Goalie
Printer
The printer is a salvaged AppleŠ Style
Writer 4100 Desktop Printer (1997). The printer was chosen for meeting our
desired goals of linear motion, a powerful DC motor, and a high-resolution
optical encoder, all within a pre-assembled package. All of the extraneous
circuitry and components were removed from the printer, leaving only the two
wire leads to the motor and the four wire leads to the encoder.
Motor
Motor Specifications
|
Rating (volts) |
|
19 |
|
Max (volts) |
|
24 |
|
Stall Current (amps) |
|
2.5 |
|
Stall Torque (N-cm) |
|
28.7 |
|
Stall Torque (in-oz) |
|
40.68 |
|
No Load Speed (rpm) |
|
4,550 |
|
No Load Speed (rad/sec) |
|
476 |
|
Max Power (Watts) |
|
34.2 |
|
Max Power (milli-HP) |
|
45.83 |
|
Duration (sec) |
|
30 |
|
Energy (Joules) |
|
1026 |
|
Weight (grams) |
|
224 |
|
Weight (oz) |
|
7.88 |
|
Power/Weight (Watts/kg) |
|
153 |
|
Energy/Weight (Joules/kg) |
|
4580 |
|
No Load Current (amps) |
|
0.15 |
|
Start Up Voltage (volts) |
|
2 |
|
Resistance (ohms) |
|
8.2 |
|
Motor Const
(N-cm/watt^0.5) |
|
1.8 |
|
Torque
Constant (N-cm/amp) |
|
4.8 |
|
Inertia (g-cm2) |
|
45 |
|
Shaft Diameter (mm) |
|
3.1 |
|
Shaft Diameter (in) |
|
0.12 |
|
Shaft Length (mm) |
|
85 |
|
Motor Diameter (mm) |
|
37 |
|
Motor Length (mm) |
|
64 |
|
 Encoder
The encoder assembly used is that from
the original printer. The ribbon connections have been removed and four new
wires have been soldered to the existing circuit board.
Specification Sheets:
Agilent Optical
Encoder Modules
Rail
The rail is an aluminum tube over which
the goalie rides on a bearing. The goalie is attached to a toothed belt which
is driven by the vertically mounted motor on one end. The belt passes over an
idler return gear on the other side, which keeps the belt taut during operation.
|
Photosensor Strips
The photosensor strips (photostrips)
were fabricated for easy installation and removal into any chosen Chaockey
playing board. They consist of two layers of foamcore. (See the document on
Fabulous Foamcore.)
-
 The
top layer has evenly spaced holes to expose the photosensors.
- The bottom layer has smaller
holes to pass the sensor leads through, allowing the sensors to be pulled
securely and consistently flush to the strip.
- On the bottom side of the
bottom strip, conduit channels have been carved in the foamcore. The
leads were soldered to the connecting wires and tucked into the channels.
- One side of the strip
features only one channel, allowing connection of all sensors to the common
power line. The other side features 3 channels, each of which carries 3
of the signal wires to the pull-up circuitboard (9 wires exiting each end of
each photostrip.)
|
Click
here for more on the electrical circuit design.
The above photo shows the construction
detail on the bottom side of the bottom photostrip. Having the foamcore
serve as a conduit for all the wires allowed for high portability of the
assembly and made testing and debugging much easier.
Board
The Chaockey board is built
from wooden sheets and slats. The play surface consists of two layers of foamcore. This configuration allows for easy reconfiguration of the playing
board, should the gaps between the goalie and the photostrips need to be
changed. This reconfigurability was used in determining the current gap
dimensions. The plexiglass is finally placed over the foamcore and strips to
allow seamless and smooth play.
