Skull drill control method and system and skull drill device

Abstract

The invention relates to a cranial drill control method and system and a cranial drill device.The method comprises the steps that a cranial drill is controlled to conduct stepping downward drilling according to a first step pitch, and real-time force sampling data of axial stress of the cranial drill of current stepping are obtained; acquiring a historical maximum force value and a force change average characteristic value; under the condition that the first preset condition is met, the cranial drill is controlled to stop drilling downwards; the first preset condition includes that the real-time force peak value of the current stepping is larger than or equal to the historical maximum force value, and the ratio of the absolute value of the maximum value of the real-time force change rate of the current stepping to the force change average characteristic value is larger than a first threshold value. The cranial drill is controlled to drill downwards in a stepping mode, axial stress is collected in real time, analysis and judgment are conducted from the two aspects of the change rate and the maximum value, whether the cranial drill is likely to drill through or not is determined, the cranial drill is controlled to stop suddenly according to the judgment result, and therefore brain cells are prevented from being damaged due to excessive drilling through.

Description

Technical Field

[0001] The present invention relates to the technical field of surgical instruments, and in particular to a cranial drill control method, system and cranial drill device. Background Art

[0002] In neurosurgery experiments, holes need to be made in the skull to implant optical fibers, electrodes and other devices. Traditional handheld skull drills are prone to not being stopped in time due to human operating errors, resulting in excessive drilling and damage to brain tissue.

[0003] There are also automatic skull drilling devices in the related technology, which are based on mechanical structures (such as clutch structures) or composite sensor detection to achieve self-detection and self-stop to avoid over-drilling. However, the mechanical self-stop response delay is large and the accuracy is insufficient, and the composite sensor detection solution requires multiple different sensor detection signals and achieves precise self-stop control based on multiple different signals, making the system too complex and costly. Summary of the Invention

[0004] In order to solve at least one of the above-mentioned technical problems, the present invention provides a cranial drill control method, system and cranial drill device.

[0005] According to some embodiments of the present invention, a skull drill control method is provided, the method comprising: controlling the skull drill to drill down step by step according to the first step, obtaining real-time force sampling data of the axial force of the skull drill in the current step; obtaining a historical maximum force value and an average characteristic value of force change, the historical maximum force value indicating the maximum value of the real-time force sampling data of the historical steps before the current step, and the average characteristic value of force change indicating the average characteristic value of the maximum real-time force change rate of each historical step before the current step; controlling the skull drill to stop drilling down when a first preset condition is met; the first preset condition comprising: the real-time force peak value of the current step is greater than or equal to the historical maximum force value, and the ratio of the absolute value of the maximum value of the real-time force change rate of the current step to the average characteristic value of the force change is greater than a first threshold.

[0006] Based on the above scheme, by controlling the step-by-step drilling of the cranial drill and collecting the axial force in real time, analysis and judgment are made from two aspects: the rate of change and the maximum value. When the first preset condition is met, it means that the decrease in the axial force of the cranial drill is much greater than the average level of increase when drilling, confirming that the cranial drill may penetrate, and controlling the cranial drill to stop suddenly to avoid excessive drilling and damage to brain cells.

[0007] In some possible embodiments, after controlling the cranial drill to stop drilling when the first preset condition is met, the method further includes: obtaining a current drilling depth; controlling the cranial drill to continue drilling when the current drilling depth is less than or equal to the drill bit radius of the cranial drill; and controlling the cranial drill to stop drilling when the current drilling depth is greater than the drill bit radius, wherein the drilling depth reaching the drill bit radius indicates that the drilling contact area between the cranial drill bit and the skull reaches a maximum area.

[0008] Based on the above scheme, the drilling depth is used to determine whether the drilling contact area between the drill bit and the skull has reached the maximum area, thereby avoiding misjudgment and emergency stop caused by force sampling error when the drilling contact area has not reached the maximum area.

[0009] In some possible embodiments, after controlling the cranial drill to stop drilling when the current drilling depth is greater than the drill bit radius, the method further includes: controlling the cranial drill to drill in steps according to a second step distance when the absolute value of the maximum value of the real-time force change rate of the current step is greater than the drilling pressure reference value; wherein the drilling pressure reference value is the absolute value of the axial force change rate of the cranial drill when the drilling depth reaches the drill bit radius, and the second step distance is smaller than the first step distance.

