Design and Experimental Characterization of L-CADEL v2, an Assistive Device for Elbow Motion

Biomechanical study of the effect of traction on elbow joint capsule contracture

Dynamic orthoses have a significant effect on the treatment of elbow capsular contracture. Because of the lack of quantitative research on traction forces, determining the appropriate traction force to help stretch soft tissues and maintain the joint's range of motion is a challenge in the rehabilitation process. We developed a human elbow finite element (FE) model incorporating the activity behavior of the muscles and considering different capsular contracture locations, including total, anterior and posterior capsular contractures, to analyze the internal biomechanical responses of different capsular contracture models during flexion (30 to 80 degrees). Traction loads of 10, 20, 30 and 40 N were applied to the ulna and radius at the maximum flexion angle (80 degrees) to explore the appropriate traction loads at week 4 after a joint capsule injury. We observed a significant increase in posterior capsule stress with anterior capsular contracture (ACC), and the maximum peak stress was 1.3 times higher than that in the healthy model. During the fourth week after elbow capsule injury, the appropriate traction forces for total capsule contracture (TCC), ACC and posterior capsule contracture (PCC) were 20, 10 and 20 N, respectively; these forces maintained a stable biomechanical environment for the elbow joint and achieved a soft tissue pulling effect, thus increasing elbow mobility. The results can be used as a quantitative guide for the rehabilitation physicians to determine the traction load for a specific patient.

Requirements and Solutions for Motion Limb Assistance of COVID-19 Patients

COVID-19 patients are strongly affected in terms of limb motion when imbedded during the acute phase of the infection, but also during the course of recovery therapies. Peculiarities are investigated for design requirements for medical devices in limb motion assistance for those patients. Solutions are analyzed from existing medical devices to outline open issues to provide guidelines for the proper adaption or for new designs supporting patients against COVID-19 effects. Examples are reported from authors’ activities with cable driven assisting devices.

Serious Games Strategies With Cable-Driven Robots for Bimanual Rehabilitation: A Randomized Controlled Trial With Post-Stroke Patients

Cable-driven robots can be an ideal fit for performing post-stroke rehabilitation due to their specific features. For example, they have small and lightweight moving parts and a relatively large workspace. They also allow safe human-robot interactions and can be easily adapted to different patients and training protocols. However, the existing cable-driven robots are mostly unilateral devices that can allow only the rehabilitation of the most affected limb. This leaves unaddressed the rehabilitation of bimanual activities, which are predominant within the common Activities of Daily Living (ADL). Serious games can be integrated with cable-driven robots to further enhance their features by providing an interactive experience and by generating a high level of engagement in patients, while they can turn monotonous and repetitive therapy exercises into entertainment tasks. Additionally, serious game interfaces can collect detailed quantitative treatment information such as exercise time, velocities, and force, which can be very useful to monitor a patient’s progress and adjust the treatment protocols. Given the above-mentioned strong advantages of both cable driven robots, bimanual rehabilitation and serious games, this paper proposes and discusses a combination of them, in particular, for performing bilateral/bimanual rehabilitation tasks. The main design characteristics are analyzed for implementing the design of both the hardware and software components. The hardware design consists of a specifically developed cable-driven robot. The software design consists of a specifically developed serious game for performing bimanual rehabilitation exercises. The developed software also includes BiEval. This specific software allows to quantitatively measure and assess the rehabilitation therapy effects. An experimental validation is reported with 15 healthy subjects and a RCT (Randomized Controlled Trial) has been performed with 10 post-stroke patients at the Physiotherapy’s Clinic of the Federal University of Uberlândia (Minas Gerais, Brazil). The RCT results demonstrate the engineering feasibility and effectiveness of the proposed cable-driven robot in combination with the proposed BiEval software as a valuable tool to augment the conventional physiotherapy protocols and for providing reliable measurements of the patient’s rehabilitation performance and progress. The clinical trial was approved by the Research Ethics Committee of the UFU (Brazil) under the CAAE N° 00914818.5.0000.5152 on plataformabrasil@saude.gov.br.

Integration and Testing of a High-Torque Servo-Driven Joint and Its Electronic Controller with Application in a Prototype Upper Limb Exoskeleton

Mechatronic systems that allow motorized activation in robotic exoskeletons have evolved according to their specific applications and the characteristics of the actuation system, including parameters such as size, mechanical properties, efficiency, and power draw. Additionally, different control strategies and methods could be implemented in various electronic devices to improve the performance and usability of these devices, which is desirable in any application. This paper proposes the integration and testing of a high-torque, servo-driven joint and its electronic controller, exposing its use in a robotic exoskeleton prototype as a case study. Following a brief background review, the development and implementation of the proposal are presented, allowing the control of the servo-driven joint in terms of torque, rotational velocity, and position through a straightforward, closed-loop control architecture. Additionally, the stability and performance of the servo-driven joint were assessed with and without load. In conclusion and based on the obtained results, the servo-driven joint and its control system demonstrate consistent performance under the proposed test protocol (max values: angular velocity 97 °/s, torque 33 Nm, positioning RMSE 1.46°), enabling this approach for use in various applications related to robotic exoskeletons, including human performance enhancement, rehabilitation, or support for daily living activities.