Hiroomi Miyagawa

Behavior of Traction Oils under Impact Loads

The squeeze film forming ability of traction fluids is studied under impact load by a falling bearing steel ball against a stationary cylindrical surface or flat anvil made of mild steel, bearing steel, or aluminum. The effect of the pressure-viscosity coefficient and of the viscosity is investigated for plastic and elastic impact. For soft materials, oils with high pressure-viscosity coefficients maintain much greater surface separation under impact load. The time fraction of separation by the oil film increases linearly with the product of the pressure-viscosity coefficient and the yield pressure of the anvil material. It decreases with an increase in surface roughness. Similar results are observed under impact on stationary or rotating surfaces. These results can be used to estimate the solidification behavior of traction oils. In the case of the elastic impact for hard materials, the coefficient of restitution of the ball is influenced mainly by the squeeze film effect, which is governed by viscosity ...

A Method of Calculation for Contact Pressure between Femoral Head and Cup of Artificial Hip Joint

Abstract A method of calculation for contact pressure between a hard femoral head and soft plastic cup of a hip joint was studied. Providing that the contact pressure is proportional to the radial deformation of the cup, an equation of equilibrium in terms of a nondimensional parameter was derived. Once the magnitude of the parameter is determined by solving the equation, the contact pressure distribution is easily obtained. An effect of the radial clearance between a femoral head and cup on contact pressure was evaluated using the equation. Furthermore, the effect of Youngs modulus and thickness of a plastic cup on contact pressure were also evaluated. According to the results, contact pressure increased with an increment of clearance and Youngs modulus. The contact pressure increased with a decrement of thickness of the plastic cup. The analytical solution was compared with the finite element method (FEM) analysis and the agreement was confirmed. An equation of frictional torque was also derived

Home-Use Upper Limb Rehabilitation Device for Cervical Spinal Cord Injured Patients

This paper presents mechatronics device system to assess and assist the rehabilitation of the palsy arm. The device is developed for assisting the physical and occupational treatment of the patient with cervical spinal cord injury. The system consists of a PC and a joystick-type controller. The controller contains a triaxial load cell to measure the force exerted. With this system, we propose isometric training with biofeedback of visual effects as in video games. The subject is to adjust the force while tracking the target along the trajectory displayed on the screen. For evaluating the performance, accuracy is computed from the recorded training results. Pilot test is carried out on cervical spinal cord injured patients and compared with the senior able-bodied. Results of the pilot test showed that the system is capable of assessing the difference of the individuals.

The assessments by trainees and an examination about walking posture on gait training system

Our developing gait training system is the training device that tries to obtain the effect similar to the walk training in the warm water swimming pool. A train patient hangs and is supported to the slinging system and walks the force plate top. Slinging it up power is controlled on the basis of the information from the force plates. This system can give the most effective load to a training person, by adjusting to the real time while slings in accordance with the recovery degree of a train patient. It becomes possible to evaluate the training effect on the basis of the data that was obtained from force plate, etc. This system is tested by handicapped person, to inspect the function and efficacy. The problem of walking posture is found from this test. We show the device that an walking posture in gait training system is improved.

Field test of a force control rehabilitation system for quantitative evaluation of the disorder in the upper extremities

This paper reports on a field test of our simple force-sensor-based rehabilitation device that can be handled at homes or neighboring medical institutions. We propose a tri-axial load cell controller system for quantitatively evaluating the visually guided motor control characteristic of a weak palsy arm. The result is recorded in the database while evaluation is presented for each trial. The system is tested at an orthopedic clinic with outpatients: cervical spinal cord injured patient and 2 other cases. Their mid-term testing results are discussed.

The Development of Gait Training System for Computer-Aided Rehabilitation

This paper reports on the development of a gait training system and its experimental results. The outstanding feature of the system is the constant dynamic adjustment of the tension lifting the trainee based on the information from floor reaction force. The load on the trainees foot on the floor is regularly maintained at a low-burden level; therefore, the load on the foot is similar to the effect of walking in a pool. The system was tested on a handicapped person, and improvements in balancing ability were shown.

