Kenichi Asami

Mechanical modeling of a beating heart for a cardiac palpation training system

In cardiac plastic surgery, the cardiac surgeon touches the cardiac muscle to diagnose the patients heart that may be diseased due to infarction or dilate cardiomyopathy to determine the regions where it needs plastic surgery. In other words, the cardiac surgeon needs to recognize the mechanical characteristics of the thin muscle regions by the haptic sensitivity of his/her fingertips. Cardiac images available before cardiac surgery could enable a qualitative estimation of the patients heart. However, cardiac palpation is the only accurate way for making surgical plans for ventricular plastic surgery in the operating theater. Since young inexperienced cardiac surgeons have few occasions to perform cardiac palpation, even in operation cases, a cardiac palpation training system is highly desired. The training system for a cardiac palpation system we have developed consists of a virtual heart based on human left ventricular magnetic resonance images and a one-dimensional manipulator as a haptic device. Mechanical properties of the cardiac muscles of a pig and a dog are embedded into the virtual heart linked to a Windkessel model for the systemic circulation. Our experiments show that the developed training system enables users to feel the elasticity of the cardiac muscle wall through the manipulator in real-time.

Evaluation of SRAM based FPGA performance by simulating SEU through fault injection

This paper presents the technique and results of Single Event Upsets fault injection in the configuration bit-stream of SRAM-based FPGAs through partial reconfiguration of configuration frames. The Xilinx Virtex5 LX50 is used in the experiments. The Single Event Upset controller macro is used injecting faults to random locations of the FPGA bit-stream. The effects were studied on a design consisting of 4 embedded processor systems implemented in the FPGA. MATLAB is used for developing the external fault injection control environment.

Reconfigurable fault tolerant avionics system

This paper presents the design of a reconfigurable avionics system based on modern Static Random Access Memory (SRAM)-based Field Programmable Gate Array (FPGA) to be used in future generations of nano satellites. A major concern in satellite systems and especially nano satellites is to build robust systems with low-power consumption profiles. The system is designed to be flexible by providing the capability of reconfiguring itself based on its orbital position. As Single Event Upsets (SEU) do not have the same severity and intensity in all orbital locations, having the maximum at the South Atlantic Anomaly (SAA) and the polar cusps, the system does not have to be fully protected all the time in its orbit. An acceptable level of protection against high-energy cosmic rays and charged particles roaming in space is provided within the majority of the orbit through software fault tolerance. Check pointing and roll back, besides control flow assertions, is used for that level of protection. In the minority part of the orbit where severe SEUs are expected to exist, a reconfiguration for the system FPGA is initiated where the processor systems are triplicated and protection through Triple Modular Redundancy (TMR) with feedback is provided. This technique of reconfiguring the system as per the level of the threat expected from SEU-induced faults helps in reducing the average dynamic power consumption of the system to one-third of its maximum. This technique can be viewed as a smart protection through system reconfiguration. The system is built on the commercial version of the (XC5VLX50) Xilinx Virtex5 FPGA on bulk silicon with 324 IO. Simulations of orbit SEU rates were carried out using the SPENVIS web-based software package.

Real-time image processing system by using FPGA for service robots

This paper presents a real-time image processing system for a mobile service robot which is implemented by an FPGA reconfigurable logic device. The digital image processing acquired by a CMOS image sensor is performed on the embedded FPGA board and Linux-based real-time video communication module. The integrated robot vision system aims to achieve a suitable platform available from both hardware and software. In addition, we also present spatial recognition by edge detection and tracking function of moving objects by using the frame difference method which is necessary for autonomous mobile robots.

FPGA Implementation of Image Processing for Real-Time Robot Vision System

This paper presents a real-time robot vision system integrating adequate image processing and pan-tilt motion control which is implemented by FPGA reconfigurable logic device. The digital image processing acquired by CMOS image sensor is performed on the embedded FPGA board and Linux real-time video communication module. The integrated robot vision system aims to achieve a suitable platform available from both hardware and software. In addition, we also present spatial recognition by edge detection and tracking function of moving objects by determining color which are necessary for autonomous mobile robots.

Development of a diagnostic supporting tool for a circulatory system model of living body

The purpose of this research is to develop a computer-aided tool for diagnostic and educational support of the living-body circulatory system using the Human model devised by Coleman. The Human model is a dynamic model described by simultaneous differential equations, and consists of 25 physiological modules, such as the cardiovascular system, respiratory control, and kidney function, whose variables are exchanged with each other in order to emulate human-body circulatory phenomena. For application of the human model to diagnosis and education, the supporting tool should have the capability of qualitative analysis to explain the causal relationships of numerical values of relevant variables in the model. We develop a supporting function to analyze the hierarchical structure of variables and parameters. The tool can be used to diagnose the causes of an unusual variable by path tracking in the human model. Furthermore, this supporting tool provides for editing of mathematical expressions for the purpose of validating the model.

Visual navigation system based on evolutionary computation on FPGA for patrol service robot

The visual navigation system for a patrol service robot using image processing and evolutionary computation on FPGA is presented. The image processing and evolutionary computation are implemented into a reconfigurable device as original logic. The image processing circuit captures digital images from CMOS camera, extracts the edge and feature points in the images for self-localization to adjust the current course on the traveling map data. The genetic algorithm optimizes threshold values for the filtering operations according to various lighting environments. The visual navigation system has been developed for the linkage between flexible hardware circuits and real-time software applications for robot vision purpose.

Basic Study on Superconducting Magnetic Bearing (SMB) With Superconducting Coil

Our group has developed a superconducting magnetic bearing (SMB) with superconducting coil for magnetically levitated conveyers used for clean environments. The SMB is composed of a levitated permanent magnet (PM) and a supporting superconductor with superconducting coil, a control coil and a Hall sensor. The damping for the SMB with superconducting coil is compared with the SMB without superconducting coil. PD control is applied to the SMB and the damping characteristics are also discussed.

Dynamic Characteristics of Magnetically Levitated Conveyer Using High

Our group has developed a new conveyer using superconducting levitation. The conveyer is composed of a levitated table and a conveying table. The gap between levitated table and conveying table is detected by using a Hall sensor on the superconductor. The position of the table is controlled by using the PD control. In this paper, we discuss a superconducting magnetic bearing with a central superconductor. A central superconductor improves stiffness of each direction. In addition, the characteristics of magnetically levitated superconducting conveyer are studied when the levitated table moves in the horizontal direction.

T_{c}

The visual navigation system for a mobile patrol robot using image processing by FPGA and real-time Linux is presented. The CMOS image sensor and the stepper motors driver ICs are connected to external I/O ports of the FPGA. The image processing and motor drive circuits are implemented into the reconfigurable device as original logic. The image capture circuit applies state machine and FIFO memory buffer to adjust timing for pixel data transmission. The motor drive circuit generates clock signals for steps according to the value from processor in the FPGA. The real-time device driver has been developed for the linkage between flexible hardware circuits and real-time software applications for robot vision purpose.