Method for measuring positioning error of robot arm under electromagnetic navigation guidance

Abstract

The application provides a mechanical arm positioning error measurement method under electromagnetic navigation guidance, which comprises the following steps: 1, installing a positioning device at the end of the mechanical arm of an electromagnetic navigation robot controlled by an electromagnetic navigation system; the positioning device comprises a measuring ball and a position reading device, the relative pose of the two is unchanged, and the position reading device is connected with the electromagnetic navigation system; 2, placing the positioning device in the magnetic field range generated by a magnetic field generator in the electromagnetic navigation system; 3, registering the positioning device; 4, controlling the position reading device to move to the position of J1 in the magnetic field range, and recording the position information of the measuring ball at this time through a measurement system; 5, inputting incremental coordinates for at least n times in the electromagnetic navigation system, so that the position reading device moves to corresponding n points in sequence, and the measurement system records the position information of the measuring ball after each movement; and 6, calculating the positioning error of the mechanical arm. The above method has high measurement accuracy and high measurement efficiency.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of electromagnetic navigation systems, in particular to a mechanical arm positioning error measurement method under electromagnetic navigation guidance. BACKGROUND

[0002] Medical robots are increasingly widely applied, and an electromagnetic navigation system can assist doctors to complete surgeries, and positioning accuracy of the electromagnetic navigation system is an important index for ensuring safe and smooth completion of surgeries. Some devices and methods for testing positioning accuracy of electromagnetic navigation systems already exist in the prior art, for example, the device and method for testing positioning accuracy of electromagnetic navigation systems disclosed in the patent with the announcement number CN112378421B, but the method needs CT data of a precision testing device for three-dimensional model reconstruction, the testing precision is affected by machining precision of the precision testing device and shooting quality of the CT data, and the obtained measurement error is a range value, and an accurate error measurement value cannot be obtained. SUMMARY

[0003] In order to solve the problems existing in the prior art, the application provides a mechanical arm positioning error measurement method under electromagnetic navigation guidance, which has high measurement accuracy and high measurement efficiency.

[0004] In order to achieve the above-mentioned purpose, the application provides a mechanical arm positioning error measurement method under electromagnetic navigation guidance, which comprises the following steps:

[0005] Step 1, a positioning device is installed at the end of a mechanical arm of an electromagnetic navigation robot controlled by an electromagnetic navigation system; wherein the positioning device comprises a device body, a mechanical arm connecting device is arranged on the device body, the positioning device is connected to the mechanical arm of the electromagnetic navigation robot through the mechanical arm connecting device, a measurement ball and a position reading device are further arranged on the device body, the relative pose of the position reading device and the measurement ball is invariable, the position reading device is connected with an interface unit of the electromagnetic navigation system, and is used in cooperation with the electromagnetic navigation system to read position information of the positioning device; the electromagnetic navigation system comprises a host computer, a magnetic field generator, a control unit and an interface unit, the interface unit is connected with the control unit, the magnetic field generator is also connected with the control unit, and the control unit is connected with the host computer;

[0006] Step 2, the positioning device is placed in a magnetic field range generated by the magnetic field generator;

[0007] Step 3, registration of the positioning device: the coordinates of the position reading device are transmitted to the electromagnetic navigation system through a calibration algorithm;

[0008] Step 4: The electromagnetic navigation system controls the robotic arm to move the position reading device to point J1 within the magnetic field range. During the movement, the position of the position reading device remains unchanged. The measuring device in the measuring system reads the position information of the measuring ball at this time, and the measuring system records this position information as the position information of point J, denoted by x. j y j z j express;

[0009] Step 5: Input incremental coordinates at least n times into the electromagnetic navigation system, where n ≥ 4 and n is an even number, to control the robotic arm to move the position reading device sequentially to the corresponding n points within the magnetic field range. During the movement, keep the position of the position reading device unchanged. The n points form n / 2 line segments, and the intersection of any two line segments is point J1. The distance from point J1 to each of the n points is equal. After each movement, read the position information of the measuring ball through the measuring device in the measuring system. The measuring system records this position information and uses x... i y i z i express;

[0010] Step 6: Calculate the positioning error m of the robotic arm using the formula. i : Where, x j y j z j The location information recorded by the measurement system described in step 4. The coordinates of the cluster center are obtained from the n location information recorded by the measurement system in step 5, where, In the formula x i y i z i The corresponding location information recorded by the measurement system described in step 5.

[0011] In some embodiments, in step 4, the J1 point is located at the center of the magnetic field range.

[0012] In some embodiments, in step 5, when the magnetic field generated by the magnetic field generator is a square magnetic field, the eight vertices and the center point of the square magnetic field are selected as the target points to be reached by the position reading device; when the magnetic field generated by the magnetic field generator is a spherical magnetic field, the center of the spherical magnetic field and at least two pairs of points on the surface of the spherical magnetic field are selected as the target points to be reached by the position reading device, wherein two points corresponding to a diameter are recorded as a pair of points.

