Tadaaki Ikehara

Development of closed-fitting-type walking assistance device for legs and evaluation of muscle activity

A walking assistance device using a flexible shaft was developed. The combination of a flexible shaft with a worm gear was successfully adopted on this device to simplify its appearance and reduce its size. A hybrid — control system on this device controls both torque and angle at the ankle and knee joints. In this system, the torsional spring constant of the flexible shaft is taken into account by the motor in controlling the power and angle of rotation of the motor. To expand the area in which a person may use the device, it is equipped with a self-contained system powered by a Lithium-ion battery and controlled by an SH-4 microcomputer and actuators, consisting of motors and gears, all of which are carried in a small backpack. Consequently, persons using the device may walk freely in both indoor and outdoor environments.

Walking assistance apparatus using a spatial parallel link mechanism and a weight bearing lift

A prototype for a walking assistance apparatus for the elderly or motor palsy patients was developed as a next-generation vehicle or movable neuro-rehabilitation training appliance, using a novel spatial parallel link mechanism and a bearing lift. The flat steps of the apparatus move in parallel with the ground; the apparatus can support entire leg alignment (including soles) and assist; walking behavior at ankle, knee and hip joints simultaneously. In order to respond the variation of equipped persons walking velocity, the length of stride and walking cycle while walking with wearing the apparatus were compensated by using the relation of walking ratio. Therefore the apparatus can be controlled in response to equipped persons will. Motor palsy and muscle weakness patients can walk by themselves by using the apparatus; patients who have ambulation difficulty can use the apparatus with weight bearing lift that we developed. Using the apparatus with the weight bearing lift prevents stumbling and enables input of walking movement to the brain motor area. It is very effective for rehabilitation to use the apparatus with the weight bearing lift. This newly developed system facilitates motor palsy and muscle weakness patients in the rehabilitation program.

Development of a walking assistance apparatus using a spatial parallel link mechanism and evaluation of muscle activity

A prototype for a walking assistance apparatus for the elderly or motor palsy patients was developed, using a novel spatial parallel link mechanism. The flat steps of the apparatus move in parallel with the ground; the apparatus can support entire leg alignment (including soles) and assist; walking behavior at ankle, knee and hip joints simultaneously. By using a flexible link, constructed of stainless steel and rubber, the apparatus can realize the natural twisting motions of the ankle. Furthermore, in order to assist walking on uneven surfaces, we investigated walking on a slopes or stairs. For these tasks, the apparatus was equipped with a gyro sensor and an ultrasonic sensor; so the angle of the slope and the height of the stairs could be recognized. The apparatus adapted according to the signals from these sensors. Results owed that our experiment, the equipped person wearing the apparatus could walk on slopes and stairs. Motor palsy and muscle weakness patients can walk by themselves by using the apparatus; patients who have ambulation difficulty can use the apparatus with weight bearing lift that we developed. Using the apparatus with the weight bearing lift prevents stumbling and enables input of walking movement to the brain motor area. It may be beneficial for rehabilitation to use the apparatus with the weight bearing lift. This newly developed system may facilitate motor palsy and muscle weakness patients in the rehabilitation program. The effectiveness of the apparatus for one hour walking was evaluated by variation of Mean Power Frequency (MPF) of the Electromyography (EMG) data with continuous wavelet analysis. Muscle fatigue of the Tibialis Anterior muscle (TA) decreased during wearing of the apparatus. We showed the effectiveness of using the apparatus in walking.

Development of a control method of a walking assistance apparatus for the elderly or rehabilitants

A prototype for a walking assistance apparatus for the elderly or rehabilitants of motor palsy patients was developed as a next-generation vehicle or movable neuro-rehabilitation training appliance, using a novel spatial parallel link mechanism and a bearing lift. The flat steps of the apparatus move in parallel with the ground; the apparatus can support entire leg alignment (including soles) and assist; walking behavior at ankle, knee and hip joints simultaneously. To respond to the variation of equipped person’s walking velocity, the length of stride and walking cycle while walking with wearing the apparatus were compensated by using walking ratio. Therefore the apparatus can be controlled in response to equipped person’s will. Next, we developed a control method of the apparatus by using impedance control, taking into account the dynamics of the apparatus and the legs of an equipped person, and assist ratio for the equipped person. By adjusting the value of natural angular frequency of the desired dynamic equation for the equipped person, this apparatus can assist walking according to the equipped person’s desired response of the apparatus. Furthermore, motor palsy and muscle weakness patients can walk by themselves by using the apparatus; patients who have ambulation difficulty can use the apparatus with weight bearing lift that we developed. Using the apparatus with the weight bearing lift prevents stumbling and enables input of walking movement to the brain motor area. From the results of measured %MVC, the validity of the weight bearing lift was shown.Copyright