[0010] Based on the above scheme, after the first preset condition is met, the maximum value of the real-time force drop of the current step is further compared with the drilling pressure reference value to determine whether the drill bit has completely penetrated. If it has not completely penetrated, drilling is performed in small steps to ensure that brain cells are not damaged while drilling.

[0011] In some possible embodiments, after controlling the cranial drill to drill down in steps according to the second step distance, the method further includes: controlling the cranial drill to stop drilling when a second preset condition is met; the second preset condition includes: the real-time force peak value of the current step is less than or equal to the historical maximum force value, and the ratio of the absolute value of the maximum value of the real-time force change rate of the current step to the average characteristic value of the force change is greater than a second threshold, wherein the second threshold is less than the first threshold.

[0012] Based on the above solution, after drilling according to the second step length, the detection condition is changed to the second preset condition so that the detection condition corresponds to the step length, ensuring drilling through while avoiding over-drilling.

[0013] In some possible implementations, the method further includes: before controlling the cranial drill to step down, initializing the average characteristic value of the force change to zero; after completing one step, exponentially smoothing the average characteristic value of the force change according to the maximum value of the real-time force change rate of the most recently completed step.

[0014] Based on the above scheme, after each step is completed, the real-time force data of the latest completed step is used to perform exponential smoothing on the historical data, thereby achieving a one-time filtering process, which can effectively remove the high-frequency noise data caused by high-frequency sampling and improve the detection accuracy.

[0015] In some possible implementations, the ratio of the first step to the second step is equal to the ratio of the first threshold to the second threshold.

[0016] Based on the above scheme, the step size is linearly related to the threshold, which avoids the alternation error caused by inconsistent detection conditions and improves the control accuracy.

[0017] In some possible embodiments, before controlling the cranial drill to drill down in steps according to the first step, the method further includes: controlling the cranial drill to move downward without rotating the drill bit of the cranial drill, and obtaining the axial force of the cranial drill in real time; when the axial force of the cranial drill reaches a preset threshold, controlling the cranial drill to stop moving and then drilling down in steps according to the first step.

[0018] Based on the above solution, the drill bit of the cranial drill is controlled to be close to the skull to be drilled before drilling, ensuring that the initial force of the cranial drill is small enough to avoid the initial force affecting the subsequent detection accuracy.

[0019] According to some other embodiments of the present invention, a cranial drill control system is provided, the system comprising:

[0020] Real-time force sampling module, which obtains the real-time force sampling data of the axial force of the cranial drill at the current step;

[0021] a historical force acquisition module, configured to acquire a historical maximum force value and an average force change characteristic value, wherein the historical maximum force value indicates the maximum value of the real-time force sampling data of the historical step before the current step, and the average force change characteristic value indicates the average characteristic value of the maximum real-time force change rate of each historical step before the current step;

[0022] A cranial drill control module is used to control the cranial drill to drill down in steps according to the first step, and to control the cranial drill to stop drilling when a first preset condition is met; the first preset condition includes: the real-time force peak value of the current step is greater than or equal to the historical maximum force value, the maximum value of the real-time force change rate of the current step is less than zero, and the ratio of the absolute value of the real-time force change rate of the current step to the average characteristic value of the force change is greater than a first threshold.

[0023] According to other embodiments of the present invention, a cranial drilling device is provided, including a controller, a robotic arm, an electric drill and a force sensor, wherein the robotic arm is used to drive the electric drill to move, the force sensor is used to detect the axial force of the electric drill, and the controller is used in the automatic drilling stop control method described in any one of the above embodiments.

[0024] In some possible implementations, the electric drill includes a spherical drill bit, and the diameter of the spherical drill bit ranges from 0.5 mm to 2.0 mm.

[0025] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention.

[0026] Further features and aspects of the present invention will become apparent from the following detailed description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions and advantages of the embodiments of this specification or the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of this specification. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0028] Figure 1 A flowchart of a cranial drill control method according to an embodiment of the present invention is shown;

[0029] Figure 2 A sampling diagram showing real-time force data of drilling according to an embodiment of the present invention is shown;

[0030] Figure 3 A flowchart showing another cranial drill control method according to an embodiment of the present invention is shown;

[0031] Figure 4 A structural block diagram of a cranial drill control system according to an embodiment of the present invention is shown;

[0032] Figure 5 A structural diagram of a skull device according to an embodiment of the present invention is shown;

[0033] Figure 6 A structural diagram of an electric drill in a skull device according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0034] The following will be combined with the drawings in the embodiments of this specification to clearly and completely describe the technical solutions in the embodiments of this specification. Obviously, the embodiments described are only part of the embodiments of this specification, not all of the embodiments. Based on the embodiments in this specification, all other embodiments obtained by ordinary technicians in this field without making any creative efforts are within the scope of protection of this invention.