[0013] In some embodiments, in steps 4 and 5, the robotic arm is controlled to move the position reading device, and during the movement, the position of the position reading device is kept constant. The specific steps are as follows:

[0014] Step 101: The host computer receives the status information transmitted by the robotic arm. The status information includes the current pose information of the robotic arm. The current pose information of the robotic arm is converted into a 4*4 matrix as the first pose transformation matrix from the robotic arm to the position reading device. B = Trans(E,B)*E, where B represents the coordinate system of the position reading device, E represents the coordinate system of the robotic arm, and Trans(E,B) represents the first pose transformation matrix.

[0015] Step 102: The host computer obtains the second pose transformation matrix of the position reading device in the coordinate system of the magnetic field generator from the control unit, N = Trans(B,N)*B, where B represents the coordinate system of the position reading device, N represents the coordinate system of the magnetic field generator, and Trans(B,N) represents the second pose transformation matrix; the coordinates of the position reading device in the coordinate system of the magnetic field generator are obtained through the second pose transformation matrix as the current position coordinates, where the current position refers to the current position of the position reading device;

[0016] Step 103: Convert the vector from the current position to the target position into a 4*4 translation matrix, where the target position is the position to which the position reading device will move; the target position coordinates are the coordinates in the magnetic field generator coordinate system. The coordinates in the corresponding position reading device coordinate system are obtained by transforming the second pose transformation matrix Trans(B,N), and then the coordinates in the corresponding robotic arm coordinate system are obtained by transforming the first pose transformation matrix Trans(E,B). Control the robotic arm to move to the corresponding position so that the position reading device moves to the target position.

[0017] In some embodiments, the method further includes step 104: after the location reading device has moved, the current position of the location reading device is obtained again and compared with the preset target position to determine whether the location reading device has moved into place; if not, steps 101 to 103 are repeated.

[0018] The beneficial effect of this solution is that the above-mentioned method for measuring the positioning error of a robotic arm under electromagnetic navigation guidance has the advantages of high measurement accuracy and high measurement efficiency, and can effectively detect the positioning accuracy of the electromagnetic navigation system. Attached Figure Description

[0019] Fig. 1 A schematic diagram of the positioning error measurement device for a robotic arm under electromagnetic navigation guidance is shown in the embodiment.

[0020] Fig. 2A schematic diagram of the positioning device in the embodiment is shown.

[0021] Fig. 3 A schematic diagram of the measurement process in the embodiment is shown.

[0022] Reference numerals: 100-positioning device, 200-electromagnetic navigation system, 300-measurement system, 101-measuring ball, 102-position reading device, 103-robotic arm connection device, 201-magnetic field generator, 202-control unit, 203-interface unit, 301-measuring device. Detailed Implementation

[0023] The specific embodiments of this application will be further described below with reference to the accompanying drawings.

[0024] In the description of this application, it should be understood that the terms "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0025] The method for measuring the positioning error of a robotic arm under electromagnetic navigation guidance involved in this application includes the following steps:

[0026] Step 1: Install the positioning device 100 at the end of the robotic arm of the electromagnetic navigation robot controlled by the electromagnetic navigation system 200, wherein, for example... Figs. 1-2 As shown, the positioning device 100 includes a device body, on which a robotic arm connecting device 103 is provided. The positioning device 100 is connected to the robotic arm of an electromagnetic navigation robot via the robotic arm connecting device 103. A measuring ball 101 and a position reading device 102 are also installed on the device body. The relative pose of the position reading device 102 and the measuring ball 101 remains unchanged. The position reading device 102 is connected to the interface unit 203 of the electromagnetic navigation system 200 and is used in conjunction with the electromagnetic navigation system 200 to read the position information of the positioning device 100. Specifically, the position reading device 102 adopts a position reading device for use with an electromagnetic navigation system disclosed in patent number 2020227007236. The electromagnetic navigation system 200 includes a host computer, a magnetic field generator 201, a control unit 202, and an interface unit 203. The interface unit 203 is connected to the control unit 202, and the magnetic field generator 201 is also connected to the control unit 202. The control unit 202 is connected to the host computer. The electromagnetic navigation system 200 is a known system in the prior art and will not be described in more detail here.

[0027] Step 2: Place the positioning device 100 within the magnetic field range generated by the magnetic field generator 201.

[0028] Step 3: Registration of the positioning device 100: The coordinates of the location reading device 102 are transmitted to the electromagnetic navigation system 200 through a calibration algorithm.

