Torque control of a redundantly actuated passive manipulator

Abstract

The study of passivity in the robotics domain has been motivated by safety and stability concerns in applications such as haptic displays, surgical robots, teleoperation, and manufacl1u•ing. This paper describes a passive manipulator with a redundant actuation scheme which allows for enhanced control capabilities and greater overall utility. An algorithm for determining passive actuator excitations from generally active control laws is presented. The torque translation algorithm is a graphical method based upon using knowledge of the specific passivity-induced constraints to select a subset of the available actuators to provide an acceptable output torque. The algorithm successfully provides a set of passive actuator torques for all manipulator states, and experimental results are given.

Four-State Rotary Joint Control: Results With a Novel Programmable Brake

“…By contrast, robots belonging to the latter category use passive components, such as brakes, to dissipate or redirect energy, which results in an inherently safer system. Different types of brakes and clutches have been used in human-machine applications, for instance: electromagnetic brakes [7], magnetic particle brakes [20], piezoelectric actuated brakes [11], wafer disk brakes [9], shoe-type brakes [24], eddy-current based brakes [12] and magneto-rheological brakes [17], [4]. These brakes are differentiated in terms of performance characteristics such as reaction torque, activation time and power consumption.…”

“…The unlocking algorithm therefore requires an additional sensor to determine when user-applied forces are in a safe or desired direction. For example, in some devices featuring brakes, it is common to have a force sensor integrated into the mechanism ( [7], [25], [16]) in addition to joint encoders, which are used to monitor joint positions. The force sensor allows the direction and magnitude of the user's applied force to be sensed and the brakes to be engaged or disengaged depending on the configuration of the required restrictions.…”

Evaluation of Grasping Accuracy When Using a Passive Force Display Glove

“…If the passive display system fails or suffers a loss of control, the device cannot move by itself, and thus will not produce a harmful outcome [11], [12].…”

Interaction Torque Control by Impedance Control of Space Robots

“…Park and Lee [8] have applied adaptive impedance control algorithm to the force control of a haptic interface. Davis and Book [9] have presented a torque translation algorithm which translates the commands of an active torque-based control algorithm into suitable actuator commands for a redundantly actuated passive manipulator. Tholey et al [10] developed a grasper for minimal invasive surgery that is capable of generating force feedback that can be felt through a haptic interface device thereby allowing a user to feel the stiffness of the tissue being grasped.…”