Currently, the mobility of above-knee amputees is limited by the lack of available prostheses that can efficiently replicate biologically accurate movements. In this study, a powered knee prosthesis ...was designed utilizing a novel mechanism, known as a clutchable series-elastic actuator (CSEA).The CSEA includes a low-power clutch in parallel with an electric motor within a traditional series-elastic actuator. The stiffness of the series elasticity was tuned to match the elastically conservative region of the knee’s torque-angle relationship during the stance phase of locomotion. During this region, the clutch was used to efficiently store energy in the series elasticity. The fully autonomous knee prosthesis design utilized a brushless electric motor, ballscrew transmission and cable drive, as well as commercial electrical components. The knee was lighter than the eighth percentile and shorter than the first percentile male shank segment. The CSEA Knee was tested in a unilateral above-knee amputee walking at 1.3 m/s. During walking, the CSEA Knee provided biomechanically accurate torque-angle behavior, agreeing within 17% of the net work and 27% of the stance flexion angle produced by the biological knee. In addition, the process of locomotion reduced the net electrical energy consumption of the CSEA Knee. The knee’s motor generated 1.8 J/stride, and the net energy consumption was 3.6 J/stride, an order of magnitude less energy than previously published powered knee prostheses.
We developed an exoskeleton for neurorehabilitation that covered all relevant degrees of freedom of the human arm while providing enough range of motion, speed, strength, and haptic-rendering ...function for therapy of severely affected (e.g., mobilization) and mildly affected patients (e.g., strength and speed). The ANYexo 2.0, uniting these capabilities, could be the vanguard for highly versatile therapeutic robotics applicable to a broad target group and an extensive range of exercises. Thereby, the practical adoption of these devices in clinics will be fostered. The unique kinematic structure of the robot and the bio-inspired controlled shoulder coupling allowed training for most activities of daily living. We demonstrated this capability with 15 sample activities, including interaction with real objects and the own body with the robot in transparent mode. The robot's joints can reach <inline-formula><tex-math notation="LaTeX">200 \%</tex-math></inline-formula>, <inline-formula><tex-math notation="LaTeX">398 \%</tex-math></inline-formula>, and <inline-formula><tex-math notation="LaTeX">354 \%</tex-math></inline-formula> of the speed required during activities of daily living at the shoulder, elbow, and wrist, respectively. Further, the robot can provide isometric strength training. We present a detailed analysis of the kinematic properties and propose algorithms for intuitive control implementation.
This paper proposes a cable-driven parallel waist rehabilitation robot with two-level control algorithm to assist the patients with waist injuries to do some rehabilitation training. The uniqueness ...of the robot is that it can accurately implement the relative lateral bending, flexion, extension, and rotation of the waist on the premise of the safety. This is enabled by a mechanism design according to the motion characteristics of the human waist, and it can satisfy the need of different waist injury patients. The kinematics and dynamics of the robot are analyzed. In addition, a two-level controller is introduced to improve the accuracy of the rehabilitation training trajectory on the premise of the safety of patients and reduce the system calculation. The proportion-integration-differentiation (PID) algorithm is adopted to realize the position control in the low-level controller to ensure the accuracy of the robot. In the high-level controller, the fuzzy algorithm is used to adjust the parameters of the low-level controller according to the tension variation of cables, which ensures the patient safety and the stable operation of the robot. Finally, a prototype waist rehabilitation robot is developed for experimental calibration and performance testing. Results indicate that the designed robot system can achieve the waist rehabilitation training and the control algorithm can improve the system performance under the external disturbance.