[0029] Step 4: The electromagnetic navigation system 200 controls the robotic arm to move the position reading device 102 to point J1 within the magnetic field range. Ideally, point J1 should be located at the center of the magnetic field range. During the movement, the position of the position reading device 102 is kept constant, i.e., its relative direction and angle with the measuring ball 101 remain unchanged. Therefore, the measurement error of the measuring ball 101 is the measurement error of the position reading device 102. The measuring device 301 in the measuring system 300 reads the position information of the measuring ball 101 at this time. The measuring system 300 records this position information as the position information of point J, denoted by x. j y j z j In this embodiment, the measurement system 300 may employ the Polaris Vega Position Sensor optical measurement product from Northern Digital Inc.

[0030] Step 5: Input incremental coordinates at least n times into the electromagnetic navigation system 200, where n ≥ 4 and n is an even number, to control the robotic arm to move the position reading device 102 sequentially to the corresponding n points within the magnetic field range. During the movement, keep the position of the position reading device 102 unchanged. The n points form n / 2 line segments, and the intersection of any two line segments is point J1. The distance from point J1 to each of the n points is equal. After each movement, the position information of the measuring ball 101 is read by the measuring device 301 in the measuring system 300. The measuring system 300 records this position information and uses x... i y i z i Indicates, such as Fig. 3 As shown.

[0031] Specifically, in this step, when the magnetic field generated by the magnetic field generator 201 is a square magnetic field, the eight vertices and the center point of the square magnetic field are selected as the target points to be reached by the position reading device 102. When the magnetic field generated by the magnetic field generator 201 is a spherical magnetic field, the center of the spherical magnetic field and at least two pairs of points on the surface of the sphere (that is, four points corresponding to the two diameters) are selected as the target points to be reached by the position reading device 102.

[0032] Step 6: Calculate the positioning error m of the robotic arm using the formula. i The positioning error of the robotic arm is also the positioning error of the electromagnetic navigation system. Where, x j y j z j The location information recorded by the measurement system 300 in step 4. The location coordinates of the cluster center are obtained from the n location information recorded by the measurement system 300 in step 5. Specifically, In the formula x i y i z i The corresponding location information recorded by the measurement system 300 in step 5.

[0033] In this embodiment, in steps 4 and 5, the robotic arm is controlled to move the position reading device 102, and during the movement, the position of the position reading device 102 is kept unchanged. The specific steps are as follows:

[0034] Step 101: The host computer receives the status information transmitted by the robotic arm. The status information includes the current pose information of the robotic arm. The current pose information of the robotic arm is converted into a 4*4 matrix as the first pose transformation matrix from the robotic arm to the position reading device, B = Trans(E,B)*E, where B represents the coordinate system of the position reading device, E represents the coordinate system of the robotic arm, and Trans(E,B) represents the first pose transformation matrix.

[0035] Step 102: The host computer obtains the second pose transformation matrix of the position reading device 102 in the magnetic field generator coordinate system from the control unit 202, N = Trans(B,N)*B, where B represents the position reading device coordinate system, N represents the magnetic field generator coordinate system, and Trans(B,N) represents the second pose transformation matrix; the coordinates of the position reading device 102 in the magnetic field generator coordinate system obtained by the second pose transformation matrix are used as the current position coordinates, where the current position refers to the current position of the position reading device 102.

[0036] Step 103: Convert the vector from the current position to the target position into a 4*4 translation matrix, where the target position is the position that the position reading device 102 will move to; the target position coordinates are the coordinates in the magnetic field generator coordinate system, which are converted to the corresponding coordinates in the position reading device coordinate system by the second pose transformation matrix Trans(B,N), and then converted to the corresponding coordinates in the robotic arm coordinate system by the first pose transformation matrix Trans(E,B), and the robotic arm is controlled to move to the corresponding position, so that the position reading device 102 moves to the target position.

[0037] Step 104: After the position reading device 102 has finished moving, obtain the current position of the position reading device 102 again and compare it with the preset target position to determine whether the position reading device 102 has moved into place; if not, repeat steps 101 to 103. An upper limit for the number of cycles can also be set to avoid situations where the robotic arm cannot fully meet the movement requirements in certain poses due to joint rotation limitations.

[0038] In this application, the measurement range needs to cover the largest possible magnetic field range. Throughout the measurement process, because the electromagnetic navigation system 200 needs to track the position reading device 102 and adjust its position in real time, the position reading device 102 needs to remain within the magnetic field range generated by the magnetic field generator 201. When the position reading device 102 reaches each target point driven by the robotic arm, the measuring ball 101 needs to be within the measurement field of view of the measuring device 301.

[0039] The positioning error measurement method for robotic arms guided by electromagnetic navigation involved in this application has the advantages of high measurement accuracy and high measurement efficiency, and can effectively detect the positioning accuracy of electromagnetic navigation systems.

[0040] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in this application, based on the technical solution and concept of this application, should be included within the scope of protection of this application.

