Gravity-Balancing Leg Orthosis and Its Performance Evaluation

Banala, S.K.; Agrawal, Sunil K.; Fattah, Abbas; Krishnamoorthy, Vijaya; Hsu, Wei-Li; Scholz, John P.; Rudolph, Katherine S.

doi:10.1109/tro.2006.882928

Cited by 170 publications

(54 citation statements)

References 16 publications

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“…In many instances they provide partial support of the user's weight by providing a mechanical path to the ground. A more elaborate gravity-support device based entirely on passive mechanical elements has been reported by Banala [2].…”

Section: A Classification Of Assistive Exoskeletons: Passive Vs mentioning

confidence: 99%

Active-Impedance Control of a Lower-Limb Assistive Exoskeleton

Aguirre-Ollinger

Colgate

Peshkin

et al. 2007

2007 IEEE 10th International Conference on Rehabilitation Robotics

143

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Abstract-We propose a novel control method for lower-limb assist that produces a virtual modification of the mechanical impedance of the human limbs. This effect is accomplished by making the exoskeleton display active impedance properties. Active impedance control emphasizes control of the exoskeleton's dynamics and regulation of the transfer of energy between the exoskeleton and the user. Its goal is improving the dynamic response of the human limbs without sacrificing the user's control authority. The proposed method is an alternative to myoelectrical exoskeleton control, which is based on estimating muscle torques from electromyographical (EMG) activity. Implementation of an EMG-based controller is a complex task that involves modeling the user's musculoskeletal system and requires recalibration. In contrast, active impedance control is less dependent on estimation of the user's attempted motion, thereby avoiding conflicts resulting from inaccurate estimation.In this paper we also introduce a new form of human assist based on improving the kinematic response of the limbs. Reduction of average muscle torques is a common goal of research in human assist. However, less emphasis has been placed so far on improving the user's agility of motion. We aim to use active impedance control to attain such effects as increasing the user's average speed of motion, and improving their acceleration capabilities in order to compensate for perturbations from the environment.

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Section: A Classification Of Assistive Exoskeletons: Passive Vs mentioning

confidence: 99%

Active-Impedance Control of a Lower-Limb Assistive Exoskeleton

Aguirre-Ollinger

Colgate

Peshkin

et al. 2007

2007 IEEE 10th International Conference on Rehabilitation Robotics

143

View full text Add to dashboard Cite

show abstract

“…Also, the actuators can be positioned on the torso of the wearer, so that the only added weight on the upper arm are those of the attachment cuffs and cables. Finally, the use of torso-mounted actuators can be combined with parallel gravity balancing [11], as previously demonstrated in both a lower [12] and upper extremity exoskeleton [13]. With these features, we expect this exoskeleton to be better suited as an assistance device for impaired or elderly wearers for activities of daily living (ADL).…”

mentioning

confidence: 89%

Dynamics and control of a 4-dof wearable cable-driven upper arm exoskeleton

Brackbill

Mao

Agrawal

et al. 2009

2009 IEEE International Conference on Robotics and Automation

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Abstract-In this paper, we present the dynamics, control, and preliminary experiments on a wearable upper arm exoskeleton intended for human users with four degrees-of-freedom (dof), driven by six cables. The control of this cable-driven exoskeleton is complicated because the cables can transmit forces to the arm only under tension. The standard PD controllers or Computed torque controllers perform only moderately since the cables need to be in tension. Future efforts will seek to refine these control strategies and their implementations to improve functionality of a human user.

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“…In passive gravity support, an unactuated orthotic device can provide partial support of the user's weight by forming a mechanical path to the ground. Gravity balance of the freely-moving leg using springs has been implemented by Banala et al [2]. Load-carrying assist is a special case of gravity support, typified by the BLEEX system [6], in which the exoskeleton supports a load carried by the user.…”

Section: Introductionmentioning

confidence: 99%

A 1-DOF assistive exoskeleton with virtual negative damping: effects on the kinematic response of the lower limbs

Aguirre-Ollinger

Colgate

Peshkin

et al. 2007

2007 IEEE/RSJ International Conference on Intelligent Robots and Systems

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Abstract-We propose a novel control method for lowerlimb assist that produces a virtual modification of the mechanical impedance of the human limbs. This effect is accomplished through the use of an exoskeleton that displays active impedance. The proposed method is aimed at improving the dynamic response of the human limbs, while preserving the user's control authority. Our goal is to use active-impedance exoskeleton control to improve the user's agility of motion, for example by reducing the average time needed to complete a movement.Our control method has been implemented in a 1-DOF exoskeleton designed to assist human subjects performing knee flexions and extensions. In this paper we discuss an initial study on the effect of negative exoskeleton damping (a particular case of active-impedance control) on the subject's time to complete a target-reaching motion. Experimental results show this effect to be statistically significant. On average, subjects were able to reduce the time to complete the motion by 16%.

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Gravity-Balancing Leg Orthosis and Its Performance Evaluation

Cited by 170 publications

References 16 publications

Active-Impedance Control of a Lower-Limb Assistive Exoskeleton

Active-Impedance Control of a Lower-Limb Assistive Exoskeleton

Dynamics and control of a 4-dof wearable cable-driven upper arm exoskeleton

A 1-DOF assistive exoskeleton with virtual negative damping: effects on the kinematic response of the lower limbs

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