ECE 271 ROBOT PROJECT
Project members:
Chris Babcock Felipe Olvera Mike Levy Ryan Foushee
Our project will control the OWI robotic arm. The arm will perform one of four operations. The operation will be selected via Mike Levy’s probabilistic state machine. The control circuit will receive a 2-bit code from Mike's machine, which corresponds to one of the four operations. One of the commands will cause the robot to pick up an object and move it. Another command will test the range of motion of the arm by bringing it parallel with the ground, then swinging it 180 degrees. Then there is the danger command. This command will cause the wrist to rotate back and forth, while the gripper opens and closes trying to get its hands on whatever it can. The last command is the do-nothing command. The arm will also have a home function. This will allow the arm to return to the same location after each operation. Below is a list of commands with its 2-bit code and abbreviation.
| Code | Description | Abbreviation |
| 00 | do nothing | do_n |
| 01 | swing arm | Sw_a |
| 10 | danger | Dng |
| 11 | move object | Mv_o |
Besides the 2-bit command code, the control circuit will have 15 additional inputs. Ten of these inputs are from the counter. The counter is clocked at 8Hz with a 555 timer. The other 5 inputs are from the sensors on the robot. Below is a table of sensor outputs followed by a table that shows the significance of each counter bit. Keep in mind that the clock is running at 8Hz, so the LSB of the counter changes every 1/8 of a second.
| Sensor | Description of Home Position | Abbreviation |
| Base | Base has rotated all the way to the clockwise position. | B_is_home |
| Shoulder | Shoulder is all of the way up. | S_is_home |
| Elbow | Elbow is all of the way up. | E_is_home |
| Gripper | Gripper is all the way open. | G_is_home |
| Wrist | Wrist has rotated all the way to the clockwise position. | W_is_home |
Counter Bits:
| MSB | LSB | |||||||||||
| C9 | C8 | C7 | C6 | C5 | C4 | C3 | C2 | C1 | C0 | |||
| Bit: | 2 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
2 |
| Time: | 64 | 32 | 16 | 8 | 4 | 2 | 1 | 1/2 | 1/4 | 1/8 |
The following is a list of outputs with the abbreviations that are used in the flowchart.
| Description | Abbreviation |
| Base counter-clockwise | B_cc |
| Base clockwise | B_cw |
| Shoulder down | Sh_d |
| Shoulder up | Sh_u |
| Elbow down | El_d |
| Elbow up | El_u |
| Gripper open | Gr_o |
| Gripper close | Gr_c |
| Wrist counter-clockwise | W_cc |
| Wrist clockwise | W_cw |
These ten outputs are fed into a power transistor circuit that turns the motors in the appropriate direction.
So far the danger, move object, and go home function have been created in VHDL and simulated successfully.
