Actuators for Improving Robotic Arm Safety While Maintaining Performance: A Comparison Study

Abstract

Since robotic arms operating close to people are becoming increasingly common, there is a need to better understand how they can be made safe when unintended contact occurs, while still providing the required performance. Several actuators and methods for improving robot safety are studied and compared in this paper. A robotic arm moving its end effector horizontally and colliding with a person’s head is simulated. The use of a conventional electric actuator (CEA), series elastic actuator (SEA), pneumatic actuator (PA) and hybrid pneumatic electric actuator (HPEA) with model-based controllers are studied. The addition of a compliant covering to the arm and the use of collision detection and reaction strategies are also studied. The simulations include sensor noise and modeling error to improve their realism. A systematic method for tuning the controllers fairly is proposed. The motion control performance and safety of the robot are quantified using root mean square error (RMSE) between the desired and actual joint angle trajectories and maximum impact force (MIF), respectively. The results show that the RMSE values are similar when the CEA, SEA, and HPEA drive the robot’s first joint. Regarding safety, using the PA or HPEA with a compliant covering can reduce the MIF below the safety limit established by the International Organization for Standardization (ISO). To satisfy this ISO safety limit with the CEA and SEA, a collision detection and reaction strategy must be used in addition to the compliant covering. The influences of the compliant covering’s stiffness and the detection delay are also studied.

Trajectory Tracking Algorithm Study of Coal Mine Water Detector Drilling Bar Installation

“…Chongqing Research Institute achieved fully automatic drilling of a drill Z through research and testing in the areas of automatic installation and dismantling drilling bars and automated drilling. In the intelligent operation of mechanical water detection, how to ensure the connection accuracy of drilling bars when automatically completing the assembly tasks is the core technical issue for the development of water detection machinery [2]. The study of control algorithms for supplied material devices to optimize the trajectory tracing controller is a concrete safeguard measure to improve the connection accuracy [3,4].…”