A monitoring system and method for a single free tracking ball

Abstract

The present invention discloses a single free tracking ball monitoring system and method. The system includes: a locator, which is installed and fixed at the lesion site of a patient; a free tracking ball, which is installed on the body surface of the patient; an optical positioning and tracking device, which is used to obtain the position information of the locator and the free tracking ball; a processor, which is communicatively connected to the optical positioning and tracking device and is used to process the position information sent by the optical positioning and tracking device and generate a processing result; and a display, which is communicatively connected to the processor and is used to visually display the processing result. The present invention realizes real-time monitoring of the position of the locator and the patient before and during the operation, ensuring that when the positions of the two change before and during the operation, or other situations that affect the operation and registration accuracy occur, the doctor can be informed in time and re-navigation registration can be carried out to ensure the normal implementation of the operation.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and particularly relates to a monitoring system and method for a single free tracking ball. Background Art

[0002] In orthopedic AR navigation surgery, the registration accuracy is particularly important. Therefore, a relatively static state needs to be maintained between the locator and the patient before and during the operation to ensure the accuracy of navigation registration. Currently, after preoperative registration in navigation surgery technology, the doctor starts the operation according to the registered results. However, during the operation, situations such as the offset or occlusion of the locator, NDI (optical positioning and tracking device 300), and the patient's position may occur. At this time, the positions of the locator and the patient have changed, which will reduce the positioning accuracy of the navigation surgery system, and in severe cases, may cause the navigation surgery system to malfunction, directly affecting the doctor's implementation of the operation. Summary of the Invention

[0003] The present invention aims to overcome the above defects and aims to provide a monitoring system and method for a single free tracking ball, which can monitor the positions of the locator and the patient in real time before and during the operation to achieve precise position tracking.

[0004] To achieve the above object, the present invention adopts the following technical solutions:

[0005] The present invention provides a monitoring system for a single free tracking ball, which is characterized by including: a locator installed and fixed on the lesion site of the patient; a free tracking ball installed on the patient's body surface; an optical positioning and tracking device for obtaining the position information of the locator and the free tracking ball; a processor communicatively connected to the optical positioning and tracking device for processing the position information sent by the optical positioning and tracking device and generating a processing result; and a display communicatively connected to the processor for visually displaying the processing result.

[0006] Further, in the monitoring system for a single free tracking ball provided by the present invention, it may further have the following characteristics: wherein, the locator includes a fixing device, a connecting mechanism, a positioning frame, and an infrared reflective ball; the fixing device has a toothed clamp, and a locking knob is provided on the toothed clamp; the lower end of the connecting mechanism is connected to the fixing device, and the positioning frame is installed on the upper end of the connecting mechanism; an installation position is provided on the positioning frame, and the infrared reflective ball is embedded and installed in the installation position.

[0007] Further, in the monitoring system for a single free tracking ball provided by the present invention, it may further have the following characteristics: wherein, there are at least four installation positions.

[0008] Further, in the monitoring system for a single free tracking ball provided by the present invention, it may further have the following characteristics: wherein, the connecting mechanism is a multi-joint universal joint.

[0009] Further, in the monitoring system of the single free tracking ball provided by the present invention, it may also have the following features: wherein, the free tracking ball includes a passive infrared tracking ball, a connecting rod and a fixed base; an adhesive layer is provided on the bottom surface of the fixed base; the lower end of the connecting rod is connected to the fixed base; the passive infrared tracking ball is installed at the upper end of the connecting rod.

[0010] The present invention also provides a monitoring method for a single free tracking ball. This method is carried out using the above-mentioned monitoring system, and is characterized by including the following steps:

[0011] Step S1: Fix the locator at the lesion site of the patient, and fix the free tracking ball on the patient's body surface to ensure that both the infrared reflective ball and the passive infrared tracking ball are recognized by the optical positioning and tracking device. Take the position information of the recognized infrared reflective ball and passive infrared tracking ball as the first position information, and generate a first coordinate system based on the first position information and the position of the optical positioning and tracking device.

[0012] Step S2: Obtain the first position information of the locator and the free tracking ball in the first coordinate system and the quantity information of the free tracking ball in real time through the optical positioning and tracking device, and send the real-time obtained first position information and quantity information to the processor.

