Junghyeon Choi

Development of gait phase analyzing devices for the gait training equipment for hemiplegia patients

This paper describes the design and development of gait phase analyzing devices which are key components consisting of the gait training equipment for hemiplegia patients. The devices should be durable against the friction of rotating rubber belt of the gait training equipment and robust to the mechanical vibration caused by the operation of the gait training equipment so that they can detect the gait phase accurately during training. We could develop the gait phase analyzing device that can satisfy these criteria by designing and implementing of two new devices, a magnet shoe and magnetic sensor array board. The magnet shoe has three rows of magnetic sensor array and each row has different number of permanent magnets so that which parts of the shoe are touched to the magnet sensor array board. In addition, the shoe was designed as an overshoe so that a patient can attach and detach the shoe easily. The magnet sensor array board has 1,620 magnetic sensors which are arranged in 30 rows and each row consists of 54 magnetic sensors where the distance between sensors is 2 cm in horizontal and vertical direction. The experiment results show that they have spatial resolution of 1 cm in horizontal and vertical directions and temporal resolution of 20 frames per second of the gait phase. The gait phase analyzing devices developed in this study were incorporated into the design of gait training equipment for hemiplegia patients and they showed feasibility in practical operating environment. They also can be applied to other similar equipment which needs the gait phase analysis function.

A system design of gait training device for monoplegia patients

In this paper, we present a system design about a gait training device for monoplegia patients and aged people. In a conventional gait training program, the monoplegia patient takes a step leaning on the parallel guide bar or helped by a therapists arm support. But this method often does not give satisfactory result since the method fails to correct the irregular posture of the patient. The new training device has been in need for gait disorder patients, monoplegia patients and aged people. The gait training device for the patients is divided into four main units, gait phase detecting unit, lower panel controlling unit, lower limb pulling and releasing unit and additional supplementary unit for safety of the patients. The training device to be presented exhibits stableness in its operation and it may improve the effect of gait rehabilitation training compared to the conventional gait training method.

Development of Feature Points Detection Algorithm for Measuring of Pulse Wave Velocity

The compliance and stiffness of artery are closely related with disease of arteries. Pulse wave velocity(PWV) in the blood vessel is a basic and common parameter in the hemodynamics of blood pressure and blood flow wave traveling in arteries because the PWV is affected directly by the conditions of blood vessels. However, there is no standardized method to measure the PWV and it is difficult to measure. The conventional PWV measurement has being done by manual calculation of the pulse wave transmission time between coronary arterial proximal and distal points on a strip chart on which the pulse wave and ECG signal are recorded. In this study, a pressure sensor consisting of strain gauges is used to measure the blood pressure of arteries in invasive method and regular ECG electrodes are used to record the ECG signal. The R-peak point of ECG is extracted by using a reference level and time windowing technique and the ascending starting point of blood pressure is determined by using differentiation of the blood pressure signal and time windowing technique. The algorithm proposed in this study, which can measure PWV automatically, shows robust and good results in the extraction of feature points and calculation of PWV.

A Coronary Pulse Wave Velocity Measurement System

Pulse wave velocity (PWV) is a basic parameter in the dynamics of pressure and flow wave traveling in arteries. But it is difficult to measure the pulse wave transmission time between coronary arterial proximal and distal point by manual method using the graph on which pulse wave and ECG are receded. The system that can measure PWV in real time was developed and clinical experiment was carried out for patients to validate the accuracy of the measured coronary arterial PWV. The average value of the measured coronary arterial PWV was 934.764plusmn104.606 cm/sec.

An automatic pulse wave velocity estimation using a blood pressure sensor for invasive measurement

The compliance and stiffness of artery are closely related to the disease of arteries. Pulse wave velocity (PWV) in the blood vessel is a basic and common parameter in the hemodynamic. Blood pressure (BP) and blood flow wave traveling in arteries are important because the PWV is affected directly by the condition of blood vessels. However, there is no standardized method to measure the PWV and it is difficult to measure. The conventional PWV measurement uses manual calculation of the pulse wave transmission time between coronary arterial proximal and distal points on a strip chart on which the pulse wave and ECG signal are recorded. In this study, a pressure sensor consisting of strain gauges is used to measure the BP of arteries in invasive method and regular ECG electrodes are used to record the ECG signal. The R-peak point of ECG is extracted by using a reference level and time windowing technique and the ascending starting point of BP is determined by using differentiation of the BP signal and time windowing technique. The algorithm proposed in this study, which can measure PWV automatically, shows robust and good results in the extraction of feature points and calculation of PWV.

Design and development of a foot position tracking device

In this study, we developed two types of sensors which can detect foot position of monoplegia patient during walking practice on the gait training equipment and compared their accuracy and performance. The first one is based on one-dimensional laser sensor array and load cell sensors and the foot position is decided by analyzing the signals from these sensors. The second one consists of a two-dimensional magnetic sensor array and a magnet shoe and the foot position can be detected by analyzing the signal from the two-dimensional magnetic sensor array. The comparison results show that the two-dimensional magnetic sensor array is more stable and robust in practical operating condition. Also, it showed that the conventional expensive foot pressure sensors which are widely used to detect foot position can be replaced by the two-dimensional magnetic sensor array.

Development of An Automatic Ankle Stretching Device for Lower Limb Monoplegia Patients

This paper describes a rehabilitation device developed to replace a conventional wooden wedge type ankle stretching device (ASD) and this new device consists of sensors and microcontroller-controlled electro-mechanical actuators. A conventional ASD has been used for lower limb rehabilitation treatment system for training of monoplegia (hemiplegia) patients for a long time. The new automatic ASD machine can control angle between foot and calf (AFC), holding time and the number of repetition, and has four training modes. The new ASD machine consists of an embedded controller unit (ECU), a display unit and an actuator unit. The ECU consists of two clinometers, a 12-bit serial ADC, microcontroller, RS-232 serial interface with the display unit and actuator unit consists with electro-mechanical actuators. It can reduce the workload of physical therapists and improve the effect of rehabilitation exercise for lower limb monoplegia patients.

Development of Tilt Table with Visual Feedback Function for Hemiplegia Patients

Due to damaged vertebrae nerves, serious disease and aging, patients who have to lie down for long period of time need to exercise to maintain up-right standing position and recover their muscle power of paralytic leg. This study describes the development of an intelligent tilt table which can provide a patient with visual feedback of exercise to increase the effect of rehabilitation. This could be possible by measuring and displaying the knee bent angle and pressure for each foot during exercise in real time. It is expected that patients exercising effect can increase by self-monitoring these two values during exercise.

Improvement of tilt table using visual feedback function for hemiplegia patients

This paper describes the improvement of an intelligent tilt table which has an additional visual feedback function to increase the effect of exercise. Information including sliding distance and load of each leg is measured and displayed on the front panel display in real time so that the patient can get visual feed back on his/her exercise activity. The experimental results showed that this visual feedback function could increase the effect of rehabilitation exercise.

Improvement of an automatic ankle stretching device for lower limb monoplegia patients

In this study we developed an improved model of the previous automatic ankle stretching device (ASD) by using electro-mechanical cylinders which have built-in encoders. Also, a user friendly human-computer interface (HCI) device was developed and employed for this device to provide patients with easy access to the ASD and effective visual feedback of the training activity. It can reduce the workload of physical therapists and improve the effect of rehabilitation exercise for lower limb monoplegia patients.