Bidirectional antagonistic variable stiffness actuation: Analysis, design & Implementation

Author(s):  
Florian Petit ◽  
Maxime Chalon ◽  
Werner Friedl ◽  
Markus Grebenstein ◽  
Alin Albu-Schaffer ◽  
...  
2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Meera C S ◽  
Pinisetti Swami Sairam ◽  
Vineeth Veeramalla ◽  
Adarsh Kumar ◽  
Mukul Kumar Gupta

Abstract The design perspective of interfaces has strong implications on operator intuition and safety. Haptics enabled user interfaces can enhance operator skills and enhance interactivity. In this paper, an innovative method of haptic feedback in joysticks is presented for excavator control. Haptic illusion in the device is generated with the concept of the variable stiffness actuation mechanism. The force feedback (FFB) is rendered through “haptic links,” based on the effect of digging force at each joint. The stiffness in the device varies dynamically with the load and restricts the operator motion with a resistive torque in the range of 0–0.9 Nm. The haptic joystick aims to render high-fidelity kinesthetic feedback that can help to mitigate the operator error in loading operations. The user evaluation with the joystick showed an improvement of 40% in the volume of material removed and a significant drop in error rate related to force patterns and collisions.


2011 ◽  
Vol 2011 ◽  
pp. 1-15 ◽  
Author(s):  
Gianluca Palli ◽  
Claudio Melchiorri

The output-based control of a redundant robotic manipulator with relevant and adjustable joint stiffness is addressed. The proposed controller is configured as a cascade system that allows the decoupling of the actuators dynamics from the arm dynamics and the consequent reduction of the order of the manipulator dynamic model. Moreover, the proposed controller does not require the knowledge of the whole robot state: only the positions of the actuators and of the joints are necessary. This approach represents a significant simplification with respect to previously proposed state feedback techniques. The problem of controlling simultaneously the position trajectory and the desired stiffness in both the joint and work space is investigated, and the relations between the manipulator redundancy and the selection of both the joint and work space stiffness of the manipulator are discussed. The effectiveness of the proposed approach is verified by simulations of a 3 degrees of freedom planar manipulator.


Author(s):  
Sri Sadhan Jujjavarapu ◽  
Amirhossein H. Memar ◽  
Ehsan T. Esfahani

This paper presents a design of variable stiffness actuation system based on on the force interactions caused by permanent magnets. The system is designed for rehabilitation of the upper limb with the goal to enhance rehabilitation in both clinical and home environments. The proposed active rehabilitation system is composed of a lightweight 6-axes robotic arm to move the patients hand in the desired trajectory. The interaction stiffness is controlled by the mechanism attached to the end-effector. For this purpose, repelling magnet pairs in linear antagonistic configuration are used to control the stiffness of the handle. Stiffness in the mechanism can be controlled via adjusting the distance between the magnets. A mathematical model is presented to analyze the range of adjustable variable stiffness for this mechanism.


Author(s):  
Stefan O. Schrade ◽  
Katrin Dätwyler ◽  
Marius Stücheli ◽  
Kathrin Studer ◽  
Daniel-Alexander Türk ◽  
...  

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