[0013] Step S3: Detect whether the obtained first position information and quantity information meet the predetermined monitoring conditions through the processor. When there is a situation where the predetermined monitoring conditions are not met, it is determined that the monitoring fails, and proceed to step S4; when the predetermined monitoring conditions are met, proceed to step S5.

[0014] Step S4: Send a failure instruction to the display through the processor, and prompt the reason for the failure as a reference for adjustment operations.

[0015] Step S5: Execute the single-ball monitoring algorithm through the processor to determine whether the locator and the free tracking ball maintain a relatively static state, and display the result through the display to achieve real-time monitoring of the positions of the locator and the free tracking ball.

[0016] Further, in the monitoring method for a single free tracking ball provided by the present invention, it may also have the following features: wherein, the predetermined monitoring conditions in step S3 include the following three conditions. When all three conditions are met, it is considered that the predetermined monitoring conditions are met; when any one of the conditions is not met, it is considered that the predetermined monitoring conditions are not met:

[0017] Condition 1: Monitor whether the quantity of the free tracking ball is interfered. The specific judgment rule is to judge whether the quantity of the free tracking ball is equal to 1 through the quantity information of the free tracking ball. When it is not equal to 1, it is determined that condition 1 is not met.

[0018] Condition 2: Check whether the monitoring locator and the free tracking ball are simultaneously recognized by the optical positioning and tracking device. The specific judgment rule is to determine whether the monitoring locator and the free tracking ball are simultaneously recognized by the optical positioning and tracking device by checking whether the first position information of the locator and the free tracking ball is completely received. When the first position information is missing, it is determined that Condition 2 is not met;

[0019] Condition 3: Check whether the relative positions of the monitoring locator, the free tracking ball, and the optical positioning and tracking device have changed. The specific judgment rule is to determine whether the relative positions have changed by using the first position information. When the relative positions among the locator, the free tracking ball, and the optical positioning and tracking device change, it is determined that Condition 3 is not met.

[0020] Furthermore, in the single free tracking ball monitoring method provided by the present invention, it may also have the following characteristics: Among them, the single ball monitoring algorithm in step S5 specifically includes the following steps:

[0021] Step S101: Accumulate the relative position information of the locator and the free tracking ball in the first coordinate system for 0 - 100 frames. During the frame accumulation process, calculate the distance value A between the locator and the free tracking ball in each frame. At the same time, calculate the difference between the distance values of every two adjacent frames, and compare the obtained difference between the distance values with the first preset error range in the processor;

[0022] When the difference between the distance values > the upper limit of the first preset error range, the single ball monitoring algorithm terminates, and a failure instruction is sent to the display through the processor to prompt the failure reason as a reference for adjustment operations;

[0023] When the difference between the distance values is within the first preset error range, it is determined that the locator and the free tracking ball have moved relatively in the first coordinate system. Then, the frame number is reset to zero and accumulated again until the difference between the distance values of every two adjacent frames during the accumulation process is < the lower limit of the first preset error range. When the accumulation reaches 100 frames, step S102 is entered;

[0024] Step S102: When the frame number accumulation reads up to 100 frames, it is determined that the locator and the free tracking ball maintain a relatively static state, and at the same time, calculate the average distance value M between 0 - 100 frames;

[0025] After completing the accumulation of the distance values between 0 - 100 frames, continue to read the position information of the locator and the free tracking ball in each frame in the first coordinate system. At the same time, calculate the distance value B between the locator and the free tracking ball in each frame, and compare the distance value B with the average distance value M to calculate the error value between the two:

[0026] Error value H = |distance value B - average distance value M|

[0027] According to the comparison result of the error value H and the second preset error range, a warning signal is generated by the processor. At the same time, the processor compares the obtained second position information with the first position information to determine the object that has undergone displacement, and finally gives a prompt through the display.

[0028] Further, in the monitoring method of the single-free tracking ball provided by the present invention, it may also have the following feature: among them, the first preset error range in step S101 is 0.2 mm - 0.4 mm.

[0029] Further, in the monitoring method of the single-free tracking ball provided by the present invention, it may also have the following feature: among them, the second preset error range in step S103 is 0.1 mm - 0.2 mm.

