Abstract:Introduction1 KAFOs (knee-ankle-foot orthoses) are prescribed to paraplegic patients with low level spinal cord injury and with good control of the trunk muscles. According to approximate data from AACD (Associação de Assistência à Criança Deficiente -Association for the Assistance of Handicapped Children), among the patients that could use lower limb orthoses, the rejection rate is as high as 95%; the majority of the patients opts for wheelchair locomotion. The most important reasons for such a rejection rate… Show more
“…Knee-ankle-foot orthoses are frequently employed to help hemiplegic patients correct their gait. Ackermann and Cozman [7] used a spring at the patient's knee joint to generate the necessary knee extension at the end of the swing phase. Energy stored in the spring was also used to create knee flexion at the start of the swing phase.…”
Section: Introductionmentioning
confidence: 99%
“…The effect of the orthosis on the knee joint during the swing phase was not considered by Ackermann and Cozman [7]. Also, a spring was used at the knee joint to create knee and hip flexion.…”
The use of assistive devices to control the loss of strength and range of motion of hemiplegic patients is becoming common. It is difficult to develop a precise control approach for a knee orthosis system because of the unpredictability of the dynamics and the unwanted subject’s spasm, jerk, and vibration during gait assistance. In this study, an adaptive neuro-fuzzy inference system (ANFIS) control system based on a nonlinear disturbance observer (NDO) and dynamic sliding mode controller (DSMC) is presented to restore the natural gait of hemiplegic patients experiencing mobility disorder and strength loss as well as monitor patient-induced disturbances and parameter variations during semiactive assistance of both the stance and swing phases. The knee orthosis system’s nonlinear dynamic relations are first developed using the Euler–Lagrange formation. Using MATLAB/Simulink, the dynamic model and controller design for the knee orthosis system was created. The Lyapunov theory is then used to ensure the knee orthosis system is asymptotically stable in view of the proposed controller once the proposed control scheme has been designed. The proposed control scheme’s (ANFIS–NDO–DSMC) gait tracking performances are shown and contrasted with the conventional sliding mode controller (SMC). Furthermore, a comparative performance analysis for parametric uncertainties and disturbances is presented to look at the robustness of the proposed controller (ANFIS–NDO–DSMC). The coefficient of determination (
R
2
) and root mean square error (RMSE) between the reference knee angle and ANFIS–NDO–DSMC for stance phase are 1 and 0.000516 rad, respectively. For swing phase,
R
2
and RMSE are 0.9999 and 0.003202 rad, respectively. For SMC, RMSE is 0.000643 and 0.003252 rad for stance and swing phases, respectively. Stance and swing phase
R
2
is 0.9997 and 0.9994, respectively. As seen from simulation results, the proposed controller exhibited excellent gait tracking performance for the knee orthosis control with high robustness and very fast convergence to a steady state compared to SMC.
“…Knee-ankle-foot orthoses are frequently employed to help hemiplegic patients correct their gait. Ackermann and Cozman [7] used a spring at the patient's knee joint to generate the necessary knee extension at the end of the swing phase. Energy stored in the spring was also used to create knee flexion at the start of the swing phase.…”
Section: Introductionmentioning
confidence: 99%
“…The effect of the orthosis on the knee joint during the swing phase was not considered by Ackermann and Cozman [7]. Also, a spring was used at the knee joint to create knee and hip flexion.…”
The use of assistive devices to control the loss of strength and range of motion of hemiplegic patients is becoming common. It is difficult to develop a precise control approach for a knee orthosis system because of the unpredictability of the dynamics and the unwanted subject’s spasm, jerk, and vibration during gait assistance. In this study, an adaptive neuro-fuzzy inference system (ANFIS) control system based on a nonlinear disturbance observer (NDO) and dynamic sliding mode controller (DSMC) is presented to restore the natural gait of hemiplegic patients experiencing mobility disorder and strength loss as well as monitor patient-induced disturbances and parameter variations during semiactive assistance of both the stance and swing phases. The knee orthosis system’s nonlinear dynamic relations are first developed using the Euler–Lagrange formation. Using MATLAB/Simulink, the dynamic model and controller design for the knee orthosis system was created. The Lyapunov theory is then used to ensure the knee orthosis system is asymptotically stable in view of the proposed controller once the proposed control scheme has been designed. The proposed control scheme’s (ANFIS–NDO–DSMC) gait tracking performances are shown and contrasted with the conventional sliding mode controller (SMC). Furthermore, a comparative performance analysis for parametric uncertainties and disturbances is presented to look at the robustness of the proposed controller (ANFIS–NDO–DSMC). The coefficient of determination (
R
2
) and root mean square error (RMSE) between the reference knee angle and ANFIS–NDO–DSMC for stance phase are 1 and 0.000516 rad, respectively. For swing phase,
R
2
and RMSE are 0.9999 and 0.003202 rad, respectively. For SMC, RMSE is 0.000643 and 0.003252 rad for stance and swing phases, respectively. Stance and swing phase
R
2
is 0.9997 and 0.9994, respectively. As seen from simulation results, the proposed controller exhibited excellent gait tracking performance for the knee orthosis control with high robustness and very fast convergence to a steady state compared to SMC.
“…His actuation system aimed to produce an impedance-controlled gait rehabilitation robot for treadmill training. Similarly, Ackermann 15 and Sulzer 16 developed a powered knee orthosis that can provide knee flexion torque in the swing phase to compensate for the gait abnormality known as stiff-knee gait (SKG). But even though both knee actuation systems produce high torque with small impedance, they are limited to treadmill-training applications since the actuators must be located on a fixed base.…”
SUMMARYIt is important to develop a robotic orthosis or exoskeleton that can provide back-drivable and good assistive performances with lightweight structures for overground gait rehabilitation of stroke patients. In this paper, we describe a robotic knee device with a five-bar linkage to allow low-impedance voluntary knee motion within a specified rotation range during the swing phase, and to assist knee extension during the stance phase. The device can provide free motion through the five-bar linkage with 2-degree-of-freedom (DOF) actuation via the patient's shank using a linear actuator, and can assist knee extension at any controlled knee angle while bearing weight via a geared five-bar linkage with 1 DOF actuation of the linear actuator. The kinematic transition between the two modes can be implemented by contact with a circular structure and a linear link, and the resultant range of motion can be determined by the linear actuator. The kinematic weight of the device was optimized using the simple genetic algorithm to reduce the mass. The optimization cost function was based on the sum of the total link lengths and the actuator power. The optimization results reduced the total link length and motor power by 47% and 43%, respectively, compared to the initial design. We expect that the device will facilitate rehabilitation of stroke patients by allowing safe and free overground walking while providing support for stumbling.
Due to the aging of the population or diseases, the number of patients with lower limb disorders has increased, causing social concern. Scholars have designed and developed advanced robotic lower limb orthoses, which can guide patients to perform reasonable rehabilitation training with correct limb postures, enhance their daily life participation and quality of life, and help them recover quickly. In recent years, a large number of new and advanced orthopedic equipment have been developed, which require a systematic summary analysis and comparison. This article reviewed typical newly developed, robotic lower limb orthoses and their use effects, as well as the advanced theories and technologies for their applications, and systematically discussed the problems in the research, design, testing, use, and popularization of robotic lower limb orthoses, and predicted their development direction in the future research and design, to enhance the reliability, convenience, and protection functions of orthotic equipment, make its functions closer to life, and give full play to the initiative of patients in the process of rehabilitation training, and reduce costs. Robotic lower limb orthoses is poised for even greater success and development in the future.
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