CN109258059B - Method and device for determining position of mower - Google Patents
Method and device for determining position of mower Download PDFInfo
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- CN109258059B CN109258059B CN201810785434.5A CN201810785434A CN109258059B CN 109258059 B CN109258059 B CN 109258059B CN 201810785434 A CN201810785434 A CN 201810785434A CN 109258059 B CN109258059 B CN 109258059B
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- A—HUMAN NECESSITIES
- A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
- A01D—HARVESTING; MOWING
- A01D34/00—Mowers; Mowing apparatus of harvesters
- A01D34/006—Control or measuring arrangements
- A01D34/008—Control or measuring arrangements for automated or remotely controlled operation
Abstract
The invention discloses a method and a device for determining the position of a mower, which can accurately determine the straight-line running distance and the turning angle of the mower without depending on external reference and determine the walking position of the mower on the basis of the straight-line running distance and the turning angle. Firstly, carrying out secondary integration on a measurement value of an accelerometer to obtain a distance calculated by the accelerometer; acquiring the rotation angle of the mower wheels by using an angle sensor to obtain the movement distance of the mower wheels; performing Kalman filtering fusion on the distance calculated by the accelerometer and the moving distance of the wheels of the mower, and marking a fusion result as a straight-moving distance of the mower; performing Kalman filtering fusion for three times by using data acquired by a gyroscope, an accelerometer, a magnetometer and a Hall element sensor, and marking a finally obtained fusion result as a rotation angle of the mower; and obtaining the position of the mower relative to the origin after walking for unit time according to the straight-moving distance and the rotation angle of the mower.
Description
Technical Field
The invention relates to the field of robots, in particular to a method and a device for determining the position of a mower.
Background
The intelligent mower mainly helps people to complete mowing work, and is a mower capable of achieving intelligent autonomous mowing. The intelligent mower can be separated from human control factors, thereby avoiding wasting too much human resources, saving material resources, and having the advantages of high efficiency, high safety and the like.
The intelligent mowing is that a mowing area is manually defined in advance, the mower autonomously plans a path and walks in the manually defined area, traverses all positions in the area and cannot cross the area, and therefore all-around autonomous operation without repetition and omission is achieved. The method mainly comprises a self-identification technology of a working boundary, an intelligent path identification technology and an intelligent obstacle avoidance technology.
The self-recognition technology of the working boundary means that the intelligent mower can intelligently recognize a mowing path in the mowing process, so that the intelligent mower can walk without crossing the boundary. Most intelligent mowers now employ an electronic fencing approach for zone boundary selection. However, the electronic fence has the characteristic of poor flexibility, and needs to be rearranged when the shape of the area is required to be changed after the electronic fence is arranged, and the arrangement of a complicated area is difficult, and the efficiency is low. Meanwhile, the electronic fence is arranged outdoors, so that the electronic fence is easy to damage and cause accidents. Another method of identifying a working boundary is by using GPS technology. However, this technique requires a highly accurate GPS to achieve a high accuracy, which increases the cost of the mower and is not suitable for use in a home mower. And finally, the intelligent mower can acquire the coordinates of the data of the boundary points in advance and determine the boundary by an internal algorithm. However, the method needs the mower to accurately determine the movement state, namely how far the mower has moved and how many degrees the mower has rotated, so as to improve the accuracy of acquiring the position of the coordinate point, thereby ensuring that the internal algorithm can accurately plan the region boundary.
In addition, after the path planning is completed, the mower needs to walk and mow according to the planned path, and at the moment, the movement position of the mower also needs to be accurately determined, so that the mower is ensured not to deviate from the planned route.
In the prior art, most intelligent lawn mowers adopt a reference positioning device arranged at certain positions of the boundary to provide reference signals for the lawn mowers to determine and correct the movement positions, but the method is extremely inconvenient and is only suitable for places with relatively fixed mowing ranges.
Therefore, there is a lack in the art of a method for determining the position of a lawnmower that relies entirely on sensors carried by the lawnmower without external reference.
