RTK means ‘Real Time Kinematic (Positioning)’, and it is a system that works to make GPS data more accurate. So satellite data alone can help your robot lawn grass cutting machine correct detection within a few meters, but mix it with RTK positioning, and it can come down to a few centimeters.
This is the technique that has enabled modern lawnbats to navigate without a border wire. This also means that the lawnbot can mole in an order, logical fashion, rather than just cross the lawn randomly.
However, the effectiveness of the RTK position is dependent on specific factors – and if some things are closed, it cannot work very well. Give more information about how RTK Positioning works in robot lawn mawers.
Why is satellite data not sufficient enough?
We are using the word GPS, but it is actually one of the four systems that can provide satellite data that helps your lawnbot find your way – so a more correct brief name will be GNSS (Global Navigation Satellite System).
The satellites use two main signal types. The oldest type of satellite signal is L1 signal, and it cannot pass through any solid object. The new L2 signals can enter through some objects – including things like thin wood, plastic and light tree coverage – but every time doing so, the signal becomes weak.
The signal takes time to go down from the satellite to the earth which makes the status data inaccurate. Even passing through our environment is delayed; The signal passes faster than some areas than others.
How does RTK positions help?
RTK essentially helps correct impurities in satellite position data, so that it can be made more accurate. It does in real time.
The system depends on a certain, antenna-equipped base station with known coordinates (this is different from the charging station of the robot lawn grass cutting machine, which does the bot dock and recharges its battery). Both RTK base station and lawnbot connect with satellites in the sky.
To do this, they require a straight line of vision to each satellite – things such as walls, ceilings and even tree coverage can block the signal. What is more, both base stations and lawnbott need to connect Same Satellite to work.
The RTK station needs to be placed, so it has the most widespread unjusted view of the sky in as much directions as possible. It should be elevated, and away from finishing buildings and trees.
Because the lawnbot needs to be able to connect with satellites when it is docked and at the same time it is working, the charge station should also be in a position with a straight line of vision in the sky (you can usually be away along a wall behind a wall, provided the other three directions are open and the sky is good in the sky.)
The RTK base station also connects to the lawnbot, but this connection does not require a straight line of vision – it is usually a radio signal, which can pass through solid objects.
Are there any down-side of the RTK system?
The major advantage of using RTK and GPSS data for navigation is that it means that you do not need to go through the problem of adding a boundary wire to your garden.
However, this is not a failed system. There are many satellites that can connect with robot grass cutting machine and RTK station. Overhead barriers like trees and buildings will affect how effective it is, and it is important to have a good place to install your RTK station.
Because they are very sensitive to environmental factors, lawnbots that rely on RTK are more prone to losing, or wandering out of range, which use perimeter wires.
You can also find that location data is still not quite accurate. An RTK-managed robot grass cutting machine will navigate your lawn in clean lines, but because there is still a few centimeter error, you can finish with unmot strips of grass between the rows. You may also need to leave a large buffer in a possible dangerous circumference – for example, the edge of a pond. Lonbots that use boundary wires will cover the area in a much more haphazard manner, but they will never go to a border, and perhaps the possibility of remembering a location.
These potentially weak points mean that almost all modern lawnbotts will include another type of navigation system as the signal backup when the signal deteriorates. It can be radar or lidar (most of today’s best robots used in vacuum), or something like a camera. There are definitely boundaries for each system, but technologies are never getting more advanced, and as a result, so they are lawnbotts they have power.