[0030] Functions and effects of the present invention:

[0031] The monitoring system and method of the single-free tracking ball provided by the present invention are easy to operate and accurately monitor. In this monitoring system, the positioning frame, the connecting rod mechanism, and the fixing device are bolt-connected, which is convenient for assembly and replacement, and easy to carry. The single-free tracking ball adopts an integrated design with a simple structure. The monitoring software realizes automatic monitoring, judges the positions of the locator and the patient by calculating and comparing data, and at the same time, with the cooperation of the display, realizes the reminder and visualization functions. Through the monitoring system and method of the present invention, it is possible to monitor the positions of the locator and the patient in real time before and during the operation, ensuring that when the positions of the two change before and during the operation, or other situations affecting the surgical and registration accuracy occur, the doctor can be informed in time and re-navigated for registration to ensure the normal implementation of the operation. Brief Description of the Drawings

[0032] Figure 1 is a schematic structural diagram of the monitoring system of the single-free tracking ball in an embodiment of the present invention;

[0033] Figure 2 is a schematic structural diagram of the locator in an embodiment of the present invention;

[0034] Figure 3 is a schematic structural diagram of the free tracking ball in an embodiment of the present invention. Detailed Embodiments

[0035] In order to make the technical means, creative features, achieved purposes, and effects of the present invention easy to understand, the following embodiments will specifically describe the technical solutions of the present invention in conjunction with the accompanying drawings.

[0036] <Embodiment>

[0037] As Figure 1As shown in the figure, a monitoring system for a single free tracking ball according to this embodiment includes: a locator 100, a free tracking ball 200, an optical positioning and tracking device 300, a processor 400, and a display 500. Figure 1 In the figure, the reference numeral 1 represents a patient.

[0038] The locator 100 is used to be fixedly installed on the lesion site of the patient. As Figure 2 shown, the locator 100 includes a fixing device 104, a connecting mechanism 103, a positioning frame 102, and an infrared reflective ball 101. The fixing device 104 has a toothed clamp, and a locking knob is arranged on the toothed clamp. The connecting mechanism 103 is composed of multiple universal joints, and a locking knob is arranged at each joint of the universal joints. The lower end of the connecting mechanism 103 is connected to the fixing device by bolts, and the positioning frame 102 is installed on the upper end of the connecting mechanism by bolts. The positioning frame 102 is provided with an installation position for installing the infrared reflective ball, and the installation position can be a groove type, a hole type, or other suitable shapes. The installation positions are at least four. In this embodiment, as Figure 2 shown, the positioning frame 102 is in a rhombus shape, and four installation positions are correspondingly arranged at the four vertex positions. The infrared reflective ball 101 is embedded and installed in the installation position.

[0039] The free tracking ball 200 is used to be installed on the body surface of the patient. As Figure 3 shown, the free tracking ball 200 includes a passive infrared tracking ball 201, a connecting rod 202, and a fixing base 203. The bottom surface of the fixing base 203 is provided with an adhesive layer. The lower end of the connecting rod 202 is connected to the fixing base, and the upper end of the connecting rod 202 is provided with an installation position. The connecting rod 202 and the fixing base 203 are of an integral structure. The passive infrared tracking ball 201 is detachably and internally installed in the installation position at the upper end of the connecting rod. One free tracking ball 200 is provided with one passive infrared tracking ball 201.

[0040] The optical positioning and tracking device 300 is used to obtain the position information of the locator 100 and the free tracking ball 200. The processor 400 is communicatively connected to the optical positioning and tracking device 300, and is used to process the position information sent by the optical positioning and tracking device 300 and generate a processing result. The display 500 is communicatively connected to the processor 400, and is used to visually display the processing result.

[0041] This embodiment also provides a monitoring method for a single free tracking ball. This monitoring method is carried out by using the above-mentioned monitoring system for a single free tracking ball, and this method includes the following steps:

[0042] Step S1: Fix the locator 100 at the lesion site of the patient, and fix the free tracking ball 200 on the patient's body surface, ensuring that both the infrared reflective ball 101 and the passive infrared tracking ball 201 are recognized by the optical positioning and tracking device 300. Take the position information of the recognized infrared reflective ball and passive infrared tracking ball as the first position information, and generate the first coordinate system based on the first position information and the position of the optical positioning and tracking device 300.

