A positioning method and system based on an accelerometer sensor

Abstract

This invention discloses a positioning method and system based on accelerometer sensors. The method includes: S1, installing two accelerometer sensors at different positions on the vehicle body of a mobile robot, and obtaining two homogeneous position coordinates of the two accelerometer sensors in the vehicle coordinate system; S2, obtaining two homogeneous position coordinates of the two accelerometer sensors in the global coordinate system based on these two homogeneous position coordinates and the displacement of the two accelerometer sensors at their respective positions; S3, obtaining the pose of the mobile robot in the global coordinate system based on the coordinate transformation relationship between the two homogeneous position coordinates in the vehicle coordinate system and their corresponding two homogeneous position coordinates in the global coordinate system. This invention solves for the current pose of the mobile robot using two accelerometer sensors, serving as an auxiliary positioning method to traditional positioning methods, thereby improving the accuracy and reliability of local robot positioning.

Description

Technical Field

[0001] This invention relates to the field of robot positioning, and more specifically to a positioning method and system based on an acceleration sensor. Background Technology

[0002] With the increasing demand for robotic applications, more and more sensors are being installed on robots to perform various tasks. For robot localization, commonly used sensors include LiDAR, wheeled odometry, cameras, and inertial measurement units (IMUs). Based on the content they perceive, airborne sensors can be divided into two categories: those sensing the external environment and those sensing the robot's own motion. Sensors sensing the external environment, such as LiDAR and cameras, estimate the robot's relative motion and position within the environment by matching observations at different times. Sensors sensing the robot's own motion, such as odometry and IMUs, directly calculate the robot's position using observed values. Both types of sensors can be used independently for robot localization.

[0003] When a robot operates in a complex environment or performs a complex task, single-sensor-based localization systems often fail to function properly in certain scenarios due to limitations in sensor characteristics, observation errors, and the influence of the external environment. The localization results may contain significant errors or even fail entirely. For example, a localization algorithm based on a single 2D LiDAR may fail to accurately locate the robot in areas with high similarity, such as long corridors. A visual localization algorithm based on a single camera may fail to provide accurate and stable pose estimation when the robot is moving rapidly or when the texture information of the environment is not readily apparent. Furthermore, odometry contains measurement errors, the robot's speed may not remain constant over time, and factors such as uneven or slippery surfaces can cause excessive and cumulative localization errors. Therefore, odometry-based trajectory estimation localization methods are unsuitable for long-term, long-distance localization of mobile robots. To achieve higher localization accuracy, it is necessary to use data from other sensors to correct for accumulated errors.

[0004] Therefore, a new indoor positioning and navigation solution is needed to address the problem that existing sensor-based positioning systems have large errors or even fail. Summary of the Invention

[0005] The main objective of this invention is to provide a positioning method based on an acceleration sensor, thereby overcoming the shortcomings of the prior art.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: a positioning method based on an accelerometer, comprising:

[0007] S1, Install the first accelerometer and the second accelerometer at different positions on the mobile robot body, and obtain the first homogeneous position coordinates and the second homogeneous position coordinates of the two accelerometers in the vehicle coordinate system respectively;

[0008] S2, based on the first homogeneous position coordinates and the second homogeneous position coordinates, and the displacement of the two accelerometers at their respective corresponding positions, the third homogeneous position coordinates and the fourth homogeneous position coordinates of the two accelerometers in the global coordinate system are obtained.

[0009] S3. Based on the coordinate transformation relationship between the first homogeneous position coordinates and the corresponding third homogeneous position coordinates, and the coordinate transformation relationship between the second homogeneous position coordinates and the corresponding fourth homogeneous position coordinates, the pose of the mobile robot in the global coordinate system is obtained.

[0010] In a preferred embodiment, in step S2, the displacement of the two acceleration sensors is obtained by integrating the initial acceleration data obtained from the two acceleration sensors twice.

[0011] In a preferred embodiment, the two displacement quantities of the two accelerometers are respectively represented as (Δx1, Δy1). T and (Δx2, Δy2) T The following formula is used to obtain:

[0012]

[0013]

[0014]

[0015]

[0016]

[0017]

[0018]

[0019]

[0020] Where, Δx i，j Δy i，j These represent the displacement increments along the x and y axes corresponding to the j-th sampling of the accelerometer sensor j; v xi，j v yi，j These represent the velocity increments along the x and y axes corresponding to the j-th sampling of accelerometer sensor i; a xi，j ayi，j , i and j are the acceleration increments of the x and y axes corresponding to the j-th sampling of the accelerometer sensor i, respectively, where i = 1, 2, j = 1, 2, 3...n+1, n is a natural number greater than or equal to 1, and f is the sampling frequency.

