07.20.04
Welcome to the ELEC 499A Design Page. The Robot will be demonstrated on Friday, July 23rd at 3:30pm in the lobby of the ELW. A Quicktime video of the robot will also be played during the demo.


Software:

The software was implemented using Microsoft Visual C++. A DB-25 parallel port was used for communicating with the robot via the electronics. The software had to supply all operational data for the robot including: resetting the robot, selecting which motor receives clock pulse, selecting direction of each motor, and rotating the robot with the use of up to three motors simultaneously. In addition to providing an interface for the user, the software has built in text file reading and writing abilities. The user can simply create a comma delimited text file with a finite number positions that the robot will loop through.

Screenshot:

Objective:

To design and build a computer controlled robot arm with similar functionality to the commercially available CRS-Plus robot arm.


Background:

The CRS-Plus robotic system consists of a CRS-Plus mechanical manipulator with a standard hand, a system controller, and a teach pendant. The mechanical manipulator uses servomotors to move in five degrees of freedom. The CRS-Plus is initially taught manually with the teach pendant. The teach pendant is used to move the robot arm manually joint by joint. Once all the points are saved the system controller can move the arm and repeat the motions with a high degree of accuracy and precision. Unfortunately, the CRS-Plus robotic system costs thousands of dollars to purchase. The goal of this project is to create a computer controlled robot arm with similar functionality which costs much less.

Mechanical:

The robot arm's original driving mechanism was taken out and replaced with six stepper motors. Fittings were made for each stepper motor using a 1" solid PVC rod. At the end of each rod a " hole was drilled to hold the shaft of the motor. A pilot hole was made at the other end of the rod where a gear was secured using screws. The stepper motors and robot arm base were mounted onto a wooden platform as shown in the gallery.

Electronics:

The stepper motors used in this project are 5 wire unipolar motors. Each stepper motor has its own driving circuit consisting of a 4 bit shift register and four darlington sink drivers. To drive each stepper motor a clock signal is fed into the appropriate shift register. To reduce the number of control lines a demultiplexor is used to share a single clock signal. Some motors need to be running simultaneously and have been provided a dedicated clock signal.