abdrive.h File Reference

This library takes care of encoder monitoring and servo signalling, and provides a simple set of functions for making the ActivityBot go certain distances and speeds.

For more information, go here:

http://learn.parallax.com/activitybot/navigation-basics

Please submit bug reports, suggestions, and improvements to this code to edito.nosp@m.r@pa.nosp@m.ralla.nosp@m.x.co.nosp@m.m. More...

#include "simpletools.h"
#include "simpletext.h"
#include "fdserial.h"

Go to the source code of this file.

Macros
#define	_ActivityBot_EE_Start_   63418
	ActivityBot EEPROM calibration data start address.
#define	_ActivityBot_EE_Pins_   12
#define	_ActivityBot_EE_Trims_   28
#define	_ActivityBot_EE_Left_   52
#define	_ActivityBot_EE_Right_   1052
#define	_ActivityBot_EE_End_   63418 + 2052
	ActivityBot EEPROM calibration data end address.
#define	AB_RIGHT   1
#define	AB_LEFT   -1
#define	AB_FORWARD   1
#define	AB_BACKWARD   -1
#define	OFF   0
#define	ON   1

Functions
void	drive_feedback (int enabled)
	Enables or disables encoder feedback for speed control.
void	drive_trim (int enabled)
	Enables or disables drive trim which can be used to compensate for mechanical wheel alignment errors.
void	drive_trimSet (int direction, int side, int value)
	Stores trim values to EEPROM.
void	drive_trimDisplay (void)
	Display the trim settings.
void	drive_displayInterpolation (void)
	Displays the interopolation table stored in EEPROM by the calibration step. For more info, see: http://learn.parallax.com/activitybot/test-and-tune-your-activitybot.
void	drive_encoderPins (int encPinLeft, int encPinRight)
	Set encoder pins to values other than the default P14 for left encoder and P15 for right encoder. Stores values in EEPROM.
void	drive_servoPins (int servoPinLeft, int servoPinRight)
	Set servo pins to values other than the default P12 for left servo and P13 for right servo. Stores values in EEPROM.
void	drive_speed (int left, int right)
	Set wheel speeds in encoder ticks per second. An encoder tick is 1/64th of a revolution, and makes causes the wheel to roll 3.25 mm.
void	drive_ramp (int left, int right)
	Ramp up to the specified wheel speeds. It works almost the same as drive_speed, except that it steps up the speed every 50th of a second. The default ramping rate is 4 ticks per 50th of a second. This function will make your program wait while it ramps.
void	drive_rampStep (int left, int right)
	This funciton allows your code to ask for a speed repeatedly in a loop, but each time your code asks for that speed, it takes a step toward the speed. This helps cushon sudden maneuvers in sensor navigation, where the conditions might change more rapidly than you would want your ActivityBot's speed to change.
void	drive_setRampStep (int stepsize)
	Overrides the default 4 ticks/second per 50th of a second for ramping.
void	drive_distance (int left, int right)
	Make the ActivityBot wheels roll certain encoder tick distances. An encoder tick is 1/64th of a wheel turn and makes the wheel roll 3.25 mm. NOT YET IMPLEMENTED, use drive_goto instead.
void	drive_close (void)
	Stop the servo/encoder system. This is useful for reclaiming aprocessor for other tasks.
int	drive_open ()
	Start or restart the servo/encoder system. Useful if you used drive_close. NOT YET IMPLEMENTED.
void	drive_setMaxSpeed (int speed)
	Modifies the default maxiumum top speed for use with encoders. The default is 128 ticks/second = 2 revolutions per second (RPS). This is the full speed that drive_distance and drive_goto use. This value can currently be reduced, but not increased. Speeds faster than 128 ticks per second are "open loop" meaning the control system does not use the encoders to correct distance/speed.
void	drive_goto (int distLeft, int distRight)
	Make each wheel go a particular distance. Recommended for straight forward, backward, turns and pivots. Not recommended for curves. This function ramps up to full speed if the distance is long enough. It holds that speed until it needs to ramp down. After ramping down it applies compensation. This function is primarily a convenience for dead reckoning, and does not return until the maneuver has completed.
void	drive_getTicksCalc (int *left, int *right)
	Get the calculate number of ticks the encoders should have traveled. Distance is in ticks. The wheel has 64 encoder ticks, each accounting for 3.25 mm of distance.
void	drive_getTicksMeasured (int *left, int *right)
	Get the measured number of ticks the encoders should have traveled.

Detailed Description

This library takes care of encoder monitoring and servo signalling, and provides a simple set of functions for making the ActivityBot go certain distances and speeds.

For more information, go here:

http://learn.parallax.com/activitybot/navigation-basics

Please submit bug reports, suggestions, and improvements to this code to edito.nosp@m.r@pa.nosp@m.ralla.nosp@m.x.co.nosp@m.m.

Author

Andy Lindsay

Copyright

Copyright (C) Parallax, Inc. 2013. See end of file for terms of use (MIT License).

Version

0.5.1

To-Do

• Trim enabled by default. (v0.5.1)
• Clear trim settings during calibration. (v0.5.1)
• Make trim for a direction mutually exclusive to one side. (v0.5.1)
• Make sure that control system's compensation cannot cause the servo signal to cross its direction boundary
• drive_getTicksCalc
• drive_getTicksMeasured
• drive_open
• drive_encoderPins
• drive_servoPins
• Reduce calibration array elements to 16-bit
• Remove other variables
• Condense left/right duplicate code
• Code comments
• drive_distance
• drive_getSpeedCalc
• drive_getSpeedActual

Function Documentation

void drive_distance	(	int	left,
		int	right
	)

Make the ActivityBot wheels roll certain encoder tick distances. An encoder tick is 1/64th of a wheel turn and makes the wheel roll 3.25 mm. NOT YET IMPLEMENTED, use drive_goto instead.