Study on the walking support machine indoors by assisting whole legs

There is currently research to support the construction of a walking assist machine, which machine uses a spatial parallel link mechanism for the elderly or rehabilitants. The flat steps of the assist machine move in parallel with the ground and can support the legs of a person including the soles. We developed a prototype and designed to assist people walking at up to fifty percent power. To grasp the walking phase of each leg of the equipped person, pressure sensors were laid under the thenar eminence and the heel of the sole, and the pressure variation at each sensing point was measured. For safety support, we developed a control method of the walking assist machine to fit the motion in phase by phase. Furthermore, in order to support walking indoors, we investigated the assist methods of turning around during walking and walking on a slope or stairs. A flexible link was installed in the mechanism for taking into account the twisting motions of the waist and ankle. To grasp the behavior of turning around during walking of the equipped person, pressure sensors were attached outside of the flexible link in both crural parts of the machine. As a result of the experiment wearing the machine, the equipped person could turn around during walking at will. To confirm the validity of the supporting method, muscle activity of the leg while wearing the walking assist machine evaluated by using the surface electromyography (called as “EMG”), and calculated the ratio of the integrated EMG (called as “IEMG”) with and without the walking assist machine. The initial results show that the activities of the rectus femoris muscle and the tibialis anterior muscle can be held to approximately 60 percent by wearing the walking assist machine. Furthermore, in order to support walking indoors, we investigated the assist methods of walking on a slope or stairs. The machine was equipped with a gyro sensor and an ultrasonic sensor; the angle of the slope and the size of stairs could recognize and the machine could be controled according to the signals from the sensors. As a result of the experiment wearing the machine, the equipped person could walk on a slope or stairs at will. The subject assisted with the machine was able to walk on a slope up to the angle of plus or minus fifteen degrees.Copyright

Development of a device that combines exercise and entertainment

The purpose of this study is to develop a device that combines exercise and entertainment. Therefore, we developed an application and the driving device to visualize the energy consumption during exercise. The first experiment utilizes the smart phone; the second experiment utilizes the action of jumping rope, handgrip, or playing a Kendama. The result of the test is that the driving devices responded correctly to the shaking or sound input of the smart phone, as well as the jumping rope action, handgrip action, or Kendama action.

Development of a Walking-Assistance Apparatus for Neuro-Rehabilitation

We have developed a prototype for a walking-assistance apparatus that serves as a next-generation vehicle or a movable neuro-rehabilitation training appliance for the elderly or motor palsy patients. Our prototype uses a novel spatial parallel link mechanism with a weight-bearing lift. Flat steps of the apparatus move in parallel with the ground; the apparatus supports the entire leg alignment (including soles of the feet) and assists walking behavior at the ankle, knee, and hip joints simultaneously. To estimate the walking phase of each leg of the equipped person, pressure sensors were attached under the thenar eminence and the heel of the sole and the pressure variation at each sensing point was measured. To determine the direction in which the equipped person is walking, a pressure sensor was attached to the flexible crural link. Motor palsy patients and those with muscle weakness can walk with the assistance of the apparatus. Patients who have ambulation difficulty can also use the apparatus with a weight-bearing lift that we developed. Using the apparatus with the weight-bearing lift prevents stumbling and enables input of walking movement to the brain motor area. The validity of the weight-bearing lift can be confirmed from the results of the measured %maximum voluntary contraction (MVC).

Development of a Closed-Fitting-Type Walking Assistance Device for Rehabilitation

A Closed-Fitting-Type walking assistance device was developed. The combination of a flexible shaft with a worm gear was successfully adopted on this device to simplify its appearance and reduce its size. A hybrid control system on this device controls both torque and angle at the ankle and knee joints. As a result of walking that mounted a Walking Assistance Device to motor paralysis patient, the effect of support and the improvement of postural were achieved.