Modelling of the toe trajectory during normal gait using circle-fit approximation

Advanced rehabilitation in ischaemic stroke research

At present, due to the rapid progress of treatment technology in the acute phase of ischaemic stroke, the mortality of patients has been greatly reduced but the number of disabled survivors is increasing, and most of them are elderly patients. Physicians and rehabilitation therapists pay attention to develop all kinds of therapist techniques including physical therapy techniques, robot-assisted technology and artificial intelligence technology, and study the molecular, cellular or synergistic mechanisms of rehabilitation therapies to promote the effect of rehabilitation therapy. Here, we discussed different animal and in vitro models of ischaemic stroke for rehabilitation studies; the compound concept and technology of neurological rehabilitation; all kinds of biological mechanisms of physical therapy; the significance, assessment and efficacy of neurological rehabilitation; the application of brain-computer interface, rehabilitation robotic and non-invasive brain stimulation technology in stroke rehabilitation.

Untacted automated robotic upper-trunk- lower reciprocal locomotor training for knee osteoarthritis: A randomized controlled trial

BACKGROUND

Although millions of people with osteoarthritis (OA) have altered biomechanical alignment, movement, and knee joint pain during gait, there are no effective and sustainable interventions. To mitigate such impairments, we developed an untacted self-automated robotic and electromyography (EMG)-augmented upper-trunk-lower reciprocal locomotor training (SRGT) intervention.

OBJECTIVE

To compare the effects of SRGT and conventional treadmill gait training (CTGT) on the medial knee joint space width (JSW), hip adduction moment (HAM), knee varus deformity, pain, and physical function in community-dwelling older adults with OA.

METHODS

Older adults diagnosed with medial compartment knee OA (5 men, 35 women; mean age = 78.50 ± 9.10 years) were recruited and underwent either SRGT or CTGT, 30 min a day, 3 times a week, over a 4-week period. Outcome measurements included the JSW, HAM, knee varus angle (VA), and Western Ontario McMaster Universities osteoarthritis index (WOMAC).

RESULTS

Analysis of covariance (ANCOVA) showed that SRGT ed to greater changes in medial knee JSW (p= 0.00001), HAM (p= 0.00001), VA (p= 0.00001), and WOMAC (p= 0.00001) scores.

CONCLUSION

This study provides the first evidence for the long-term clinical and biomechanical effects of SRGT on JSW, knee joint kinematics, kinetics, and WOMAC scores in older adults with OA. Most importantly, self-automatic robotic gait training may be an alternative, effective, and sustainable treatment for the upper-trunk-lower reciprocal locomotor training in older adults with OA.

Development of a Belt-actuated Robotic Platform for Early Rehabilitation

In order to promote early rehabilitation, we proposed a system which provides full-body arm-leg training for patients in a bed-lying position. As the preliminary development, a platform for leg movement was investigated. An innovative system with four servo drives was designed and manufactured. An artificial leg frame was attached to the platform via belts. The positions of the hip and knee joints were recorded using potentiometers. Closed-loop PID position control algorithms were implemented for production of various stepping movements. Technical evaluation on a test participant showed that the platform tracked the circular trajectory of the foot in a supine-lying position with an area difference of 8.2%, and produced walking-like trajectories in the hip and knee joints in a side-lying position with a mean error of 10.6%. The mechanical structure can be resized, and the control system can be expanded, so as to produce 3-dimensional stepping movement in both arms and legs. This innovative platform combined with the closed-loop position control strategy shows the technical potential to be a promising full-body rehabilitation platform for the patients in the early post-injury stage.

Mechanical Design and Control System Development of a Rehabilitation Robotic System for Walking With Arm Swing

Background: Interlimb neural coupling implies that arm swing should be included during gait training to improve rehabilitation outcomes. We previously developed several systems for production of walking with arm swing, but the reaction forces on the foot sole during usage of the systems were not satisfactory and there was potential to improve control system performance. This work aimed to design and technically evaluate a novel system for producing walking with synchronised arm and leg movement and with dynamic force loading on the foot soles.

Methods: The robotic system included a passive curved treadmill and a trunk frame, upon which the rigs for the upper and lower limbs were mounted. Ten actuators and servocontrollers with EtherCAT communication protocol controlled the bilateral shoulder, elbow, hip, knee and ankle joints. Impedance control algorithms were developed and ran in an industrial PC. Flexible pressure sensors recorded the plantar forces on the foot soles. The criteria of implementation and responsiveness were used to formally evaluate the technical feasibility of the system.

