An Examination of Echoic Flow Based Autonomous Guidance Using the Lego Mindstorms NXT Robot

Student: Yuyao Chen

Advisors: Christopher Baker and Graeme Smith (Engineering)

Abstract: It is well known that some animals, such as bats, can find their routes home autonomously and are able to avoid crashing into each other while traveling in a group. They do this using echolocation that enables them to function at dusk and in the dark. My research project is to investigate how these complicated behaviors can be replicated using robot vehicles that have echolocation sensors. Echoic flow fields are computed and simple rules to govern subsequent behavior are implemented. Echoic flow is defined to be the ratio of a sensed parameter such as range or intensity to a change in that parameter per unit time. The ratio of these two quantities gives the time over which two bodies will come into contact (collide). This “time to collision” can be used to provide feedback to the robot to either avoid collisions or to control the form of a collision. Previous theoretical research has shown that echoic flow can be used to control the behaviors of objects in relative motion. Experimental work has shown that the Lego NXT robot and its ultrasonic echolocation sensors can enable obstacle avoidance. My project develops extends this earlier experimental research to determine if echoic flow can be used to control two robots so that one leads and has to avoid obstacles as it autonomously navigates a course while the other follows the first robot maintaining a constant time to collision. In order to accomplish this experiment, two robots are needed. The leading robot can be controlled by a remote control with a vertical flat board, and the following robot is Lego NXT robot which can be programmed by Matlab and it also has two ultrasonic sensors connected by wires. The function of ultrasonic sensors is to test the range from current position to the wall (solid board). This project helps us to understand bat’s echolocation behavior by applying echoic flow theorem to Lego NXT robot with ultrasonic sensors.

Booth: 209