Yes it can.· You can see a video of the Boe-Bot robot using a Ping))) sensor mounted on a servo to·scan for objects·and·roam around avoiding walls; the links to the video and sample source code·are at the bottom of the Ping))) sensor's product page:
ltmhall said...
Can the ping Ultrasonic Sensor be used for obstacle avoidance, for stationary objects.
The simple answer: Yes.
The "but..."?· You must write the BS2 program to manage the Ping and the data which the Ping provides. And, you must understand enough about your "obstacle"(s) --e.g., their shape, size, echoing characteristics, movement (speed, direction of both the Ping and the obstacle target(s)), so that your program can account for the variations in echo signals (and other attributes/situations/elements)·that your system must know about, to detect and to avoid (or seek out).
That's the fun....· Defining/describing/understanding the detailed characteristics·of the system you want to build, and then designing the microcontroller program to handle those static and dynamic characteristics.
The latest Stamps in Class book, Smart Sensors and Applications, has a chapter about the Ping))) sensor that addresses a few of those details he mentions, and also shows you how to account for air temperature affecting the speed of sound in your measurements, if that is an issue. You can download the book here:
In addition to the sample code that goes with the "Roaming with Ping" video, you can find a couple more applications with source code to study in·the Stamps in Class Mini Projects sticky-thread:
I would like to know basic stuff like variance in measurments. My search in the PING))) docs didn't reveal if it was plus or minus 3inches or any variances along those lines.
Implemented correctly (see http://forums.parallax.com/forums/default.aspx?f=10&m=162746), it seems to be pretty consistent and "accurate"... like anything else, you will need to implement some "calibration" in your code if you are looking to take detailed measurements... because it is sound based, many external factors will impact the accuracy (temperature of the air, etc.).
AIman said...
Are there any tech details on PING))?
I would like to know basic stuff like variance in measurments. My search in the PING))) docs didn't reveal if it was plus or minus 3inches or any variances along those lines.
The published documentation is on the product page.· Look for the download entitled PING)))™ Documentation v1.2 (.pdf) link on the PING))) Ultrasonic Sensor page.
From personal experience, my Ping))) projects had accuracy of·+/-·1 cm/m·in controlled·conditions (solid cylindrical object, in direct line of sight, temperature measured and used to scale the speed of sound in air).· There's a little more variation up close when the sides of the distance triangle (speaker -> object -> transducer) since the sides of the triangle approach equilateral.·
In robotic circumstances, if you don't know the shape of the object, the angle of its reflecting surface with respect to the bot, its acoustic properties (solid·vs. stuffed animal), well then it's the measurement is pretty much anybody's guess.··That's where extensive testing comes in·to make sure your robot can detect the object and its distance given the variety of conditions you expect to subject it to.·
I am currently working on a project that requires the I roam around an area and collect gps data and tilt information. Can the ping sensor be used for obstacle avoidance even if i want my BOE-Bot to move in a ladder path? If yes, are there any sample programs that use the ping sensor as a secondary navigation accessory?
What do you mean by "a ladder path"? Are you speaking of a squared zig-zag route like the following pattern: ··· _
|_| |_|
Generally speaking regardless of what type of structured travel you are attempting, any sort of obstacle detector can be used. You (via the program) will be required to get the mobile platform back on track, after the object is avoided. Please remember that the PING)) sensor was designed as a distance measuring device although it can be used in other manners. You might want to consider infrared sensors as well, as a less expensive alternative, unless this is an outdoor application.
As far a sample programs are concerned, that will depend highly on what it is that you're actually trying to do. It sounds rather like maze solving (if you were to treat it that way) so someone may have some code like that.
Regards,
Bruce Bates
Post Edited (Bruce Bates) : 3/26/2007 7:36:36 AM GMT
I have a doubt around this subject... Can the PING))) sensor be used while the robot is moving? The sound speed is very high comparing to the speed of a normal robot, so I suppose there are not any problems, aren't they?
· I know there are factors like air density, object type, and angle to consider but just from my experience the PING·ALMOST ALWAYS·detects objects that are within object-avoidance range (for a small robot).· I get very satisfactory results without any averaging or temperature compensating.· The PING just seems to be ideal for object avoidance.
· Sorry, I forgot to mention that I use a fixed PING sensor mounted 3" above ground on a tracked vehicle that
operates indoors at room temperature on a linoleum floor.....your results may vary
The ping mounted on a servo works very reliably. Since the speed of sound in air is about 1100 feet per second (give or take 100), it is very unlikely that you robot will need to compensate for it's own movement when taking measurements. The ping is very reliable, but keep in mind that the area around the module (say about 3" in all dirrections) should be as clear as possible.