Claims

1. A method for measuring the positioning error of a robotic arm under electromagnetic navigation guidance, characterized in that: Includes the following steps: Step 1: Install the positioning device at the end of the robotic arm of the electromagnetic navigation robot controlled by the electromagnetic navigation system. The positioning device includes a device body with a robotic arm connection device. The positioning device is connected to the robotic arm of the electromagnetic navigation robot via the robotic arm connection device. A measuring ball and a position reading device are also installed on the device body. The relative position of the position reading device and the measuring ball remains unchanged. The position reading device is connected to the interface unit of the electromagnetic navigation system for use in conjunction with the electromagnetic navigation system to read the position information of the positioning device. The electromagnetic navigation system includes a host computer, a magnetic field generator, a control unit, and an interface unit. The interface unit is connected to the control unit, the magnetic field generator is also connected to the control unit, and the control unit is connected to the host computer. Step 2: Place the positioning device within the magnetic field range generated by the magnetic field generator; Step 3, Registration of the positioning device: The coordinates of the location reading device are transmitted to the electromagnetic navigation system through a calibration algorithm; Step 4: The electromagnetic navigation system controls the robotic arm to move the position reading device to point J1 within the magnetic field range. During the movement, the position of the position reading device remains unchanged. The measuring device in the measuring system reads the position information of the measuring ball at this time, and the measuring system records this position information as the position information of point J, denoted by x. j y j z j express; Step 5: Input incremental coordinates at least n times into the electromagnetic navigation system, where n ≥ 4 and n is an even number, to control the robotic arm to move the position reading device sequentially to the corresponding n points within the magnetic field range. During the movement, keep the position of the position reading device unchanged. The n points form n / 2 line segments, and the intersection of any two line segments is point J1. The distance from point J1 to each of the n points is equal. After each movement, read the position information of the measuring ball through the measuring device in the measuring system. The measuring system records this position information and uses x... i y i z i express; Step 6: Calculate the positioning error m of the robotic arm using the formula. i : Where, x j y j z j The location information recorded by the measurement system described in step 4. The coordinates of the cluster center are obtained from the n location information recorded by the measurement system in step 5, where, In the formula x i y i z i The corresponding location information recorded by the measurement system described in step 5.

2. The method for measuring the positioning error of a robotic arm under electromagnetic navigation guidance according to claim 1, characterized in that: In step 4, point J1 is located at the center of the magnetic field range.

3. The method for measuring the positioning error of a robotic arm under electromagnetic navigation guidance according to claim 1, characterized in that: In step 5, when the magnetic field generated by the magnetic field generator is a square magnetic field, the eight vertices and the center point of the square magnetic field are selected as the target points to be reached by the position reading device; when the magnetic field generated by the magnetic field generator is a spherical magnetic field, the center of the spherical magnetic field and at least two pairs of points on the surface of the spherical magnetic field are selected as the target points to be reached by the position reading device, wherein two points corresponding to a diameter are recorded as a pair of points.

4. The method for measuring the positioning error of a robotic arm under electromagnetic navigation guidance according to claim 1, characterized in that: In steps 4 and 5, the robotic arm is controlled to move the position reading device, and during the movement, the position of the position reading device is kept constant. The specific steps are as follows: Step 101: The host computer receives the status information transmitted by the robotic arm. The status information includes the current pose information of the robotic arm. The current pose information of the robotic arm is converted into a 4*4 matrix as the first pose transformation matrix from the robotic arm to the position reading device. B = Trans(E,B)*E, where B represents the coordinate system of the position reading device, E represents the coordinate system of the robotic arm, and Trans(E,B) represents the first pose transformation matrix. Step 102: The host computer obtains the second pose transformation matrix of the position reading device in the coordinate system of the magnetic field generator from the control unit, N = Trans(B,N)*B, where B represents the coordinate system of the position reading device, N represents the coordinate system of the magnetic field generator, and Trans(B,N) represents the second pose transformation matrix; the coordinates of the position reading device in the coordinate system of the magnetic field generator are obtained through the second pose transformation matrix as the current position coordinates, where the current position refers to the current position of the position reading device; Step 103: Convert the vector from the current position to the target position into a 4*4 translation matrix, where the target position is the position to which the position reading device will move; the target position coordinates are the coordinates in the magnetic field generator coordinate system. The coordinates in the corresponding position reading device coordinate system are obtained by transforming the second pose transformation matrix Trans(B,N), and then the coordinates in the corresponding robotic arm coordinate system are obtained by transforming the first pose transformation matrix Trans(E,B). Control the robotic arm to move to the corresponding position so that the position reading device moves to the target position.

5. The method for measuring the positioning error of a robotic arm under electromagnetic navigation guidance according to claim 4, characterized in that: It also includes step 104: after the position reading device has moved, obtain the current position of the position reading device again, compare it with the preset target position, and determine whether the position reading device has moved into place; if not, repeat steps 101 to 103.

Images