[bhaazee]

A pre-programmed robot has to be employed for collecting soil samples from agricultural farms. The robot moves along a pre-assigned path to collect samples. For the purpose of navigation, suitable sensors have to be employed. The accuracy of the travelling path from the actual co-ordinates should be less than 0.5 m. Although GPS is the usually employed method for navigation purposes, the accuracy of GPS is between 1 to 10 m (which is very low).

Assume the size of farm is between 10 to 20 hectares

Please note that this is not a project nor some assignment. I just want to provide some typical scenario

Could someone suggest some suitable navigation assistance systems for such projects and if possible some case study or related articles

Regards

[kisai]

Are you allowed to put radio beacons in the field?

[bhaazee]

Since the bots could be used for collecting samples in various farm, use of portable beacons could be possible. However, this could be considered as one of the option. One other option could be, using accelerometers with magnetic compass (like in Inertial measurement Units) to guide navigation. I am not sure of its usage in large scale applications.

I would also like to know the availability of other options


Regards

This post has been edited by bhaazee: 6 March 2012 - 06:54 AM

[PaulS1950]

Using radio beacons to triangulate its position can keep you within your tolerance of .5 meters. Laser becons can be far more accurate but would require modulation at different frequencies to differentiate between the different laser "home" positions. Lasers may also require a vertical scan component as well as a horizontal scan as the terrain differs in altitude. Ultrasonic "sonar" could be used within the .5 meter using a transmitter on the robot and targets around the field (say at the four corners).I doubt that accelerometers would be any more accurate than a wheel with directional indication built in and measuring distance with the number of rotations. The slippage and directional errors would quickly lead to the accumulation of errors the would get you lost.You need an outside "standard" to measure from to maintain a real time position.

Paul

[Xittenn]

PaulS1950, on 8 March 2012 - 04:45 PM, said:

I doubt that accelerometers would be any more accurate than a wheel with directional indication built in and measuring distance with the number of rotations. The slippage and directional errors would quickly lead to the accumulation of errors the would get you lost.You need an outside "standard" to measure from to maintain a real time position.

I have to second this, using an accelerometer in conjunction with a compass isn't something that will give you the accuracy that you desire, especially on rough terrain like farmland. I would even go as far to say that you might as well use mensuration, employing an internal clock and calendar, and the use of the position of the sun and shadows, to track your movements. If you wanted to employ a system that included an accelerometer I would suggest the only way to accomplish this would be to set the navigation system in an airborne state navigating from a few meters above the drone. Laser beacons are by far the most ideal present day solution to your problem.

[bhaazee]

I back your views on using an accelerometer. Quiet a bad option.
Have to check out if using beacons would be affordable for the project.

@ Xitten, You mean to say that using accelerometers on a airborne navigation yields accurate results?

However, out of curiosity, would like to know how the Roomba vacuum robot returns back to its charger automatically. Means how the Roomba senses the location and position of vacuum cleaner?

and Thnx everyone for the replies

This post has been edited by bhaazee: 9 March 2012 - 12:26 AM

[Xittenn]

bhaazee, on 9 March 2012 - 12:25 AM, said:

I back your views on using an accelerometer. Quiet a bad option.
Have to check out if using beacons would be affordable for the project.

@ Xitten, You mean to say that using accelerometers on a airborne navigation yields accurate results?

However, out of curiosity, would like to know how the Roomba vacuum robot returns back to its charger automatically. Means how the Roomba senses the location and position of vacuum cleaner?

and Thnx everyone for the replies

Smooth surfaces where good traction can be obtained are ideal for this sort of navigational system. Making the navigation system airborne in your case makes the navigation system independent of the surface over which the drone is traveling. Making the navigation system airborne synthesizes the ideal condition that we see in the case of the Roomba. An aerial perspective also gives the software a better picture of the terrain to gain visual cues for navigating.

Laser beacons these days I imagine, are relatively inexpensive.

This post has been edited by Xittenn: 9 March 2012 - 02:03 AM

[InigoMontoya]

Just a thought but....

1) Small stakes with corner reflectors mounted in a few very well defined locations in the field.
2) Periodically the robot sweeps a laser (mounted to a mast) in the direction(s) it expects to see the reflectors.
3) Based on what it "saw" when it did the sweep, it makes location corrections and continues on.

[EDV]

I use"AVM Navigator" for autonomous robot navigation and this module needs only in motorized video camera and works pretty well



Navigation by map

This post has been edited by EDV: 8 May 2012 - 11:09 AM