Disclosure of Invention
The invention provides a method and a device for determining the position of a mower, which overcome the defect of poor flexibility of the existing method for determining the movement position of the mower, do not need external reference, can determine the position of the mower only by a sensor on the mower, and are flexible, convenient, simple and efficient. In order to achieve the purpose, the invention adopts the following technical scheme:
a method of determining a mower position, comprising:
and S1, marking the initial position as the origin.
S2, collecting the acceleration measured by the accelerometer in unit time when the mower walks in unit time, and performing quadratic integration on the acceleration to obtain the distance calculated by the accelerometer, wherein the distance calculated by the accelerometer is inaccurate.
And S3, converting the Hall element sensor to obtain the rotation number and the angle of the mower wheel, and combining the rotation number and the angle with the radius of the mower wheel to obtain the movement distance of the mower wheel.
And S4, performing Kalman filtering fusion on the distance calculated by the accelerometer and the moving distance of the wheels of the mower, and marking the fusion result as the straight-moving distance of the mower. The distance converted by the number of the Hall signals returned by the Hall element sensor may be inaccurate due to wheel slip, the distance calculated by the accelerometer may be accumulated error due to null shift and temperature shift, and after the two are subjected to Kalman filtering, the reliability of the moving distance of the mower wheel and the distance calculated by the accelerometer is considered, and the two distances are fused to obtain the accurate walking distance.
S5, performing three-level Kalman filtering fusion by using data acquired by a gyroscope, an accelerometer, a magnetometer and a Hall element sensor, and marking a finally obtained fusion result as a rotation angle of the mower;
and S6, obtaining the position of the mower relative to the origin after walking for unit time according to the straight-moving distance and the rotating angle of the mower.
Further, in S5, the three-level kalman filter fusion includes:
and S51, integrating the angular velocity collected by the gyroscope to obtain an integral angle of the gyroscope, respectively collecting the accelerations in three directions by the three-axis accelerometer, and calculating the calculated angle of the accelerometer according to the collected accelerations. The integrated angle of the gyroscope has accumulated errors, and the calculated angle of the accelerometer has larger noise.
And S52, performing first-level Kalman filtering fusion on the gyroscope integral angle and the accelerometer calculation angle to obtain a fused angle. The fused angle makes up the defects of accumulated error of the integral angle of the gyroscope and high noise of the calculated angle of the accelerometer, because the accelerometer can make up the defect that the output zero point of the gyroscope is affected by temperature, the integral error is greatly reduced, and the integral angle of the gyroscope can reduce the output noise of the calculated angle of the accelerometer.
And S53, performing two-stage Kalman filtering fusion on the absolute angle acquired by the magnetometer and the fused angle to obtain a two-stage fused angle.
S54, Hall element sensors are installed on the mower wheels, and the rotating distance of the wheels corresponds to the number of Hall signals measured by the sensors. When the mower turns, the left wheel and the right wheel are reversed at the same angular speed, so that the rotation angle of the mower can correspond to the rotation angle of the wheels, namely the number of Hall signals. Therefore, the rotating angle of the mower can be obtained through the number of Hall signals collected by the Hall element sensor, and the rotating angle cannot be changed under the influence of a magnetic field. And carrying out three-level Kalman filtering fusion on the rotation angle measured by the Hall element sensor and the angle subjected to the two-level fusion, and marking the obtained result as the rotation angle of the mower.
The present invention also provides a device for determining a mower position, comprising: accelerometer, gyroscope, magnetometer, Hall element sensor. The accelerometer, the gyroscope and the magnetometer are arranged on the central axis of the mower body and are horizontal to the ground. The Hall element sensor is arranged in the mowing motor and used for recording the number of turns of the motor.
The walking of the mower is divided into turning and straight walking, the direction angle and the displacement do not change in the straight walking process, and therefore the position of the mower relative to the departure point can be calculated according to the walking distance and the rotation angle.