[0035] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way are interchangeable where appropriate so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or server that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0036] Various exemplary embodiments, features, and aspects of the present invention will be described in detail below with reference to the accompanying drawings. The same reference numerals in the accompanying drawings represent elements with the same or similar functions. Although various aspects of the embodiments are shown in the accompanying drawings, the drawings are not necessarily drawn to scale unless otherwise indicated.

[0037] The word “exemplary” is used exclusively herein to mean “serving as an example, example, or illustration.” Any embodiment described herein as “exemplary” is not necessarily to be construed as preferred or advantageous over other embodiments.

[0038] The term "and / or" herein simply describes an association relationship between associated objects, indicating that three relationships can exist. For example, "A and / or B" can represent the existence of three situations: A alone, A and B simultaneously, and B alone. Furthermore, the term "at least one" herein refers to any combination of at least two of any one or more of a plurality of items. For example, "at least one of A, B, and C" can represent any one or more elements selected from the set consisting of A, B, and C.

[0039] In addition, numerous specific details are provided in the following detailed description to better illustrate the present invention. Those skilled in the art will appreciate that the present invention may be practiced without certain specific details. In some instances, methods, means, components, and circuits well known to those skilled in the art have not been described in detail in order to highlight the main points of the present invention.

[0040] An embodiment of the present invention provides a cranial drill control method that can be applied to a cranial drill device equipped with a force sensor. The force sensor can sample the axial force applied to the cranial drill in real time at a specific frequency during the drilling process. This method performs gradient analysis based on the force sensor signal to monitor the dynamic changes in force during the drilling process. Based on these dynamic changes in force, the method promptly adjusts and controls the operating state of the cranial drill, ensuring accurate determination of penetration status and reducing the risk of overdrilling.

[0041] The implementation of this method does not require reliance on a complex composite force detection system, nor does it require the setting up of an additional mechanical structure. That is, this method has no special requirements or restrictions on the structure of the cranial drill device and can be directly applied to existing cranial drill devices. High-precision, low-latency skull drilling detection can be achieved through force sensor signals, which can ensure compatibility and accuracy, simplify the device system structure, and reduce equipment costs.

[0042] Figure 1 FIG. 4 shows a flow chart of a cranial drill control method according to an embodiment of the present invention. Figure 1 As shown, the method includes:

[0043] S101, controlling the cranial drill to drill down in a stepwise manner according to the first step, and obtaining real-time force sampling data of the axial force of the cranial drill at the current step.

[0044] The cranial drill has a motion mechanism that enables the axial movement of the cranial drill bit to be automated. In response to control signals from a controller, the cranial drill can perform step-by-step drilling. Step-by-step drilling means the cranial drill drills downwards in a predetermined step size, which corresponds to the drilling depth. Each time the cranial drill reaches the first step size, the cranial drill completes one step.

[0045] This embodiment does not limit the specific length of the first step distance. It should be understood that the first step distance corresponds to the drill bit size of the cranial drill. Generally, the drill bit of a cranial drill is a spherical drill bit, so the first step distance corresponds to the diameter of the drill bit. For example, the ratio of the first step distance to the drill bit diameter is 1:5 to 1:10.

[0046] The cranial drill also includes a force sensor that can detect the axial force acting on the cranial drill. During the stepping and lowering of the cranial drill, the controller samples the axial force acting on the cranial drill in real time based on the signal from the force sensor. This embodiment does not limit the resolution of the force sensor or the sampling frequency. To improve the accuracy of detection and control, the resolution of the force sensor should be as small as possible, for example, less than or equal to 0.005N. Correspondingly, the sampling frequency should be as large as possible, for example, greater than or equal to 100Hz.

[0047] Step S102: Obtain the historical maximum force value and the average characteristic value of force change.

[0048] In this embodiment, the historical maximum force value indicates the maximum value of the sampled data of the historical step before the current step. Before the cranial drill performs a step-down drilling, the historical maximum force value is initialized and set to zero. Each time the cranial drill completes a step-down drilling, the maximum value of the real-time force sampled data of that step is compared with the historical maximum force value. If the maximum value of the real-time force sampled data of that step is greater than the historical maximum force value, the maximum value of the real-time force sampled data of that step is used to update the historical maximum force value. Based on the above operation, the historical maximum force value can be updated once after each step is completed, thereby improving data processing efficiency.

