In this study, we estimated and validated the pressure distribution profile between the residuum and two types of prosthetic sockets for transfemoral amputees by utilizing a finite element analysis. Correct shaping of the socket for an appropriate load distribution is a critical process in the design of lower-limb prosthesis sockets. The pressure distribution profile provides an understanding of the relationship between the socket design and the level of subject comfortability. Estimating the pressure profile is important, as it helps improve the prosthesis through an evaluation of the socket design before it undergoes the fabrication process. This study focused on utilizing a magnetic resonance imaging (MRI)-based three-dimensional (3D) model inside a predetermined finite element simulation. The simulation was predetermined by mimicking the actual socket-fitting environment. The results showed that the potential MRI-based 3D model simulation could be used as an estimation tool for a pressure distribution profile due to the high correlation coefficient value (R² > 0.8) calculated when the pressure profiles were compared to the experiment data. The simulation also showed that the pressure distribution in the proximal area was higher (~30%) than in the distal area of the prosthetic socket for every subject. The results of this study will be of tremendous interest for fabricators through the use of a finite element model as an alternative method for the prefabrication and evaluation of prosthetic sockets. In future prosthetic socket fabrications, less intervention will be required in the development of a socket, and the participation of the subject in the socket-fitting session will not be necessary. The results suggest that this study will contribute to expanding the development of an overall prefabrication evaluation system to allow healthcare providers and engineers to simulate the fit and comfort of transfemoral prosthetics.

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.

A prosthetic limb control system to operate powered 2-DOF wrist and 1-DOF hand with environmental information, myoelectric signal, and forearm posture signal is composed and evaluated. Our concept model on fusing biosignal and environmental information for easier manipulation with upper limb prosthesis is assembled utilizing networking software and prosthetic component interlink platform. The target is to enhance the controllability of the powered wrist’s orientation by processing the information to derive the joint movement in a physiologically appropriate manner. We applied a manipulative skill model of prehension which is constrained by forearm properties, grasping object properties, and task. The myoelectric and forearm posture sensor signals were combined with the work plane posture and the operation mode for grasping object properties. To verify the reduction of the operational load with the proposed method, we conducted 2 performance tests: system performance test to identify the powered 2-DOF wrist’s tracking performance and user operation tests. From the system performance experiment, the fusion control was confirmed to be sufficient to control the wrist joint with respect to the work plane posture. Forearm posture angle ranges were reduced when the prosthesis was operated companying environmental information in the user operation tests.

Recent technologies have suggested the utilization of three-dimensional (3D) printing technology to enhance the fabrication accuracy of prosthetics. Accordingly, simulations are used to obtain precise parameters for subject-specified prosthetic socket. This study proposes an evaluation system to measure the accuracy of a subject-specific 3D transfemoral residuum model during the interaction with the socket in conjunction with the application of finite element methods. The proposed system can be used in future validations of socket fabrication. The evaluation is based on the measurement of the residuum’s soft tissue deformation inside two types of prosthetic sockets. In comparison with other studies, the 3D models were constructed with magnetic resonance images (MRI) with the aid of computer-aided design (CAD) software. The measurement of soft tissue deformation was conducted based on the measurement of the volumetric value of fat, muscle and skin in the pre- and post-donning phases. The result yielded a promising correlation coefficient value between the simulation and the experiment in the soft tissue deformation evaluation. The relation of the muscle–fat ratio in the residuum is extremely important in the determination of the ability of the prosthetic to deform. The environment during the socket fitting session was similar to that defined by the set boundary conditions in simulations. In view of the promising results of this study, the evaluation system proposed herein is considered reliable and is envisaged to be used in future research.

This paper reports on the development of a 2 degree-of-freedom swaying motion platform and a basic experiment on measurement and evaluation of the driving posture stability. A motion base with pneumatic cylinders to rotationally accelerate the subject in the driver's seat was made. With this motion base, an experiment was conducted to evaluate the indices of driver's posture stability placing a mannequin in the seat. Accelerometer was attached to the mannequin and inclination sensors were mounted on the motion base. Two postural conditions were set and tested on unidirectional swaying motion on each axis. Motion base's angular velocity and of the mannequin's velocity were computed from the sensor signals and the relation is plotted for each situation. Results showed feature points in the axes and directions that are to be evaluated in human subjects.