General Model of Human-Robot Cooperation Using a Novel Velocity Based Variable Impedance Control

Proactive behavior of a humanoid robot in a haptic transportation task with a human partner

“…Coupling our approach with a variable impedance one as in [3] may improve the proactivity as well as the quality of the haptic feeling for the human partner.…”

“…We mainly use velocity thresholds to detect the switches of primitives. For example, when the current primitive is Stop and the effective velocity V of the object is zero, the robot senses a force on its wrists and updates V with (3). If the first component of V exceeds a given threshold, the robot switches to the primitive Walk.…”

“…Proactivity aims at solving this problem: guessing the human partner's intentions to decrease this horizontal load. An approach is to regulate the robot's impedance according to the perceived intentions [3] [4]. An other way to be proactive is to guess the human partner's intended trajectory.…”

Adaptive Hands-On Control for Reaching and Targeting Tasks in Surgery

“…Different variable impedance controllers for human-robot cooperation have been presented for surgical [8], industrial [19][20][21] and assistive robotics [22][23][24][25][26] applications. The damping factor of the impedance controller was changed with respect to a threshold, based on the speed of manipulation by direct switching [19], by time dependent functions [20] or by linear variation [21].…”

“…The variable impedance approach, based on the end-effector position, is appropriate for the aforementioned surgical scenario, due to the varying accuracy and safety requirements in the operating theatre, which depend on the position of the patient and therefore also the surgical area of interest. Additionally, the impedance would not depend on the characteristics and weight of the surgical tool, as would be the case in [22][23][24][25]. Differently from [26], where a computational demanding potential field is computed to describe an environment assumed to be static, in this work, a space variable (SV) damping criterion is presented in order to build an intra-operative "accuracy map", based on the knowledge of the surgeon's intention of motion (i.e., the position of the surgical target at the end of the reaching gesture).…”