Ball Balancing Challenge - Revision history

AlexanderLeung: /* Circuit Components */

2008-03-21T08:23:29Z

Circuit Components

AlexanderLeung: /* Circuit Components */

2008-03-21T08:23:08Z

Circuit Components

AlexanderLeung: /* Circuit Components */

2008-03-21T08:22:47Z

Circuit Components

JeremyDarling at 08:19, 21 March 2008

2008-03-21T08:19:53Z

JeremyDarling at 08:19, 21 March 2008

2008-03-21T08:19:30Z

JeremyDarling: /* Electrical Design */

2008-03-21T08:19:02Z

Electrical Design

JeremyDarling: /* Mechanical Design */

2008-03-21T08:17:26Z

Mechanical Design

JeremyDarling at 08:15, 21 March 2008

2008-03-21T08:15:33Z

JeremyDarling at 08:15, 21 March 2008

2008-03-21T08:15:13Z

JeremyDarling: /* Electrical Design */

2008-03-21T08:10:41Z

Electrical Design

@@ Line 63: / Line 63: @@
 <tr><td>Joystick</td><td>N/A</td><td>1</td><td>N/A</td><td>N/A</td></tr>
 </table>
 [[Image:T14-electronics-photo-closeup.JPG|right|thumb|Circuit Board|200px]]

@@ Line 64: / Line 64: @@
 </table>
-[[Image:T14-electronics-photo-closeup.JPG|right|thumb|Circuit Board|200px]]
+[[Image:T14-electronics-photo-closeup.JPG|right|thumb|Circuit Board|200px]]
 <b>Diagram:</b>

← Older revision		Revision as of 08:22, 21 March 2008
Line 65:		Line 65:

	[[Image:T14-electronics-photo-closeup.JPG\|right\|thumb\|Circuit Board\|200px]]		[[Image:T14-electronics-photo-closeup.JPG\|right\|thumb\|Circuit Board\|200px]]


	<b>Diagram:</b>		<b>Diagram:</b>

← Older revision		Revision as of 08:19, 21 March 2008
Line 1:		Line 1:
	[[image:T14-project-action-08.jpg\|~~300px~~\|right]]		[[image:T14-project-action-08.jpg\|350px\|right]]

← Older revision		Revision as of 08:19, 21 March 2008
Line 1:		Line 1:
	[[image:T14-project-action-08.jpg\|~~250px~~\|right]]		[[image:T14-project-action-08.jpg\|300px\|right]]

@@ Line 34: / Line 34: @@
 ==Electrical Design==
+=== Overview ===
 The Electrical Design was fairly simple for this project. The inputs to the PIC were the joystick, coin slot, and the touchscreen. The outputs were the motors, LED "strike" array, and buzzer. The touchscreen was also an output as it was controlled by the PIC.
 [[Image:TouchscreenControlpanel.JPG|left|thumb|Touch screen controls and LED display|200px]]
+=== PIC Inputs ===
 The user would control the joystick that was simply two potentiometers that would output a value between 0V and 5V, corresponding to both the x-axis and the y-axis. This went to one of the PIC's analog inputs. The coin would simply fall on a simple switch, connecting 5V to the PIC. The touchscreen input looks like a square wave, except the two values being received correspond to the voltage from each axis. Separating these two values is done in software.
 Toggle switches were added to allow easy powering on and off of our system. Also, a switch for automatic and manual control was implemented which was designed to have the purpose of switching the design from joystick control to automatic system control (self-adjusting touchscreen). The reset button was implemented to end the game at any time and end the main loop so that the motors would be inactive.
+=== PIC Outputs ===
 The PIC output to the motors corresponds directly to the joystick input. The PIC output goes both to the H-bridge and an inverter for each motor, so that the motor sees not a PWM signal and ground, but a PWM signal with its inverse PWM signal. As a result of this, both poles of the motor see the same thing when the high and low pulses of the signal are equal. The motors turn one way proportionally to the joystick position when the PWM has more time high than low (when that joystick potentiometer is sending a higher signal)and the other way when the PWM is more low than high.
 The PIC output to the touchscreen is very simple. Although we had it go through an H-bridge to amplify the current, this is probably not necessary. Because the diagonally opposite corners of the touchscreen always have an opposite voltage going into them, we just ran the signal through an inverter so that we could control all four corners with only two PIC outputs.
-Information about the specifics, implementation and code that was used for the reading of the resistive touchscreen can be found [http://hades.mech.northwestern.edu/wiki/index.php/Resistive_Touchscreen here].
 === Circuit Components ===
+Information about the specifics, implementation and code that was used for the reading of the resistive touchscreen can be found [http://hades.mech.northwestern.edu/wiki/index.php/Resistive_Touchscreen here].
 <b>Parts List:</b>

@@ Line 20: / Line 20: @@
 [[Image:Motorandconnection.JPG|right|thumb|Faulhaber Motor with epoxy connection to metal frame|200px]]
+=== Overview ===
 Our team weighed several alternatives for a mechanical system that could turn the screen in two axes.  Potential solutions included a gimble system with a double-frame design and a pully-operated system that would lift up on two sides of the screen.  Eventually, we decided on a system that was theoretically less precise, but much simpler and requiring less power (since one motor does not need to lift another).  The system worked well under joystick control, but is only reliable for small tilting angles.
+=== Mechanical Explanation ===
 A sheet metal frame was built around the frame for protection, supported at its center of gravity by a pillar attached to the wooden base.  The frame can freely tilt in two directions, allowing all possible ball movements.  By raising and lowering two adjacent sides of the frame, the touch screen can be tilted in two directions.  This motion is provided by two [http://hades.mech.northwestern.edu/wiki/index.php/Actuators_Available_in_the_Mechatronics_Lab#Faulhaber_1524E006S_motor_with_141:1_gearhead_and_HES164A_magnetic_quadrature_encoder Faulhaber motors] mounted underneath the screen.  The output shaft of the motors' gear boxes are attached to a threaded rod by couplers that we machined for the purpose.  The couplers are attached to the motor shaft by a radial set screw and to the threaded rods by locking nuts.  Riding on these rods are two threaded aluminum pieces, which are attached to the bottom of the frame via flexible tubing and epoxy.  As the angle of the screen changes in one direction, the location of the attachment of the other motor moves slightly relative to the base of the motor.  The flexible coupling allows for this motion, while providing vertical stability and transferring the up and down motion of the threaded pieces to the sides of the frame.  [[Image:Coinslotopen.JPG|left|thumb|Coinslot with top off|200px]] Provided that the tilt angle remains small, its value can be approximated by the inverse tangent of the vertical motion of the threaded rod divided by 9cm (the horizontal distance from the tubing connection to the center of the frame). By controlling the speed of the motors via [http://hades.mech.northwestern.edu/wiki/index.php/Pulse_Width_Modulation pulse width modulation], the tilt angles of the touch screen can be changed at a variety of speeds.
+=== Other features ===
 Other features include adjustable legs for stabilizing the wooden base on an uneven surface, and an upper frame above the touchscreen that prevents the ball from rolling onto the non-sensing regions at the periphery of the touchscreen.  The mechanical design for this project was the simplest and most inexpensive option for this application; if a greater level of precision were required, a more complicated mechanism may have been necessary.

← Older revision		Revision as of 08:15, 21 March 2008
Line 1:		Line 1:
	[[image:T14-project-action-08.jpg\|~~2500px~~\|right]]		[[image:T14-project-action-08.jpg\|250px\|right]]