This paper presents an integration of two significant targets, i.e., reducing the output impedance and the vibration at the trajectory tracking, into one variable stiffness actuator (VSA) system. The ...VSA is operated within the cascade impedance control framework, in which the inner torque control loop is designed with the unknown input observer (UIO). The gain-scheduled UIO cooperates with the low and high physical stiffness of the VSA to achieve the low-output impedance and steady trajectory tracking, respectively. The rationality of these implementations is presented considering the stiffness constant and the performance of the control system. The VSA and the gain scheduling-based variable impedance control follow the paradigm of the continuous variable impedance task. In accordance with the knee joint torque, the low and high impedance task with the enhanced performance are applied to a knee exoskeleton with the VSA joint. The effectiveness of the controllers is experimentally verified on a VSA prototype and the exoskeleton with the test person. The robust stability and passivity of the whole control system with the bounded parameter variation rate are investigated.
•A novel application of UIO enhances the performance of the VSA system.•The low-output impedance and trajectory tracking performance can be enhanced.•The gain scheduling-based impedance control, torque control and UIO are designed.•The tests for stability and passivity (interaction stability) are investigated.
The term Cerebral Palsy (CP) is a set of neurological disorders that appear in infancy or early childhood and permanently affect body movement and muscle coordination. The prevalence of CP is ...two–three per 1000 births. Emerging rehabilitation therapies through new strategies are needed to diminish the assistance required for these patients, promoting their functional capability. This paper presents a new robotic platform called CPWalker for gait rehabilitation in patients with CP, which allows them to start experiencing autonomous locomotion through novel robot-based therapies. The platform (smart walker + exoskeleton) is controlled by a multimodal interface that gives high versatility. The therapeutic approach, as well as the details of the interactions may be defined through this interface. CPWalker concept aims to promote the earlier incorporation of patients with CP to the rehabilitation treatment and increases the level of intensity and frequency of the exercises. This will enable the maintenance of therapeutic methods on a daily basis, with the intention of leading to significant improvements in the treatment outcomes.
•Rehabilitation with free displacement and not restricted to a treadmill.•Integration of central nervous system into therapies.•Postural control and partial body weight support for individuals with more severe disorders.•“Assist as needed” approach.•Locomotion strategy based on laser sensor.
This article presents the design and validation of a backdrivable powered knee orthosis for partial assistance of lower-limb musculature, which aims to facilitate daily activities in individuals with ...musculoskeletal disorders. The actuator design is guided by design principles that prioritize backdrivability, output torque, and compactness. First, we show that increasing the motor diameter while reducing the gear ratio for a fixed output torque ultimately reduces the reflected inertia (and thus backdrive torque). We also identify a tradeoff with actuator torque density that can be addressed by improving the motor's thermal environment, motivating our design of a custom brushless dc motor with encapsulated windings. Finally, by designing a 7:1 planetary gearset directly into the stator, the actuator has a high package factor that reduces size and weight. Benchtop tests verify that the custom actuator can produce at least 23.9-N<inline-formula><tex-math notation="LaTeX">\,\cdot\,</tex-math></inline-formula>m peak torque and 12.78-N<inline-formula><tex-math notation="LaTeX">\,\cdot\,</tex-math></inline-formula>m continuous torque, yet has less than 2.68-N<inline-formula><tex-math notation="LaTeX">\,\cdot\,</tex-math></inline-formula>m backdrive torque during walking conditions. Able-bodied human subject experiments (<inline-formula><tex-math notation="LaTeX">N=3</tex-math></inline-formula>) demonstrate reduced quadricep activation with bilateral orthosis assistance during lifting-lowering, sit-to-stand, and stair climbing. The minimal transmission also produces negligible acoustic noise.
This paper describes a lower limb exoskeleton control approach that facilitates a desired movement coordination between the hip and knee joints during the swing phase of gait. An important feature of ...the proposed controller is that it provides movement guidance while allowing a user to control step time and step length. Specifically, control of step time is enabled by the use of time-invariant movement constraints, while control of step length is enabled by a real-time path-planning feature. As such, the controller provides movement coordination, but still enables a user to retain the step-to-step variability required to maintain balance during walking. The controller was implemented on a lower limb exoskeleton and tested on five healthy subjects. The subjects walked overground in the exoskeleton without a stability aid under two conditions: with the proposed coordination controller (i.e., with sagittal plane movement constraints) and with no control implemented (i.e., without sagittal plane movement constraints). Data from these assessments indicate that the controller provided substantial movement coordination while still allowing subjects substantive control of step time and length across a range of walking speeds.
