Active movement-assistive devices aim to increase the quality of life for patients with neuromusculoskeletal disorders. This technology requires interaction between the user and the device through a control interface that detects the user’s movement intention. Researchers have explored a wide variety of invasive and non-invasive control interfaces. To summarize the wide spectrum of strategies, this paper presents a comprehensive review focused on non-invasive control interfaces used to operate active movement-assistive devices. A novel systematic classification method is proposed to categorize the control interfaces based on: (I) the source of the physiological signal, (II) the physiological phenomena responsible for generating the signal, and (III) the sensors used to measure the physiological signal. The proposed classification method can successfully categorize all the existing control interfaces providing a comprehensive overview of the state of the art. Each sensing modality is briefly described in the body of the paper following the same structure used in the classification method. Furthermore, we discuss several design considerations, challenges, and future directions of non-invasive control interfaces for active movement-assistive devices.Electronic supplementary materialThe online version of this article (doi:10.1186/1743-0003-11-168) contains supplementary material, which is available to authorized users.

While there is an extensive number of studies on the development and evaluation of electromyography (EMG)- and force-based control interfaces for assistive devices, no studies have focused on testing these control strategies for the specific case of adults with Duchenne muscular dystrophy (DMD). This paper presents a feasibility study on the use of EMG and force as control interfaces for the operation of active arm supports for men with DMD. We have built an experimental active elbow support, with a threefold objective: 1) to investigate whether adult men with DMD could use EMG- and force-based control interfaces; 2) to evaluate their performance during a discrete position-tracking task; and 3) to examine users' acceptance of the control methods. The system was tested in three adults with DMD (21-22 years). Although none of the three participants had performed any voluntary movements with their arms for the past 3-5 years, all of them were 100% successful in performing the series of tracking tasks using both control interfaces (mean task completion time EMG: [Formula: see text] , force: [Formula: see text] ). While movements with the force-based control were considerably smoother in Subject 3 and faster in Subject 1, EMG based-control was perceived as less fatiguing by all three subjects. Both EMG- and force-based interfaces are feasible solutions for the control of active elbow supports in adults with DMD and should be considered for further investigations on multi-DOF control.

BackgroundPersons suffering from progressive muscular weakness, like those with Duchenne muscular dystrophy (DMD), gradually lose the ability to stand, walk and to use their arms. This hinders them from performing daily activities, social participation and being independent. Wheelchairs are used to overcome the loss of walking. However, there are currently few efficient functional substitutes to support the arms. Arm supports or robotic arms can be mounted to wheelchairs to aid in arm motion, but they are quite visible (stigmatizing), and limited in their possibilities due to their fixation to the wheelchair. The users prefer inconspicuous arm supports that are comfortable to wear and easy to control.MethodsIn this paper the design, characterization, and pilot validation of a passive arm support prototype, which is worn on the body, is presented. The A-gear runs along the body from the contact surface between seat and upper legs via torso and upper arm to the forearm. Freedom of motion is accomplished by mechanical joints, which are nearly aligned with the human joints. The system compensates for the arm weight, using elastic bands for static balance, in every position of the arm. As opposed to existing devices, the proposed kinematic structure allows trunk motion and requires fewer links and less joint space without compromising balancing precision.The functional prototype has been validated in three DMD patients, using 3D motion analysis.ResultsMeasurements have shown increased arm performance when the subjects were wearing the prototype. Upward and forward movements were easier to perform. The arm support is easy to put on and remove. Moreover, the device felt comfortable for the subjects. However, downward movements were more difficult, and the patients would prefer the device to be even more inconspicuous.ConclusionThe A-gear prototype is a step towards inconspicuousness and therefore well-received dynamic arm supports for people with muscular weakness.Electronic supplementary materialThe online version of this article (doi:10.1186/s12984-015-0072-y) contains supplementary material, which is available to authorized users.

Due to progressive muscle weakness, the arm function in boys with Duchenne muscular dystrophy (DMD) reduces. An arm support can compensate for this loss of function. Existing arm supports are wheelchair bound, which restricts the ability to perform trunk movements. To evaluate the function of a body-bound arm support, a prototype (based on the Wilmington robotic exoskeleton (WREX) arm support) that allows trunk movements was built. In order to examine the effect of this device and to compare it with an existing wheelchair-bound device, three healthy subjects performed single joint movements (SJMs) and activities of daily living (ADL) with and without the devices. The range of motion (RoM) of the arm and the surface electromyography (sEMG) signal of five different arm muscles were measured. The range of motion increased when compared to the wheelchair-bound device, and the trunk motion was perceived as important to make specific movements easier and more natural, especially the more extreme movements like reaching for a far object and reaching to the top of the head. The sEMG signal was comparable to that of the wheelchair-bound device. This means that an arm support with trunk motion capability can increase the range of motion of the user, while the amount of support to the arm is equal.

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