Shaojie Ge

Design Overview  The robot simulates the movements of a four leg walking animal. Its basic function include: Walking with four legs, sensing the obstacles, determining the size of the obstacle, and walking backwards or turning direction(left/right) with respect to the size and orientation of the obstacle.

Main Structure  The robot has 4 legs and 9 degree of freedom. Each of the legs has 2 joints, and every degree of freedom is to be accomplished by a embed servo motor. Given certain electrical pulses, the servo motor will make the joint perform the desired rotation of the joint.  Robot Structure

Control and sense system  I use Arduino mega 2560 as the controlling board of the robot. SSC-32 servo motor controller to control the servo motors of the robot. By using UARTs of Arduino mega 2560, I can transmit data between Arduido mega 2560 r3 and SSC- 32 servo motor control board.  Arduino mega 2560 SSC32 servo driver

 I use one IR sensor for obstacle detection and avoidance. It is mounted on a servo motor to give it ability to detect signal from different direction. IR sensor

Actuator  The servo on the joints of legs are supposed to withstand a relatively high torque during walking. I choose DELUXE HS- 485HB servo motor. HS-485HB

 My special sensor system is the walk mechanism of my robot. The basic concept is alternating gait. It consists of upshifting and advancing. By making legs upshifting and advancing in certain sequence, the robot can get force to walk and turn. Special Sensor System

 Walking Forward: The motion of walking can be divided into 8 portions. When the front-left and rear-right legs are upshifting to push the robot forward, the other two advancing. Similarly, when front-right and rear-left legs are upshifting, the other legs are advancing.  Turning Direction: The issue in this part is that the legs cannot move simultaneously when turning. Because it will give apply force of opposite direction to the robot, basically they just counteract with each other. I made its two legs of the same side stay still while other two moving in sequence (upshifting and advancing)to actually apply force to the robot to turn.

Conclusion  On the demo day. I will make the robot stand up, walk forward. When there is something blocking its way, it will act based on the size of the obstacle: If it’s a big one, the robot will move back; If it’s a relatively small one, it will turn to direction where there is no obstacle ahead, and keep moving.