Basketball - Revision history

John Rula: /* Code */

2009-03-20T08:51:56Z

Code

@@ Line 77: / Line 77: @@
 Full source code of the motor controller can be found [[Media:Motor-Control.c|here]]. <br>
 Full source code of the turntable controller can be found [[Media:Turntable-Control.c|here]]
 == PD Controller ==

John Rula: /* Code */

2009-03-20T08:48:52Z

Code

← Older revision		Revision as of 03:48, 20 March 2009
Line 72:		Line 72:

	The motor was controlled using a PD controller which controlled both speed and position. Theory behind the controller was that if accurate speed control could be achieved along with the ability to control the release point by stopping the motor, we could control the distance the ball traveled to a high degree of accuracy having it follow simple kinematic equations. The launch was triggered when the ultrasonic sensor distance was sent to it. We opted against I2C and instead went with RS-232 for simplicity since we were only sending two bytes of data.		The motor was controlled using a PD controller which controlled both speed and position. Theory behind the controller was that if accurate speed control could be achieved along with the ability to control the release point by stopping the motor, we could control the distance the ball traveled to a high degree of accuracy having it follow simple kinematic equations. The launch was triggered when the ultrasonic sensor distance was sent to it. We opted against I2C and instead went with RS-232 for simplicity since we were only sending two bytes of data.

			The turntable PIC controlled the RC servo, infrared emitter, infrared phototransistor, and PING ultrasonic ranger. The servo cycled through its full range while recording the maximum value from the phototransistor and its position in the servo cycle, returning to the position of maximum infrared light. The [[Ultrasonic_ranging\|PING]] ultrasonic ranger was then used to determine the distance, which was then sent over RS-232 to the motor controlling PIC.

	Full source code of the motor controller can be found [[Media:Motor-Control.c\|here]].		Full source code of the motor controller can be found [[Media:Motor-Control.c\|here]]. <br>
			Full source code of the turntable controller can be found [[Media:Turntable-Control.c\|here]]

	== PD Controller ==		== PD Controller ==

John Rula: /* PIC to PIC communication with RS-232 */

2009-03-20T08:30:41Z

PIC to PIC communication with RS-232

@@ Line 174: / Line 174: @@
 This interrupt is called when the hardware RS-232 receives a byte of data. Once two bytes of data are received (int16), the interrupt reassembles them into a single int16 and calls CalculateAndLaunch().
 == Distance Calculation ==
 Shot distance was based on a second order polynomial fit we obtained experimentally. The data we collected is shown in the image on the right. [[Image:Distance-Calibration-basketball.png|Calibration data and Trendline|thumb|250px|right]]

John Rula: /* Distance Calculation */

2009-03-20T08:30:06Z

Distance Calculation

← Older revision		Revision as of 03:30, 20 March 2009
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	}		}
	== Distance Calculation ==		== Distance Calculation ==
	Shot distance was based on a second order polynomial fit we obtained experimentally. The data we collected is shown in the image on the right. [[Image:Distance-Calibration-basketball.png \| Calibration data and ~~trendline~~ \| thumb \| ~~300px~~ \| right]]		Shot distance was based on a second order polynomial fit we obtained experimentally. The data we collected is shown in the image on the right. [[Image:Distance-Calibration-basketball.png\|Calibration data and Trendline\|thumb\|250px\|right]]
	void LaunchBall(int16 speed, int16 angle) {		void LaunchBall(int16 speed, int16 angle) {
	targetSpeed = speed;		targetSpeed = speed;

John Rula: /* Distance Calculation */

2009-03-20T08:15:42Z

Distance Calculation

← Older revision		Revision as of 03:15, 20 March 2009
Line 209:		Line 209:
	}		}
	== Distance Calculation ==		== Distance Calculation ==
	Shot distance was based on a second order polynomial fit we obtained experimentally. The data we collected is shown in the image on the right. [[Image:Distance-Calibration-basketball.png]]		Shot distance was based on a second order polynomial fit we obtained experimentally. The data we collected is shown in the image on the right. [[Image:Distance-Calibration-basketball.png \| Calibration data and trendline \| thumb \| 300px \| right]]
	void LaunchBall(int16 speed, int16 angle) {		void LaunchBall(int16 speed, int16 angle) {
	targetSpeed = speed;		targetSpeed = speed;

