Noriaki Kiyohiro

Development of the robotic travel aid “HITOMI”

Abstract The Robotic Travel Aid (RoTA) is a motorized wheelchair equipped with vision, sonar, and tactile sensors, in addition to a map database system. The visually impaired can get orientation, mobility and obstacle information from RoTA, and can inquire about their present location, landmarks and the future part of the route. The concept is implemented on a RoTA called “HITOMI”. It can guide the impaired to avoid vehicles along a road with lane marks or along a sidewalk marked with Braille.

The ultrasonic range finder for outdoor mobile robots

Ultrasonic rangefinders have already been used successfully for indoor mobile robots. However, in an outdoor environment, the sensor should be robust against noise from vehicle engines and other sound sources. The robust sensor has already been proposed, but it requires a high-performance processor. In this paper the authors propose a new ultrasonic ranging sensor which is simple and low-cost. This sonar is robust in noisy environments. A RTZ (return to zero) signal having a certain time duration modulated with a 40 KHz carrier is transmitted from a transducer, then cross-correlation is calculated between the transmitted wave form and the demodulated received wave form. If objects are present the calculated cross-correlation has relatively large value. The authors can measure the range from the sensor to the objects by the time interval between the starting time of the transmitted signal and the time which has the peak value. The experimental results show the robustness of this sensor against the impulse noises. Furthermore, the authors propose that several sonar sensors can work at the same time without mutual interference, when the different time duration signals are used as the transmitting signals.

HITOMI: Design and Development of a Robotic Travel Aid

A Robotic Travel Aid (RoTA) is a motorized wheelchair equipped with vision, sonar, and tactile sensors and a map database system. A RoTA can provide a visually impaired user assistance with orientation and obstacle avoidance, as well as information about their present location, landmarks, and the route being followed. In this paper we describe HITOMI, an implementation of the RoTA concept that can guide a visually impaired user along a road with lane marks or along a sidewalk while avoiding obstacles.

A method of pedestrian detection based on rhythm of walking

It is important for mobile robots and security purposes to discriminate a pedestrian among moving objects in a video. This paper proposes a method which discriminates a pedestrian from other objects by using periodic motions of the feet, and the characteristics of the rhythm of pace and stride. This method uses brightness changes in sequential images of a moving object contacting with the ground, and extracts the main component of the frequency using a power spectrum estimation. Therefore, the method is independent of pedestrians appearance such as clothes, build, and hair style. The system realizing this method consists of three processes: moving object detection which uses the difference between successive image frames; tracking of the moving object using a moving model with an extended Kahman filter and an observation model; and detection of the pedestrian based on rhythm of walking using the difference of brightness between images on successive frames. The whole process is performed in real time. Experiments using real scenes confirm the effectiveness of the proposed method: 446 pedestrians out of 470 were successfully detected (detection rate 94.9%), and 101 persons out of 106 were successfully detected as non-pedestrians (96.2%).

Research and development of WEarable walKing mate system

A wearable travel aid to guide visually impaired without special infrastructures has been developed. We call this system WEarable walKing mate system (WEK). The WEK has three functions that 1) Create courses data, 2) Guide a visually impaired to the destinations, and 3) Warm the dangerous places. This paper described the estimation method of travel distance using Optical Flow in the WEK, which is effective for various ways of walking. The experimental results in an indoor environment show the each error of estimated travel distance is less than at previous method to three kinds of how, a shuffle, a natural walking, and a march. There are shown that the WEK is efficient for guiding the visually impaired to the destinations.

Indoor localization using infrared global vision system and LRF for twin brushes floor polishing robots

We have been developing floor polishing robots, which have two rotary brush polishers. These omnidirectional mobile robots require no driving for locomotion and steering because the friction between the floor and rotating brushes is used as the driving force. The localization for these robots cannot be used dead reckoning because water and washing liquid make wheels slip. This paper proposed the localization using the infrared global vision system and a laser range finder (LRF) without touching the floor. In the infrared global vision system, assuming the model that the infrared LED is a point light source, we calculated the center of a LED from a gray scale image. From the experimental result that the processing time was approximately 40(ms) and the accuracy was approximately 16(mm), a high-speed and accurate localization was achieved. And the method using a LRF was also achieved a high speed and precise localization by the comparison with the infrared global vision system. Furthermore, we proposed the method of the precise localization and the obstacle avoidance in all of a room by using these two methods at the same time.

The Robotic Travel Aid “HITOMI”

Publisher Summary Various kinds of electronic travel aid (ETA) have been developed for the visually impaired. Among them, the moat sensor and sonic guide have been available for 20 years, but have not yet become widespread. Recently, vision-guided vehicles have been investigated by many researchers. The robotic travel aid (RoTA) is not a replacement for the guide dog, but it is an advancement of ETA. RoTA is a motorized wheelchair equipped with vision, sonar, and tactile sensors, in addition to a map database system. The visually impaired can get orientation, mobility, and obstacle information from RoTA, and can inquire about their present location, landmarks, and the future part of the route. The concept is implemented on a RoTA called “HITOMI.” It can guide the impaired to avoid vehicles along a road with lane marks or along a sidewalk marked with Braille.

Study on DOD Inkjet Using Electrically Controlled Fluid

This paper describes tat the theoretical analysis and the experimental results of the new drop on demand inkjet system using electric field sensitive fluid as ink. The resistance to flow of this fluid can be altered over a wide range by subjecting the fluid to applied electric fields. The fluid is composed of substantial particles such as silica, oily liquid as a vehicle and some suface active agents. The composition of this fluid is similar to that of printing ink. Therefore, we will expect that the copy quality of this inkjet system is as high as that of lithographic printing, A couple of the electrodes is place inside the printhead and the ink is pressurized with the pump. If a sufficient magnitude voltage is applied between the electrodes, the effective fluid viscosity extremely increases so the fluid cannot flow in the prin-thead. When the applied voltage is removed for a short period, the jet of ink is produced because of decreased fluid viscosity. Experimental results show that the ink droplets can be produced by controlled electric fields.