Navigation for a robotic work tool
A robotic work tool for movable operation within a work area. The robotic lawnmower comprises a satellite navigation device; and a controller, the controller being configured to cause the robotic work tool to movably operate within the work area based on positions partly or in whole determined from satellite signals received by the satellite navigation device being a differential satellite navigation device and on phase information received from a reference station, by: receiving phase information from the reference station for a satellite signal received by the reference station; storing the phase information; determining that further phase information from the reference station for the satellite signal received by the reference station is not available or erroneous, and in response thereto; extrapolating phase information based on the stored phase information; receiving a satellite signal received by the robotic work tool; comparing the extrapolated phase information to phase information of the satellite signal received by the robotic work tool; determining a position based on the comparison for movably operating the robotic work tool.
1. A robotic work tool for movable operation within a work area, the robotic work tool comprising:
a satellite navigation device; and
a controller, the controller being configured to cause the robotic work tool to movably operate within the work area based on positions partly or in whole determined from satellite signals received by the satellite navigation device being a differential satellite navigation device and on phase information received from a reference station, by:
receiving phase information from the reference station for a satellite signal received by the reference station;
storing the phase information;
determining that further phase information from the reference station for the satellite signal received by the reference station is not available or erroneous, and in response thereto:
extrapolating phase information based on the stored phase information;
receiving a satellite signal received by the robotic work tool;
comparing the extrapolated phase information to phase information of the satellite signal received by the robotic work tool; and
determining a position based on the comparison for movably operating the robotic work tool.
2. The robotic work tool as defined in claim 1 , wherein the phase information is the phase for the satellite signal received by the reference station.
3. The robotic work tool as defined in claim 1 , wherein the robotic work tool is further configured to extrapolate by fitting a curve based on the stored phase information to the stored phase information.
4. The robotic work tool as defined in claim 1 , wherein the robotic work tool is further configured to extrapolate by fitting a curve based on movement of a corresponding satellite to the stored phase information.
5. The robotic work tool as defined in claim 1 , wherein the satellite navigation device is a Real Time Kinematics Global Positioning System device.
6. The robotic work tool as defined in claim 1 , wherein the robotic work tool is required to operate in the work area in a methodical and systematic or position oriented manner.
7. The robotic work tool as defined in claim 1 , wherein the robotic work tool is a robotic lawnmower.
8. A robotic work tool system comprising a charging station and the robotic work tool according to claim 1 .
9. The robotic work tool system as defined in claim 8 further comprising the reference station.
10. The robotic work tool as defined in claim 1 , wherein extrapolating the phase information comprises extrapolating the phase information in accordance with a fitted curve that is a least squares curve.
11. The robotic work tool as defined in claim 1 , wherein extrapolating the phase information comprises filtering the phase information received from the reference station for noise by applying a smoothing operation to the phase information.
12. The robotic work tool as defined in claim 1 , wherein the further phase information from the reference station for the satellite signal received by the reference station is determine to be not available due to a loss of reception of a signal comprising the further phase information from the reference station.
13. A method of controlling a robotic work tool, by a controller of the robotic work tool, for movable operation within a work area based on positions partly or in whole determined from satellite signals received by a satellite navigation device being a differential satellite navigation device and on phase information received from a reference station, the method comprising:
receiving phase information from the reference station for a satellite signal received by the reference station;
storing the phase information;
determining that further phase information from the reference station for the satellite signal received by the reference station is not available, and in response thereto:
extrapolating phase information based on the stored phase information;
receiving a satellite signal received by the robotic work tool;
comparing the extrapolated phase information to phase information of the satellite signal received by the robotic work tool; and
determining a position based on the comparison for movably operating the robotic work tool.
14. A non-transitory computer readable storage medium encoded with instructions that, when executed on a processor, perform the method according to claim 13 .