Hospital patients, persons of old age, and physically handicapped persons need wheelchairs and helpers. When a helper carries one of these persons, he/she must be attend on the person ridden on a wheelchair. The helpers are busy and have a lot of work. Patients without helpers grow very tired navigating their wheelchairs. To help, we propose an autonomous fuzzy navigation system for an automatic control of a wheelchair. This system consists of a navigation planning part, a navigation control part, and an environment recognition part. In this paper, we describe an intelligent wheelchair with a fuzzy navigation system and discuss experimental results.

FM-FDM (frequency division multiplexing) optical transmission equipment has been developed for 34-channel MUSE HDTV (high-definition television) signals to realize optical CATV (cable television) systems. The equipment uses an LD (laser diode) with a 1.3 mu m wavelength, a single-mode optical fiber, and an avalanche photodiode (APD). A good picture is received after a 42 km transmission. A part of the multiplexed signals is distorted near or below the threshold of an LD. When the number of transmission channels is small and the total optical modulation depth is large, this nonlinearity governs the power ratio of an FM signal to one distortion component-the DU ratio. However, when the number of transmission channels is large, the DU ratio is determined by the effective optical modulation depth rather than the total optical modulation depth. Furthermore, the method of system design is clarified for an optical trunk line CATV system. If no restriction on the transmission bandwidth of optical devices exists, approximately 30 km transmission of 100-channel MUSE HDTV signals is available with a received CN ratio of 17.5 dB.>