John Rula: /* PD Controller */

2009-03-20T08:14:26Z

PD Controller

← Older revision		Revision as of 03:14, 20 March 2009
Line 83:		Line 83:
	//update counters and encoder		//update counters and encoder
	upCount = get_timer0();		upCount = get_timer0();
	encoderActual += upCount - lastUpCount; ~~//NEW HERE (REMOVED (SIGNED INT16 CAST)~~		encoderActual += upCount - lastUpCount;
	downCount = get_timer1();		downCount = get_timer1();
	encoderActual -= downCount - lastDownCount; ~~//NEW HERE SAME AS ABOVE~~		encoderActual -= downCount - lastDownCount;
	lastUpCount = upCount;		lastUpCount = upCount;
	lastDownCount = downCount;		lastDownCount = downCount;
			We used hardware encoders due to the speed of rotation of the shaft.

	theta = (int16)(encoderActual - offset) % EncCount;		theta = (int16)(encoderActual - offset) % EncCount;
	thetaError = (signed int32)thetaTarget- (signed int32)theta;		thetaError = (signed int32)thetaTarget- (signed int32)theta;
			Theta was used for position control. Due to the way we implemented it, the motor was only was only allowed 359.9 degrees of rotation which was suitable for our launching arm.

	//speed controls whether it is in forward or reverse		//speed controls whether it is in forward or reverse
	if(thetaError > 0) speed = targetSpeed;		if(thetaError > 0) speed = targetSpeed;
	else if(thetaError < 0) speed = -targetSpeed;		else if(thetaError < 0) speed = -targetSpeed;
			A positive thetaError indicated that the motor needed to move CCW to reach its destination A negative thetaError indicated that the motor needed to move CW to reach its destination.

	encoderTarget += speed; //need to add accuracy to speed		encoderTarget += speed; //need to add accuracy to speed
	encoderTargetTheta = (int16)(encoderTarget) % EncCount;		encoderTargetTheta = (int16)(encoderTarget) % EncCount;


	if(encoderTargetTheta > thetaTarget && speed > 0) {		if(encoderTargetTheta > thetaTarget && speed > 0) {
	encoderTarget -= encoderTargetTheta - thetaTarget;		encoderTarget -= encoderTargetTheta - thetaTarget;
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	targetSpeed = 0;		targetSpeed = 0;
	}		}
			The encoderTargetTheta was used to handle the case of overshoots and was the theta value of the encoderTarget after the speed was added. If that theta value was above/below (depending on direction) the target theta value, it represented that the input had reached its destination, so the speed drops to zero, and the encoderTarget is set to the correct target value.

	//do calculations for PD controller with new error		//do calculations for PD controller with new error
	error = encoderTarget - (encoderActual - initialCount);		error = encoderTarget - (encoderActual - initialCount);
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	Torque = pGain * error + dGain * derivative;		Torque = pGain * error + dGain * derivative;
	}		}
			In tuning the PD controller, it was found that different speeds needed different tunings in order to receive a smooth and accurate response. These values represent the best values we were able to obtain in tuning.

	if(error > 0) { //going in the CCW direction, Torque positive		if(error > 0) { //going in the CCW direction, Torque positive
	output_low(PIN_C4);		output_low(PIN_C4);
Line 137:		Line 137:
	}		}
	}		}
			Set PWM values to make motor go forward or reverse. Also, the case where 'launching==1' is to return the arm to a loading position after the arm has shot a ball.

	if(Torque < 0) Torque = 0;		if(Torque < 0) Torque = 0;
	if(Torque > 624) Torque = 624;		if(Torque > 624) Torque = 624;
Line 144:		Line 144:
	}		}
	}		}
			Set the motor's PWM and check for maximum and minimum values. 624 was used instead of 78 for PWM values based on how we set up our timer2.

