This paper propose a new method of sensor fusion of an omni-directional ultrasonic sensor and an omnidirectional vision sensor. A new omni-directional sonar, which we developed, can measure accurate distance and direction of reflecting points, and an omnidirectional vision can give direction to edges of segment. We propose a sensor fusion method using both the reflecting points measured by the sonar and the edges of segment measured by the vision, based on the angles. Those data are different in character, so they compensate each other in the proposed method, and it becomes possible to get better information which are useful for environment recognition of mobile robots. We describe the proposed method and an experimental result to show its potential.

Proposes a method of adding the amplitude of ultrasound echo from reflecting points. An omni-directional sonar which we developed, can measure accurate distance and direction of the reflecting points, and it is possible to measure amplitude of the echo which corresponds to the reflecting points. We propose a method to add information from the amplitude of the echo from the reflecting points for environment recognition. This method can give useful information such as character of reflecting objects and it makes possible to correspond each reflecting point with others using this information. We describe the proposed method and an experimental result to show its usefulness.

This research aims at development of sensors for small size indoor mobile robots. We have proposed a new sonar-ring which can measure accurate direction and distance to reflecting points rapidly for this purpose. This new sonar-ring needs to receive echo signal by multiple receivers and to detect multiple Time-of-Flights (TOFs) in received signal at each receiver simultaneously for achieving fast and accurate measurement. However, it is impossible to satisfy them by conventional circuit. This paper proposes 30 channel 1 bit wave memory system to achieve these two points simultaneously and shows its usefulness.

A sonar-ring is one of the most popular sensors for indoor mobile robots, because it is simple and gives omni-directional distance information directly. However, it is difficult to measure the accurate direction of reflecting points by a conventional sonar-ring sensor. Further more, conventional sonar-ring sensors are slow to get full 360 degrees information due to sequential driving of transducers for avoiding interference. We propose a new sonar-ring sensor system for a mobile robot which can measure the accurate bearing angles of reflecting objects in a single measurement. The proposed system employs measurement by using differences of time-of-flight and by simultaneous transmit/receive of all directions, and consequently achieve fast measurement. We implemented a prototype of the proposed sonar-ring on a mobile robot. Experimental data show the effectiveness of the proposed system.

Conventional wall following with an ultrasonic sensor uses only range data to the nearest reflecting point. However, the bearing angle information to the wall is more useful for a wall following motion. In this paper, we propose a simple wall following algorithm, where the robot moves perpendicular to the direction to the nearest reflecting point. Also, in conventional ultrasonic pulse-echo sensing, an accurate target bearing measurement is often regarded as difficult due to the wide directivity of ultrasonic transducers. However, by assuming that the ultrasonic echo returns from a single direction, the bearing angle can be measured. A new sensing method is also proposed to determine accurately the bearing angle to the reflecting point by a single ultrasonic transducer. This paper also presents experimental results from mobile robot wall following experiments using only bearing information measured by a single ultrasonic transducer. These experiments illustrate the effectiveness of proposed method.