Robotic working tool
First Claim
1. A robotic work tool for use with a guiding wire, the guiding wire being configured to conduct electric current to generate a magnetic field around the guiding wire, the robotic work tool comprising:
- a sensing system configured to detect a strength of the magnetic field, the sensing system comprising a first magnetic field sensor and a second magnetic field sensor, the second magnetic field sensor being positioned at an offset with respect to the first magnetic field sensor;
a steering system; and
a controller configured to control said steering system in response to output from said sensing system by means of a feedback control loop so as to cause movement of said robotic work tool along said guiding wire, wherein the controller is configured to;
determine a distance measure indicative of a distance between the robotic work tool and the guiding wire, wherein determining the distance measure comprisesreading a first sensor signal value from the first magnetic field sensor,reading a second sensor signal value from the second magnetic field sensor,assessing the first sensor signal value and a relation between the first sensor signal value and the second sensor signal value, anddetermining a present distance value, in response to multiple possible present distance values, based on the relation between the first sensor signal value and the second sensor signal value; and
adjust at least one parameter of the feedback control loop in response to the distance measure determined.
1 Assignment
0 Petitions
Accused Products
Abstract
Disclosed is a robotic work tool (100) for use with at least one guiding wire (250; 260) adapted to conduct electric current to generate a magnetic field around the guiding wire. The robotic work tool has a sensing system (510) adapted to detect a strength of the magnetic field, a steering system (540), a controller (530) configured to control the steering system in response to output from the sensing system by means of a feedback control loop (532) so as to cause movement of the robotic work tool along the guiding wire. The controller is configured to determine a measure indicative of a distance between the robotic work tool and the guiding wire, and adjust at least one parameter of the feedback control loop in response to the determined distance measure.
23 Citations
20 Claims
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1. A robotic work tool for use with a guiding wire, the guiding wire being configured to conduct electric current to generate a magnetic field around the guiding wire, the robotic work tool comprising:
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a sensing system configured to detect a strength of the magnetic field, the sensing system comprising a first magnetic field sensor and a second magnetic field sensor, the second magnetic field sensor being positioned at an offset with respect to the first magnetic field sensor; a steering system; and a controller configured to control said steering system in response to output from said sensing system by means of a feedback control loop so as to cause movement of said robotic work tool along said guiding wire, wherein the controller is configured to; determine a distance measure indicative of a distance between the robotic work tool and the guiding wire, wherein determining the distance measure comprises reading a first sensor signal value from the first magnetic field sensor, reading a second sensor signal value from the second magnetic field sensor, assessing the first sensor signal value and a relation between the first sensor signal value and the second sensor signal value, and determining a present distance value, in response to multiple possible present distance values, based on the relation between the first sensor signal value and the second sensor signal value; and adjust at least one parameter of the feedback control loop in response to the distance measure determined. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 20)
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16. A robotic work tool system, comprising a charging station, a guiding wire, a signal generator for generating and transmitting an electric signal through said guiding wire to generate a magnetic field around the guiding wire, and a robotic work tool, the robotic work tool comprising:
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a sensing system configured to detect a strength of the magnetic field, the sensing system comprising a first magnetic field sensor and a second magnetic field sensor, the second magnetic field sensor being positioned at an offset with respect to the first magnetic field sensor; a steering system; and a controller configured to control said steering system in response to output from said sensing system by means of a feedback control loop so as to cause movement of said robotic work tool along said guiding wire, wherein the controller is configured to; determine a distance measure indicative of a distance between the robotic work tool and the guiding wire, wherein determining the distance measure comprises reading a first sensor signal value from the first magnetic field sensor, reading a second sensor signal value from the second magnetic field sensor, assessing the first sensor signal value and a relation between the first sensor signal value and the second sensor signal value, and determining a present distance value, in response to multiple possible present distance values, based on the relation between the first sensor signal value and the second sensor signal value; and adjust at least one parameter of the feedback control loop in response to the distance measure determined. - View Dependent Claims (18, 19)
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17. A method of controlling a robotic work tool to follow along a guiding wire, the guiding wire being configured to conduct electric current and generate a magnetic field around the guiding wire, the method comprising:
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controlling a steering system of the robotic work tool by means of a feedback control loop based on a detected magnetic field strength; determining a distance measure indicative of a distance between the robotic work tool and the guiding wire, wherein determining the distance measure comprises reading a first sensor signal value from a first magnetic field sensor, reading a second sensor signal value from a second magnetic field sensor, assessing the first sensor signal value and a relation between the first sensor signal value and the second sensor signal value, and determining a present distance value, in response to multiple possible present distance values, based on the relation between the first sensor signal value and the second sensor signal value; and adjusting at least one parameter of the feedback control loop in response to the distance measure determined.
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Specification