A gait training system for human adaptive walking posture

This paper deal with the modification of a gait training system. This system is designed to produce artificially similar the effects to gait training in a swimming pool. The weight of the patient is supported by a slinging system, while the patient walks on force plates placed on a round track. The slinging force is controlled by the data collected from the force plates. The purpose of the system is to control the slinging force to maintain the most effective load on the patients lower extremity during training, and to adapt the slinging force to the patients recovery. To achieve this purpose, the load meter on the force plate is designed to enhance the measurement performance. Tests revealed that dynamic response improved with the new design. Furthermore, the human interface also improved by mounting a display that projects the patients foot by means of a movie camera. The patients gait posture can be significantly improved by adapting this method.

Upper Limb Rehabilitation System for Self-Supervised Therapy: Computer-Aided Daily Performance Evaluation for the Trauma and Disorder in the Spinal Cord and Peripheral Nerves

With the serious impact on life caused by the disability after cerebrovascular accidents and other serious trauma of the nervous system, prevention strategies and survivors’ rehabilitation programs are one of the social needs in many countries. As in super-graying society with low death and birth rate like Japan, an approach of just fostering aid personnel with necessary expertise will not be satisfactory to ensure the quality of the care services. Research in therapeutic technique needs to be paralleled by technology development to reduce the load on the care givers and medical staffs, as well as the development of devices that directly assists the survivors’ independent living. Furthermore, advanced efforts are made in Japan to generally decentralize healthcare from clinics to homes and local communities. The escalating healthcare service need to be halted, and strategies such as shortening the patient’s hospital stay by reducing the time spent in bed and maximizing the time spent for rehabilitation with the support of technology. To meet our goals, further scientific research is required to understand the factors for enhancing the rehabilitation effects. This will reduce the hands-on one-on-one treatment so that the therapy programs can be provided in homes and local clinics without full-time supervision. With the promising achievements in rehabilitatio n robotics, we believe further studies on sensorbased assessments and motion control with intelligent systems can support reliable advancements of the therapy programs. In this chapter, our work on developing a rehabilitator system for cervical spinal cord injured clients is presented. Our main aim is to provide post-hospital-discharge clients with opportunity for voluntary training and to assist self-supervised therapy. Automatic recording, adaptive exercise control, and multilateral analysis are the key technology that we target for recruiting and assisting the client’s rehabilitation and medical staff’s interest in using the device.

Development of a robotic digit joint mechanism for knot tying task

In this paper, we propose a novel transmission mechanism for developing a robotic hand for performing knot tying task. Our goal is to develop a robotic hand system that supports the people with disability in dexterous hand movements. The target is to handle clothing and other soft material which require both precision and strong grasp during its sequence. First, the design concept is discussed by analyzing the digit movements and their functions in a knot tying sequence. An issue of developing transmission mechanism is discussed from the result. A mechanism applying a swash plate cam is presented for joint movement control to minimize weight and complexity, while being capable of holding high torque. A prototype digit is assembled and tested to confirm its characteristic and discussion of future modification is presented.

An examination about walking posture on Gait Training System for computer-aided rehabilitation

Our Gait Training System is a training device that aims to obtain the effect of the walk training in the warm water swimming pool. A trainee is supported by the slinging system while walking on the force plate. Slinging power is controlled on the basis of information instrumented from the force plates. The training effects are evaluated on the basis of the data that obtained from the force plate etc. This system is tested by handicapped person to inspect the function and efficacy. A major problem of deficient body alignment of the walking posture is found from the test. We propose mounting a monitor and the result of improvement is shown. The effect on the walking posture using the Gait Training System is experimented on normal persons. The difference of the posture in normal gait and device-supported gait is shown.