Abstract
Robots driven by variable stiffness actuators (VSAs) have been an important technology as they could provide intrinsic compliance for safe human-robot interaction. The internal compliance of VSA also makes it possible for the actuator to act as a torque sensor and estimate the external force. This paper presents a physical human-robot interaction control strategy for robots driven by VSA with force self-sensing. The VSA adopted in the robotic system improves the safe performance of physical human-robot interaction. The interaction force is directly estimated by measuring the internal deformation of VSA with a stiffness region control which ensures a better resolution of force estimation and avoids transgressing the limits of deformation simultaneously. Then an online estimation method for the human motion intention is developed to generate the desired trajectory based on the estimated force. The impedance control is designed to enable the robot to actively follow the desired trajectory with compliance. Under the proposed control strategy, the robot is capable of actively tracking the “motion intention” of human with the estimated interaction force, which is demonstrated through experiment studies.
Highlights
In recent years, society has recognized the significance of robots in assisting human motions, such as reducing workload, improving the efficiency, enhancing the productivity, rehabilitation therapy, and so on
The contributions can be highlighted as follows: (i) The interaction force is directly estimated by measuring the internal deflection of variable stiffness actuators (VSAs), and the stiffness region control is developed to improve the performance of force estimation. (ii) The motion intention is achieved through the medium of interaction force, by estimating the limb model with only two unknown parameters to be updated, decreasing the computation cost
In this paper, the control strategy for physical human-robot interaction has been investigated for robots driven by VSA
Summary
Society has recognized the significance of robots in assisting human motions, such as reducing workload, improving the efficiency, enhancing the productivity, rehabilitation therapy, and so on. These biological signals require higher concentration of subjects’ attention, and these signals would be affected by the individual difference Another medium for motion intention estimation is the interaction force. In [17], [18], the motion intentions were recognized by the difference between the estimated and measured torque of robots Such approach requires the accurate dynamics of robots and human arms or legs. The motion intention is achieved through the medium of interaction force which is directly estimated by measuring the internal deflection of VSA. The motion intention is generated by estimating the dynamic model of upper limb which involves minimizing the interaction force between the human and robot.
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