[0021] In a preferred embodiment, the first homogeneous position coordinates are represented as P. old1 =(x old1 , t old1 ,1) T The second homogeneous position coordinates are represented as P. old2 =(x old2 , t old2 ,1) T The third homogeneous position coordinates are represented as P. new1 =(x new1 , t new1 ,1) T The fourth homogeneous position coordinates are represented as P. new2 =x new2 , t new2 ,1) T The coordinates of the third homogeneous position and the fourth homogeneous position are obtained by the following formula:

[0022] x new1 =x old1 +Δx1

[0023] t new1 =t old1 +Δy1

[0024] x new2 =x old2 +Δx2

[0025] t new2 =t old2 +Δt2.

[0026] In a preferred embodiment, in step S3, the coordinate transformation relationship is a transformation matrix T between the vehicle coordinate system and the global coordinate system, and the transformation matrix T is expressed as:

[0027]

[0028] Where Δx is the change in position of the geometric center point of the mobile robot in the x-axis direction of the global coordinate system within the time interval Δt; Δy is the change in position of the geometric center point of the mobile robot in the y-axis direction of the global coordinate system within the time interval Δt; and Δφ is the change in attitude angle of the mobile robot after the time interval Δt.

[0029] In a preferred embodiment, based on the coordinate transformation relationship, three equations containing vehicle pose parameters are obtained, specifically:

[0030] TP old1 =P new1

[0031] TP old2 =P new2

[0032] T(P old1 ×P old2 ) = P new1 ×P new2 .

[0033] In a preferred embodiment, in step S1, the first acceleration sensor and the second acceleration sensor are respectively installed at diagonal positions on the vehicle body that are symmetrical about the center point of the vehicle body, i.e., x old1 =-x old2 , t old11 =-t old2 .

[0034] In a preferred embodiment, the simplified pose parameter solution is:

[0035]

[0036] In a preferred embodiment, the pose of the mobile robot in the global coordinate system is:

[0037] x new =x old +Δx

[0038] t new =t old +Δy

[0039]

[0040] On the other hand, the present invention also discloses a positioning system based on an acceleration sensor, the system comprising:

[0041] The first accelerometer and the second accelerometer are respectively installed at different positions on the mobile robot body to obtain the first homogeneous position coordinates and the second homogeneous position coordinates of the two accelerometers in the vehicle coordinate system.

[0042] The processor is configured to obtain the third and fourth homogeneous position coordinates of the two accelerometers in the global coordinate system based on the first homogeneous position coordinates and the second homogeneous position coordinates, as well as the displacement of the two accelerometers at their respective corresponding positions; and to obtain the pose of the mobile robot in the global coordinate system based on the coordinate transformation relationship between the first homogeneous position coordinates and the corresponding third homogeneous position coordinates, and the coordinate transformation relationship between the second homogeneous position coordinates and the corresponding fourth homogeneous position coordinates.

[0043] Compared with the prior art, the beneficial effects of the present invention are at least as follows:

[0044] This invention solves the problem of difficult positioning when traditional robot positioning methods are limited, while maintaining low cost. It acquires two-axis acceleration information by using two accelerometers, establishes homogeneous coordinates of the two accelerometers in the vehicle coordinate system and the global coordinate system, and solves the current pose of the mobile robot based on the homogeneous coordinate transformation relationship, thus realizing the indoor local positioning of the mobile robot. As an auxiliary positioning method for traditional positioning methods, it improves the accuracy and reliability of robot local positioning. Attached Figure Description

[0045] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0046] Figure 1 This is a flowchart illustrating a positioning method based on an accelerometer according to the present invention.

[0047] Figure 2 This is a block diagram of a positioning system based on an acceleration sensor according to the present invention. Detailed Implementation

[0048] The invention will be more fully understood through the following detailed description, which should be read in conjunction with the accompanying drawings. Detailed embodiments of the invention are disclosed herein; however, it should be understood that the disclosed embodiments are merely exemplary of the invention, which may be embodied in various forms. Therefore, the specific functional details disclosed herein should not be construed as limiting, but rather as the basis for the claims and as intended to teach those skilled in the art to employ the representative basis of the invention in different ways in any suitable detailed embodiment.