[0049] In this embodiment, the average force variation characteristic value indicates the average characteristic value of the maximum real-time force change rate of each historical step before the current step. Specifically, for each completed historical step, the maximum real-time force change rate of each historical step is obtained, and then the average characteristic value of these multiple maximum real-time force change rates is calculated to obtain the above-mentioned average force variation characteristic value.

[0050] The reason why the average characteristic value of force change is obtained in this embodiment is that the average characteristic value of force change can represent the force change during the drilling process of the cranial drill, so as to facilitate the subsequent drilling judgment and emergency stop control. Since the cranial drill is drilled in a step-by-step drilling manner, for each step, when the drilling depth reaches the set step distance, a step is completed, that is, the start and stop of the step-by-step drilling is only related to the drilling depth. Based on this, before drilling through, the real-time force change rate of each step has similar characteristics. It is worth noting that the real-time force change rate in this embodiment should be understood in a broad sense, that is, the real-time force change rate can be a first-order change rate, that is, the first-order derivative of the real-time force with respect to time, and the real-time force change rate can also be a high-order change rate, such as the second-order derivative of the real-time force with respect to time. In the absence of special instructions, the real-time force change rate in subsequent embodiments can be understood as a second-order change rate by default.

[0051] For details, please refer to Figure 2 , Figure 2A sampling diagram of real-time drilling force data according to an embodiment of the present invention is shown, where the horizontal axis represents the sampling points, the left vertical axis represents the real-time force, and the right vertical axis represents the real-time force change rate. During the actual drilling process, for each step before penetration, the axial force on the cranial drill changes in a pattern of first increasing and then remaining stable or decreasing, corresponding to a real-time force change rate that first increases and then decreases. For the entire process before penetration, the real-time force change rate fluctuates, and the real-time force change rates for each step are relatively close. Therefore, by averaging and characterizing the real-time force change rate data for each step, the force change level before penetration can be determined, facilitating subsequent determination of penetration. It is worth noting that the force change during each step is represented by an inverted triangle, divided into ascending and descending phases. In practical applications, only the real-time force change rate during the descending phase needs to be calculated. Since this real-time force change rate is generally negative, the absolute value of the real-time force change rate must be taken before calculation.

[0052] This embodiment does not limit the specific method of average characterization processing of the real-time force change rate data of each step. That is to say, the above-mentioned average characterization processing can be to obtain the average value, median value, variance or standard deviation of the maximum real-time force change rate of each historical step before the current step. The above-mentioned average characterization processing can also be other methods, such as weighted average, probability distribution, etc.

[0053] In a specific embodiment, the above-mentioned average characterization processing can adopt exponential smoothing processing. Based on the above content, it can be seen that in order to improve the accuracy of detection and control, the sampling frequency of the real-time force should be as large as possible, which will correspondingly bring high-frequency noise. Therefore, the use of exponential smoothing processing helps to filter out high-frequency noise, thereby obtaining the average characteristic value of force change. Specifically, the average characterization processing method includes: before controlling the cranial drill to step down, the average characteristic value of the force change is initialized to zero; after completing one step, the average characteristic value of the force change is updated exponentially smoothed according to the maximum value of the real-time force change rate of the most recently completed step.

[0054] Based on the above scheme, the maximum real-time force change rate is defined as dFmax, and the average characteristic value of the force change is defined as dFmax_avg. Before the cranial drill is stepped down, that is, when the number of steps is 0, dFmax_avg = 0, so dFmax_avg(n) = 0, where n represents the step number. The above exponential smoothing processing method can be expressed as the following formula: dFmax_avg(n) = (1-k) × dFmax_avg(n-1) + k × dFmax_avg(n), where n is the step number and k is the smoothing coefficient. There is no specific restriction on the smoothing coefficient k. The smaller the smoothing coefficient, the stronger the smoothing effect and the more obvious the capture of long-term change trends. In some possible situations, the smoothing coefficient k is less than 0.5. Preferably, the smoothing coefficient k = 0.2. The above formula is changed to: dFmax_avg(n) = 0.8 × dFmax_avg(n-1) + 0.2 × dFmax_avg(n).

