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EP-4268034-B1 - NAVIGATING A ROBOTIC MOWER ALONG A WIRE

EP4268034B1EP 4268034 B1EP4268034 B1EP 4268034B1EP-4268034-B1

Inventors

  • LUNDKVIST, Andre
  • TRUONG, Daniel

Dates

Publication Date
20260513
Application Date
20201225

Claims (14)

  1. A method for navigating a robotic mower (2) by means of a wire (4, 8), said robotic mower (2) comprising at least one sensor (12; 14), the method comprising: - controlling the robotic mower (2) to exit a parking position at a station (11), in which parking position the robotic mower (2) is at least partially arranged at an inside of a loop (10) of the station (11), by driving the robotic mower (2) straight backwards, - determining that the robotic mower (2) has moved further outside of the loop (10) by detecting at least one signal of the loop (10) by means of the at least one sensor (12, 14), at which time the robotic mower (2) continues to drive straight backwards for an additional, random distance, - detecting at least one signal of the wire (4, 8) by means of the at least one sensor (12, 14), - turning the robotic mower (2) in one direction, and - controlling the robotic mower (2) to straddle along the wire (4, 8).
  2. The method according to claim 1, further comprising: - controlling the robotic mower (2) to increase the distance between the robotic mower (2) and the wire (4, 8) so that the robotic mower (2) is displaced from the wire (4, 8) by a displacement distance, - measuring, by means of the at least one sensor (12, 14), a signal level of at least one signal from the wire (4, 8), and - controlling the robotic mower (2) to follow the wire (4, 8) based on the measured signal level.
  3. The method according to claim 2, wherein the displacement distance is randomly determined between a minimum displacement distance and a maximum displacement distance.
  4. The method according to any of the preceding claims, further comprising controlling the robotic mower (2) to return to the station (11).
  5. The method according to claim 3, further comprising controlling the robotic mower (2) to return to the station (11), and controlling the robotic mower (2) to follow the wire (4, 8) in the minimum distance when returning to the station (11).
  6. The method according to any of the preceding claims, wherein the wire (4) is a boundary wire delimiting an area (A).
  7. The method according to any one of the preceding claims, wherein turning the robotic mower (2) in one direction comprises turning the robotic mower (2) by an angle, measuring, by means of the at least one sensor (12, 14), a signal level of at least one signal from the loop (10), and controlling the robotic mower (2) to follow the loop (10) based on the measured signal level until detecting at least one signal from the boundary wire (4).
  8. The method according to any of the preceding claims, wherein the wire (4) is a boundary wire delimiting an area (A), further comprising, before controlling the robotic mower (2) to increase the distance between the robotic mower (2) and the boundary wire (4) by driving a displacement distance, controlling the robotic mower (2) to straddle along the boundary wire (4) in a first direction until detecting a straight section of the boundary wire (4), and, in response to detecting the straight section, controlling the robotic mower (2) to straddle along the boundary wire (4) in a second direction opposite the first direction before.
  9. The method according to any of claims 1 to 5, wherein the wire (8) is a guide wire arranged within an area (A) delimited by a boundary wire (4).
  10. The method according to claim 9, further comprising turning the robotic mower (2) in one direction and determining the orientation of the robotic mower (2) relative to the guide wire (8) using at least one signal measured by means of each of two sensors (12, 14) of the robotic mower (2).
  11. The method according to claim 10, further comprising, before controlling the robotic mower (2) to increase the distance between the robotic mower (2) and the guide wire (8) by driving a displacement distance, controlling the robotic mower (2) to straddle along the guide wire (8) for a predetermined time or over a predetermined distance.
  12. The method according to any of the preceding claims, further comprising measuring a distance driven by the robotic mower (2), and controlling the robotic mower (2) to abort following the wire (4, 8) when the driven distance equals a preconfigured distance and/or when a driving time equals a preconfigured time.
  13. The method according to claim 12, further comprising, in response to the driven distance equaling the preconfigured distance and/or the driving time equaling the preconfigured time, controlling the robotic mower (2) to mow within the area (A).
  14. A robotic mower (2) for navigating by means of a wire (4, 8) and comprising at least one sensor (12, 14), and adapted to: - exit a parking position at a station (11), in which parking position the robotic mower (2) is at least partially arranged at an inside of a loop (10) of the station (11), by driving the robotic mower (2) straight backwards, - determine that the robotic mower (2) is at least substantially arranged outside of the loop (10) by detecting at least one signal of the loop (10) by means of the at least one sensor (12, 14), at which time the robotic mower (2) is adapted to continue to drive straight backwards for an additional, random distance, - detect at least one signal of the wire (4, 8) by means of the at least one sensor (12, 14) - turn the robotic mower (2) in one direction, and - straddle along the wire (4, 8).

