GPS Fence - Project Overview
GPS Fence Module:
A GPS fence uses a GPS module and software to track and limit the movements of the rover/mower/vehicle within a defined area. The GPS fence is created by inputting the GPS coordinates into the Arduino Software. A line is projected around these coordinates so that if the mower crosses the line, a signal is sent so that action can be taken. (e.g. turn around and go back into the fenced zone)
This system provides a very flexible way to monitor the position of robots and therefore control and limit its movements. The fence can be setup for almost any terrain. The GPS fence has many applications for robots which can move within large areas where traditional cable based perimeter systems are impractical.
The project consist of:
1. GPS Rover Module and Arduino Software.
2. GPS Ground Station Module (for cm accurate RTK GPS)
3. Smartphone APP to monitor the Rover
Smartphone APP Screenshots:
In the following video the GPS fence coordinates of the golf course have been cretaed giving a very accurate fence around the fairway.
The software tracks the position of the vehicle/mower and compares it to the GPS fence coordinates. If the vehicle crosses the fence an OUT(0) signal is given which turns the vehicle/mower around. The Arduino software allows you to simulate the vehicle in the fence to test that all is correct before using it live.
The following video shows the simulation mode testing the fence. The screen is from the Smartphone Blynk app. If the mower has a WIFI connection it can send data to the APP which can be monitored from anywhere in the world:
The accuracy of this system depends on the Latitude and Longitude coordinates the GPS module provides. The more accurate the location of the module is given the better the system will work.
Typical low cost GPS modules give an accuracy of 3-4m. If this is acceptable for your project then these module can be a very affordable option.
More expensive RTK GPS systems can give an accuracy of a few cm.
For this projet the RTK module will be implemented as a 3-4m accuracy is not acceptable for the mower project. With an RTK system the goal is to have an accuracy of <30cm.