Towards a multi-DOF passive balancing mechanism for upper limbs

Cheng, Zhuoqi; Foong, Shaohui; Sun, Defeng; Tan, U-Xuan

doi:10.1109/icorr.2015.7281250

Cited by 18 publications

(27 citation statements)

References 16 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The core of this study is the synthesis and experimental evaluation of three spring designs. The first spring, though different in topology and shape, is comparable to the design shown by Cheng et al [15], featuring a constant crosssection. It is consequently suffering from similar shortcomings.…”

Section: Scopesupporting

confidence: 61%

“…In the scope of this paper we design an elbow orthosis featuring a flexure spring that undergoes large deflections and balances the forearm against gravity when the upper arm maintains a low elevation angle. In previous work by Cheng et al [14], [15] it was shown that such flexure springs can be synthesized and used to balance a planar linkage, representing the upper arm and forearm. Similar work outside the scope of assistive devices was conducted by Radaelli and Herder [16], [17], [18], where beam shapes have been synthesized that are used for general gravity balancing purposes.…”

Section: Scopementioning

confidence: 99%

“…Due to its passive nature, one side of the spring needs to maintain a fixed orientation relative to the gravity vector. Balancing of multiple joints across body segments can be achieved by decoupling mechanisms as shown in [15]. However, the technical embodiment may lead to and increased complexity, size and weight of the device and may impede the mobility of the affected joints.…”

Section: Applicationmentioning

confidence: 99%

See 2 more Smart Citations

Gravity Balancing Flexure Springs for an Assistive Elbow Orthosis

Tschiersky

Hekman

Brouwer

et al. 2019

IEEE Trans. Med. Robot. Bionics

View full text Add to dashboard Cite

In this paper, we propose a flexure spring based gravity compensation device which provides assistance to lift the forearm. Three different spring designs are obtained and evaluated. The synthesis method to obtain these is explained in detail and an experimental evaluation validates the desired gravity balancing properties. It is found that in comparison to a flexure spring with constant thickness, a variable thickness distribution along the spring leads to a drastic reduction of its width, which amounts to 81 % in the presented case, and offers an energy to weight ratio that is 94 % higher. Employing a nested spring design further increases the storable elastic energy of the variable thickness design by 145 % through utilization of the otherwise unused space within the original spring envelope. A proof-of-concept prototype is built to illustrate a practical implementation. The presented synthesis method provides a tool to obtain gravity balancing flexure springs that offer a promising solution for the design of assistive devices which aim to be both wearable and inconspicuous.Index Terms-Gravity balancing, wearable device, assistive orthosis, arm support, flexure spring.

show abstract

Section: Scopesupporting

confidence: 61%

Section: Scopementioning

confidence: 99%

Section: Applicationmentioning

confidence: 99%

See 1 more Smart Citation

Gravity Balancing Flexure Springs for an Assistive Elbow Orthosis

Tschiersky

Hekman

Brouwer

et al. 2019

IEEE Trans. Med. Robot. Bionics

View full text Add to dashboard Cite

show abstract

“…Although, position control in rehabilitation robots could counteract the effect of gravity weight of upper limb, it focused on control accuracy and ignores patients' voluntary participation in task execution, and its effectiveness in rehabilitation therapy needed further improvement. For patients who suffer from muscle weakness, gravity support showed promising results in minimizing the gravity-induced interference for tasks execution (van Elk et al, 2005 ; Cheng et al, 2015 ; Runnalls et al, 2015 ).…”

Section: Introductionmentioning

confidence: 99%

“…Hsu et al proposed an active control strategy to estimate the subject's movement intention and the control strategy included a gravity compensation term modified by the upper limb dynamics (Hsu et al, 2012 ). Cheng et al developed a two degrees of freedom (2-DOF) compliant beam which could compensate the torques on each joint based on the dynamic of the upper limb (Cheng et al, 2015 ). A torque-angle model containing a gravity compensation term was proposed by Lin et al to evaluate motion quality of adhesive capsulitis patients (Lin et al, 2014 ).…”

Section: Introductionmentioning

confidence: 99%

Assessment of Motor Control during Three-Dimensional Movements Tracking with Position-Varying Gravity Compensation

et al. 2017

View full text Add to dashboard Cite

Active movements are important in the rehabilitation training for patients with neurological motor disorders, while weight of upper limb impedes movements due to muscles weakness. The objective of this study is to develop a position-varying gravity compensation strategy for a cable-based rehabilitation robot. The control strategy can estimate real-time gravity torque according to position feedback. Then, the performance of this control strategy was compared with the other two kinds of gravity compensation strategies (i.e., without compensation and with fixed compensation) during movements tracking. Seven healthy subjects were invited to conduct tracking tasks along four different directions (i.e., upward, forward, leftward, and rightward). The performance of movements with different compensation strategies was compared in terms of root mean square error (RMSE) between target and actual moving trajectories, normalized jerk score (NJS), mean velocity ratio (MVR) of main motion direction, and the activation of six muscles. The results showed that there were significant effects in control strategies in all four directions with the RMSE and NJS values in the following order: without compensation > fixed compensation > position-varying compensation and MVR values in the following order: without compensation < fixed compensation < position-varying compensation (p < 0.05). Comparing with movements without compensation in all four directions, the activation of muscles during movements with position-varying compensation showed significant reductions, except the activations of triceps and in forward and leftward movements, the activations of upper trapezius and middle parts of deltoid in upward movements and the activations of posterior parts of deltoid in all four directions (p < 0.05). Therefore, with position-varying gravity compensation, the upper limb cable-based rehabilitation robotic system might assist subjects to perform movements with higher quality and improve the participation of robot-aided rehabilitation training. Further studies are needed to explore the effectiveness and clinic application across pathologies.

show abstract