Results: Using impedance algorithms, the system produced synchronous walking with arm swing on the curved treadmill, with mean RMS angular tracking error <2° in the 10 joint profiles. The foot trajectories relative to the hip presented similar shapes to those during normal gait, with mean RMS displacement error <1.5 cm. A force pattern that started at the heel and finished at the forefoot was observed during walking using the system, which was similar to the pattern from overground walking.

Conclusion: The robotic system produced walking-like kinematics in the 10 joints and in the foot trajectories. Integrated with the curved treadmill, the system also produced walking-like force patterns on the foot soles. The system is considered feasible as far as implementation and responsiveness are concerned. Future work will focus on improvement of the mechanical system for future clinical application.

Preliminary development and technical evaluation of a belt-actuated robotic rehabilitation platform

BACKGROUND:

To provide effective rehabilitation in the early post-injury stage, a novel robotic rehabilitation platform is proposed, which provides full-body arm-leg rehabilitation via belt actuation to severely disabled patients who are restricted to bed rest.

OBJECTIVE:

To design and technically evaluate the preliminary development of the rehabilitation platform, with focus on the generation of various leg movements.

METHODS:

Two computer models were developed by importing the components from SolidWorks into Simscape Multibody in MATLAB. This allowed simulation of various stepping movements in supine-lying and side-lying positions. Two belt-actuated test rigs were manufactured and automatic control programs were developed in TIA Portal. Finally, the functionality of the test rigs was technically evaluated.

RESULTS:

Computer simulation yielded target positions for the generation of various stepping movements in the experimental platforms. The control system enabled the two-drive test rig to provide three modes of stepping in a supine position. In addition, the four-drive test rig produced walking-like stepping in a side-lying position.

CONCLUSIONS:

This work confirmed the feasibility of the mechanical development and control system of the test rigs, which are deemed applicable for further development of the overall novel robotic rehabilitation platform.

Development of an Improved Rotational Orthosis for Walking With Arm Swing and Active Ankle Control

Based on interlimb neural coupling, gait robotic systems should produce walking-like movement in both upper and lower limbs for effective walking restoration. Two orthoses were previously designed in our lab to provide passive walking with arm swing. However, an active system for walking with arm swing is desirable to serve as a testbed for investigation of interlimb neural coupling in response to voluntary input. Given the important function of the ankle joint during normal walking, this work aimed to develop an improved rotational orthosis for walking with arm swing, which is called ROWAS II, and especially to develop and evaluate the algorithms for active ankle control. After description of the mechanical structure and control schemes of the overall ROWAS II system, the closed-loop position control and adjustable admittance control algorithms were firstly deduced, then simulated in Matlab/Simulink and finally implemented in the ROWAS II system. Six able-bodied participants were recruited to use the ROWAS II system in passive mode, and then to estimate the active ankle mechanism. It was showed that the closed-loop position control algorithms enabled the ROWAS II system to track the target arm-leg walking movement patterns well in passive mode, with the tracking error of each joint <0.7°. The adjustable admittance control algorithms enabled the participants to voluntarily adjust the ankle movement by exerting various active force. Higher admittance gains enabled the participants to more easily adjust the movement trajectory of the ankle mechanism. The ROWAS II system is technically feasible to produce walking-like movement in the bilateral upper and lower limbs in passive mode, and the ankle mechanism has technical potential to provide various active ankle training during gait rehabilitation. This novel ROWAS II system can serve as a testbed for further investigation of interlimb neural coupling in response to voluntary ankle movement and is technically feasible to provide a new training paradigm of walking with arm swing and active ankle control.

Admittance Control of the Ankle Mechanism in a Rotational Orthosis for Walking with Arm Swing

In order to provide an effective system for rehabilitation of walking, a new rotational orthosis for walking with arm swing, called ROWAS II, was developed. This study focused on development and implementation of admittance control of the ankle mechanism in the ROWAS II system for promoting active training. Firstly, the mechanical structure of the ankle mechanism is briefly introduced. Then the algorithms of the closed-loop position control and the admittance control for the ankle mechanism are described in detail. Four able-bodied participants were recruited to use the ankle mechanism running in passive and active modes. The experimental results showed that the ankle mechanism well tracked the target trajectory in passive mode. In active mode, the participants interacted with the ankle mechanism, and adjusted their ankle movement based on their active force. The ankle mechanism has the technical potential to meet the requirements of passive and active training in the ankle movement for patients in different post-stroke stages.

