Robotic Knee Orthosis Research Articles

DESIGN OF A ROBOTIC EXO-SUIT FOR KNEE LATERAL SUPPORT WITH AN INTERACTION CONTROL BASED ON RELATIVE MOTION ANGLE

In this study, we focused on the design and control of a single DoF laterally supported knee exoskeleton robot designed to improve the load-carrying and strength capacity of healthy individuals, especially soldiers and workers. First, a nonlinear second-order differential model of the robotic knee orthosis was produced. Then, a single degree of freedom exoskeleton robot was designed and manufactured. An interactive motion control method based on the relative angle measurement principle between the knee joint of the user and the exo-suit knee joint was proposed. The user’s knee joint motion is detected via an IMU sensor, and a controller was provided to allow the exo-suit to track the human knee joint in synchrony. In this study, a conventional PID, SMC, and moving surface SMC controllers were designed, and the controllers’ performance were tested in real-time experiments. The maximum tracking errors in the PID, SMC, and MSMC controllers were 2.631∘, 1.578∘, and 1.289∘, respectively, and the average tracking time errors were 0.10, 0.08, and 0.06 s, respectively. In addition, the designed and produced knee orthosis weighs 2.5 kg, making it one of the lightest and most compact designs for use by healthy individuals. The knee orthosis was made of steel, and thus it is very durable for use in all kinds of terrain conditions (military, industrial, etc.). Experimental findings about the proposed design and control method are analyzed in the results and discussion section.

Effects of Assistance During Early Stance Phase Using a Robotic Knee Orthosis on Energetics, Muscle Activity, and Joint Mechanics During Incline and Decline Walking.

The knee joint performs a significant amount of positive or negative mechanical work during gradient walking, and targeted assistance during periods of high mechanical work could yield strong human augmentation benefits. This paper explores the biomechanical effects of providing knee extension assistance during the early stance phase of the gait cycle using a powered unilateral knee exoskeleton during gradient walking on able-bodied subjects. Twelve subjects walked on 15% gradient incline and decline surfaces with the exoskeleton providing knee extension assistance during the early stance phase of the gait cycle. For both incline and decline walking, the exoskeleton assistance reduced the muscle activation of the knee extensors on the assisted leg ( ). However, only approximately half the individuals responded to exoskeleton assistance positively by reducing their metabolic cost of walking for both incline and decline tasks. The results indicate that, unlike the individuals who did respond, the individuals who did not respond to the assistance may have penalized their metabolic cost by their biomechanical compensatory behaviors from the unassisted leg.

Examination of the intervention effect of the rehabilitation of the robotic knee orthosis

Examination of the intervention effect of the rehabilitation of the robotic knee orthosis

Development and Evaluation of a Powered Artificial Gastrocnemius for Transtibial Amputee Gait

Existing robotic transtibial prostheses provide only ankle joint actuation and do not restore biarticular function of the gastrocnemius muscle. This paper presents the first powered biarticular transtibial prosthesis, which is a combination of a commercial powered ankle-foot prosthesis and a motorized robotic knee orthosis. The orthosis is controlled to emulate the human gastrocnemius based on neuromuscular models of matched nonamputees. Together with the ankle-foot prosthesis, the devices provide biarticular actuation. We evaluate differences between this biarticular condition and a monoarticular condition with the orthosis behaving as a free-joint. Six participants with transtibial amputation walk with the prosthesis on a treadmill while motion, force, and metabolic data are collected and analyzed for differences between conditions. The biarticular prosthesis reduces affected-side biological knee flexion moment impulse and hip positive work during late-stance knee flexion, compared to the monoarticular condition. The data do not support our hypothesis that metabolism decreases for all participants, but some participants demonstrate large metabolic reductions with the biarticular condition. These preliminary results suggest that a powered artificial gastrocnemius may be capable of providing large metabolic reductions compared to a monoarticular prosthesis, but further study is warranted to determine an appropriate controller for achieving more consistent metabolic benefits.

Exercise using a robotic knee orthosis in stroke patients with hemiplegia.

