an accurate control of the applied force on a surface, requires a robot that is either equipped with a force/torque sensor or, alternatively, with a force compliance device. However, without a direct performance comparison, it is hard to know which is the best option for a specific surface treatment operation. Compared to the evaluation of the robot positioning accuracy, using the ISO 9283 test, no standardized test for the quality assessment of robot force control exists yet. In trying to fill this gap, this paper introduces different test scenarios and a test set-up for such a force control quality assessment. As a start, the force control of a Universal Robots UR10e model and a FerRobotics ACF-K 109/04 model are experimentally evaluated. The latter is an external device with controlled force/compliance characteristics, which is referred to as an active contact flange (ACF). For the performance comparison, an ATI force/torque sensor, which is mounted below a work piece, measures the applied force either by the UR or by the ACF. The measured forces are further transformed to the UR tool centre point (TCP) frame. Then, only the z component of the force, or rather the normal force, is relevant for surface treatment and hence important for the evaluation. For each test case, the average value of five test runs with the same parameters is used for the assessment. Results for both the UR and ACF force control are presented for varying desired contact velocities and desired forces. These results indicate the advantage of the ACF-K 109/04 over the UR10e force control for highly dynamic force control scenarios.