[0043] In this step, when installing the locator 100, place the toothed clamp on the pedicle spinous process of the patient's surgical site, and fix the toothed clamp on the pedicle spinous process through the locking knob to complete the installation. The free tracking ball 200 is installed by pasting and fixing the free tracking ball 200 on the patient's body surface through the adhesive layer to complete the installation.

[0044] Step S2: The optical positioning and tracking device 300 emits infrared light, and then obtains the infrared light reflected by the infrared reflective ball 101 and the passive infrared tracking ball 201 through the optical positioning and tracking device 300, so as to obtain the first position information of the locator 100 and the free tracking ball 200 in the first coordinate system in real time, and at the same time obtain the quantity information of the free tracking ball 200 in real time. The optical positioning and tracking device 300 sends the first position information and quantity information obtained in real time to the processor 400.

[0045] Step S3: The processor 400 detects whether the obtained first position information and quantity information meet the predetermined monitoring conditions. When there is a failure to meet the predetermined monitoring conditions, it is determined that the monitoring fails and proceeds to step S4; when the predetermined monitoring conditions are met, it proceeds to step S5.

[0046] The predetermined monitoring conditions include the following three conditions. When all three conditions are met, it is considered to meet the predetermined monitoring conditions. When any one condition is not met, it is considered not to meet the predetermined monitoring conditions:

[0047] Condition 1: Monitor whether the quantity of the free tracking ball 200 is interfered:

[0048] The specific judgment rule is to judge whether the quantity of the free tracking ball 200 is equal to 1 through the quantity information of the free tracking ball 200. When it is not equal to 1, it is determined that Condition 1 is not met.

[0049] Possible reasons for failure corresponding to the non - fulfillment of Condition 1:

[0050] (1) The free tracking ball 200 is blocked, and at this time, the quantity of the free tracking ball 200 recognized by the optical positioning and tracking device 300 is 0.

[0051] (2) There are other free tracking balls, and at this time, the quantity of the free tracking ball 200 recognized by the optical positioning and tracking device 300 is greater than 1.

[0052] Condition 2: Monitor whether the monitoring locator 100 and the free tracking ball 200 are simultaneously recognized by the optical positioning and tracking device 300:

[0053] The specific judgment rule is to determine whether the monitoring locator 100 and the free tracking ball 200 are simultaneously recognized by the optical positioning and tracking device 300 by whether the first position information of the locator 100 and the free tracking ball 200 is completely received. When the first position information is missing, it is determined that Condition 2 is not satisfied.

[0054] Possible reasons for failure corresponding to the non-satisfaction of Condition 2:

[0055] (1) The locator 100 is blocked, and at this time, the optical positioning and tracking device 300 cannot recognize the locator 100.

[0056] (2) The optical positioning and tracking device 300 is blocked, and at this time, the locator 100 and the free tracking ball 200 cannot be recognized.

[0057] Condition 3: Whether the relative positions of the monitoring locator 100, the free tracking ball 200, and the optical positioning and tracking device 300 have changed:

[0058] The specific judgment rule is to determine whether the relative position has changed through the first position information. When the relative positions of the locator 100, the free tracking ball 200, and the optical positioning and tracking device 300 change, it is determined that Condition 3 is not satisfied.

[0059] Possible reasons for failure corresponding to the non-satisfaction of Condition 3: The position of any one of the locator 100, the free tracking ball 200, and the optical positioning and tracking device 300 has changed.

[0060] Step S4: Send a failure instruction to the display 500 through the processor 400, and prompt the failure reason as a reference for the adjustment operation. When the doctor sees the failure reason, make adjustments according to the failure reason prompt, and return to Step S3 for re-judgment until the predetermined monitoring conditions are met.

[0061] Step S5: Execute the single-ball monitoring algorithm through the processor 400 to determine whether the locator 100 and the free tracking ball 200 remain relatively stationary, and display the result through the display 500 to achieve real-time monitoring of the positions of the locator 100 and the free tracking ball 200.

[0062] The single-ball monitoring algorithm specifically includes the following steps:

[0063] Step S101: Accumulate the relative position information of the locator 100 and the free tracking ball 200 in the first coordinate system for 0 - 100 frames. During the frame accumulation process, calculate the distance value A between the locator 100 and the free tracking ball 200 for each frame. At the same time, calculate the difference in distance values between every two adjacent frames, and compare the obtained difference in distance values with the first preset error range in the processor 400:

[0064] In this embodiment, the first preset error range is 0.2mm - 0.4mm.