[Purpose] The Robotics Knee Orthosis (RKO) is a knee–ankle–foot orthosis with active robot assisting technology. The purpose of this study is to examine the effects of exercise with the RKO (RKO-exercise) in stroke patients with hemiplegia. [Subjects and Methods] Participants were nine stroke patients with hemiplegia, residing in a convalescent rehabilitation ward. The duration of the RKO-exercise program was 10 days. Participants were evaluated three times prior to intervention, once after intervention, and one month post intervention. Each session consisted of standard-of-care physical therapy for 60 minutes and RKO-exercise for 20 minutes. Dependent variables were 10-meter gait speed, cadence, Berg Balance Scale (BBS) score, stride length, the absolute value of left-right symmetry of the step length, and one-leg support period while walking. Data were analyzed using a one-way repeated measures ANOVA. [Results] Stride length, left-right symmetry of the step length, and one-leg support period while walking changed following the RKO exercise program. 10-meter walking speed, cadence, percentage of one-leg support period (affected side), and BBS changed significantly at one month post treatment time points. [Conclusion] It is expected that RKO-exercise helps recovery process after the stroke. RKO-exercise effectively treats impaired mobility in patient status-post stroke.

脳血管障害片麻痺患者に対するRobotics Knee Orthosisを使用した練習の効果

脳血管障害片麻痺患者に対するRobotics Knee Orthosisを使用した練習の効果

Robot-Aided Gait Training in an Individual With Chronic Spinal Cord Injury

Traditional physical therapy is beneficial in restoring mobility in individuals who have sustained spinal cord injury (SCI), but residual limitations often persist. Robotic technologies may offer opportunities for further gains. The purpose of this case study was to document the use and practicality of gait training for an individual with chronic, incomplete SCI with asymmetric lower limb motor deficits using a novel robotic knee orthosis (RKO). The participant was a 22-year-old woman who sustained fractures of the odontoid process and C5-C6 vertebrae from a motor vehicle accident resulting in incomplete SCI with asymmetric tetraparesis, right side more severe than left side. She required supervised assistance with gait and balance tasks, minimal assistance to ascend/descend steps using a handrail, and upper extremity assistance for sit-to-stand tasks. The participant underwent 7 one-hour sessions of mobility training, using a novel RKO. Her primary goal was to increase independence and endurance with mobility. Functional measures included the 6-Minute Walk Test, the Berg Balance Scale, the Timed Up & Go Test, and the 10-Meter Walk Test. Outcomes were assessed and recorded at baseline and on completion of 7 hours of training with the device over a 2-week period. No adverse events occurred. The RKO was well received by both the participant and the treating therapist. The participant demonstrated improvements in the 6-Minute Walk Test and Berg Balance Scale after RKO-training intervention. Outcomes suggest that the use of this device during a physical therapy program for an individual with incomplete SCI is practical and this device may be a useful adjunct to standard training.

A wearable robotic knee orthosis for gait training

Until recently, robotic devices for stroke rehabilitation had multi-joint designs that were often tethered to a treadmill for gait training. A new single-joint wearable robotic knee orthosis (RKO) has been designed that provides patient-initiated powered-assistance in untethered functional mobility. This case-series documents application of the wearable RKO in untethered functional training with stroke survivors. Three ambulatory adult stroke survivors used a wearable RKO during 18 one-hour sessions within a six-week physical therapy programme. Subjects were assessed with a variety of balance, gait and functional tests including the Berg Balance Scale (BBS); six-minute walk test (6MWT); and Emory Functional Ambulation Profile (EFAP) at pre-treatment, post-treatment, one-month and three-month follow-up. All subjects improved balance, gait and functional performances with mean individual improvements of 12.6% for BBS, 12.0% for 6MWT and 16.7% for EFAP post-treatment. No adverse events occurred. These three stroke survivors may have benefited from the task-specific functional training programme augmented by RKO use.

