Hiroaki Kawamoto

Intention-Based Walking Support for Paraplegia Patients with Robot Suit HAL

This paper proposes an algorithm to estimate human intentions related to walking in order to comfortably and safely support a paraplegia patients walk. Robot Suit HAL (Hybrid Assistive Limb) has been developed for enhancement of a healthy persons activities and for support of a physically challenged persons daily life. The assisting method based on bioelectrical signals such as myoelectricity successfully supports a healthy persons walking. These bioelectrical signals, however, cannot be measured properly from a paraplegia patient. Therefore another interface that can estimate a patients intentions without any manual controller is desired for robot control since a manual controller deprives a patient of his/her hand freedom. Estimation of a patients intentions contributes to providing not only comfortable support but also safe support, because any inconformity between the robot suit motion and the patient motion results in his/her stumbling or falling. The proposed algorithm estimates a patients in...

Control method of robot suit HAL working as operator's muscle using biological and dynamical information

For assisting human motion, assistive devices working as muscles would be useful. A robot suit HAL (hybrid assistive limb) has been developed as an assistive device for lower limbs. Human can appropriately produce muscle contraction torque and control joint viscoelasticity by muscle effort such as co-contraction. Thus, to implement functions equivalent to human muscles using HAL, it is necessary to control viscoelasticity of HAL as well as to produce torque in accordance with operators intention. Therefore the purpose of this study is to propose a control method of HAL using biological and motion information. In this method, HAL produces torque corresponding to muscle contraction torque by referring to the myoelectricity that is biological information to control operators muscles. In addition, the viscoelasticities of HAL are adjusted in proportion to operators viscoelasticity that is estimated from motion information by using an on-line parameter identification method. To evaluate the effectiveness of the proposed method, the method was applied to a swinging motion of a lower leg. When this method was applied, HAL could work like operators muscles in the swinging motion, and as a consequence, the muscle activities of the operator were reduced. As a result of this experiment, we confirmed the effectiveness of the proposed method.

Power assist method for HAL-3 using EMG-based feedback controller

We have developed the exoskeletal robotics suite HAL (Hybrid Assistive Leg) which is integrated with human and assists suitable power for lower limb of people with gait disorder. This study proposes the method of assist motion and assist torque to realize a power assist corresponding to the operators intention. In the method of assist motion, we adopted Phase Sequence control which generates a series of assist motions by transiting some simple basic motions called Phase. We used the feedback controller to adjust the assist torque to maintain myoelectricity signals which were generated while performing the power assist walking. The experiment results showed the effective power assist according to operators intention by using these control, methods.

Power Assist System HAL-3 for Gait Disorder Person

We have developed the power assistive suit, HAL (Hybrid Assistive Leg) which provide the self-walking aid for gait disorder persons or aged persons. In this paper, We introduce HAL-3 system, improving HAL-1,2 systems which had developed previously. EMG signal was used as the input information of power assist controller. We propose a calibration method to identify parameters which relates the EMG to joint torque by using HAL-3. We could obtain suitable torque estimated by EMG and realize an apparatus that enables power to be used for walking and standing up according to the intention of the operator.

Power assist method based on Phase Sequence and muscle force condition for HAL

An exoskeleton robot can replace the wearers motion function by operating the humans body. The purpose of this study is to propose a power assist method of walking, standing up and going up stairs based on autonomous motion of the exoskeleton robot suit, HAL (Hybrid assistive Limb), and verify the effectiveness of this method by experiment. In order to realize power assist of tasks (walking, standing up and going up stairs) autonomically, we used the Phase Sequence control which generates a task by transiting some simple basic motions called Phases. A task was divided into some Phases on the basis of the task performed by a normal person. The joint moving modes were categorized into active, passive and free modes according to the characteristic of the muscle force conditions. The autonomous motions which HAL generates in each Phase were designed corresponding to one of the categorized modes. The power assist experiments were performed by using the autonomous motion with a focus on the active mode. The experimental results showed that the wearers muscle activation levels in each Phase were significantly reduced. With this, we confirmed the effectiveness of the proposed assist method.

