Objective: To control an X Y coordinate system with a robotic arm using a Motorola 68020 Microproscessor with assembly language.
Application: The Varry 2000 can be used in many types of application. There are many areas and conditions where it is unhelthy for humans to work in, such as toxic areas. The Varry 2000 can be exposed to such an environment. This system can handle small and delicate objects using accurate, sensitive and precise movement. Also, it is clean and free of unwanted microscopic materials. Such real world application can be applied on handling wafers for semiconductors, vacuumed areas, testing satellite components in thermo vac environments, and the automotive assembly line.
Block Diagram:
Operation of the Varry 2000: The Varry 2000 is a very versatile machine. During execution, the Varry 2000 has an emergency button that will halt all operations. It has three operating modes which are the Super Manual, Manual, and Laser Mode. A manual switch is used ot change modes as in figure 1A.
The Super Manual Mode is the mode in which every component can be operated manually. Pressng a key on the keypad, figure 1B (O open, C close, U up, D down, L left, R right), does this manual operation. In the Super Manual Mode, the operation consist of moving each stepper motor back or forward and moving the robotic arm in any such directions; i.e. Opening or closing the claw or moving the shoulder up or down. This mode is good for adjusting the robotic arm to make changes in the program (assembly language) for picking up objects.
Next is the Manual Mode. The difference between the Manual Mode and the Super Manual Mode is that in the Manual Mode, it uses the robotic arm to directly pick up an object instead of moving the robotic arm manually. This way you can pick up an object and move it ot any position you desire. These keypad operations are shown in figure 1C.
The final mode is the Laser Mode. The objective of this mode is ot locate an object anywhere on the X Y plane, pick it up and place it at the origin of the robotic arm's position. The first stepper motor moves a laser back and forth until the laser touches an object. A button is then presed. The X axis then follows to the same location. Next, the Y axis will scan that row until the laser touch the same object and another button is pressed. Once both lasers touch the same object, the robotic arm will reach down to grab the object and take it ot the origin of the robotic arm. Teh keypad operation is shown in figure 1D.
A. Switch for switching modes.
Bit 0 = 0 Laser Mode
Bit 0 = 1 Manual Mode
Bit 1 = 1 Super Manual Mode
Bit 2 = 1 Search for what mode
Interfacing a Control Unit to the Varry 2000: The electronic control units for the Varry 2000 consist of three unipolar stepper motors and five servomotors. The unipolar stepper motors controls the X Y axes and one of tghe lasers scan. To buffer and interface the three stepper motors, there where 12 darlington pair transistors (NTE 2336) used. These transistors are capable of handling up to 8A. To rotate the stepper motors, you must send a logical sequence of parallel data:
The five servomotors were controlled by a Serial Servo Controller (SSC). There are three configurations for the SSC, which are the range, identification, and the baud rate. The SSC was configured for the Varry 2000 at 9600 baud-rate, identification for servos 0-7, and a range of +/- 90 degrees. To command a servo to a new position requires sending three bytes at the appropriate baud rate.
To view the schematics for the control unit and periferials, click on the following:
Motorolla 68020
EPROM SRAM
Glue Logic
Control Unit Periferals
Control 68020 clock setup
Specification:
Here are some graphic pictures of me and my project.
Conclusion: This project has been very challenging to me. The main problem that I encountered was building the X Y Coordinate System. The blueprints was kept in my head and every thing had to be built from scratch. It took me weeks to find the right size stepper motors, cutting the plexy glass (without breaking it), finding the right size rods and bushings, and finding the most affordable pulleys and pulley belts. Next, I had a minor problem of finding the most affordable stepper motor drivers that can handle up to 2A. The solution to that was the NTE 2336 transistors with the 74ls373 octal latch D-flip flops. Once all the problems were solved, every thing else was a piece of cake. It took me about three days to write the majority of my assemble language, which consisted of about nine pages. Finally, I added an extra mode that then made my program fithteen pagers. I had to learn all this plus A LOT MORE in just two almost three years. I knew absolutly nothing about computers or electronics before I came to DeVry. I started DeVry in the summer of 1996 and I did this project in May of 1999. This project took 1st PLACE. I competed against twenty five other projects, consisting of both Pomona and Long Beach Devry. I was representing Long Beach of course. I am currently working at Qualcomm now learning a whole lot more!!!!
If you have any questions or comments email me at:
Number of Visitors:
Composed with care by:
(Tavares R Forby)
Control Unit:
Processor:
68020 Microprocessor
System Speed:
10 MHz
Input Voltage:
5 Vdc
Typical Controller Curent:
700 mA
RAM:
SRAM 6264 (8k X 8)
ROM:
EPROM 27128 (16k X 8)
DUART:
SCN68681
16 Keypad:
Grayhill 84BC1-001
Transistors:
NTE 2336(Ic = 8A, hFE = 2000)
Robotic Arm:
SSC:
Serial Servo Control
Servo:
HITEC
Input Voltage Requirement:
4.8-6 Vdc
Servo Current(idle):
9.7 mA(each)
Servo Current(moving):
130 mA(each)
X Y Coordinate System:
Stepper Motor:
NEMA Size 17(Unipolar)
Stepper Motor Current(idle):
1.2A(each)
Stepper Motor Current(moving):
600 mA(each)
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