[0049] The present invention discloses a positioning method and system based on accelerometers, which solves the current pose of a mobile robot by using two accelerometers as an auxiliary positioning method to improve the accuracy and reliability of local positioning of the robot.

[0050] Combination Figure 1 As shown in the embodiments of the present invention, a positioning method based on an accelerometer specifically includes the following steps:

[0051] S1, a first accelerometer and a second accelerometer are installed at different positions on the mobile robot body, and the first homogeneous position coordinates and the second homogeneous position coordinates of the two accelerometers in the vehicle coordinate system are obtained respectively.

[0052] Specifically, two accelerometer sensors, sensor1 and sensor2, are installed at different locations on the mobile robot's body. For example, accelerometer sensor1 is installed at position 1 on the mobile robot's body, and accelerometer sensor2 is installed at position 2. Based on the geometric positions of the accelerometer sensors, homogeneous coordinates of the two accelerometer sensors in the vehicle's coordinate system are established. Thus, the first and second homogeneous position coordinates of accelerometer sensors 1 and 2 in the vehicle's coordinate system are respectively expressed as: P old1 =(x old1 , t old1 ,1) T P old2 =(x old2 , t old2 ,1) T In this embodiment, the two accelerometers are biaxial or multiaxial linear accelerometers. The accelerometers are primarily used to acquire biaxial linear acceleration data from sensors 1 and 2 over a certain time interval. and Among them, a x1 and a y1 The x-axis and y-axis initial linear acceleration data acquired by acceleration sensor sensor1 are respectively; a x2 and a y2 These are the initial linear acceleration data along the x-axis and y-axis obtained by the accelerometer sensor2, respectively.

[0053] S2. Based on the first homogeneous position coordinates and the second homogeneous position coordinates, as well as the displacement of the two accelerometers at their respective corresponding positions, the third homogeneous position coordinates and the fourth homogeneous position coordinates of the two accelerometers in the global coordinate system are obtained.

[0054] Specifically, after time Δt, since the accelerometers still transmit non-zero data when they are stationary, the initial acceleration data obtained by the two accelerometers needs to be filtered to eliminate noise. Then, by integrating the acceleration data twice, the displacements of the two accelerometers are obtained, which are represented as (Δx1, Δy1) respectively. T and (Δx2, Δy2) T .

[0055] As an optional implementation, to minimize the error caused by the integration of the accelerometer over time, the displacement is obtained by integrating the two accelerometers twice using the following formula:

[0056]

[0057]

[0058]

[0059]

[0060]

[0061]

[0062]

[0063]

[0064] Where, Δx i，j Δy i，j These represent the x and y axis displacement increments corresponding to the j-th sampling of accelerometer sensor i; v xi，j v yi，j These represent the velocity increments along the x and y axes corresponding to the j-th sampling of accelerometer sensor i; a xi，j a yi，j Let Δx and y be the acceleration increments of the x and y axes respectively at the j-th sampling of accelerometer sensor i, where i = 1, 2, j = 1, 2, 3...n+1, n is a natural number greater than or equal to 1, and f is the sampling frequency. In other words, Δx 1，n+1 Δy 1，n+1 Let Δx be the displacement increment along the x and y axes corresponding to the (n+1)th sampling of the accelerometer sensor sensor1. 1，n v y1，n Let v be the displacement increments along the x and y axes corresponding to the nth sampling of the accelerometer sensor sensor1. x1，n+1 , Δt 1，n+1v represents the velocity increments along the x and y axes corresponding to the (n+1)th sampling of the accelerometer sensor 1. x1，n v y1，n Let v be the velocity increments along the x and y axes corresponding to the nth sampling of accelerometer sensor1. x1，n-1 v y1，n-1 Let a be the velocity increments along the x and y axes corresponding to the (n-1)th sampling of the accelerometer sensor 1. x1，n a y1，n Let a be the x and y axis acceleration increments corresponding to the nth sampling of accelerometer sensor1. x1，n-1 a y1，n-1 This represents the x and y axis acceleration increments corresponding to the (n-1)th sampling of the accelerometer sensor 1. Similarly, Δx 2，n+1 Δy 2，n+1 Let Δx be the displacement increment along the x and y axes corresponding to the (n+1)th sampling of the accelerometer sensor sensor2. 2，n Δy 2，n Let v be the displacement increments along the x and y axes corresponding to the nth sampling of the accelerometer sensor sensor2. x2，n+1 v y2，n+1 v represents the velocity increments along the x and y axes corresponding to the (n+1)th sampling of the accelerometer sensor2. x2，n v y2，n Let v be the velocity increments along the x and y axes corresponding to the nth sampling of the accelerometer sensor sensor2. x2，n-1 v y2，n-1 Let a be the velocity increments along the x and y axes corresponding to the (n-1)th sampling of the accelerometer sensor 2. x2，n a y2，n Let a be the acceleration increments along the x and y axes corresponding to the nth sampling of the accelerometer sensor sensor2. x2，n-1 a y2，n-1 This represents the acceleration increments along the x and y axes corresponding to the (n-1)th sampling of the accelerometer sensor sensor2.

