# US 2019/0378360 A1 · Robotic working tool > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2019/0378360 A1 - Document ID: US20190378360A1 - Status: Published application - Kind: A1 - Application number: 16/434,250 - Filed: 2019-06-07 - Published: 2019-12-12 - Earliest claimed: 2018-06-07 - Assignees: Husqvarna AB - Applicants: Husqvarna AB - Inventors: Magnus Bergenholm; Johan Rogö; Lars Ederfors - Web page: https://patentgrep.com/patent/US20190378360A1 ## CPC - G07C 5/02: Registering or indicating driving, working, idle, or waiting time only (apparatus forming part of taximeters G07B13/00) - G07C 5/085: {using electronic data carriers} - G05D 1/027: {comprising intertial navigation means, e.g. azimuth detector (inertial navigation G01C21/16; inertial navigation combined with non-inertial navigation instruments G01C21/165)} - G07C: TIME OR ATTENDANCE REGISTERS; REGISTERING OR INDICATING THE WORKING OF MACHINES; GENERATING RANDOM NUMBERS; VOTING OR LOTTERY APPARATUS; ARRANGEMENTS, SYSTEMS OR APPARATUS FOR CHECKING NOT PROVIDED FOR ELSEWHERE - G05D: SYSTEMS FOR CONTROLLING OR REGULATING NON-ELECTRIC VARIABLES ## Abstract The present disclosure relates to an articulated self-propelled robotic tool 1 with first and second platforms 3, 7, each comprising a wheel set 5, 9 driven by motors. A link arrangement connects the first platform to the second platform at a turning axis 11. A driving error is determined by recording a driving input to the motors and a resulting movement parameter, comparing the resulting movement with an estimated resulting movement which is based on the driving input. Slip is detected using the driving error. ## Claims ### Claim 1 An articulated self-propelled robotic tool comprising a first platform with a first wheel set driven by a first set of motors, a second platform with a second wheel set, a link arrangement connecting the first platform to the second platform at a turning axis, such that one of said first and second platforms are pivotable in relation to the other at said turning axis to an angular position, characterized by a slip detection arrangement configured to: record a driving input to the first set of motors, record at least one resulting movement parameter correlated to movement of the first wheel set, determine a driving error by: determining an estimated resulting movement parameter based on recorded driving input, and comparing the estimated resulting movement parameter with a recorded resulting movement parameter to provide the driving error, or determining estimated driving input based on the recorded resulting movement parameter and comparing the estimated driving input with the recorded driving input to provide the driving error, and detect slip based on the driving error. ### Claim 2 (depends on 1) The self-propelled robotic tool according to claim 1, wherein the second wheel assembly is driven by a second set of motors, and the slip detection arrangement is configured to record a driving input to the second set of motors and base the slip detection also on the driving input to the second set of motors. ### Claim 3 (depends on 1) The self-propelled robotic tool according to claim 1, wherein said at least one resulting movement parameter includes a detected angle between the first and second platforms. ### Claim 4 (depends on 1) The self-propelled robotic tool according to claim 1, wherein said at least one resulting movement parameter includes data from an inertia measurement unit. ### Claim 5 (depends on 4) The self-propelled robotic tool according to claim 4, wherein said data from the inertia measurement unit includes at least one of data from an accelerometer, a gyro, or an electronic compass. ### Claim 6 (depends on 1) The self-propelled robotic tool according to claim 1, wherein said at least one resulting movement parameter includes data from a positioning system. ### Claim 7 (depends on 1) The self-propelled robotic tool according to claim 1, wherein the robotic tool is configured to carry out a slip elimination procedure in case a slip exceeding a slip threshold is detected. ### Claim 8 (depends on 1) The self-propelled robotic tool according to claim 1, wherein the self-propelled robotic tool is a robotic lawnmower. ### Claim 9 A method in a self-propelled robotic tool for detecting wheel slip, the self-propelled robotic tool being articulated and comprising a first platform with a first wheel assembly driven by a first set of motors, a second platform with a second wheel assembly, a link arrangement connecting the first platform to the second platform at a turning axis, such that one of said first and second platforms are pivotable in relation to the other at said turning axis to an angular position, the method comprising: recording a driving input to the first set of motors, recording at least one resulting movement parameter correlated to movement of the first wheel assembly, determining a driving error by: determining an estimated resulting movement parameter based on recorded driving input, and comparing the estimated resulting movement parameter with a recorded resulting movement parameter to provide the driving error, or determining an estimated driving input based on the recorded resulting movement parameter and comparing the estimated driving input with recorded driving input to provide the driving error, and detecting slip based on the driving error. ### Claim 10 (depends on 9) The method according to claim 9, wherein the second wheel assembly is driven by a second set of motors, and the slip detection method records a driving input to the second set of motors and bases the slip detection also on the driving input to the second set of motors. ### Claim 11 (depends on 9) The method according to claim 9, wherein said at least one resulting movement parameter includes a detected angle between the first and second platform. ### Claim 12 (depends on 9) The method according to claim 9, wherein said at least one resulting movement parameter includes data from an inertia measurement unit (IMU). ### Claim 13 (depends on 12) The method according to claim 12, wherein said data from the IMU includes at least one of data from an accelerometer, a gyro, or an electronic compass. ### Claim 14 (depends on 9) The method according to claim 9, wherein said at least one resulting movement parameter includes data from a positioning system. ### Claim 15 (depends on 9) The method according to claim 9, wherein the robotic tool is configured to carry out a slip elimination procedure in case a slip exceeding a slip threshold is detected. ### Claim 16 (depends on 9) The method according to claim 9, wherein the self-propelled robotic tool is a robotic lawnmower.