Comfortable power assist control method for walking aid by HAL-3

We have developed the power assist suit HAL (Hybrid Assistive Leg) which provide the self-walking aid for gait disorder persons or aged persons. The power assist was performed according to the operators intention by using myoelectricity(EMG) signal as the primary command signal. However, there remains the problem that the operator senses the discomfort while the power assist is performed by EMG-based control. The scope of the present research is to propose the control methods to reduce the discomfort which the operator sense while the EMG-based power assist is performed in walking and standing up respectively; 1) the control method that the integrated motion between HAL-3 and the operator corresponds with the particularity of operators musculo-skeletal system while in the power assist walking, 2) the predictive control method applying feedforward controller to remove the discomfort while in standing up. As the result, the power assist walking was performed corresponding to the joint kinematics of the normal walking without the assistance. Applying feedforward controller realized the quick response while in standing up power assist. These control methods enabled HAL-3 to realize the power assist that the operator sensed the reduce of discomfort.

Power assist method for HAL-3 estimating operator's intention based on motion information

This paper describes the recognition method and the control method to realize the power assist which reflects operators intention by grasping the interaction between operators intention and motion information. The basic control method for HAL had been performed by using myoelectricity which reflects operators intention. As the application of the basic method, we considered the control method of power assist based on another information by considering the relation between myoelectricity and another information of motion, and the recognition method for the control method. We adopted phase sequence control which generated a series of assist motions by the transition of some fundamental motions called phase. The result of experiments showed the effective power assist which reflected operators intention by using this control method.

Development of single leg version of HAL for hemiplegia

Our goal is to try to enhance the QoL of persons with hemiplegia by the mean of an active motion support system based on the HAL’s technology. The HAL (Hybrid Assistive Limb) in its standard version is an exoskeleton-based robot suit to support and enhance the human motor functions. The purpose of the research presented in this paper is the development of a new version of the HAL to be used as an assistive device providing walking motion support to persons with hemiplegia. It includes the realization of the single leg version of the HAL and the redesign of the original HAL’s Autonomous Controller to execute human-like walking motions in an autonomous way. Clinical trials were conducted in order to assess the effectiveness of the developed system. The first stage of the trials described in this paper involved the participation of one hemiplegic patient who has difficulties to flex his right knee. As a result, the knee flexion support for walking provided by the HAL appeared to improve the subject’s walking (longer stride and faster steps). The first evaluation of the system with one subject showed promising results for the future developments.

Feasibility of rehabilitation training with a newly developed wearable robot for patients with limited mobility

OBJECTIVE To investigate the feasibility of rehabilitation training with a new wearable robot. DESIGN Before-after clinical intervention. SETTING University hospital and private rehabilitation facilities. PARTICIPANTS A convenience sample of patients (N=38) with limited mobility. The underlying diseases were stroke (n=12), spinal cord injuries (n=8), musculoskeletal diseases (n=4), and other diseases (n=14). INTERVENTIONS The patients received 90-minute training with a wearable robot twice per week for 8 weeks (16 sessions). MAIN OUTCOME MEASURES Functional ambulation was assessed with the 10-m walk test (10MWT) and the Timed Up & Go (TUG) test, and balance ability was assessed with the Berg Balance Scale (BBS). Both assessments were performed at baseline and after rehabilitation. RESULTS Thirty-two patients completed 16 sessions of training with the wearable robot. The results of the 10MWT included significant improvements in gait speed, number of steps, and cadence. Although improvements were observed, as measured with the TUG test and BBS, the results were not statistically significant. No serious adverse events were observed during the training. CONCLUSIONS Eight weeks of rehabilitative training with the wearable robot (16 sessions of 90min) could be performed safely and effectively, even many years after the subjects received their diagnosis.

Voluntary motion support control of Robot Suit HAL triggered by bioelectrical signal for hemiplegia

Our goal is to enhance the quality of life of patients with hemiplegia by means of an active motion support system that assists the impaired motion such as to make it as close as possible to the motion of an able bodied person. We have developed the Robot Suit HAL (Hybrid Assistive Limb) to actively support and enhance the human motor functions. The purpose of the research presented in this paper is to propose the required control method to support voluntarily motion using a trigger based on patients bioelectrical signal. Clinical trials were conducted in order to investigate the effectiveness of the proposed control method. The first stage of the trials, described in this paper, involved the participation of one hemiplegic patient who is not able to bend his right knee. As a result, the motion support provided by the HAL moved the paralyzed knee joint according to his intention and improved the range of the subjects knee flexion. The first evaluation of the control method with one subject showed promising results for future trials to explore the effectiveness for a wide range of types of hemiplegia.