Local-behavior determination for an omnidirectional mobile robot using an integration-type sonar ring

Abstract

Time-of-flight ranging methods are generally utilized to measure distance using an ultrasonic wave sensor. However, faint reflected waves tend to be overlooked by this method. We have proposed an integration-type ultrasonic wave sensor that effectively uses faint reflected waves. This paper proposes a local-behavior determination method for autonomous mobile robots using a sonar ring, which consists of multiple integration-type ultrasonic wave sensors. This sonar ring can reduce the sensing time because it simultaneously obtains information from multiple directions. We apply our previously developed pathgeneration method to an omnidirectional mobile robot. Generally, the objective of a mobile robot is to reach a target position as quickly as possible. At the same time, the robot is required to avoid collisions with obstacles. Therefore, it needs to slow down to safely bypass obstacles in high-obstacle-density environments. This paper also proposes a method for controlling the velocity of the robot by generating the target acceleration. Our proposed method takes the upper limit of the input torque into account. Experimental results show that in the presence of obstacles in the vicinity of the mobile robot, the proposed method can decrease the velocity of the mobile robot in order to avoid collision with obstacles.