[0065] When the difference in distance values > the upper limit of the first preset error range, that is, the difference in distance values > 0.4mm, it is determined that the positions of the locator 100 and / or the free tracking ball 200 have shifted severely. At this time, the "single - ball monitoring algorithm" will terminate. Meanwhile, a failure instruction is sent to the display 500 through the processor 400, and the failure reason is prompted as a reference for adjustment operations. The doctor needs to adjust the locator 100 and the free tracking ball 200, and after the adjustment is completed, it is necessary to return to step S3 for re - inspection.

[0066] When the difference in distance values is within the first preset error range, that is, 0.2mm ≤ the difference in distance values ≤ 0.4mm, it is determined that the locator 100 and the free tracking ball 200 have made a relative movement in the first coordinate system. Then, the frame number is reset to zero and accumulated again. Until the difference in distance values between every two adjacent frames during the accumulation process is < the lower limit of the first preset error range, that is, the difference in distance values < 0.2mm, and when the accumulation reaches 100 frames, step S102 is entered.

[0067] Step S102: When the frame number accumulates to 100 frames, it is determined that the locator 100 and the free tracking ball 200 are in a relatively static state, and at the same time, the average distance M between 0 - 100 frames is calculated.

[0068] After completing the accumulation of distance values between 0 - 100 frames, continue to read the position information of the locator 100 and the free tracking ball 200 for each frame in the first coordinate system. At the same time, calculate the distance value B between the locator 100 and the free tracking ball 200 for each frame, and compare the distance value B with the average distance M, and calculate the error value between the two:

[0069] Error value H = |distance value B - average distance M|

[0070] Compare the error value H with the second preset error range, which is 0.1 mm - 0.2 mm in this embodiment. When the error value H is between 0.1 mm and 0.2 mm or greater than 0.2 mm, the processor 400 generates a warning signal. At the same time, the processor 400 compares the obtained second position information with the first position information to determine the object that has undergone displacement, and finally gives a prompt through the display 500.

[0071] During the continuous monitoring of the "single-ball monitoring algorithm", the situations that can also cause the "single-ball monitoring algorithm" to recumulate or terminate are as follows:

[0072] (1) When the error value H is within the second preset error range, that is, 0.1 mm ≤ error value H ≤ 0.2 mm, the "single-ball monitoring algorithm" will return to step S101 and recumulate the relative first position information of the locator 100 and the free tracking ball 200 in the first coordinate system for 0 - 100 frames again.

[0073] (2) When the error value H is greater than 0.2 mm, that is, error value H > 0.2 mm, the "single-ball monitoring algorithm" will terminate. At this time, the doctor needs to adjust the locator 100 and / or the free tracking ball 200 according to the prompt, and then return to step S1 to operate again after adjustment.

[0074] (3) When any one of the locator 100, the free tracking ball 200, or the optical positioning and tracking device 300 is blocked and the blocking time is greater than 3 seconds, the "single-ball monitoring algorithm" will terminate. At this time, the doctor needs to adjust the locator 100 and / or the free tracking ball 200 according to the prompt, and then return to step S1 to operate again after adjustment.

[0075] The above embodiments are only the preferred embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention are included in the protection scope of the present invention.

