Shuuji Kajita

Estimation and control of the attitude of a dynamic mobile robot using internal sensors

For the control of a dynamic mobile robot, the attitude in gravity space is an important state of the robot. Usually, the attitude is difficult to detect by simply using the signals from sensors. For example, an external sensor contacting the ground suffers disturbances from the roughness of the ground; the integration of a gyroscope signal has the problem of drift; an inclination sensor does not indicate the direction of gravity when acceleration exists. To solve these problems, we propose a control method in which the attitude of a mobile robot is estimated by an observer considering the robot dynamics and using only the information obtained by internal sensors. We applied this method to a wheeled inverted pendulum as an example of a dynamic mobile robot. The estimation of the attitude was made with good accuracy using the signals from the rate gyroscope and the motor encoder, and the control of stable running of the pendulum on a flat level plane worked successfully. We also realized the running contro...

The concept of model free robotics for robots to act in uncertain environments

A concept of model free robotics was proposed for a robot to act stably in an uncertain environment, which is a bounded but unpredictable environment. In the concept a robot is devised to act stably in an uncertain environment with little or no sensing of the environment. The stability may be realized by control, by mechanisms, or by both. The concept of model free robotics was demonstrated using such robots as a wheeled inverted pendulum, a four-wheeled active suspension robot, a biped robot, and a wall climbing robot with scanning type suction cups. It also applies to many robotic developments achieved by researchers other than the authors as well. This concept will hopefully help robots solve some problems of the global environment.<<ETX>>

Wheeled Robots to Overcome Ground Unevenness in Construction Areas

The recent demands for use of robots in construction areas require realization of robots that can run and work over rough grounds. We seek for the technological possibilities to allow wheeled robots to move freely by overcoming unevenness of the ground. We have studied active suspensions for wheeled robots to minimize the body shake, a wheeled inverted pendulum to detect its attitude and the ground slope, and a wheeled jumping robot to pass over a step. Refining and combining these element technologies, we hope, to realize useful wheeled terrain robots.