Parameters

left	Left wheel encoder tick distance.
right	Right wheel encoder tick distance.

void drive_encoderPins	(	int	encPinLeft,
		int	encPinRight
	)

Set encoder pins to values other than the default P14 for left encoder and P15 for right encoder. Stores values in EEPROM.

Not implemented yet.

Parameters

encPinLeft	I/O pin number for the left encoder signal connection.
encPinLeft	I/O pin number for the left encoder signal connection.

void drive_feedback

(

int

enabled

)

Enables or disables encoder feedback for speed control.

Parameters

enabled

Set to 1 to enable feedback (default) or 0 to disable.

void drive_getTicksCalc	(	int *	left,
		int *	right
	)

Get the calculate number of ticks the encoders should have traveled. Distance is in ticks. The wheel has 64 encoder ticks, each accounting for 3.25 mm of distance.

The system updates the predicted distance 400 times per second, based on the speed the wheels should be going.

Parameters

*left	Pointer to variable to receive the calcualted left distance.
*right	Pointer to variable to receive the calcualted right distance.

void drive_getTicksMeasured	(	int *	left,
		int *	right
	)

Get the measured number of ticks the encoders should have traveled.

The system samples the encoders at 400 times per second.

Parameters

*left	Pointer to variable to receive the measured left distance.
*right	Pointer to variable to receive the measured right distance.

void drive_goto	(	int	distLeft,
		int	distRight
	)

Make each wheel go a particular distance. Recommended for straight forward, backward, turns and pivots. Not recommended for curves. This function ramps up to full speed if the distance is long enough. It holds that speed until it needs to ramp down. After ramping down it applies compensation. This function is primarily a convenience for dead reckoning, and does not return until the maneuver has completed.

Parameters

distLeft	Left wheel distance.
distRight	Right wheel distance.

void drive_ramp	(	int	left,
		int	right
	)

Ramp up to the specified wheel speeds. It works almost the same as drive_speed, except that it steps up the speed every 50th of a second. The default ramping rate is 4 ticks per 50th of a second. This function will make your program wait while it ramps.

Parameters

left	Left wheel speed in ticks per second.
right	Left wheel speed in ticks per second.

void drive_rampStep	(	int	left,
		int	right
	)

This funciton allows your code to ask for a speed repeatedly in a loop, but each time your code asks for that speed, it takes a step toward the speed. This helps cushon sudden maneuvers in sensor navigation, where the conditions might change more rapidly than you would want your ActivityBot's speed to change.

Parameters

left	Left wheel speed in ticks per second.
right	Left wheel speed in ticks per second.

void drive_servoPins	(	int	servoPinLeft,
		int	servoPinRight
	)

Set servo pins to values other than the default P12 for left servo and P13 for right servo. Stores values in EEPROM.

Not implemented yet.

Parameters

servoPinLeft	I/O pin number for the left servo signal connection.
servoPinLeft	I/O pin number for the left servo signal connection.

void drive_setMaxSpeed

(

int

speed

)

Modifies the default maxiumum top speed for use with encoders. The default is 128 ticks/second = 2 revolutions per second (RPS). This is the full speed that drive_distance and drive_goto use. This value can currently be reduced, but not increased. Speeds faster than 128 ticks per second are "open loop" meaning the control system does not use the encoders to correct distance/speed.

Parameters

speed

Maximum cruising speed for drive_distance and drive_goto.

void drive_setRampStep

(

int

stepsize

)

Overrides the default 4 ticks/second per 50th of a second for ramping.

Parameters

stepSize

The size of each step in ticks/second to change every 50th of a second

void drive_speed	(	int	left,
		int	right
	)

Set wheel speeds in encoder ticks per second. An encoder tick is 1/64th of a revolution, and makes causes the wheel to roll 3.25 mm.

Parameters

left	Left wheel speed in ticks per second.
right	Left wheel speed in ticks per second.

void drive_trim

(

int

enabled

)

Enables or disables drive trim which can be used to compensate for mechanical wheel alignment errors.

Parameters

enabled

Set to 1 to enable trim (default) or 0 to disable.

void drive_trimDisplay

(

void

)

Display the trim settings.

Displays most recent direction, side, and value settings from the most recent call to drive_trimSet.

void drive_trimSet	(	int	direction,
		int	side,
		int	value
	)

Stores trim values to EEPROM.

Trim values can compensate for mechanical wheel alignment errors. When you set the ActivityBot's trim, you are telling it to make a certain wheel turn an extra tick per certain number of ticks. For example, you can use this to make the right wheel turn 1 extra tick per every 64 ticks. It will actually just expect to see an encoder transition 1/64th of a tick sooner with every tick.

Parameters

direction	Selects to set the trim for a given direction. Use AB_FORWARD OR AB_BACKWARD.
side	Selects the side to make one more or less ticks per number of ticks. Use AB_LEFT or AB_RIGHT to select the left or right wheel.
value	Number of ticks that should elapse before the extra tick will have accumulated. Use a negative number if you want a given wheel to go one less tick per number of ticks instead of one more tick.