Observer Based Method for Joint Torque Estimation in Active Orthoses

Grün, Markus; Konigorski, Ulrich

doi:10.3182/20120215-3-at-3016.00035

Cited by 8 publications

(9 citation statements)

References 8 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Hence, the assistive torque provided by the exoskeleton can be naturally increased. The peak of the reference stiffness occurs at t = 4.3sec when the sum of all the antagonistic muscle torques is maximum (see (10)), while the applied torque reaches its peak at t = 4.1sec according to (15). In the final phase of the task (when the subject is close to the standing posture) the muscle activation decreases (gravitational load decreases) and consequently the reference stiffness and the provided assistive torque reduce.…”

Section: Resultsmentioning

confidence: 99%

“…Another important issue that needs discussion regards the adopted stiffness estimation approach. As it is described in section 5, we select to linearly map the stiffness trend index to a desired task-related and subjectspecific stiffness range (see (10) and (11)). This assumption was sufficient in our setup, as the goal in this work is to replicate the stiffness trends of the human to the exoskeleton, rather than quantify joint stiffness.…”

Section: Discussionmentioning

confidence: 99%

“…Common approach is to use joint angles to infer about the subject's posture [9], or ground reaction forces measurements to estimate the desired torques with an inverse dynamic model [1]. In [10] authors proposed an observer to correct the desired joint torques computed from the ground reaction forces. However, due to the increased need in exoskeletons for achieving desired response to disturbance, the integration of biological signals into the exoskeleton control has gained a lot of attention by many researchers over the last decade [6,11,12].…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Tele-impedance based assistive control for a compliant knee exoskeleton

Karavas

Ajoudani

Tsagarakis

et al. 2015

Robotics and Autonomous Systems

113

View full text Add to dashboard Cite

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Tele-impedance based assistive control for a compliant knee exoskeleton

Karavas

Ajoudani

Tsagarakis

et al. 2015

Robotics and Autonomous Systems

113

View full text Add to dashboard Cite

“…1. During the STS movement, the human body in the sagittal plane can be modeled using a triple inverted pendulum [33], [34]. The whole body includes three segments: shank-foot, thigh and HAT (Head-Arm-Torso).…”

Section: System Modelingmentioning

confidence: 99%

Impedance Modulation Control of a Lower-Limb Exoskeleton to Assist Sit-to-Stand Movements

et al. 2022

View full text Add to dashboard Cite

As an important movement of the daily living activities, sit-to-stand (STS) movement is usually a difficult task facing elderly and dependent people. In this article, a novel impedance modulation strategy of a lower limb exoskeleton is proposed to provide appropriate power and balance assistance during STS movements while preserving the wearer's control priority. The impedance modulation control strategy ensures adaptation of the mechanical impedance of the human-exoskeleton system towards a desired one requiring less wearer's effect while reinforcing the wearer's balance control ability during STS movements. A human joint torque observer is designed to estimate the joint torques developed by the wearer using joint position kinematics instead of electromyography (EMG) or force sensors; a time-varying desired impedance model is proposed according to the wearer's lower limb motion ability. A virtual environmental force is designed for the balance reinforcement control. Stability and robustness of the proposed method are theoretically analyzed. Simulations were implemented to illustrate the characteristics and performance of the proposed approach. Experiments with four healthy subjects were carried out to evaluate the effectiveness of the proposed method and show satisfactory results in terms of appropriate power assist and balance reinforcement.

show abstract

“…Robotic exoskeletons find ample use in rehabilitation engineering as devices which can help impaired people to regain their gait and mobility as well as their limbs' functionality after serious injuries [1][2][3][4][5][6]. Besides, they can be used in defense and security tasks by providing to humans in military or police corps the ability to lift and transfer heavy loads or to walk for longer distances without fatigue [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

A Nonlinear Optimal Control Approach for a Lower-Limb Robotic Exoskeleton

Rigatos

Abbaszadeh

Pomares

et al. 2020

Int. J. Human. Robot.

View full text Add to dashboard Cite

The use of robotic limb exoskeletons is growing fast either for rehabilitation purposes or in an aim to enhance human ability for lifting heavy objects or for walking for long distances without fatigue. The paper proposes a nonlinear optimal control approach for a lower-limb robotic exoskeleton. The method has been successfully tested so far on the control problem of several types of robotic manipulators and this paper shows that it can also provide an optimal solution to the control problem of limb robotic exoskeletons. To implement this control scheme, the state-space model of the lower-limb robotic exoskeleton undergoes first approximate linearization around a temporary operating point, through first-order Taylor series expansion and through the computation of the associated Jacobian matrices. To select the feedback gains of the H-infinity controller an algebraic Riccati equation is solved at each time-step of the control method. The global stability properties of the control loop are proven through Lyapunov analysis. Finally, to implement state estimation-based feedback control, the H-infinity Kalman Filter is used as a robust state estimator.

show abstract

Observer Based Method for Joint Torque Estimation in Active Orthoses

Cited by 8 publications

References 8 publications

Tele-impedance based assistive control for a compliant knee exoskeleton

Tele-impedance based assistive control for a compliant knee exoskeleton

Impedance Modulation Control of a Lower-Limb Exoskeleton to Assist Sit-to-Stand Movements

A Nonlinear Optimal Control Approach for a Lower-Limb Robotic Exoskeleton

Contact Info

Product

Resources

About