유전자 알고리즘을 이용한 새로운 무릎 보장구의 최적 설계

The objective of this paper is to optimize the design parameters of a novel mechanism for a robotic knee orthosis. The feature of the proposed knee othosis is to drive a knee joint with independent actuation during swing and stance phases, which can allow an actuator with fast rotation to control swing motions and an actuator with high torque to control stance motions, respectively. The quadriceps device operates in five-bar links with 2-DOF motions during swing phase and is changed to six-bar links during stance phase by the contact motion to the patella device. The hamstring device operates in a slider-crank mechanism for entire gait cycle. The suggested kinematic model will allow a robotic knee orthosis to use compact and light actuators with full support during walking. However, the proposed orthosis must use additional linkages than a simple four-bar mechanism. To maximize the benefit of reducing the actuators power by using the developed kinematic design, it is necessary to minimize total weight of the device, while keeping necessary actuator performances of torques and angular velocities for support. In this paper, we use a SGA (Simple Genetic Algorithm) to minimize sum of total link lengths and motor power by reducing the weight of the novel knee orthosis. To find feasible parameters, kinematic constraints of the hamstring and quadriceps mechanisms have been applied to the algorithm. The proposed optimization scheme could reduce sum of total link lengths to half of the initial value. The proposed optimization scheme can be applied to reduce total weight of general multi-linkages while keeping necessary actuator specifications.

회전기 및 착지기 분리 구동을 가능케 하는 새로운 무릎 보장구의 기구부 설계

Nowadays many neurological diseases such as stroke and Parkinson diseases are continually increasing. Orthotic devices as well as exoskeletons have been widely developed for supporting movement assistance and therapy of patients. Robotic knee orthosis can compensate stiff-knee gait of the paralyzed limb and can provide patients consistent assistance at wearable environments. With keeping a robotic orthosis wearable, however, it is not easy to develop a compact and safe actuator with fast rotation and high torque for consistent supports of patients during walking. In this paper, we propose a novel kinematic model for a robotic knee orthosis to drive a knee joint with independent actuation during swing and stance phases, which can allow an actuator with fast rotation to control swing motions and an actuator with high torque to control stance motions, respectively. The suggested kinematic model is composed of a hamstring device with a slide-crank mechanism, a quadriceps device with five-bar/six-bar links, and a patella device for knee covering. The quadriceps device operates in five-bar links with 2-dof motions during swing phase and is changed to six-bar links during stance phase by the contact motion to the patella device. The hamstring device operates in a slider-crank mechanism for entire gait cycle. The kinematics and velocity/force relations are analyzed for the quadriceps and hamstring devices. Finally, the adequate actuators for the suggested kinematic model are designed based on normal gait requirements. The suggested kinematic model will allow a robotic knee orthosis to use compact and light actuators with full support during walking.

Preswing Knee Flexion Assistance Is Coupled With Hip Abduction in People With Stiff-Knee Gait After Stroke

Stiff-knee gait is defined as reduced knee flexion during the swing phase. It is accompanied by frontal plane compensatory movements (eg, circumduction and hip hiking) typically thought to result from reduced toe clearance. As such, we examined if knee flexion assistance before foot-off would reduce exaggerated frontal plane movements in people with stiff-knee gait after stroke. We used a robotic knee orthosis to assist knee flexion torque during the preswing phase in 9 chronic stroke subjects with stiff-knee gait on a treadmill and compared peak knee flexion, hip abduction, and pelvic obliquity angles with 5 nondisabled control subjects. Maximum knee flexion angle significantly increased in both groups, but instead of reducing gait compensations, hip abduction significantly increased during assistance in stroke subjects by 2.5 degrees , whereas no change was observed in nondisabled control subjects. No change in pelvic obliquity was observed in either group. Hip abduction increased when stroke subjects received assistive knee flexion torque at foot-off. These findings are in direct contrast to the traditional belief that pelvic obliquity combined with hip abduction is a compensatory mechanism to facilitate foot clearance during swing. Because no evidence suggested a voluntary mechanism for this behavior, we argue that these results were most likely a reflection of an altered motor template occurring after stroke.