Akihiko Hanafusa

Self-aided manipulator system for bed-ridden patients - Evaluation of psychological influence for the generated approach motion -

Rehabilitation robots that are used to assist patients should be able to move naturally and cause no discomfort to the patients. In this study, a self-aided manipulator system that can generate natural motion and assist bed-ridden patients has been developed. The self-aided manipulator is designed so that it can grasp a glass of water from a side table for the patient. The system can detect the starting position (position of the glass) and the target position (position of the patients lips) by using a video camera. The direction angle of the patients face is also determined, and approach motions are generated on the basis of these angles. Approach motions are generated by changing the peak velocity time, maximum speed, and detour point position of the manipulator, and the psychological influence on the patient is evaluated on the basis of their heart rate variability (HRV), skin potential response (SPR), and response to questionnaires. The results suggested that a peak velocity time of 75% of the total movement time, a maximum speed of 36 cm/s, and an approach path from the right when the patients head is facing straight or to the left tended to have the strongest psychological influence on the patient. From these results, it was indicated that the following conditions are preferable for the approach motion of the manipulator: a peak velocity time of approximately 25 to 50% of the total movement time, a maximum speed from 18 to 24 cm/s, and an approach path in the direction in which the head faces.

Development of computer assisted orthosis design and manufacturing system for malformed ears.

Most cases of malformed ears in neonates can be treated by mounting a suitably shaped orthosis. Our objective was to develop a computer-assisted orthosis design and manufacturing system for the treatment of malformed ears. Also, we aimed to manufacture a first experimental orthosis made of nitinol shape-memory alloy wire. First, the target posttherapeutic auricular shape is input from computed tomography scans, and characteristic points and contours are extracted. The shape of the orthosis is then created by tracing the necessary contours automatically. Finally, the orthosis shape data are projected onto one or more approximate planes and autoconverted into numerical control (NC) data for plate groove processing. The nitinol shape-memory alloy wires are inserted in the groove and the shape is memorized by heat treatment. The shape of the manufactured orthosis can be memorized from the generated NC data within 1.0 mm of error. Stahls ear in a 9-month-old baby was treated 7 months ago by mounting the orthosis manufactured by the system. The developed system allows the design and manufacture of orthoses made of nitinol shape-memory alloy wire for the treatment of malformed ears.

Approach Motion Generation of the Self-Aided Manipulator for Bed-ridden Patients

Rehabilitation robots that are used with humans should move naturally and should not cause discomfort. A system that can generate natural approach motion for a self-aided manipulator for bed-ridden patients based on the individual patient’s characteristic motion has been developed. The self-aided manipulator is assumed to provide the function of bringing a drink from a side table to the patient.

Makeup support system for visually impaired persons: overview of system functions

A questionnaire survey carried out among 25 visually impaired women indicates that they feel uncertainty to their makeup. It is observed that there is a need to develop a system to teach them how to apply makeup and to check their makeup. We have been developing a prototype of a makeup support system for visually impaired persons. The system provides information on makeup and imparts knowledge on how to apply makeup. Further, for checking the current makeup condition, an image processing system that can recognize the face and its parts and check for excess lipstick and the shape of the eyebrows has been developed. From a series of input images, the best image for checking can be selected on the basis of the sum of squares of residual errors after an affine transformation. Further, a usability assessment was carried out by considering eight visually impaired women, and the result could achieve a high score related to the content of information on makeup.

Orthosis Design System for Malformed Ears Based on Spline Approximation

Malformed ears of neonates can be effectively treated by employing an orthosis of suitable shape. Currently, we use orthoses made of nitinol shape memory alloy wire and have developed a computer-assisted design system to manufacture the orthosis. Using this method, extracted contours of the helix and auriculotemporal sulcus are approximated to spline, and orthosis shape can be designed by moving the control points of spline with reference to control points of the target auricular shape. The system also functions to evaluate the contact force between the orthosis and auricle. Using this system, orthoses were designed and manufactured for 16 patients with malformed ears. Treatment was more effective in cases where it was necessary to extend the helix.

Accuracy Evaluation of 3D Reconstruction of Transfemoral Residual Limb Model Using Basic Spline Interpolation

In this paper, a study on the accurateness of 3D reconstruction for transfemoral residual limb based on Magnetic Resonance Imaging (MRI) using basic spline (B-Spline) interpolation feature is presented. Many researches have constructed 3D models by using the Non-Uniform Rational B-Spline (NURBS) approach; however, almost none of those studies have elaborated in detail the methodology used in the project and the accuracy of the model’s volume against the residual limb volume. This study focuses on the optimization of the residual limb model’s volume by investigating the effect of spline points on the volume value. This project is divided into 3 phases, namely pre-segmentation, segmentation, and 3D reconstruction. However, this study focuses on the segmentation phase in which four different spline point numbers are chosen, namely 72, 36, 24, and 12 points; CAD software CREO Parametric (PTC) was used for this process. A higher number of spline points achieved greater accuracy for the model’s volume. The volume (mm3) of the 3D model with the specified number of spline points was evaluated by comparing it with the volume of the 3D model created by using image processing tools from MATLAB (Math Works). The results show the increment in accuracy of the volume value when the number of spline points is increased. The highest accuracy in terms of volume value is achieved when the model is created with 72 and 36 spline points, with an average error percentage of 6.36%, which realized the hypothesis. The results indicate that CAD software, which is a technical drawing tool, can also be used in the biomedical field to design 3D models of the human anatomy with high accuracy, if the software includes a spline interpolation feature.