Claims

1. A monitoring system for a single free tracking ball, characterized in that, Including: A locator, which is installed and fixed at the lesion site of the patient; A free tracking ball, which is installed on the body surface of the patient; An optical positioning and tracking device, which is used to obtain the position information of the locator and the free tracking ball; A processor, which is communicatively connected to the optical positioning and tracking device, and is used to process the position information sent by the optical positioning and tracking device and generate a processing result; A display, which is communicatively connected to the processor, and is used to visually display the processing result; Wherein, the optical positioning and tracking device obtains in real time the first position information of the locator and the free tracking ball in the first coordinate system and the number information of the free tracking balls, and sends the obtained first position information and number information to the processor in real time; The processor detects whether the obtained first position information and number information meet the predetermined monitoring conditions. When there is a situation where the predetermined monitoring conditions are not met, it is determined that the monitoring fails; when the predetermined monitoring conditions are met, the single-ball monitoring algorithm is executed by the processor, so as to judge whether the locator and the free tracking ball maintain a relatively static state, and the result is displayed through the display, realizing real-time monitoring of the positions of the locator and the free tracking ball; The predetermined monitoring conditions include the following three conditions. When all three conditions are met, it is regarded as meeting the predetermined monitoring conditions. When any one of the conditions is not met, it is regarded as not meeting the predetermined monitoring conditions: Condition 1 is to monitor whether the number of free tracking balls is interfered. The specific judgment rule is to judge whether the number of free tracking balls is equal to 1 through the number information of the free tracking balls. When it is not equal to 1, it is determined that Condition 1 is not met; Condition 2 is to monitor whether the locator and the free tracking ball are simultaneously recognized by the optical positioning and tracking device. The specific judgment rule is to judge whether the locator and the free tracking ball are simultaneously recognized by the optical positioning and tracking device by whether the first position information of the locator and the free tracking ball is completely received. When there is a missing first position information, it is determined that Condition 2 is not met; Condition 3 is to monitor whether the relative positions of the locator, the free tracking ball and the optical positioning and tracking device have changed. The specific judgment rule is to judge whether the relative position has changed through the first position information. When the relative positions among the locator, the free tracking ball and the optical positioning and tracking device have changed, it is determined that Condition 3 is not met; The single-ball monitoring algorithm specifically includes the following steps: Step S101, accumulate the relative position information of the locator and the free tracking ball in the first coordinate system for 0 - 100 frames. During the frame accumulation process, calculate the distance value A between the locator and the free tracking ball in each frame, and at the same time calculate the difference between the distance values of every two adjacent frames, and compare the obtained difference between the distance values with the first preset error range in the processor; When the difference between the distance values > the upper limit of the first preset error range, the single-ball monitoring algorithm terminates, and a failure instruction is sent by the processor to the display to prompt the failure reason for reference in the adjustment operation; When the difference between the distance values is within the first preset error range, it is determined that there is relative movement between the locator and the free tracking ball in the first coordinate system. Then, the frame number is reset to zero and accumulated again until the difference between the distance values of every two adjacent frames during the accumulation process is less than the lower limit of the first preset error range. When the accumulation reaches 100 frames, step S102 is entered; Step S102, when the frame number is accumulated and read to 100 frames, it is determined that the locator and the free tracking ball are in a relatively static state, and at the same time, the average distance M between frames 0 - 100 is calculated; Step S103, after completing the accumulation of the distance values between frames 0 - 100, continue to read the position information of each frame of the locator and the free tracking ball in the first coordinate system, and at the same time calculate the distance value B between the locator and the free tracking ball for each frame, and compare the distance value B with the average distance M, and calculate the error value between the two: Error value H = |distance value B - average distance M| According to the comparison result between the error value H and the second preset error range, a warning signal is generated by the processor. At the same time, the processor compares the obtained second position information with the first position information to determine the object that has undergone displacement, and finally gives a prompt through the display.

2. The monitoring system of a single free tracking ball according to claim 1, characterized in that: Among them, The locator includes a fixing device, a connecting mechanism, a positioning frame, and an infrared reflective ball; The fixing device has a toothed clamp, and a locking knob is provided on the toothed clamp; The lower end of the connecting mechanism is connected to the fixing device, and the positioning frame is installed on the upper end of the connecting mechanism; The positioning frame is provided with a mounting position, and the infrared reflective ball is embedded and installed in the mounting position.

3. The monitoring system of a single free tracking ball according to claim 2, characterized in that: Among them, There are at least four mounting positions.

4. The monitoring system of a single free tracking ball according to claim 2, characterized in that: Among them, The connecting mechanism is a multi-segment universal joint.

5. The monitoring system of a single free tracking ball according to claim 1, characterized in that: Among them, The free tracking ball includes a passive infrared tracking ball, a connecting rod, and a fixing base; The bottom surface of the fixing base is provided with an adhesive layer; The lower end of the connecting rod is connected to the fixing base; The passive infrared tracking ball is installed at the upper end of the connecting rod.

6. The monitoring system of a single free tracking ball according to claim 1, characterized in that: Among them, The first preset error range is 0.2 mm - 0.4 mm.

7. The monitoring system of a single free tracking ball according to claim 1, characterized in that: Among them, The second preset error range is 0.1 mm - 0.2 mm.

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