[0055] S103. Controlling the cranial drill to stop drilling if a first preset condition is met. The first preset condition includes: the real-time force peak value of the current step is greater than or equal to the historical maximum force value, and the ratio of the absolute value of the maximum real-time force change rate of the current step to the average force change characteristic value is greater than a first threshold.

[0056] In this embodiment, the first preset condition can be determined after a step is completed or during the stepping process. That is, in the first preset condition, the real-time force peak value and the maximum real-time force change rate of the current step can be determined based on the real-time force data already available in the current step, rather than waiting until the step is completed. By performing real-time detection and judgment during the stepping process, it is helpful to promptly detect real-time force changes, thereby determining drilling penetration and triggering emergency stop control.

[0057] The purpose of setting the first preset condition in this embodiment is to determine whether the cranial drill is about to drill through. The purpose of detecting the real-time force peak value of the current step and comparing it with the historical maximum force value is to determine the implementation stage of the cranial drill.

[0058] The actual drilling process can be divided into two phases: the first phase and the second phase. The first phase involves multiple steps, during which the axial force gradually increases as the number of steps increases, i.e., the drilling depth increases. The second phase, on the other hand, lasts for a shorter period of time, corresponding to fewer steps, which may even be less than one step. During the second phase, the drill progresses from nearing penetration to complete penetration.

[0059] Since the drilling stage and the step are not strictly aligned, that is, the step where the starting point of the second stage is located also partially belongs to the first stage. During this step, the real-time force initially increases and then drops rapidly. This step is a stage transition, so it is necessary to detect the real-time force peak to determine whether the current step is in a stage transition. Specifically, if the real-time force peak of the current step is greater than or equal to the historical maximum force value, it is still judged to be in the first stage. If the current step peak force is less than the historical maximum force, and the maximum value of the real-time force change of the current step is much greater than the average characteristic value of the force change, it is judged that this step is in a stage transition, which facilitates subsequent emergency stop control.

[0060] In the first precondition, the maximum real-time force rate of change during the current step reflects the extent of the real-time force change. Because the real-time force rate of change during the current step is significantly greater than the average force change eigenvalue, the maximum real-time force rate of change reflects the dramatic decrease in the axial force applied to the cranial drill. As shown in the previous step, the average force change eigenvalue indicates the increase in real-time force during drilling. By comparing the absolute value of the maximum real-time force rate of change during the current step with the average force change eigenvalue, it is possible to analyze the probability of a cranial drill penetration.

[0061] In this embodiment, if the ratio of the absolute value of the maximum value of the real-time force change rate of the current step to the average characteristic value of the force change is greater than the first threshold, it indicates that the drill may have penetrated. At this time, the cranial drill is controlled to stop suddenly. The first threshold is greater than 1 and can be flexibly adjusted according to the actual experimental subject. For example, when the experimental subject is a mouse, the first threshold can be set to 4.

[0062] Since the drill bit of the cranial drill is a spherical drill bit, the contact area between the spherical drill bit and the skull has not yet reached its maximum value when the cranial drill is first drilled. At this time, the real-time force change during the step-by-step drilling process is prone to sudden changes. Therefore, in order to avoid false stops due to insufficient drilling depth, after the above step S103, the cranial drill control method further includes:

[0063] The current drilling depth is obtained; if the current drilling depth is less than or equal to the drill bit radius of the cranial drill, the cranial drill is controlled to continue drilling; if the current drilling depth is greater than the drill bit radius, the cranial drill is controlled to stop drilling, wherein the drilling depth reaching the drill bit radius indicates that the drilling contact area between the cranial drill bit and the skull has reached the maximum area.

[0064] It should be understood that there is no strict order between the above steps and the determination of the first preset condition. That is, while determining the first preset condition, the current drilling depth can also be determined simultaneously; or, before determining the first preset condition, the determination of the drilling depth can be completed first.

[0065] In one specific embodiment, during the step-by-step drilling process of the cranial drill, the drilling depth is acquired in real time. If the drilling depth is less than or equal to the drill bit radius of the cranial drill, the first preset condition determination is not performed. The first preset condition determination is performed only after the drilling depth exceeds the drill bit radius of the cranial drill. Based on this configuration, the computational load pressure can be effectively reduced.

[0066] Based on the cranial drill control method of the above embodiment, when the first preset condition is met, the actual drilling status may be that the hole has been drilled through or is close to being drilled through. In order to ensure that the hole is drilled through, further testing is required. Specifically, after the first preset condition test and the drilling depth test, the cranial drill control method further includes:

[0067] When the absolute value of the maximum real-time force change rate of the current step is greater than the drilling pressure reference value, the cranial drill is controlled to drill in a step-by-step manner according to the second step distance; wherein the drilling pressure reference value is the absolute value of the axial force change rate of the cranial drill when the drilling depth reaches the drill bit radius, and the second step distance is smaller than the first step distance.

[0068] During the initial descent of the cranial drill, the contact area between the drill bit and the skull gradually increases. However, during the penetration process, the contact area between the drill bit and the skull gradually decreases. This means that the initial descent and penetration processes can be compared. Specifically, during the initial descent, as the drilling depth increases, the hole diameter gradually increases until the drilling depth reaches the drill bit radius, at which point the hole diameter also increases to the drill bit radius. Correspondingly, during the penetration process, the perforated hole diameter also gradually increases to the drill bit radius. Therefore, the absolute value of the axial force change rate of the cranial drill when the drilling depth reaches the drill bit radius can be used as a reference for the change in axial force of the cranial drill when the hole diameter reaches the drill bit radius.

[0069] Based on the above settings, if the absolute value of the maximum real-time force change rate during the current step is greater than the reference drilling pressure, it indicates that the drill has not fully penetrated the skull, and further control of the drill is required. This can occur in two ways: the drill is close to the inner wall of the skull, or the drill penetrates but the hole diameter does not reach the drill radius. To prevent the drill from damaging brain cells, the step size is adjusted from the first step size to the second step size, and the drill enters micro-step mode.

[0070] After the drill enters micro-step mode, it's nearing penetration. Due to variations in skull bone density, which decreases closer to the brain, the drill's axial force decreases. Continuing to use the first preset condition could lead to over-drilling and potentially damage brain cells, so the penetration determination criteria need to be reset.

[0071] In some embodiments, after the cranial drill enters micro-step mode, the cranial drill control method further includes: controlling the cranial drill to stop drilling if a second preset condition is met; the second preset condition includes: the real-time force peak value of the current step is less than or equal to the historical maximum force value, and the ratio of the absolute value of the maximum real-time force change rate of the current step to the average force change characteristic value is greater than a second threshold, wherein the second threshold is less than the first threshold. Based on the detection of the second preset condition, it can be ensured that the cranial drill bit will completely penetrate the skull, wherein complete penetration should be understood as the perforation hole diameter reaching the drill bit radius.

[0072] In this embodiment, the second preset condition is set relative to the first preset condition, and the detection of the two preset conditions is based on the step switching of the step drilling. When the cranial drill is stepping down according to the first step, the first preset condition is detected to determine whether the drill has penetrated. The first preset condition includes a first threshold. After the cranial drill switches to micro-step mode, the cranial drill is stepping down according to the first step. At this time, the second preset condition is used to determine whether the drill has penetrated. The second preset condition includes a second threshold. During the same cranial drilling process, the first step should be set corresponding to the first threshold, and the second step should be set corresponding to the second threshold to reduce alternation error.

[0073] In a preferred embodiment, the ratio of the first step to the second step is equal to the ratio of the first threshold to the second threshold. For example, if the second step is half of the first step, the second threshold is correspondingly set to half of the first threshold.

[0074] In some embodiments, before the cranial drill is lowered, it is also necessary to ensure that the cranial drill bit is in contact with the skull and that the initial axial force of the cranial drill is zero, so as to avoid errors in subsequent detection and control caused by the initial force of the cranial drill. Specifically, before controlling the cranial drill to drill step by step according to the first step, the cranial drill control method further includes:

[0075] S201, controlling the cranial drill to move downward without rotating the drill bit of the cranial drill, and obtaining the axial force of the cranial drill in real time;

[0076] S202: When the axial force of the cranial drill reaches a preset threshold, the cranial drill is controlled to stop moving and then drills downward in a stepwise manner according to the first step.

[0077] In this embodiment, the preset threshold should be as close to zero as possible. For example, the preset threshold can be set to the minimum resolution of the force sensor configured for the cranial drill. Based on the above settings, the cranial drill slowly descends along its axis. When the axial force reaches the preset threshold, indicating that the drill bit has contacted the skull, the cranial drill is controlled to stop descending, the initial force is recorded, and the cranial drill is then controlled to enter the drilling process.

[0078] The above-mentioned multiple embodiments have detailed the steps, principles and effects of a cranial drill control method of the present invention. It is worth noting that there is no strict order restriction on the detection method steps of the above-mentioned different embodiments, that is, the execution order of some steps can be swapped. In the absence of conflict, the characteristic schemes of different embodiments can be freely combined to form new schemes. According to the actual application scenario, the detection conditions in the above-mentioned embodiments can also be adjusted to conditions with equivalent effects. This article will not elaborate on this.

[0079] To facilitate understanding of the cranial drill control method of the present invention, a complete embodiment is shown below to illustrate the execution process of the method in detail.

[0080] In this embodiment, the resolution of the force sensor of the cranial drill is 0.005N, the sampling frequency is 100Hz, the drill bit of the cranial drill is a spherical drill bit, the radius of the spherical drill bit r is 0.3mm, the first step distance x1 is 0.1mm, the first threshold is 4, the second step distance x2 is 0.05mm, and the second threshold is 2.

[0081] Based on the above configuration, please refer to Figure 3 , the cranial drill control method process includes:

[0082] S301, control the cranial drill to slowly move down along the drill axis and stop after contacting the skull, with the contact force threshold being 0.08N;

[0083] S302, initialization parameters: historical maximum force value Fmax = 0, real-time force change rate dF = 0, average characteristic value of force change dFmax_avg(0) = 0;

[0084] S303, set step size X=x1;

[0085] S304, controlling the cranial drill to complete one step-by-step drilling;

[0086] S305, obtaining the real-time force peak value Fpeak during stepping, if Fpeak>Fmax, then update Fmax=Fpeak and jump to S306; otherwise, jump to S309;

[0087] S306. Get the drilling depth h. If h≤r, update dFmax_avg(n)=0.8×dFmax_avg(n-1)+0.2×dFmax_avg(n), where n is the step number, and jump to S304; otherwise, jump to S307.

[0088] S307. Obtain the maximum value of the real-time force change rate during the step dFmax(n). If dFmax(n) < 0 and |dFmax(n)| > 4×dFmax_avg(n-1), jump to S308; otherwise, update dFmax_avg(n) = 0.8×dFmax_avg(n-1) + 0.2×dFmax_avg(n), where n is the step number, and jump to S304.

[0089] S308. Obtain the absolute value of the axial force change rate of the cranial drill when the drilling depth reaches the drill bit radius as the drilling pressure reference value dF0. If |dFmax(n)|>dF0, update dFmax_avg(n)=0.8×dFmax_avg(n-1)+0.2×dFmax_avg(n), where n is the step number, update the step size X=x2, and jump to S304; otherwise, end;

[0090] S309. Obtain the maximum real-time force change rate dFmax(n) during stepping. If dFmax(n) < 0 and |dFmax(n)| > 2×dFmax_avg(n-1), end; otherwise, update dFmax_avg(n) = 0.8×dFmax_avg(n-1) + 0.2×dFmax_avg(n), where n is the step number, update the step size X = x2, and jump to S304.

[0091] Please refer to Figure 4 The embodiment of the present invention further provides a cranial drill control system, the system comprising:

[0092] The real-time force sampling module 100 obtains the real-time force sampling data of the axial force of the cranial drill at the current step;

[0093] A historical force acquisition module 200 is configured to acquire a historical maximum force value and an average force change characteristic value, wherein the historical maximum force value indicates the maximum value of the real-time force sampling data of the historical step before the current step, and the average force change characteristic value indicates the average characteristic value of the maximum real-time force change rate of each historical step before the current step;

[0094] The cranial drill control module 300 is used to control the cranial drill to drill down in steps according to the first step, and to control the cranial drill to stop drilling when a first preset condition is met; the first preset condition includes: the real-time force peak value of the current step is greater than the historical maximum force value, the maximum value of the real-time force change rate of the current step is less than zero, and the ratio of the absolute value of the maximum value of the real-time force change rate of the current step to the average characteristic value of the force change is greater than a first threshold.

[0095] Please refer to Figure 5-Figure 6An embodiment of the present invention further provides a cranial drill device, including a controller, a robotic arm, an electric drill, and a force sensor. The robotic arm is used to drive the electric drill to move, the force sensor is used to detect the axial force of the electric drill, and the controller is used in the automatic drill stop control method described in any one of the above embodiments.

[0096] In a further embodiment, the electric drill includes a spherical drill bit, and the diameter of the spherical drill bit is in the range of 0.5 mm to 2.0 mm.

[0097] While various embodiments of the present invention have been described above, the above descriptions are intended to be illustrative, non-exhaustive, and not limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein is selected to best explain the principles of the embodiments, their practical applications, or technological improvements in the marketplace, or to enable others skilled in the art to understand the embodiments disclosed herein.

Claims

1. A cranial drill control method, characterized in that: The method comprises: Control the cranial drill to drill down step by step according to the first step, and obtain the real-time force sampling data of the axial force of the cranial drill at the current step; Obtaining a historical maximum force value and an average force change characteristic value, wherein the historical maximum force value indicates the maximum value of the real-time force sampling data of the historical step before the current step, and the average force change characteristic value indicates the average characteristic value of the maximum real-time force change rate of each historical step before the current step; When a first preset condition is met, the cranial drill is controlled to stop drilling; the first preset condition includes: the real-time force peak value of the current step is greater than or equal to the historical maximum force value, and the ratio of the absolute value of the maximum value of the real-time force change rate of the current step to the average characteristic value of the force change is greater than a first threshold.

2. The method according to claim 1, characterized in that After controlling the cranial drill to stop drilling when the first preset condition is met, the method further includes: Obtain the current drilling depth; if the current drilling depth is less than or equal to the drill bit radius of the cranial drill, control the cranial drill to continue drilling; if the current drilling depth is greater than the drill bit radius, control the cranial drill to stop drilling, wherein the drilling depth reaching the drill bit radius indicates that the drilling contact area between the drill bit of the cranial drill and the skull has reached a maximum area.

3. The method according to claim 2, characterized in that After controlling the cranial drill to stop drilling when the current drilling depth is greater than the drill bit radius, the method further includes: When the absolute value of the maximum real-time force change rate of the current step is greater than the drilling pressure reference value, the cranial drill is controlled to drill in steps according to the second step distance; wherein, the drilling pressure reference value is the absolute value of the axial force change rate of the cranial drill when the drilling depth reaches the drill bit radius, and the second step distance is smaller than the first step distance.

4. The method according to claim 3, characterized in that After controlling the cranial drill to drill downward in a stepwise manner according to the second step distance, the method further includes: When a second preset condition is met, the cranial drill is controlled to stop drilling; the second preset condition includes: The real-time force peak value of the current step is less than or equal to the historical maximum force value, and the ratio of the absolute value of the maximum value of the real-time force change rate of the current step to the average characteristic value of the force change is greater than a second threshold, wherein the second threshold is less than the first threshold.

5. The method according to claim 4, characterized in that The method further comprises: Before controlling the cranial drill to step down, the average characteristic value of the force change is initialized to zero; After completing one step, the force change average characteristic value is updated by exponential smoothing according to the maximum value of the real-time force change rate of the latest completed step.

6. The method according to claim 5, characterized in that The ratio of the first step to the second step is equal to the ratio of the first threshold to the second threshold.

7. The method according to claim 1, characterized in that Before controlling the cranial drill to drill down step by step according to the first step, the method further includes: When the drill bit of the cranial drill does not rotate, the cranial drill is controlled to move downward and the axial force of the cranial drill is obtained in real time; When the axial force of the cranial drill reaches a preset threshold, the cranial drill is controlled to stop moving and then drills downward in steps according to the first step.

8. A cranial drill control system, characterized in that: The system comprises: Real-time force sampling module, which obtains the real-time force sampling data of the axial force of the cranial drill at the current step; a historical force acquisition module, configured to acquire a historical maximum force value and an average force change characteristic value, wherein the historical maximum force value indicates the maximum value of the real-time force sampling data of the historical step before the current step, and the average force change characteristic value indicates the average characteristic value of the maximum real-time force change rate of each historical step before the current step; A cranial drill control module is used to control the cranial drill to drill down in steps according to the first step, and to control the cranial drill to stop drilling when a first preset condition is met; the first preset condition includes: the real-time force peak value of the current step is greater than or equal to the historical maximum force value, and the ratio of the absolute value of the maximum value of the real-time force change rate of the current step to the average characteristic value of the force change is greater than a first threshold.

9. A cranial drilling device, characterized in that: It includes a controller, a robotic arm, an electric drill and a force sensor, wherein the robotic arm is used to drive the electric drill to move, the force sensor is used to detect the axial force of the electric drill, and the controller is used to execute the automatic drilling stop control method according to any one of claims 1 to 7.

10. The cranial drilling device according to claim 9, characterized in that: The electric drill includes a spherical drill bit, and the diameter of the spherical drill bit ranges from 0.5 mm to 2.0 mm.

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