Description

Technical field The present invention generally relates to a method and a robotic mower for navigating the robotic mower along a signal wire out of the charging station, e.g., when the robotic mower starts mowing after recharging the battery. Background art Robotic mowers, also called self-propelled lawnmowers, are generally known. These robotic mowers are provided with a rechargeable battery. When the remaining power in the battery is below a certain level, the robotic mower is programmed to return to the charging station to recharge the battery. There are different possibilities for returning the robotic mower to the charging station. One possible method is that the robotic mower, upon a command to return to the charging station, continues its movement until a boundary wire is detected nearby and then follows the boundary wire to the charging station that is provided somewhere along the boundary wire. Another option when returning to the charging station is to use a guide wire, which the robotic mower follows back to the charging station. The use of a guide wire may in some situations enable a shorter way back to the charging station compared to following the boundary wire. The guide wire can also be beneficial to use when the robotic mower needs to navigate through a narrow passage. In other situations, the robotic mower may find the boundary wire first, and it can be faster to then follow the boundary wire instead of searching further for the guide wire. WO2022082334 discloses a method for navigating a robotic mower comprising at least one sensor. The method comprises detecting, by means of the at least one sensor, at least one signal from a wire as a first signal source; controlling the robotic mower to follow the wire at a first distance to the wire; detecting, by means of the at least one sensor, at least one signal from a second signal source; detecting a second distance based on the at least one signal from the second signal source; and navigating the robotic mower along a path determined based on the first distance and the second distance. US2020042008 discloses a method and a system for docking a robotic mower with a charging station. The system includes a boundary wire and a charging station loop wherein the boundary wire makes a loop in the charging station that is narrower than and crosses the charging station loop. A return signal is received from a control unit commanding the robotic mower to return to the charging station. In response thereto, the robotic mower is controlled to follow the boundary wire until the charging station loop is detected. US8942862 discloses a method and a system for guiding a robotic garden tool to a predetermined position. The robotic garden tool includes a control unit and a sensor unit to detect guiding signals. The sensor unit detects a first guiding signal from a first signal source and the robotic garden tool follows the first guiding signal at a variable distance from the first signal source towards the predetermined position. While within a predetermined distance from the predetermined position, the sensor unit detects a second guiding signal from a second signal source. Within the predetermined distance, the robotic garden tool follows one of the first and the second guiding signals towards the predetermined position at a pre-configured distance from the corresponding signal source. WO2021208010 discloses a method for navigating a robotic mower by means of a wire. The robotic mower comprises at least one sensor. The method comprises detecting, by means of the at least one sensor, at least one signal from the wire, controlling the robotic mower to align with the wire, controlling the robotic mower to turn by an angle with respect to a section of the wire, controlling the robotic mower to increase the distance between the robotic mower and the wire by driving a displacement distance based on a random distance value, measuring, by means of the at least one sensor, a signal level of the at least one signal from the wire, and controlling the robotic mower to follow the wire based on the measured signal level. WO2022021299 discloses a method navigating a robotic mower by means of a wire. The robotic mower comprises at least two sensors. The method comprises detecting, by means of the at least two sensors, at least one signal from the wire, measuring a polarity of the at least one signal of the wire by means of each one of the at least two sensors, determining a direction based on the polarities measured by means of the at least two sensors and turning the robotic mower towards the determined direction. Particularly when exiting the charging station, it is desirable to reduce tracks formed in the lawn that could be created by driving over the same locations multiple times, and to improve the efficiency of mowing and navigation. Summary An object of the present invention is to provide an improved navigation of a robotic mower by means of a wire when exiting a stat