Robotic Arm: Team A-November
Team A-November is a lab group for the E-5 Robot Arm project. The A-November arm consists of two servos, two pieces of aluminum tubing, and various other hardware,used to create an arm of total length 35.5 cm with two degrees of freedom and the ability to be controlled by a computer. Specifically the arm draws a circle in a box, when a MatLab script is run.
To build the arm we were given two servos and our choice of several brackets and pieces of tubing. First we attached the servo motors to brackets so that they could be attached to other parts. The first bracket (the "shoulder") is a stand that holds the motor fixed several inches above the writing surface. The second, "elbow", bracket consists of a piece of sheet metal used to attach the servo to the upper arm and a "C" shaped bracket attached to output of the servo on one end and the lower arm on the other. The aluminum tubes we used were longer than most of the choices available because we felt that the shorter arms would limit both the range of motion of the arm and the size of our drawings. As we were choosing parts to make the arm we did use smaller tubes originally, but in the end we found that we preferred the longer arm. As we found out when we were testing it, the long arm did have its drawbacks. The distance from the servos of the pencil made every jerk of the motor a big jump. A smaller, sturdier design may have produced smoother drawings.
To draw the circle inside the square, and to create a real time on-screen simulation we used one script. here is he source for that script: