Ren Buggy
A program that allows the RenBuggy to detect the direction of a light source and drive towards it.
Revision 0:575ce3f4b7ec, committed 2016-03-11
- Comitter:
- RenBuggy
- Date:
- Fri Mar 11 10:39:05 2016 +0000
- Commit message:
- version 1
Changed in this revision
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/ServoDrive.cpp Fri Mar 11 10:39:05 2016 +0000
@@ -0,0 +1,112 @@
+/*********************************************************
+*ServoDrive.cpp *
+*Author: Elijah Orr *
+* *
+*A library of functions that can be used to control the *
+*RenBuggy via a servo motor. *
+*********************************************************/
+
+#ifndef SERVODRIVE_C
+#define SERVODRIVE_C
+
+#include "mbed.h"
+#include "ServoDrive.h"
+
+
+/* A pin is configured as PwmOut to output the PWM signal that will
+control the servo. Two pins are configured as DigitalOut to switch
+the drive motors on/off. Information about classes used here can be
+found in the mbed library. */
+PwmOut servo(servoPin);
+DigitalOut Lmotor(LeftMotorPin);
+DigitalOut Rmotor(RightMotorPin);
+
+/* functions to start and stop the drive motors simply set the DigitalOut
+pins to 1 or 0 to switch the motors on/off */
+
+/****************************************************************
+* Function: go() *
+* *
+* Enables the two drive motors of the RenBuggy *
+* *
+* Inputs: none *
+* *
+* Returns: none *
+****************************************************************/
+extern void go()
+{
+ Lmotor = Rmotor = 1;
+}
+
+/****************************************************************
+* Function: stop() *
+* *
+* Disables the two drive motors of the RenBuggy *
+* *
+* Inputs: none *
+* *
+* Returns: none *
+****************************************************************/
+extern void stop()
+{
+ Lmotor = Rmotor = 0;
+}
+
+/* a function is set up to configure the PWM output so that it will have the
+correct properties to operate the servo. */
+
+/****************************************************************
+* Function: configurePWM() *
+* *
+* Configures a PWM signal for controlling the servo *
+* *
+* Inputs: Period is the period of the signal in microseconds *
+* and Pulsewidth is the pulsewidth of the signal in microseconds*
+* *
+* Returns: none *
+****************************************************************/
+extern void configurePWM(int Period, int Pulsewidth)
+{
+ /* classes that set the properties of the PWM signal are passed the variables
+ Period and Pulsewidth to set the frequency and duty cycle of the signal. */
+ servo.period_us(Period);
+ servo.pulsewidth_us(Pulsewidth);
+}
+
+/* to make the main function easy to write, setDirection will allow a value in
+degrees to be passed to it, and then do any necessary conversions. angle must be
+a float as the conversion involves non integer values. */
+
+/****************************************************************
+* Function: setDirection() *
+* *
+* Sets the direction in which the steering servo is pointing *
+* *
+* Inputs: A floating point value representing the angle of the *
+* servo in degrees *
+* *
+* Returns: The pulsewith of the signal in microseconds *
+****************************************************************/
+extern int setDirection(float angle)
+{
+ /* it is possible to pass numbers outside the operational range of the servo
+ to setDirection, to resolve this there are two checks here. If angle is outside
+ the boundaries it will be set to either the maximum or minimum value. */
+ if(angle < 0)
+ {
+ angle = 0;
+ }
+ if(angle > 90)
+ {
+ angle = 90;
+ }
+ /* to properly control the servo, the pulsewidth must be between 1000 and 2000
+ micro seconds, so a simple conversion is used to translate the angle into a value
+ within these bounds. The new value is stored in the variable pulse. */
+ int pulse = 1000 + ((angle/90)*1000);
+ servo.pulsewidth_us(pulse);
+
+ return pulse;
+}
+
+#endif //SERVODRIVE_C
\ No newline at end of file
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/ServoDrive.h Fri Mar 11 10:39:05 2016 +0000 @@ -0,0 +1,33 @@ +/********************************************************* +*ServoDrive.h * +*Author: Elijah Orr * +* * +*A library of functions that can be used to control the * +*RenBuggy via a servo motor. * +*********************************************************/ + +/* include guards are used to prevent problems caused by +multiple definitions */ +#ifndef SERVODRIVE_H +#define SERVODRIVE_H + +/* mbed.h must be included in this file also */ +#include "mbed.h" + +/* #define is used to set the pins that will be used to control the motors. +Using this method means that selecting which pins are used requires only +changing values here, rather than in every function that contains them. */ +#define servoPin p10 +#define LeftMotorPin p5 +#define RightMotorPin p6 + +/* function declarations go here */ +extern void go(); +extern void stop(); +/* setDirection takes a variable of type float (non integer) that will represent an angle in +degrees. */ +extern int setDirection(float); +/* configurePWM expects two variables of type int */ +extern void configurePWM(int, int); + +#endif //SERVODRIVE_H \ No newline at end of file
--- /dev/null Thu Jan 01 00:00:00 1970 +0000
+++ b/main.cpp Fri Mar 11 10:39:05 2016 +0000
@@ -0,0 +1,117 @@
+/****************************************************************
+* LightSeekingRobot *
+* Author: Elijah Orr *
+* *
+* This program uses the values of two analog inputs (LDRs) to *
+* steer the RenBuggy via a servo motor. *
+*****************************************************************/
+
+/* The library ServoDrive is used in this program to control the
+servo and drive motors. Libraries are a useful tool for creating
+code that can be reused in multiple programs. */
+#include "mbed.h"
+#include "ServoDrive.h"
+
+AnalogIn LDR1(p15);
+AnalogIn LDR2(p16);
+
+/****************************************************************
+* Function: main() *
+* *
+* Steers a servo controlled wheel of the Renbuggy according to *
+* the relative light levels of two LDRs *
+* *
+* Inputs: none *
+* *
+* Returns: none *
+****************************************************************/
+int main()
+{
+ /* variables that will be used in the main are declared */
+ float angle;
+ float LDR1value;
+ float LDR2value;
+ int i;
+
+ /* these variables are initialised values to be used to
+ control certain behaviors of the buggy. tolerance sets
+ how much the light levels must differ for it to turn,
+ centreValue is the value in degrees that corresponds to
+ the wheel pointing directly forward, and difAdjust is
+ used make the values of the two LDR inputs more similar */
+ float tolerance = 0.03;
+ int centreValue = 45;
+ float difAdjust = 0.03;
+
+ /* call the function to set up the PWM signal for the servo */
+ configurePWM(20000, 1500);
+
+ /* the angle of the servo is initially set to centre it */
+ angle = centreValue;
+
+ /* start the buggy moving */
+ go();
+
+ /* opening a for loop without any conditions starts an infinite
+ loop, so that the contained code runs forever */
+ for(;;)
+ {
+ /* the class member function read() in AnalogIn.h reads the
+ voltage of the of the LDR pins into variables as a floating
+ point value between 0.0 and 1.0 */
+ LDR1value = LDR1.read();
+ LDR2value = LDR2.read();
+
+ /* LDR2value has difAdjust added to it to make both LDR values
+ similar enough to compare effectively. The value 0.03 stored in
+ difAdjust was chosen by printing the LDR values to console via
+ USB and observing the difference between values (USBSerial.h was
+ used for this) */
+ LDR2value = LDR2value + difAdjust;
+
+ /* the behavior of the RenBuggy is defined by a series of if
+ statements. If the conditions in the parentheses are true,
+ then the code in the if statement will run, if not the program
+ moves on. */
+
+ /* && is known as the logical AND operator. If both operands are
+ non zero (i.e. true), then the condition will be true. If one LDR
+ value is significantly larger than the other, then angle will
+ increment (angle++ means that the value of angle will increase
+ by one) */
+ if((LDR1value - LDR2value > tolerance) && (angle < 90)){
+ angle++;
+ }
+
+ /* if statements can be followed by an optional else if statement,
+ which will execute when the above if statement is false, and the
+ else if condition is true. */
+ else if((LDR2value - LDR1value > tolerance) && (angle > 0)){
+ angle--; /* angle-- means that angle will decrease by one */
+ }
+
+ /* If the difference between values is within tolerance, point the
+ wheel straight forward */
+ else if((LDR1value - LDR2value < tolerance) && (LDR2value - LDR1value < tolerance)){
+ angle = centreValue;
+ }
+
+ /* a for loop is used to create a delay in the program to make it run
+ a little slower, so that the servo position is updated less freqently */
+ for(i=0;i<400000;i++){}
+
+ /* the function setDirection is called and passed the variable angle to
+ set the servo position to the new value of angle */
+ setDirection(angle);
+ }
+}
+
+
+
+
+
+
+
+
+
+
\ No newline at end of file
--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/mbed.bld Fri Mar 11 10:39:05 2016 +0000 @@ -0,0 +1,1 @@ +http://mbed.org/users/mbed_official/code/mbed/builds/252557024ec3 \ No newline at end of file