Navigating with Ultrasonic Distance Sensor
PPra
Posts: 10
So for my physics project, my partner and I wanted to use an ultrasonic distance sensor to navigate a maze. The problem is, we can only read the distance between the robot and an obstacle, and the sensor plays no part in navigating the robot. How would I program it so that the robot could manuever based on its readings from the sensor? I'm completely new to programming, sorry. Is there a way to program the robot so it doesn't have to be attached to the CPU to display the distance readings? Do we have to buy the mounting bracket, or should the sensor work by itself, without having to rotate around? Thanks in advance!!
Comments
or this http://www.parallax.com/downloads/roaming-ping-simple-basic-stamp-code
The first download Franklin linked to, incorporates both the IR and Ping Sensors. This program has been around for quite a while and is well tested.
http://www.parallax.com/downloads/roaming-ping-advanced-basic-stamp-code
If you are having problems with the program, you might want to include a picture of how you have it hooked up.
here is a video of my maze and the robot...the robot needs to move forward but it will only rotate around..i am using the basic stamp code roaming with ping, and just pressed play and disconnected the robot after and this is what happens
Try making the walls a little higher. You will have to rely on the IR sensor on the breadboard for walls that low. Is see you do not have IR sensors.
Here is the photo of the connection as well as the connection we got from the internet we used as an example to set it up. I think our board is unusual, because most of them had the 3 black thingies encircling the white portion (at least in the pictures we looked online), but ours only had black thingies on the top and to the left, not on the bottom (sorry I do not know the correct terminology).
Here is the video of the programming...it is basically exactly what I downloaded Roaming with Ping Basic, I believe.
[/B]' =========================================================================' ' File...... RoamingWithPING.bs2 ' Purpose... Roam And Scan Using PING))) Mounting Bracket ' Author.... Parallax, Inc. ' E-mail.... support@parallax.com ' Started... ' Updated... 12-21-2005 ' ' {$STAMP BS2} ' {$PBASIC 2.5} ' ' ========================================================================= ' -----[ Program Description ]--------------------------------------------- ' This programs demonstrates roaming with the Parallax PING))) Mounting ' Bracket, which allows you to pan-scan with your Parallax PING))) sensor. ' ' This program assumes you have already set your BOE-Bot up for roaming ' with IR sensors. You must also have the PING))) Mounting bracket ' installed as per the instructions, with the servo connected to P14 and ' the PING))) sensor connected to P15. ' ' Due to the way the PING))) bracket mounts you may have to trim your IR ' detectors down so that they don't stick up in the way of the moving ' PING))) bracket as it rotates. It's best to angle them off at 45 ' degree angles so that the BOE-Bot doesn't run into anything while ' moving along a wall at a narrow angle. ' ' The BOE-Bot will now roam around and when it senses an object, it will ' scan within a 180 degree field of view for the clearest path, which it ' will then navigate scanning for an object again. The IR Sensors prevent ' hitting a wall when coming at it from a narrow angle where the PING))) ' might have trouble seeing it due to the lack of reflection of sound. ' ' Calibration is important to this code working properly. If you do not ' have the correct values for your servos then you may get strange results ' from your BOE-Bot. The necessary calibration information is listed in ' each section of the code where it is required. ' -----[ Revision History ]------------------------------------------------ ' This code is basically a modified version of the Roaming With IR code ' from the Robotics With The BOE-Bot Manual, written by Andy Lindsay. ' Much of the original code was left untouched so you can see how it was ' altered. ' -----[ I/O Definitions ]------------------------------------------------- Piezo PIN 4 ' Piezo Speaker RightServo PIN 12 ' Right Servo LeftServo PIN 13 ' Left Servo PingServo PIN 14 ' PING))) Servo Ping PIN 15 ' PING))) Sensor ' -----[ Variables ]------------------------------------------------------- irDetectLeft VAR Bit ' Variable For Left IR Input irDetectRight VAR Bit ' Variable For Right IR Input pulseCount VAR Byte ' Used For Measuring Turns distance VAR Word ' Current Distance Of Object oldDistance VAR Word ' Old Distance Value counter VAR Word ' PING))) Cycle Counter task VAR Nib ' Current Task ' -----[ Initialization ]-------------------------------------------------- FREQOUT Piezo, 2000, 3000 ' Signal Program Start/Reset ' -----[ Program Code ]---------------------------------------------------- Main: DO FREQOUT 8, 1, 38500 ' Emit 38.5 kHz IR To Left irDetectLeft = IN9 ' Store IR Detection Values FREQOUT 2, 1, 38500 ' Emit 38.5 kHz IR To Right irDetectRight = IN0 ' Store IR Detection Values IF (irDetectLeft = 0) AND (irDetectRight = 0) THEN GOSUB Ping_Around ' Object Detected via IR Forward ELSEIF (irDetectLeft = 0) THEN GOSUB Ping_Around ' Object Detected via IR Left ELSEIF (irDetectRight = 0) THEN GOSUB Ping_Around ' Object Detected via IR Right ENDIF counter = counter + 1 ' Increment Passive Counter IF counter > 10 THEN ' Wait For 10 Servo Pulses GOSUB Ping_Out ' Activate PING))) ENDIF IF (distance > 30) THEN ' Is Object Farther Than 30 cm? GOSUB Forward_Pulse ' If Yes Go Forward ELSE GOSUB Ping_Around ' Otherwise Scan For Clear Path ENDIF LOOP ' -----[ Subroutines ]----------------------------------------------------- ' ************************************************************************* ' * USE THE APPROPRIATE PULSOUT VALUES TO MAKE YOUR BOE-BOT MOVE FORWARD * ' * WHILE THE PING))) IS FACING FORWARD. * ' ************************************************************************* Forward_Pulse: ' Send A Single Forward Pulse PULSOUT PingServo, 750 ' Ping Servo Forward Pulse Value PULSOUT LeftServo, 850 ' Left Servo Forward Pulse Value PULSOUT RightServo, 650 ' Right Servo Forward Pulse Value PAUSE 20 ' Refresh Delay RETURN ' ************************************************************************* ' * USE THE APPROPRIATE PULSOUT VALUES TO MAKE YOUR BOE-BOT TURN LEFT 90 * ' * DEGREES. USE THE SAME VALUE AS ABOVE FOR THE PING))) BRACKET SERVO. * ' ************************************************************************* Turn_Left: ' Left Turn, About 45 Degrees FOR pulseCount = 0 TO 7 ' Number Of Pulses To Turn PULSOUT PingServo, 750 ' Ping Servo Forward Pulse Value PULSOUT LeftServo, 650 ' Left Servo Left Pulse Value PULSOUT RightServo, 650 ' Right Servo Left Pulse Value PAUSE 20 ' Refresh Delay NEXT RETURN ' ************************************************************************* ' * USE THE APPROPRIATE PULSOUT VALUES TO MAKE YOUR BOE-BOT TURN RIGHT 90 * ' * DEGREES. USE THE SAME VALUE AS ABOVE FOR THE PING))) BRACKET SERVO. * ' ************************************************************************* Turn_Right: ' Right Turn, About 45 Degrees FOR pulseCount = 0 TO 7 ' Number Of Pulses To Turn PULSOUT PingServo, 750 ' Ping Servo Forward Pulse Value PULSOUT LeftServo, 850 ' Left Servo Right Pulse Value PULSOUT RightServo, 850 ' Right Servo Right Pulse Value PAUSE 20 ' Refresh Delay NEXT RETURN ' ************************************************************************* ' * USE THE APPROPRIATE PULSOUT VALUES TO MAKE YOUR BOE-BOT MOVE BACKWARD * ' * WHILE THE PING))) IS FACING FORWARD. * ' ************************************************************************* Back_Up: ' Back Up FOR pulseCount = 0 TO 40 ' Number Of Pulses To Backup PULSOUT PingServo, 750 ' Ping Servo Forward Pulse Value PULSOUT LeftServo, 650 ' Left Servo Backup Pulse Value PULSOUT RightServo, 850 ' Right Servo Backup Pulse Value PAUSE 20 ' Refresh Delay NEXT RETURN Ping_Out: ' PING))) counter = 0 ' Reset Passive Delay Counter LOW Ping ' Force PING))) Line Low PULSOUT Ping, 5 ' Activate PING))) Pulse PULSIN Ping, 1, distance ' Receive Return Pulse distance = distance ** 2257 ' Calculate Distance RETURN Ping_Around: ' Start 180 Degree Pan-Scan counter = 0 ' Reset Passive Delay Counter oldDistance = 30 ' Current Old Distance Values task = 0 ' Current Task Priority ' ************************************************************************* ' * USE THE APPROPRIATE PULSOUT VALUE TO MAKE YOUR PING))) * ' * TURN 90 DEGREES LEFT. * ' ************************************************************************* FOR pulseCount = 0 TO 20 ' Number Of Pulses To Spin LOW Ping ' Force PING))) Line Low PULSOUT PingServo, 1085 ' Ping Servo 90 Left Pulse Value PULSOUT Ping, 5 ' Activate PING))) PULSIN Ping, 1, distance ' Receive Distance Value PAUSE 20 ' Refresh Delay NEXT distance = distance ** 2257 ' Calculate Distance In cm IF distance > oldDistance THEN ' Is distance > Last Clear Path oldDistance = distance ' Update oldDistance Value task = 1 ENDIF ' ************************************************************************* ' * USE THE APPROPRIATE PULSOUT VALUE TO MAKE YOUR PING))) * ' * TURN 45 DEGREES LEFT. * ' ************************************************************************* FOR pulseCount = 0 TO 20 ' Number Of Pulses To Spin LOW Ping ' Force PING))) Line Low PULSOUT PingServo, 850 ' Ping Servo 45 Left Pulse Value PULSOUT Ping, 5 ' Activate PING))) PULSIN Ping, 1, distance ' Receive Distance Value PAUSE 20 ' Refresh Delay NEXT distance = distance ** 2257 ' Calculate Distance In cm IF distance > oldDistance THEN ' Is distance > Last