Masataka Hirai

Development of an Intelligent Senior-Car in a Pedestrian Walkway

Abstract This research aims at development of a stable mobile robot (personal mobility robot) that can navigate automatically on sidewalks where ordinary citizens are coming and going. Many studies have investigated automated vehicles that move on public roads. In the case of a road environment, many infrastructures and traffic regulations exist. In contrast, in a sidewalk environment, human and robots cross the same area without clear rules. For these reasons, some paths or landmarks are often blocked by unknown obstacles such as bicycles and passing pedestrians. Therefore, the most important requirements for a mobile robot are robust localization and safe navigation without collisions. We proposed simple and novel algorithms for localization using a grid map and navigation for four-wheeled robots. We also developed an intelligent robotic cart (senior car) that moves autonomously along a given course to help people transfer luggage or themselves. The sensors used in this system are three small laser scanners and an optical fiber gyroscope. The robot estimates its global position by using the integrated sensor information and generates local paths for avoiding nearby obstacles. This article describes the structure of the developed senior car and details of the proposed algorithms. We also describe a field experiment of our system in the Tsukuba Challenge 2010. Our robot successfully and autonomously ran the 1.1 km course in a realistic environment. The experiment showed the robot could estimate its position and follow the specified path effectively.

Development of an intelligent mobility scooter

This paper describes a development of a robot scooter platform for intelligent personal mobility robot. Recently, a lot of personal mobility has been used by aged and handicapped people. Intelligent mobility robot provides safer and more convenient transfer service such as driving support and automatic transfer. It is necessary to develop a platform equipped with sensors, electronic devices and intelligent navigation functions. In this paper, we describe the hardware components and the configuration of the robot platform. The navigation system, including the functions of localization using grid map matching, path following, and obstacle avoidance, is implemented on the proposed robot platform. We also present the results of an open-field experiment in Tsukuba Challenge 2010 and evaluate the proposed systems. The newly developed robot scooter successfully and autonomously ran a 1.1 km course in a normal living environment.

Human friendly path tracking for autonomous robot cart: Determine look-ahead target points under shortcut controlling

We have constructed a car type personal mobility (a robot cart) that moves around autonomously to help people transfer their luggage and to bring people to their target location. For an autonomous mobility, it is important to avoid making passengers uncomfortable or anxious, as well as to provide safety for the people around them. One reason of the anxious feeling is movements by autonomous navigation that is unexpected for passengers, and it can be reduced by taking a navigation algorithm that is similar to a human way of steering. Based on this concept, focusing on the human way of steering by changing gaze points depending on curvature of the path, we developed an algorithm of look-ahead path tracking for autonomous robot carts according to change the target point from the curvature of the path. First, we formulated the geometrical relationship among the curvature of a path, the position of target points, and the trajectory of a robot, and then, proposed the algorithm to control a robot using the relationship. We implemented the algorithm on the robot cart we constructed, and conducted experiments to evaluate it.

Carrier envelope offset control of broad Raman sidebands by locking two pump laser frequencies to a single optical cavity

We generate broad Raman sidebands with zero carrier-envelope-offset by frequencylocking the pump lasers to a single optical cavity. It is shown in both spectral and temporal domains that the carrier-envelope-offset is controlled to discrete values.

Generation of broad Raman sidebands with zero carrier envelope offset by locking two pump-laser frequencies to a single optical cavity

We generate broad Raman sidebands with controlled carrier-envelope-offset (CEO) by locking the pump frequencies to a cavity. The CEOs controlled to integer multiples of the cavity FSR are observed both in spectral and temporal domains.