Vol.2 No.2 2009

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Research paper : A secure and reliable next generation mobility (Y. Satoh et al.)−114−Synthesiology - English edition Vol.2 No.2 (2009) PC was installed outside the wheelchair and connected by cable along with an exterior power source. To mount all these devices on the chair, it was necessary to implement all functions that required large amounts of computation on just one small PC for stereo image processing, image integration, camera pose estimation and correction, risk detection, and gesture detection. To realize this, we developed and implemented various high-speed computation algorithms as described in chapter 3, and supplemented the decreased processing capacity due to downsizing the PC from the software side. We conducted thorough review of the implementations such as eliminating overlapping computation, using look-up tables as much as possible, along with introduction of parallel processing. In hardware, to deal with a small motherboard, we changed the interface of the stereo omni-directional camera from PCI-X to PCI-Express standard. Although the PCI-X standard has wide bandwidth for data transfer, it is limited for use in a server motherboard. PCI-Express standard is recently being used widely and can be used in almost all motherboards, and can maintain sufficient bandwidth for data transfer of the stereo omni-directional camera.Figure 12 shows the exterior view of the PC mounted on a wheelchair. The PC fits compactly in the cover behind the seat. The interface unit for the electric wheelchair and PC, the joystick interface unit, and the wireless LAN device are all fitted under the seat. Lead battery (12 V, 52 Ah × 2) for driving the motor is used as the power supply for other devices as well. This requires no exterior cables, and about four hour continuous operation is possible.4.3 Exterior designTo create something that will “present the potential and necessity of advanced welfare device through future-oriented advanced technology” according to the research scenario, the product must draw people’s interest and convey the concept and future potential. It is necessary to be concerned about the exterior design, and our team repeated discussions and created prototypes. Figure 13 left shows a scene during prototype creation. The right photo is a design for Prototype 1, and a press release[3], exhibitions, and demonstration on the TV news were done using this design (currently, the devices mounted on the wheelchair are downsized further; Prototype 2 shown in Fig. 11 is also in operation).The points of the design are as follows. (1) The mechanics and cables should be covered as much as possible. To show them exposed will express that the product is “still at the level of laboratory experiment” and that will not be appropriate for the mission. (2) The cover should not be forcedly made small with no consideration for the design theory. If the cover is made small to appeal that the mounted devices are small, the overall balance will be lost and the covered part will stand out as an “extra area.” For example Fig. 14 Detection of obstacles.Fig. 12 Mounted PC.Right photo shows the device exposed without the cover. The PC is mounted behind the seat.Fig. 13 Consideration of the exterior design.Left photo shows the process of designing. The design was determined after repeated trials. The right photo is the design for Prototype 1. This model was used for the press release.(1)(4)(3)(2)STOPSlow DownSTOP

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