Clear Path oldDistance = distance ' Update oldDistance Value task = 2 ENDIF ' ************************************************************************* ' * USE THE APPROPRIATE PULSOUT VALUE TO MAKE YOUR PING))) * ' * TURN 45 DEGREES RIGHT. * ' ************************************************************************* FOR pulseCount = 0 TO 20 ' Number Of Pulses To Spin LOW Ping ' Force PING))) Line Low PULSOUT PingServo, 400 ' Ping Servo 45 Right Pulse Value PULSOUT Ping, 5 ' Activate PING))) PULSIN Ping, 1, distance ' Receive Distance Value PAUSE 20 ' Refresh Delay NEXT distance = distance ** 2257 ' Calculate Distance In cm IF distance > oldDistance THEN ' Is distance > Last Clear Path oldDistance = distance ' Update oldDistance Value task = 3 ENDIF ' ************************************************************************* ' * USE THE APPROPRIATE PULSOUT VALUE TO MAKE YOUR PING))) * ' * TURN 90 DEGREES RIGHT. * ' ************************************************************************* FOR pulseCount = 0 TO 20 ' Number Of Pulses To Spin LOW Ping ' Force PING))) Line Low PULSOUT PingServo, 225 ' Ping Servo 90 Right Pulse Value PULSOUT Ping, 5 ' Activate PING))) PULSIN Ping, 1, distance ' Receive Distance Value PAUSE 20 ' Refresh Delay NEXT distance = distance ** 2257 ' Calculate Distance In cm IF distance > oldDistance THEN ' Is distance > Last Clear Path oldDistance = distance ' Update oldDistance Value task = 4 ENDIF ON task GOSUB Task0, Task1, Task2, Task3, Task4 distance = 50 ' Prevent Scan From Looping RETURN Task0: ' Forward Was Clearest Path GOSUB Turn_Right ' This Could Mean Narrow Path GOSUB Turn_Right ' So We'll Turn Around GOSUB Turn_Right ' You Can Change The Behavior GOSUB Turn_Right ' Of Any Of The Tasks RETURN Task1: ' 90 Degrees Left Was Clearest GOSUB Turn_Left GOSUB Turn_Left RETURN Task2: ' 45 Degrees Left Was Clearest GOSUB Turn_Left RETURN Task3: ' 45 Degrees Right Was Clearest GOSUB Turn_Right RETURN Task4: ' 90 Degrees Right Was Clearest GOSUB Turn_Right GOSUB Turn_Right RETURN [COLOR=#333333] [/COLOR][B]Without the IR sensors how are you going to keep the bot from trying to climb the low walls of the maze? Two servos will always run at slightly different speeds, no matter how well calibrated. Also, any slight irregularity of the rolling surface could alter the direction the bot is headed. How will the bot know it is travelling down the center of the corridor and not dragging itself along one side? The IR sensors are there to correct the path the bot is taking so that it does not eventually run up against a side wall. They will also help in deciding which way to turn when reaching a corner since the rigidly mounted ultrasonic sensor will only report distance to whatever obstruction is straight ahead. If you don't have the IR sensors you could also try wire whiskers to help detect the side walls.
I did correct my post #6 after I saw your video with no IR sensors.
You need another set of sensors for that. There is really no way to get around that.
1. The Code you posted requires IR sensors (I'm not sure what a input value a disconnected pin has, but you probably don't want that.) The second link to code in post 2 does not require the IR sensors, but does use the bracket & ping servo.
2. The pin definitions in the code have the ping)) sensor on pin 15. Your wiring diagram has it on pin 0. And the ping servo (which you don't have) is on pin 14 in the code. Make sure that the pin definitions in your code agree with your actual wiring.
3. Without the ping bracket and servo, the ping will only point straight ahead. So if the BOT approaches a wall diagonally, it will hit the wall and not be able to adjust. With the bracket and servo, the ping would sweep from side to side and you could use those distances and adjust the BOTs direction. You can do the same without the bracket by:
traveling a short distance forward - stop - rotate the BOT - measure distance - use that value to adjust the bots motion - rotate the bot back to the desired direction - repeat.
That is significantly more complex code in addition to the maze solving code and much slower travel.
Hope this helps
Tom
Not with a single, fixed mounted Ping. In order for a bot to traverse a maze it has to know what is to its left and right as well as what is up ahead. When the bot approaches a corner, all it knows is that something is in front of it at xx inches. How is the bot going to determine which way to turn? All it "sees" is the wall in front of it. At least with a rotatable Ping you will have angular information along with distance to object. With IR sensors or whiskers the bot will also know where it is relative to the walls and correct its direction of travel to keep it near the center. Also, with the IR sensors or whiskers the bot will orient itself to the new direction of travel after making the turn.