The invention has the beneficial effects that:
the method comprises the steps of mutually fusing the distance calculated by an accelerometer and the distance converted by a Hall element sensor to obtain the running distance information of the mower; the method is characterized in that an accelerometer, a gyroscope, a magnetometer and a Hall element sensor are utilized to perform multi-signal multi-level fusion to obtain real-time turning angle information of the mower, only the accelerometer, the gyroscope, the magnetometer and the Hall element sensor carried by the mower are used, no external reference source is modified to determine the walking position of the mower, an external reference source is abandoned, and the defect that autonomous intelligent mowing cannot be performed due to damage of the reference source is overcome.
Drawings
In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a flow chart of the method of the present invention;
FIG. 2 is a flow chart of distance fusion;
FIG. 3 is a flow chart of fusion of angles;
FIG. 4 is a diagram of a walking scheme of the intelligent mower;
fig. 5 is a diagram showing the placement and connection of the respective devices.
Detailed Description
In order that those skilled in the art will better understand the technical solutions of the present invention, the present invention will be further described in detail with reference to the following detailed description.
The embodiment of the invention provides a method for determining the position of a mower, and a device for determining the position of the mower is required to be used. A lawn mower position determining apparatus, as shown in fig. 5, includes: the lawn mower comprises an accelerometer, a gyroscope, a magnetometer, a Hall element sensor and a main controller, wherein the accelerometer, the gyroscope and the magnetometer are arranged in the central axis of a mower body and are horizontal to the ground; the Hall element sensor is arranged in the mowing motor and used for recording the number of turns of the motor, and the main controller collects parameters of the accelerometer, the gyroscope, the magnetometer and the Hall element sensor and performs operation and control.
A schematic flow chart of a method for determining mower position is shown in fig. 1, and includes:
the acceleration obtained by measurement of the accelerometer in unit time is collected, the velocity is obtained through primary integration, the distance calculated by the accelerometer is obtained through primary integration of the velocity, and the inaccurate straight-moving distance A is obtained.
A counting Hall element sensor is arranged in the motor, the Hall element sensor is used for collecting the rotation angle of the wheel of the mower, and the rotation angle is combined with the radius of the wheel of the mower to obtain the moving distance B of the wheel of the mower.
And performing Kalman filtering fusion on the distance calculated by the accelerometer and the moving distance of the wheels of the mower, and marking a fusion result as the straight-moving distance of the mower. Because the distance converted by the number of hall signals returned by the angular hall element sensor may be inaccurate due to wheel slip, and the distance calculated by the accelerometer may cause accumulated errors due to null shift and temperature shift, after the two are subjected to kalman filtering, the reliability of the moving distance B of the mower wheel and the distance a calculated by the accelerometer is considered, and the two distances are fused to obtain the accurate walking distance C, as shown in fig. 3.
And performing three-level Kalman filtering fusion by using data acquired by a gyroscope, an accelerometer, a magnetometer and a Hall element sensor, and marking a finally obtained fusion result as a rotation angle of the mower. Wherein, three-level Kalman filtering fusion includes:
and acquiring angular velocity integral by the gyroscope to obtain an integral angle a of the gyroscope, acquiring accelerations in three directions by the three-axis accelerometer respectively, and calculating by using the acquired accelerations to obtain an accelerometer calculation angle b. The integrated angle of the gyroscope has accumulated errors, and the calculated angle of the accelerometer has larger noise.
And performing primary Kalman filtering fusion on the gyroscope integral angle a and the accelerometer calculation angle b to obtain a fused angle c. The fused angle makes up the defects of accumulated error of the integral angle of the gyroscope and high noise of the calculated angle of the accelerometer, because the accelerometer can make up the defect that the output zero point of the gyroscope is affected by temperature, the integral error is greatly reduced, and the integral angle of the gyroscope can reduce the output noise of the calculated angle of the accelerometer.
