scholarly journals Modeling of a Cable-Based Revolute Joint Using Biphasic Media Variable Stiffness Actuation

2019 ◽  
Author(s):  
Jesus H. Lugo ◽  
Vishal Ramadoss ◽  
Matteo Zoppi ◽  
Giorgio Cannata ◽  
Rezia Molfino
Keyword(s):  
Variable Stiffness ◽  
Revolute Joint ◽  
Variable Stiffness Actuation

scholarly journals Simultaneous position and stiffness control of a revolute joint using a biphasic media variable stiffness actuator

2019 ◽  
Vol 1 (2) ◽  
pp. 80-97
Author(s):  
Jesus H Lugo
Keyword(s):  
Control Method ◽  
Variable Stiffness ◽  
Industrial Processes ◽  
Revolute Joint ◽  
Additional Information ◽  
Physical Prototype ◽  
Stiffness Control ◽  
Variable Stiffness Actuator ◽  
Control Fluid ◽  
And Control

Safe interactions between humans and robots are needed in several industrial processes and service tasks. Compliance design and control of mechanisms is a way to increase safety. This article presents a compliant revolute joint mechanism using a biphasic media variable stiffness actuator. The actuator has a member configured to transmit motion that is connected to a fluidic circuit, into which a biphasic control fluid circulates. Stiffness is controlled by changing pressure of control fluid into distribution lines. A mathematical model of the actuator is presented, a model-based control method is implemented to track the desired position and stiffness, and equations relating to the dynamics of the mechanism are provided. Results from force loaded and unloaded simulations and experiments with a physical prototype are discussed. The additional information covers a detailed description of the system and its physical implementation.

Design and Analysis of New Haptic Joysticks for Enhancing Operational Skills in Excavator Control

2020 ◽  
Vol 142 (12) ◽  
Author(s):  
Meera C S ◽  
Pinisetti Swami Sairam ◽  
Vineeth Veeramalla ◽  
Adarsh Kumar ◽  
Mukul Kumar Gupta
Keyword(s):  
User Interfaces ◽  
Force Feedback ◽  
Haptic Feedback ◽  
Variable Stiffness ◽  
Significant Drop ◽  
Innovative Method ◽  
Resistive Torque ◽  
Kinesthetic Feedback ◽  
Variable Stiffness Actuation ◽  
Design Perspective

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.

Bidirectional antagonistic variable stiffness actuation: Analysis, design & Implementation

2010 ◽  
Author(s):  
Florian Petit ◽  
Maxime Chalon ◽  
Werner Friedl ◽  
Markus Grebenstein ◽  
Alin Albu-Schaffer ◽  
...  
Keyword(s):  
Variable Stiffness ◽  
Variable Stiffness Actuation ◽  
Analysis Design

scholarly journals Output-Based Control of Robots with Variable Stiffness Actuation

2011 ◽  
Vol 2011 ◽  
pp. 1-15 ◽  
Author(s):  
Gianluca Palli ◽  
Claudio Melchiorri
Keyword(s):  
Degrees Of Freedom ◽  
State Feedback ◽  
Joint Stiffness ◽  
Variable Stiffness ◽  
Cascade System ◽  
Work Space ◽  
Consequent Reduction ◽  
Variable Stiffness Actuation ◽  
Feedback Techniques ◽  
Selection Of

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.

Design of a 2D Haptic System With Passive Variable Stiffness Using Permanent Magnets for Upper-Limb Rehabilitation

2017 ◽  
Author(s):  
Sri Sadhan Jujjavarapu ◽  
Amirhossein H. Memar ◽  
Ehsan T. Esfahani
Keyword(s):  
Upper Limb ◽  
Permanent Magnets ◽  
Variable Stiffness ◽  
End Effector ◽  
Upper Limb Rehabilitation ◽  
Actuation System ◽  
Rehabilitation System ◽  
Variable Stiffness Actuation ◽  
Active Rehabilitation ◽  
Limb Rehabilitation

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.

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