Development of an active upper limb orthosis controlled by EMG with upper arm rotation

An active upper limb orthosis was developed for patients who cannot move their upper limb. The system has two independent motors that allow flexion and extension of the shoulder and elbow, and in addition, rotation of the upper arm. By incorporating arm rotation, activities of daily living (ADLs) are improved. If the patient is able to move their wrist as in Erb’s paralysis, electromyogram (EMG) generated by the movement of the wrist is processed by an original system and used to control the orthosis. Evaluations were performed on moving range of orthosis by a healthy subject and on ADL tasks by an Erb’s palsy subject. There were tasks that the subject could not complete because of lack of function or range of motion of orthosis. However, tasks that require use of two arms, which the subject could not complete previously, were completed using the orthosis.

Finite element analysis for the estimation of the ground reaction force and pressure beneath the foot prosthesis during the gait of transfemoral patients

Ground reaction forces (GRF) and pressure beneath the foot prosthesis are the main parameters used in biomechanical analysis to estimate the joint load and evaluate the quality of the prosthesis, especially with transfemoral patient who have amputation that occurs through the femur. The information of ground reaction forces and beneath pressure of foot prosthesis is conventionally achieved using dynamics method or the experimental method. However, these methods have some limitation for a prosthetist and designers to choose the best prosthesis solution for transfemoral patient. In the dynamics method, the deformation of the foot prosthesis and the variation in the shape of the residual limb in the socket is neglected and the center of gravity of the prosthesis component is estimated; thus, the method is less accurate because the prosthesis consists of several parts with different materials and shapes. The experimental method involves time and cost in setting-up the device. Data can be acquired only after the patient wears the prosthesis. In this study, the authors were implemented a finite element (FE) method for computing the GRF, and the pressure beneath the foot prosthesis and its distribution. The finite element model of all components of transfemoral of the prosthesis was created. The ground reaction forces, beneath pressure of foot prosthesis and other parameters were disclosed after solving by explicit solver of LS-Dyna software. The results of the vertical ground reaction forces exhibit consistently similar data between the simulation and the measurement. A correlation coefficient of 0.91 between them denotes their correspondence. The reaction force at knee joint, distribution of beneath pressure of foot prosthesis were included in results and discussion. These results can be used for prosthesis design and optimization; they can assist the prosthetist in selecting a comfortable prosthesis for the patient and in improving the rehabilitation training.

Development and evaluation of navigation system with voice and vibration output specialized for persons with higher brain dysfunction

Higher brain dysfunction (HBD) is an umbrella term used for the aftereffects of conditions such as traumatic brain injuries, cerebrovascular disturbances, and encephalitis. Approximately 60 % of persons with HBD lose topographical orientation very easily, which prevents them from walking outdoors without a caregiver. Persons with HBD find existing smartphone navigation applications difficult to master even with extended periods of training; therefore, a smartphone application that can be used by persons with HBD to facilitate independent walking was developed. The new application is simple and easy to use and routes can be specified by caregivers. The system outputs messages via dialogs and voice with vibration, when attention is necessary in cases where the user has arrived at certain sub-goals or has gone off-route. Experiments were conducted with subjects without a disability and HBD subjects to evaluate the effectiveness of the voice and vibration functions. The results showed that the subjects felt that the system was effective and highly usable. However, the average result from the eye mark recorder showed that the viewpoint was concentrated on the smartphone. The result of a second trial conducted with HBD subjects revealed that the average value of time spent observing the device, the number of times the device was observed, and the percentage of time tend to reduce.

Wheelchair seating evaluation system ∼ Introduction of system functions ∼

In this study, a system for evaluating the wheelchair seating posture is introduced. The system consists of three subsystems: a seating posture changing system, a seating posture analysis system, and a propulsion analysis system. The seating posture changing system uses pneumatically controlled airbags installed in the wheelchair seat to change the posture of the patient and aims to generate a good posture heuristically. The seating posture analysis system uses seat sensors, video cameras, and whose analysis software to measure and analyze the current posture by seat sensors. One of the features of the analysis system is that the shape of the spine is estimated virtually, as the shape is one of the best indicators of a patients posture. From the current seating posture, the propulsion analysis system estimates the posture, driving force, and muscular forces necessary to propel the wheelchair. Basic hardware and software for the pneumatically controlled functions have been developed for the posture changing system, and the displacements of the human body were measured by a 3D motion analysis system when four airbags were filled with air independently. A method to estimate the spinal shape by the finite element method (FEM) using beam elements has been developed for the seating posture analysis system. This method has a fast processing time and takes external forces into consideration. A method that can estimate the position of the neutral axis of the spine from markers placed on body surfaces was also developed. For the propulsion analysis system, propulsion motion and muscular forces of a subject in the wheelchair with a seat cushion or a back seat cushion were analyzed. Future work includes the development of the remaining functions, such as the overlay display function of the video camera images and sensor data, and the integration of the entire system.