Robot-assisted rehabilitation for three-degree-of-freedom joints, such as hip and ankle, is significant for patients with motor function injuries. The control of such robots involves attitude ...control. To adapt to different disease stages, multi-mode hybrid control is considered to be one of the best choices. Passive mode is based on trajectory tracking control, while active mode is based on field-based assist-as-needed (AAN) control. The key to AAN control is the solution of the closest attitude point. However, the attitude point belongs to a special orthogonal group SO(3), and its topology is completely different from Euclidean space, which causes difficulties to the solution. Both passive and active control methods are affected by the inaccuracy of model parameters and external disturbances. Therefore, this paper proposes a multi-mode hybrid control method on SO(3). First, the expressions of trajectory tracking and contour tracking errors are proposed. To solve the contour tracking error, a feedback linearization algorithm based on sliding surface was used. A radial basis function (RBF) neural network was used for adaptive compensation. Subsequently, a controller for different modes was designed and its stability was analysed. Experiments were conducted using a hip exoskeleton, and the results verified the effectiveness of the proposed control method.
Rehabilitation robots have become important tools in stroke rehabilitation. Compared to manual arm training, robot-supported training can be more intensive, of longer duration and more repetitive. ...Therefore, robots have the potential to improve the rehabilitation process in stroke patients. Whereas a majority of previous work in upper limb rehabilitation robotics has focused on end-effector-based robots, a shift towards exoskeleton robots is taking place because they offer a better guidance of the human arm, especially for movements with a large range of motion. However, the implementation of an exoskeleton device introduces the challenge of reproducing the motion of the human shoulder, which is one of the most complex joints of the body. Thus, this paper starts with describing a simplified model of the human shoulder. On the basis of that model, a new ergonomic shoulder actuation principle that provides motion of the humerus head is proposed, and its implementation in the ARMin III arm therapy robot is described. The focus lies on the mechanics and actuation principle. The ARMin III robot provides three actuated degrees of freedom for the shoulder and one for the elbow joint. An additional module provides actuated lower arm pro/supination and wrist flexion/extension. Five ARMin III devices have been manufactured and they are currently undergoing clinical evaluation in hospitals in Switzerland and in the United States.
Exoskeleton robots found application in neurorehabilitation, telemanipulation, and power augmentation. The human-robot attachment system of an exoskeleton should transmit all the interaction forces ...while keeping the anatomical and robotic joint axes aligned. Existing attachment concepts were bounding the performance of modern exoskeletons due to insufficient stiffness for high-performance force control, time-consuming adaption processes, and/or bulkiness. Therefore, we developed an augmented attachment system for a recent fully actuated nine-degree-of-freedom upper limb exoskeleton. The proposed system was compared to a conventional solution in a case study with four participants. The proposed attachment system lowered the relative motion between the human and the robot under static loads for all defined landmarks by 45% on average. The occurrence of undesired contacts in the trials was mitigated by 74%, thus improving conditions for closed-loop force control. Furthermore, the proposed system adapted better to the user's anatomy facilitating more accurate alignment and less obstruction. On average, self-attachment took <inline-formula><tex-math notation="LaTeX">\mathbf {43(8.3)}</tex-math></inline-formula> <inline-formula><tex-math notation="LaTeX">\mathrm{s}</tex-math></inline-formula> to don(doff). Thereby, the alignment of anatomic landmarks had typically less than 15 mm offset to a thorough expert alignment, making self-attachment eligible. The augmented attachment system and the insights gained by the case study are expected to enable improvement of the physical human-robot interaction of exoskeletons.
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