Satoshi Muramatsu

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.

A standing assistance based on a load estimation considering with a muscle arrangements at the human leg

In our previous research, we have developed a novel standing assistance system, which uses a remaining physical strength of an elderly person. For realizing it, the assistance system needs to estimate the load of a patient and in many cases, the previous researchers use a joint traction which can be derived by a human linkages model kinematically for evaluating it. However, human body motions are generated by many muscles and a joint traction, which muscles can generate, changes according to the relative position between the muscles and links. This means there is not always mutual relation between a muscle activity and a joint traction, and it is difficult to evaluate the muscular power of a patient during a standing motion simply using a joint traction. Therefore, in this paper, we propose a load estimation scheme which consider the muscle functionality of the patient. Our key idea is a load estimation using the human musculo-skeletal model of a lower limb, which expresses a biarticular muscle function. In general, the human generates a natural standing motion using the biarticular muscle function. This model enables the standing assistance system to estimate a load of the subject without biosensors such as an electromyograph and to assist the standing motion using a remaining physical strength of the subject maximally.

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.

Analysis of a design index for the service robot in a human-coexistence environment

In recent years, service robots are required to execute various tasks in a human-coexistence environment. These robots should be designed not to induce discomfort and aversion in people who use them. To realize this, we focus on the design method for the service robot which runs around in a public space. These service robots should avoid giving a negative impression to these people. Thus, in this paper, we investigate pairs of polar adjectives which consist of the robots body with a questionnaire employing 142 subjects - 92 men and 50 women - aged 18 to 63. The answers of this questionnaire reveal 22 appropriate pairs of polar adjectives which are suitable for a psychological assessment of subjects who use the robot or coexist around the robot. Furthermore, using them, we investigate a potential which realizes the proposed service robots design method for giving a positive impression to people.

A localization based on a space observation model in a crowded environment

This paper describes a localization technique for a mobile robot in an environment with many unknown obstacles, such as pedestrians. To realize robust localization against unknown obstacles by using a particle filter, a free-space observation model and an area-observation model have previously been proposed. Although these localization methods are very effective, both methods evaluate the likelihood by using only the free-space model. Thus, in the environment where only the left or the right side is open, the likelihood of a particle separated from a fixed obstacle cannot be lowered. For this reason, the particle continues to spread and cannot converge when the fixed obstacle is observed on only one side. In the present research, we solve these problems by two likelihood evaluations based on the free space and the occupied space. We evaluate the robustness and verify the validity of the proposed method by a simulation and an experiment in a real environment.

Standing assistance considering a voluntary movement and a postural adjustment

In this paper, we propose a standing assistance scheme that uses a patients own physical strength. In the previous researches, conventional assistive robots do not require patients to use their own physical strength to stand, which leads to decreased strength in the elderly. Therefore, an assistive robot that allows a patient to maximally use their remaining physical strength is desired. For realizing this objective, we propose a standing assistance scheme that realizes two functions, one is a motion assistance function using a patients own physical strength, and the other is postural adjustment function. In general, a human movement consists of a voluntary movement which mainly generates the body motion and a postural adjustment which keeps the body stability during the motion. Our proposed scheme assists with the minimum force that enables the voluntary movement with their remaining physical strength and keeps the body stability according to their postural adjustment. For realizing two different approaches in same time, we propose a body movement vector for dividing a human motion into a voluntary movement and a postural adjustment. Using the proposed idea, our prototype assistive robot can help elderly patients to stand using their remaining physical strength maximally by two assistive functions.

Consideration of the preliminary announcement function for the human friendly service robot

The preliminary announcement, for example, the turn-signal of the automobile, the tracks announcement use turning or reversing and voice announcement of the train arrives at the platform are used in the various scenes in a daily life. These preliminary announcements are used to suppress the negative impression such as discomfort, aversion and surprise of the human. In this sturdy, we clarify the effective service robots preliminary announcement that does not give discomfort and aversion to humans in the actual outdoor symbiotic environment. In this paper, we clarified the effective preliminary announcement of the service robot in a real outdoor symbiotic environment that is used three revolving lights on the top of our prototype robot. Furthermore, we investigated the effectiveness of preliminary announcement in the actual outdoor symbiotic environment.

Robot navigation according to the characteristics of pedestrian flow

In recent years, service robots have tended to have the ability to move autonomously in an environment in which they co-exist with humans. Thus, the robots must engage in obstacle avoidance and arrive at the goal point. The potential method is one of the path planning methods for obstacle avoidance. Because pedestrian is moving obstacle, he/she may go outside of artificial potential in a similar method suggested by a previous study. However, if the robot avoids collision too securely, robots performance is limited so a trade-off problem arises between collision avoidance and robots performance. A potential method requires a function that allows a robot to plan an effective path without collision with pedestrian by predicting a pedestrians next position during robot operation. In this study, we develop a robot navigation method according to the characteristics of pedestrian flow. We spread a repulsive potential that adapts the pedestrian potential equation based on the route estimation model. In the proposed method, the repulsive potential changes depending on the position or the velocity of the pedestrian. The robot plans a path without including unnecessary potential, according to the pedestrians route estimation range. Compared with the previous potential method, wherein the potential field is distributed equally around a pedestrian the same way as a static obstacle, the proposed method enables the robot to plan an effective path with pedestrian characteristics. The proposed methods effectiveness is demonstrated through experiments.

Robotic driving assistance system for manual wheelchair user on uneven ground

This paper proposes a novel driving assistance system for a manual wheelchair. On an inclined road, there is a high risk of a wheelchair moving in a direction that the user does not intend. Using only servo brakes on each wheel, our proposed system negates the wheel traction that is generated by the roads inclination. Our system measures the roads inclination and estimates the wheel traction generated by gravitational force. Our system then cancels this traction and the user can drive the wheelchair as they would on flat ground. The system is intuitive because the user drives the wheelchair in the usual manner, and our assistance system works passively to complement the users intentional force. Our system uses only servo brakes that can generate the various required levels of brake traction. Our system does not require actuators, and its mechanism is simple and inexpensive. There is no risk of malfunction of servomotors. We verified the effectiveness of our proposed assistance system by conducting experiments with a prototype.

Error revision of pictographs detection by removing feature points from the background

In this paper, we propose a novel pictograph detection scheme by removing miss matching points. In our previous work, we developed a robot navigation which uses only one CCD camera equipped on the robot and estimates localize self-position by pictographs on a general environment. However, our system sometimes misjudges feature points on the background as feature points on pictographs. Threfore, our proposed scheme removes these misjudge points by making color histograms. Misjudge points are distinguished from their similarity, and are removed. In matching experiment, we verified correcting misjudge points and the error of the detected position of the pictograph in the image. As a result, in every kind of pictographs which were used for the experiment, we verified the effectiveness of our proposed methods.