But the fused angle c lacks the correction of a reference value independent of the mower, and the absolute angle acquired by the magnetometer and the fused angle are subjected to secondary Kalman filtering fusion to obtain a secondary fused angle d.
Hall element sensors are installed on wheels of the mower, and the turning angle of the mower is set to be forward turning and backward turning at the same angular speed of the left wheel and the right wheel, so that the turning angle of the mower corresponds to the turning distance of the wheels, and the turning distance of the wheels corresponds to the number of Hall signals collected by the Hall element sensors. The rotation angle e converted by the hall element sensor is an absolute angle and does not change under the influence of a magnetic field. And (3) carrying out three-level Kalman filtering fusion on the rotation angle e obtained by converting the Hall element sensor and the angle d obtained after two-level fusion to obtain a result, and marking the result as a rotation angle f of the mower, as shown in figure 3.
And obtaining the position of the mower relative to the origin after walking for unit time according to the straight-moving distance and the rotation angle of the mower.
As shown in fig. 4, the walking process of the intelligent lawn mower is divided into: the straight line and the turning at any angle are bent. Go straight for a certain distance
Then rotate by a certain angle
Go straight a distance again
Angle of rotation
And the straight-going distance and the turning angle can be accurately controlled each time by circulating the steps, so that the position of the mower relative to the original starting point can be obtained by recording the turning angle and the straight-going distance each time. After the walking position of the mower can be accurately controlledThe intelligent mower can get rid of the constraint of an external reference source, and the accurate autonomous planning of the path and the path walking are realized.
The invention has the beneficial effects that:
the method comprises the steps of mutually fusing the distance calculated by an accelerometer and the distance converted by a Hall element sensor to obtain the running distance information of the mower; the method is characterized in that an accelerometer, a gyroscope, a magnetometer and a Hall element sensor are utilized to perform multi-signal multi-level fusion to obtain real-time turning angle information of the mower, only the accelerometer, the gyroscope, the magnetometer and the Hall element sensor carried by the mower are used, no external reference source is modified to determine the walking position of the mower, an external reference source is abandoned, and the defect that autonomous intelligent mowing cannot be performed due to damage of the reference source is overcome.
The above description is only for the specific embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the protection scope of the claims.
Claims (2)
1. A method of determining a mower position, comprising:
s1, marking the initial position as an origin;
s2, the mower walks in unit time, the acceleration obtained by measuring the accelerometer in unit time is collected, and the acceleration is subjected to secondary integration to obtain the distance calculated by the accelerometer;
s3, obtaining the number of turns and the angle of the wheel by using the signal collected by the Hall element sensor, and obtaining the moving distance of the wheel of the mower and the rotating angle of the mower by combining the number of turns and the angle with the radius of the wheel of the mower;
s4, performing Kalman filtering fusion on the distance calculated by the accelerometer and the moving distance of the mower wheel converted by the Hall element sensor, and marking the fusion result as the straight-moving distance of the mower;
s5, performing three-level Kalman filtering fusion by using data acquired by a gyroscope, the accelerometer and a magnetometer, and marking a finally obtained fusion result as a rotation angle of the mower;
and S6, obtaining the position of the mower relative to the origin after walking in unit time according to the straight-moving distance and the rotation angle of the mower.
2. The method according to claim 1, in the S5, the three-level kalman filter fusion includes:
s51, collecting angular velocity integrals of the gyroscope to obtain integral angles of the gyroscope, respectively collecting accelerations in three directions of an x axis, a y axis and a z axis by the accelerometer, and calculating the calculation angles of the accelerometer according to the accelerations in the three directions;
s52, performing first-level Kalman filtering fusion on the gyroscope integral angle and the accelerometer calculation angle to obtain a fused angle;
s53, performing secondary Kalman filtering fusion on the absolute angle acquired by the magnetometer and the fused angle to obtain a secondary fused angle;
and S54, performing three-level Kalman filtering fusion on the angle obtained by converting the Hall element sensor and the angle obtained after the two-level fusion, and marking the obtained result as the rotation angle of the mower.
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