[0065] The third homogeneous position coordinate is represented as P. new1 =(x new1 , t new1 ,1) T The fourth homogeneous position coordinates are represented as P. new2 =(x new2 , t new2 ,1) T The coordinates of the third homogeneous position and the fourth homogeneous position are obtained by the following formula:

[0066] x new1 =x old1+Δx x

[0067] t new1 =t old1 +Δy1

[0068] x new2 =x old2 +Δx2

[0069] t new2 =t old2 +Δy2.

[0070] S3. Based on the coordinate transformation relationship between the first homogeneous position coordinates and the corresponding third homogeneous position coordinates, and the coordinate transformation relationship between the second homogeneous position coordinates and the corresponding fourth homogeneous position coordinates, the pose of the mobile robot in the global coordinate system is obtained.

[0071] Specifically, based on the coordinate transformation relationship, three equations containing the vehicle body pose parameters can be listed, which can be expressed as follows:

[0072] TP old1 =P new1

[0073] TP old2 =P new2

[0074] T(P old1 ×P old2 ) = P new1 ×P new2 .

[0075] Where T is the transformation matrix describing the mobile robot's body coordinates and global coordinates, and this transformation matrix T is expressed as:

[0076]

[0077] Where Δx is the change in position of the geometric center point of the mobile robot in the x-axis direction of the global coordinate system within the time interval Δt; Δy is the change in position of the geometric center point of the mobile robot in the y-axis direction of the global coordinate system within the time interval Δt; and Δφ is the change in attitude angle of the mobile robot after the time interval Δt.

[0078] In one specific embodiment, matrix T can be obtained by matrix inversion:

[0079] T = [P] new1 P new2 P new1 ×P new2 ][P old1 P old2 P old1×P old2 ] -1 .

[0080] The specific pose parameters can be obtained by matching the corresponding matrix elements, which means that the pose changes of the mobile robot before and after the time interval Δt [Δx Δy Δφ] can be solved.

[0081] As an optional installation method, the two acceleration sensors can be installed diagonally across the vehicle body, i.e., centrally symmetrical about the vehicle's geometric center. Then u = x old1 =-x old2 v = t old1 =-t old2 Therefore, the simplified pose parameter solution can be obtained:

[0082]

[0083] The pose of the mobile robot in the global coordinate system is:

[0084] x new =x old +Δx

[0085] t new =t old +Δy

[0086]

[0087] in, This represents the initial attitude angle of the mobile robot in the global coordinate system. This represents the robot's attitude angle in the global coordinate system after a time interval Δt. Similar to Δφ mentioned above, it represents the change in the attitude angle of the mobile robot after a time interval Δt.

[0088] Through the above technical solution, the present invention can solve the current pose of a mobile robot using two accelerometers, serving as an auxiliary positioning method for traditional positioning methods.

[0089] Combination Figure 2As shown, the present invention discloses a positioning system based on an accelerometer sensor, comprising: a first accelerometer sensor, a second accelerometer sensor, and a processor. The first and second accelerometer sensors are respectively installed at different positions on the vehicle body of a mobile robot, used to obtain the first homogeneous position coordinates and the second homogeneous position coordinates of the two accelerometer sensors in the vehicle coordinate system, respectively. The processor is used to obtain the third and fourth homogeneous position coordinates of the two accelerometer sensors in the global coordinate system based on the first and second homogeneous position coordinates and the displacement of the two accelerometer sensors at their respective corresponding positions. Furthermore, the processor is used to obtain the pose of the mobile robot in the global coordinate system based on the coordinate transformation relationship between the first homogeneous position coordinates and their corresponding third homogeneous position coordinates, and the coordinate transformation relationship between the second homogeneous position coordinates and their corresponding fourth homogeneous position coordinates. The specific principles of the first accelerometer sensor, the second accelerometer sensor, and the processor are described above and will not be repeated here.