The published documentation is on the product page.· Look for the download entitled PING)))™ Documentation v1.2 (.pdf) link on the PING))) Ultrasonic Sensor page.
Hey all, not to hijack this thread but I have a question relating to what cprcrack's question. I have a BoeBot on tracks and I have the PING sensor with the mounting bracket kit. If I were to incorporate a servo controller would I be able to use the PING while the bot is in motion or will it still need to stop and scan?
Bryan,
With the servo controller, you can have the Ping scanning while the robot is in motion. You can use the ramp parameter on the serial command to the controller to slowly sweep the ping assembly from one side to the other without any additional input from the stamp. This allows you to continuously read the ping while the servo controller takes care of moving the sensor head.
One thing that I have learned about the Ping. Upolstered furniture, including the dust ruffle on our bed, is almost invisable to the Ping!
The documentation shows the reception pattern for the sensor. You can compute the maximum range from the information (maximum time) in the documentation. Practically, it's limited by the environment and by false echoes (and the reflectivity of objects).
ltmhall
Posts: 102
Comments
http://www.parallax.com/detail.asp?product_id=28015
-Stephanie Lindsay
Editor, Parallax Inc.
The "but..."?· You must write the BS2 program to manage the Ping and the data which the Ping provides. And, you must understand enough about your "obstacle"(s) --e.g., their shape, size, echoing characteristics, movement (speed, direction of both the Ping and the obstacle target(s)), so that your program can account for the variations in echo signals (and other attributes/situations/elements)·that your system must know about, to detect and to avoid (or seek out).
That's the fun....· Defining/describing/understanding the detailed characteristics·of the system you want to build, and then designing the microcontroller program to handle those static and dynamic characteristics.
PAR
The latest Stamps in Class book, Smart Sensors and Applications, has a chapter about the Ping))) sensor that addresses a few of those details he mentions, and also shows you how to account for air temperature affecting the speed of sound in your measurements, if that is an issue. You can download the book here:
http://www.parallax.com/detail.asp?product_id=28029
In addition to the sample code that goes with the "Roaming with Ping" video, you can find a couple more applications with source code to study in·the Stamps in Class Mini Projects sticky-thread:
·Boe-Bot + Ping))) Ultrasonic Rangefinder
· Ping)))Dar - a Radar Style Display
· Scan for and Go to Closest Object
I would like to know basic stuff like variance in measurments. My search in the PING))) docs didn't reveal if it was plus or minus 3inches or any variances along those lines.
From personal experience, my Ping))) projects had accuracy of·+/-·1 cm/m·in controlled·conditions (solid cylindrical object, in direct line of sight, temperature measured and used to scale the speed of sound in air).· There's a little more variation up close when the sides of the distance triangle (speaker -> object -> transducer) since the sides of the triangle approach equilateral.·
In robotic circumstances, if you don't know the shape of the object, the angle of its reflecting surface with respect to the bot, its acoustic properties (solid·vs. stuffed animal), well then it's the measurement is pretty much anybody's guess.··That's where extensive testing comes in·to make sure your robot can detect the object and its distance given the variety of conditions you expect to subject it to.·
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Andy Lindsay
Education Department
Parallax, Inc.
What do you mean by "a ladder path"? Are you speaking of a squared zig-zag route like the following pattern:
··· _
|_| |_|
Generally speaking regardless of what type of structured travel you are attempting, any sort of obstacle detector can be used. You (via the program) will be required to get the mobile platform back on track, after the object is avoided. Please remember that the PING)) sensor was designed as a distance measuring device although it can be used in other manners. You might want to consider infrared sensors as well, as a less expensive alternative, unless this is an outdoor application.
As far a sample programs are concerned, that will depend highly on what it is that you're actually trying to do. It sounds rather like maze solving (if you were to treat it that way) so someone may have some code like that.
Regards,
Bruce Bates
Post Edited (Bruce Bates) : 3/26/2007 7:36:36 AM GMT
operates indoors at room temperature on a linoleum floor.....your results may vary
Edit - Sorry for the post - I just saw how old the original post is. The guy is probably a in Ping))) expert by now!
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Whit+
"We keep moving forward, opening new doors, and doing new things, because we're curious and curiosity keeps leading us down new paths." - Walt Disney
Bryan
With the servo controller, you can have the Ping scanning while the robot is in motion. You can use the ramp parameter on the serial command to the controller to slowly sweep the ping assembly from one side to the other without any additional input from the stamp. This allows you to continuously read the ping while the servo controller takes care of moving the sensor head.
One thing that I have learned about the Ping. Upolstered furniture, including the dust ruffle on our bed, is almost invisable to the Ping!