			== PIC to PIC communication with RS-232 ==
			We choose to use RS-232 to communicate between PICs because of the small amount of data we were sending (a single int16) and to avoid the overhead required by I2C. We accomplished this by breaking our values into 8-bit chunks cast as chars and sending them one at a time.

			sendDistance = avgdistance*100; //distance in cm\

			//Break distance into two 8-bit ints and cast as chars to send over RS-232
			//Will be reassembled on other pic
			putc((char)(sendDistance>>8));
			putc((char)(sendDistance & 255));
			Code to send value.

	#INT_RDA		#INT_RDA
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	}		}
	}		}
			== Distance Calculation ==

			Shot distance was based on a second order polynomial fit we obtained experimentally. The data we collected is shown in the image on the right. [[Image:Distance-Calibration-basketball.png]]
	void LaunchBall(int16 speed, int16 angle) {		void LaunchBall(int16 speed, int16 angle) {
	targetSpeed = speed;		targetSpeed = speed;
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	launching=1;		launching=1;
	}		}


	void CalculateAndLaunch(float dist) {		void CalculateAndLaunch(float dist) {
	dist = dist+30; //adjust for distance between ranger and motor		dist = dist+30; //adjust for distance between ranger and motor

John Rula: /* Results */

2009-03-20T07:31:22Z

Results

← Older revision		Revision as of 02:31, 20 March 2009
Line 212:		Line 212:
	In the end, the project ultimately succeeded -- baskets could be made. However, better tuning for the motor control and needs to be developed for more consistent results.		In the end, the project ultimately succeeded -- baskets could be made. However, better tuning for the motor control and needs to be developed for more consistent results.

			[http://www.youtube.com/watch?v=Y466dzP-qiY Link To Video]
	LINK TO VIDEO HERE

	===Problems Encountered===		===Problems Encountered===

John Rula: /* Code */

2009-03-20T07:18:22Z

Code

@@ Line 73: / Line 73: @@
 The motor was controlled using a PD controller which controlled both speed and position. Theory behind the controller was that if accurate speed control could be achieved along with the ability to control the release point by stopping the motor, we could control the distance the ball traveled to a high degree of accuracy having it follow simple kinematic equations. The launch was triggered when the ultrasonic sensor distance was sent to it. We opted against I2C and instead went with RS-232 for simplicity since we were only sending two bytes of data.
-Full source code of the motor controller can be found here:[[Media:Motor-Control.c]].
+Full source code of the motor controller can be found [[Media:Motor-Control.c|here]].
  #INT_TIMER2       // designates that this is the routine to call when timer3 overflows
@@ Line 160: / Line 144: @@
+   }
+ }
  void main() {

Meredith Chow: /* Electrical Design */

2009-03-20T07:17:21Z

Electrical Design

← Older revision		Revision as of 02:17, 20 March 2009
Line 46:		Line 46:
	The Pittman motor, H-Bridge, and encoder chip circuit is more complex. This circuit is run by PIC2. The information collected about the hoop location is communicated from PIC1 to PIC2. The Pittman is used to launch the ball. After the hoop is found, the arm attached to the Pittman launches the ball into the hoop. The shaft rotates forward and then reverses to its previous position. The device is then ready to find the hoop and launch the ball again.		The Pittman motor, H-Bridge, and encoder chip circuit is more complex. This circuit is run by PIC2. The information collected about the hoop location is communicated from PIC1 to PIC2. The Pittman is used to launch the ball. After the hoop is found, the arm attached to the Pittman launches the ball into the hoop. The shaft rotates forward and then reverses to its previous position. The device is then ready to find the hoop and launch the ball again.

	The two ~~pics~~ communicated with a common ground and wire connecting RC6 and RC7 as shown in the diagram. The power supply was two 12 volt power supplies connected in series to give a total of 24 volts.		The two PICs communicated with a common ground and wire connecting RC6 and RC7 as shown in the diagram. The power supply was two 12 volt power supplies connected in series to give a total of 24 volts.

	=== Electrical Components ===		=== Electrical Components ===

John Rula: /* Code */

2009-03-20T06:40:44Z

Code

@@ Line 68: / Line 68: @@
 == Code ==
  #INT_RDA
@@ Line 117: / Line 90: @@
     if(rsCount >= 2) rsCount = 0;
+ }
  #INT_TIMER2       // designates that this is the routine to call when timer3 overflows