[0090] This invention solves the problem of difficult positioning when traditional robot positioning methods are limited, while maintaining low cost. It acquires two-axis acceleration information by using two accelerometers, establishes homogeneous coordinates of the two accelerometers in the vehicle coordinate system and the global coordinate system, and solves the current pose of the mobile robot based on the homogeneous coordinate transformation relationship, thus realizing the indoor local positioning of the mobile robot. As an auxiliary positioning method for traditional positioning methods, it improves the accuracy and reliability of robot local positioning.

[0091] All aspects, embodiments, features, and examples of this invention are to be regarded as illustrative in all respects and are not intended to limit the invention, the scope of which is defined only by the claims. Other embodiments, modifications, and uses will become apparent to those skilled in the art without departing from the spirit and scope of the invention as claimed.

Claims

1. A positioning method based on an accelerometer, characterized in that, The method includes: S1, Install the first accelerometer and the second accelerometer at different positions on the mobile robot body, and obtain the first homogeneous position coordinates and the second homogeneous position coordinates of the two accelerometers in the vehicle coordinate system respectively; S2, based on the first homogeneous position coordinates and the second homogeneous position coordinates, as well as the displacement of the two accelerometers at their respective corresponding positions, the third homogeneous position coordinates and the fourth homogeneous position coordinates of the two accelerometers in the global coordinate system are obtained. S3. Based on the coordinate transformation relationship between the first homogeneous position coordinates and the corresponding third homogeneous position coordinates, and the coordinate transformation relationship between the second homogeneous position coordinates and the corresponding fourth homogeneous position coordinates, the pose of the mobile robot in the global coordinate system is obtained. In step S2, the displacement of the two acceleration sensors is obtained by integrating the initial acceleration data obtained from the two acceleration sensors twice. The two displacements of the two accelerometers are respectively expressed as and The following formula is used to obtain: ； ； ； ； ； ； ； ； in, , Accelerometers No. The corresponding sampling time Two-axis displacement increments; , Accelerometers No. The corresponding sampling time Two-axis speed increment; , Accelerometers No. The corresponding sampling time Two-axis velocity increment; where i=1,2, j=1,2,3……n+1, n is a natural number greater than or equal to 1, and f is the sampling frequency; The first homogeneous position coordinates are represented as The second homogeneous position coordinates are represented as The third homogeneous position coordinates are represented as The fourth homogeneous position coordinates are represented as The coordinates of the third homogeneous position and the fourth homogeneous position are obtained by the following formula: ， ， ， ， The pose change parameters of the mobile robot are: ； Where, u= v= ; The pose of the mobile robot in the global coordinate system is: ； ； ； in, This represents the initial attitude angle of the mobile robot in the global coordinate system. Indicates the robot passed by The attitude angle in the global coordinate system after time.

2. The positioning method based on an accelerometer according to claim 1, characterized in that, In S3, the coordinate transformation relationship is the transformation matrix T between the vehicle coordinate system and the global coordinate system, and the transformation matrix T is expressed as: ； in, The geometric center point of the mobile robot at the time interval The change in position along the x-axis of the global coordinate system; The geometric center point of the mobile robot at the time interval The change in position along the y-axis in the global coordinate system; For mobile robots after a time interval Then, the change in attitude angle.

3. The positioning method based on an accelerometer according to claim 2, characterized in that, Based on the coordinate transformation relationship, three equations containing vehicle pose parameters are obtained, specifically: ； ； 。 4. The positioning method based on an accelerometer according to claim 1, characterized in that, In step S1, the first acceleration sensor and the second acceleration sensor are respectively installed at diagonal positions on the vehicle body that are symmetrical about the center point of the vehicle body. =- , =- .

5. A positioning system based on an accelerometer sensor according to the positioning method based on an accelerometer sensor as described in any one of claims 1 to 4, characterized in that, The system includes: The first accelerometer and the second accelerometer are respectively installed at different positions on the mobile robot body to obtain the first homogeneous position coordinates and the second homogeneous position coordinates of the two accelerometers in the vehicle coordinate system. The processor is configured to obtain the third and fourth homogeneous position coordinates of the two accelerometers in the global coordinate system based on the first homogeneous position coordinates and the second homogeneous position coordinates, as well as the displacement of the two accelerometers at their respective corresponding positions; and to obtain the pose of the mobile robot in the global coordinate system based on the coordinate transformation relationship between the first homogeneous position coordinates and the corresponding third homogeneous position coordinates, and the coordinate transformation relationship between the second homogeneous position coordinates and the corresponding fourth homogeneous position coordinates.

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