picaxe gps

tropper

New Member
hi,
could you tell me any informations on the module gps ls-40eb and picaxe 18x and their applications? Is there a tutorial for module gps?
thanks:confused:
 

rigidigital

Senior Member
Same here, they just quoted my dad $5000 for a gps for his tractor, to plant etc accuratly in a padock! I wonder if picaxe can do this .
 

papaof2

Senior Member
The difference is in the accuracy - which depends on the GPS module itself, the mode in which it is running, and whether calculations are averaged - and in the packaging. I expect the tractor version has a large display screen and nearly indestructable construction ;-)

John
 

rigidigital

Senior Member
Well, the display does not have to be any larger than a smalish car type gps LCD. The GPS module I looked at receives from up to 19 satallites at one. For around $100- $150.
I thought I could run a lap around the paddocks , say and store in size of the area. Then input the width of the Planter or sprayer, plough. and have a pointer keeping the machinerery in right lane give or take 15- 20 cm. Enen a buzzer or other LCD indicator that the driver is going to sleep :)
 

MFB

Senior Member
GPS

There is no way that a standard GPS receiver will give you a position accuracy of "give or take 15-20cm. Their accuracy would be more like 10metres! However, there are other ways of processing GPS signals that can give tens of cm accuracy but they are much more expensive.
 

pbunyan

Member
I'm probably missing something here, but do you really need a GPS locator to help plant the crops? one other solution could be to have an infra-red laser at certain points in the field, making lines across the field where you want to plant. just get the picaxe to tell you how far away you are from beam and what to do to correct youself. should be less than $5000. or even a piece of string across the field as a visual aid may work ;)
 
Car GPSes

The problem with GPSs designed for cars is that they 'lock on' to roads and do not like going off the roads on the map. Therefore these would not be suitable for a tractor in a field :)
 

Fowkc

Senior Member
GPS doesn't sound like the best option here. You'd be better off making your own PPS (Paddock Positioning System). Perhaps along similar lines to GPS, where you have several "satellites" at the corners of the paddock (ultrasonic transmitters perhaps), and a receiver in the tractor to compare time-of-flight of signals. Due to timing inaccuracies, I'd suggest a way of starting each transmission from a t=0 point, perhaps by sending a "start" signal by radio or high-power IR. Dunno if you'd get 15-20cm accuracy even with that method though.
 

papaof2

Senior Member
Sounds like a project that might incorporate the laser rangefinders (true laser device, not an ultrasonic rangefinder with a laser pointer). They are available for about $100US and are advertised as accurate to something like 1/16 inch in 150 feet (about 46m). If the area is larger than that, then using 2 devices at 180 degrees to each other would double the distance covered and maintain the accuracy. Your interface code would have to recognize which rnagefinder had a valid measurement and use it.
If there's a fence around the area, then just maintaining a fixed distance from the fence would provide parallel (to the fence) rows.
This would probably require some interfacing electronics, as the only laser rangefinders I've seen have LCD displays.
You would need to check the duty cycle & operating life of the laser diode used - something designed for intermittent handheld use typically won't have a long life in continuous operation.

John
 

demonicpicaxeguy

Senior Member
if your paddock is surrounded by a fence that an ultrasonic distance module can pickup ,then simply use two of them, one to get your x position and 1 to pickup your y position

the question is up to how far does one of the ultrasonic modules detect up to?
 

rigidigital

Senior Member
Who Said ?

The problem with GPSs designed for cars is that they 'lock on' to roads and do not like going off the roads on the map. Therefore these would not be suitable for a tractor in a field :)
I was refering to the size of display of the cars LCD! As far as the operation of a Garmin, or navman etc, they seem extreemly accurate "on the road", they actually indicate if you are in the left or right lane of a City street and even direct with "move over to the right lane" !!

I pretty sure the thousands of tractor GPS systems used in australia ,don't worry about city roads :)
 

inglewoodpete

Senior Member
I have had recent experience on the agricultural use of GPS on my cousin's farm. Far from the simple crop seeding that we city folk think of in farming are the realities of pest and weed control. In broad acre farming, machines like sprayers often cover widths of 100ft (30m). This makes it difficult to align accurate coverage from the driver's position. Overlapping of spread wastes chemicals and the double dosing can raise health/quality issues of the crop when selling the produce. "Underlapping" (missing areas) leaves weeds flourishing, affecting harvest or pests remain alive to reinfest the crop.

The GPS is used to control machine alignment (eg exactly 30m from previous pass) and control the application rate of seed/fertiliser/chemicals by accurately determining ground speed.

The devices are quite specialised and only a few thousand (hundred?) of each model might be sold in a country like Australia. Consequently, the development and support costs can be high. From memory, my cousin paid around $A10,000 for his unit, which he considered to be good value for money. Accuracy was to within 200mm (8") which he was able to demonstrate by doing a return pass: the tractor wheel tracks aligned almost perfectly.
 
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toxicmouse

Senior Member
i think all you need for the GPS is the Locksence LS-40 EB datasheet which should be available from their site. when you read the datasheet it is quite straightforward and a tutorial isnt really necessary.

as for the infectious tractor GPS topic, i can safely diagnose this as Nesbititis. the Ghost of the Rabbit returns.

i like the idea of a laser guided tractor...
 
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