Towards safe physical human-robot interaction: An online optimal control scheme

Abstract

Abstract-Operating in the proximity of humans has been a long-term challenge in robotics research. To achieve this objective, one of the main issues is to ensure safe and comfortable physical human-robot interaction (pHRI). In this paper, we tackle the safety problem at the control level. To ensure operation is within perceived safe zone, we use model predictive control, which finds the optimal control signal online, while imposing predefined safety constraints on the robotic system. The strength of this method lies in allowing the system to perform close to, or at the edge of the constraints' boundaries. In contrast to other works we consider here perceived safety; the constraints for perceived safety are derived in a competitive pHRI experiment. The perceived safety and comfort of the proposed approach is then evaluated with a second, game-like pHRI experiment.

Safe Close-Proximity and Physical Human-Robot Interaction Using Industrial Robots

“…This method is sensitive to the reflectance of object surfaces as well as ambient lighting. Despite the calibration procedure described in [15] which is meant to improve the accuracy of the individual IR sensors, it is difficult to predict the exact characteristics of each surface that could possibly be encountered in any given situation. The external sensor array is more affected by this type of uncertainty than the internal sensor array.…”

“…1. Since the publication of [15], it has undergone a few minor changes in order to address some key issues, namely an increase in the amount of translational compliance available by lengthening the central shaft, as well as an outward extension of the external sensor mounting brackets meant to negate the effects of interference caused by the first modification. By increasing the distance of the movable plate, it entered into the field of view of the sensors which produce a cone shaped beam of infrared light rather than a narrow beam.…”

“…It creates a behavioral model according to the actions of the human counterpart. Norouzzadeh et al [15] proposed an online optimal control method which imposes constraints on interaction forces, position, and velocity of the robot to ensure safe physical human-robot interaction.…”

“…The goal of this work is to address the flexibility and safety issues of industrial robots for physical and proximity interactions with humans without the need for retrofitting the robotic platform or making significant hardware modifications such as including new actuators or adding internal joint sensors. We attempt to solve the flexibility problem through the use of an adaptable compliant wrist [15] designed to incorporate a degree of compliance onto an initially non-compliant manipulator providing a greater degree of flexibility and adaptability for physical and proximity human-robot interaction.…”

Safety control for impedance haptic interfaces

“…Traditional robotic controllers such as proportional-integral-derivative (PID) controllers may not be very suitable to the safety control [21]. The reported studies on solving safety issues in pHRI can be divided into two main approaches, namely, passive safety and active safety [26]. The approaches of passive safety resort to safe mechanical design, by reducing the manipulator link inertia and weight using lightweight but stiff compliant components to achieve intrinsic safety.…”