Models for temporal-spatial parameters in walking with cadence ratio as the independent variable

Accurate models that describe temporal-spatial parameters are desirable in gait estimation and rehabilitation. This study aimed to explore simple but relatively accurate models to describe stride length (SL), speed (SP) and walk ratio (WR) at various cadences. Twenty-four able-bodied participants (16 in a test group and 8 in a validation group) walked at seven cadence ratios (CRs). The individual and group mean SL, SP and WR were studied. Suitable temporal-spatial model structures were proposed and used to approximate the individual SL, SP and WR at various CRs. After the temporal-spatial model structures were found to be feasible, the general temporal-spatial models were analysed using the test group mean SL, SP and WR. Accuracy was assessed using the validation group mean values. Individual approximation accuracies showed that the proposed model structure deduced from the linear SL model was suitable for WR approximation. The linear, deduced quadratic and power functions approximated the individual SL, SP and WR, respectively, with high accuracy. Based on the test group mean SL, SP and WR, the general temporal-spatial models were obtained and produced comparable approximation accuracies in the validation group. The general temporal-spatial models predicted well the individual gait parameters with similar individual errors for both groups. These temporal-spatial models clearly describe SL, SP and especially WR at various cadences. They provide accurate reference data for gait estimation and have potential to guide speed modulation in robot-assisted gait rehabilitation.

Graphical abstract

Development of an automatic rotational orthosis for walking with arm swing

Interlimb neural coupling is often observed during normal gait and is postulated to be important for gait restoration. In order to provide a testbed for investigation of interlimb neural coupling, we previously developed a rotational orthosis for walking with arm swing (ROWAS). The present study aimed to develop and evaluate the feasibility of a new system, viz. an automatic ROWAS (aROWAS). We developed the mechanical structures of aROWAS in SolidWorks, and implemented the concept in a prototype. Normal gait data from walking at various speeds were used as reference trajectories of the shoulder, hip, knee and ankle joints. The aROWAS prototype was tested in three able-bodied subjects. The prototype could automatically adjust to size and height, and automatically produced adaptable coordinated performance in the upper and lower limbs, with joint profiles similar to those occurring in normal gait. The subjects reported better acceptance in aROWAS than in ROWAS. The aROWAS system was deemed feasible among able-bodied subjects.

Development and Feasibility Assessment of a Rotational Orthosis for Walking with Arm Swing

Interlimb neural coupling might underlie human bipedal locomotion, which is reflected in the fact that people swing their arms synchronously with leg movement in normal gait. Therefore, arm swing should be included in gait training to provide coordinated interlimb performance. The present study aimed to develop a Rotational Orthosis for Walking with Arm Swing (ROWAS), and evaluate its feasibility from the perspectives of implementation, acceptability and responsiveness. We developed the mechanical structures of the ROWAS system in SolidWorks, and implemented the concept in a prototype. Normal gait data were used as the reference performance of the shoulder, hip, knee and ankle joints of the prototype. The ROWAS prototype was tested for function assessment and further evaluated using five able-bodied subjects for user feedback. The ROWAS prototype produced coordinated performance in the upper and lower limbs, with joint profiles similar to those occurring in normal gait. The subjects reported a stronger feeling of walking with arm swing than without. The ROWAS system was deemed feasible according to the formal assessment criteria.

Selection of clinical features for pattern recognition applied to gait analysis

This paper deals with the opportunity of extracting useful information from medical data retrieved directly from a stereophotogrammetric system applied to gait analysis. A feature selection method to exhaustively evaluate all the possible combinations of the gait parameters is presented, in order to find the best subset able to classify among diseased and healthy subjects. This procedure will be used for estimating the performance of widely used classification algorithms, whose performance has been ascertained in many real-world problems with respect to well-known classification benchmarks, both in terms of number of selected features and classification accuracy. Precisely, support vector machine, Naive Bayes and K nearest neighbor classifiers can obtain the lowest classification error, with an accuracy greater than 97 %. For the considered classification problem, the whole set of features will be proved to be redundant and it can be significantly pruned. Namely, groups of 3 or 5 features only are able to preserve high accuracy when the aim is to check the anomaly of a gait. The step length and the swing speed are the most informative features for the gait analysis, but also cadence and stride may add useful information for the movement evaluation.