11 – Cricket Robot Documentation
How Cricket Works
The following paragraphs explain how Cricket is able to walk, make sounds, and how his
various behaviors and features work.
How Does Cricket Walk?
Cricket uses what is called a tri-gate walk. Tri-gate walking is one of the most efficient
ways to implement a walking robot with a minimum number of motors. The right and left
servo motors move the right and left pairs of legs forward and backward. In order for this
leg movement to move the robot forward, the center legs rock the robot to one side so the
legs can move forward without touching the ground. When the legs are touching the
ground a backward movement pulls the robot forward one step. This stepping alternates
from one side to the other causing the robot to walk forward. Walking backward is the
same as forward except that the legs are off the ground when being moved backward and
touching the ground when being pulled forward. Watch the robot for a while and you will
begin to see how it works. Cricket executes a turn by stepping forward with one side
while the other side steps backwards.
Obstacle Avoidance
Cricket’s Arduino microcontroller is constantly monitoring his sonar and his feeler switches
to detect obstacles. When Cricket detects an object with his sonar or his feelers, he stops,
makes a noise, backs up three steps, scans the area in front of him for the best direction,
and then continues moving forward in the best direction. If either the feelers are bumped,
Cricket will also do a sonar survey of what is in front of him and select the best direction to
proceed. The best direction is the longest unobstructed distance he can measure.
Random Noises
You may notice that Cricket chirps from time to time but not always. Sometimes he will
chirp three or four times in a row. This random chirping is part of the Arduino program.
For every step the robot takes he looks up a random number. If the number is less than a
preset value, Cricket stays quiet, but if the number is larger than a preset value, Cricket
makes a chirp sound.
Flashing LED Eyes
Cricket has two LED eyes. After Cricket is powered up, the green LED eyes will light and
randomly turn on and off. These LEDs are all under the program control and are not just
blinking on their own. Cricket’s eyes will alternate turning on when he is sleeping. Try
pushing the mute button.
Remote Control
The square black module on the controller board is a TV remote receiver module, which
responds to the Remote Control by directing Cricket to actions other than his normal
automatic behavior. During each step Cricket takes, he also checks to see if any remote
control commands were received. The remote module receives the remote control signal
and the Arduino turns the information into commands which Cricket can use to perform
actions. Cricket is able to understand almost all of the keys on the remote.
Summary of Contents for Arduino Walking Robot
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Page 90: ...90 Cricket Robot Documentation Appendix A Schematics...
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Page 92: ...92 Cricket Robot Documentation Appendix B Parts List...
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Page 94: ...94 Cricket Robot Documentation Appendix C PC Board Layout All Layers Parts Layout...
