A device for detecting lateral force state of a robot bone drilling tool and a method for using the same

Abstract

The present invention discloses a device for detecting the lateral force state of a robot bone drilling tool and a method for using the device. The device includes a linear drive mechanism and a tool rotary motor. The tool rotary motor is driven by the linear drive mechanism. The axis of the drilling tool passes through the measuring shaft of the axial force sensor, the hollow output shaft of the tool rotary motor, and the hollow hole of the axial force sensor in sequence from the back to the front, and the tool rotary motor can drive the drilling tool to rotate. The drilling tool portion passing through the axial force sensor is sleeved with a lateral force transmission mechanism whose tail end is fixed to the axial force sensor. A constraint protrusion is provided on the front inner wall of the lateral force transmission mechanism. When in use, the spatial coordinates of the tool rotary motor on the end of the robotic arm are determined and the tip of the drilling tool is returned to the origin. When performing a bone drilling operation, the tip offset of the drilling tool is automatically calculated. The device of the present invention can help the robot sense the lateral force of the drilling tool and calculate the degree of lateral offset of the drilling path.

Description

Technical Field

[0001] The present invention relates to the field of computer-assisted medical technology, and in particular to equipment used in robot-assisted deep bone tissue drilling surgery, specifically a device for detecting the lateral force state of a robot bone drilling tool and a method for using the device. Background Art

[0002] In recent years, robot-assisted bone drilling surgery has been widely used in clinical practice. Due to the different surface morphologies of bone tissue, the drilling action between the drill bit and the complex bone tissue will not only generate axial thrust and torque of the drill bit, but also lateral thrust. For minimally invasive drilling surgery of deep bone tissue, a slender drilling tool is often required to complete the drilling. The lateral thrust during the drilling process can easily cause the slender drill bit to bend laterally, thereby deviating from the predetermined surgical path. The surgical robot navigation system can only obtain the spatial position information of the tail of the drill bit. The robot system cannot perceive the deformation and displacement caused by the lateral force on the drill tip. The safety risks caused by this cannot be ignored.

[0003] The force sensing information of existing robotic systems during bone drilling mainly focuses on the axial thrust and torque of the drill bit. A typical example is the invention patent (application number: 201310676213) that installs a force sensor on the bone drilling feed unit. Its essence is to detect the thrust information of bone drilling. A research group at the University of Bern in Switzerland used the similarity between the thrust curve of the robot bone drilling process and the grayscale distribution curve of the CT image of the drilling path to estimate the actual path after the drilling offset. It also only used the thrust information of bone drilling (Williamson TM, Bell BJ, Gerber N, et al. Estimation of tool pose based on force-density correlation during robotic drilling [J]. IEEE Trans Biomed Eng, 2013, 60 (4): 969-976.). In addition, some surgical robot systems have a 6-axis force sensor installed at the tail end of the drill bit (a typical example is the French Rosa spine spinal surgical robot, which installs a 6-axis force sensor at the wrist of the robotic arm). Although the lateral force information of the drill tip will be contained in the force sensing information at the tail end, the drill bit force position is too far away from the sensor position. The intermediate mechanical transmission structure itself will couple other force information. At the same time, the coordinate relationship between the sensor force and the drill tip force also needs to be carefully calibrated.

[0004] The lateral force information of the drill bit during robotic bone drilling is of great significance for the robot to complete surgical tasks more safely. Existing technologies do not have a good solution to the problem of tool lateral force detection and deformation during the drilling process for minimally invasive drilling of deep bone tissue. Summary of the Invention

[0005] The purpose of the present invention is to provide a device for detecting the lateral force state of a robot bone drilling tool and a method for using the device in response to the problems existing in the prior art; the technical solution provided mainly solves two problems: first, a mechanical structure and a sensor device solution are provided to realize effective acquisition of the lateral force information of the drilling tool during the robot deep bone drilling process; second, a method for using the above-mentioned device is provided to solve the problem of calculating the lateral deformation displacement of the drilling tool from the lateral force sensing information of the drilling tool.

[0006] The purpose of the present invention is to be solved by the following technical solutions:

[0007] A device for detecting the lateral force state of a robot bone drilling tool is characterized in that: the device includes a linear drive mechanism, a tool rotating motor, an axial force sensor, and a lateral force sensor; the tool rotating motor is driven by the linear drive mechanism; an axial force sensor is provided at the tail end of the tool rotating motor and a lateral force sensor is provided at the front; the axis of the drilling tool passes through the measuring shaft of the axial force sensor, the hollow output shaft of the tool rotating motor, and the hollow hole of the lateral force sensor from the back to the front, and the tool rotating motor can drive the drilling tool to rotate; the drilling tool portion passing through the lateral force sensor is sleeved with a lateral force transmission mechanism whose tail end is fixed on the lateral force sensor; a constraint protrusion for constraining the lateral movement of the drilling tool is provided on the front inner wall.

[0008] Among them, the constraint protrusion is the first-level constraint, and the overall lateral force transmission mechanism is the second-level constraint. The constraint protrusion contacts the side wall of the drilling tool to obtain lateral force on the drilling tool. Under normal circumstances, the drilling tool will not contact other parts of the lateral force transmission mechanism, but only contact the protrusion, which is regarded as the first-level constraint; when the force is too large, the lateral force transmission mechanism will again constrain the deformation of the drilling tool, which is regarded as the second-level constraint.

[0009] The lateral force transmission mechanism includes a long lateral force transmission sleeve and a short lateral force contact sleeve. The rear inner wall of the lateral force contact sleeve and the front outer wall of the lateral force transmission sleeve are axially connected through precision threads. The rear end of the lateral force transmission sleeve is fixed to the lateral force sensor through a sleeve fixing seat, and the restraining protrusion is located on the front inner wall of the lateral force contact sleeve.

[0010] The axis of the lateral force transmission mechanism coincides with the axis of the hollow hole of the lateral force sensor.

[0011] The lateral force sensor is fixed on a lateral force sensor fixing bracket, and the L-shaped lateral force sensor fixing bracket is fixed on the front end of the feed motor bracket in the linear drive mechanism.

[0012] The tail end of the tool rotary motor is rigidly connected to the L-shaped rotary motor bracket through an axial force sensor, so that the tool rotary motor is suspended relative to the rotary motor bracket; the drilling tool chuck at the front end of the tool rotary motor is used to fix the drilling tool.

[0013] The linear drive mechanism includes a feed motor bracket, a feed motor, a screw coupling and a screw feed screw. The feed motor is installed at the tail of the feed motor bracket. The feed motor drives the screw feed screw through the screw coupling to drive the rotating motor bracket to complete the feed and retract movement along the drilling path. The rotating motor bracket and the screw feed screw constitute a screw nut structure.

[0014] The feed motor bracket is fixed to the end of the robotic arm of the bone drilling surgical robot through the robotic arm fixing flange at the bottom thereof.

[0015] The feed motor and tool rotation motor in the linear drive mechanism are respectively connected to the information control system through drivers, and the axial force sensor and lateral force sensor are respectively connected to the information control system through corresponding signal acquisition cards; the information control system is also connected to the bone drilling surgical robot system to read the coordinate information of the end of the mechanical arm of the bone drilling surgical robot and control the bone drilling surgical robot system.

[0016] A method for using a device for detecting the lateral force state of a robot bone drilling tool is characterized in that the method comprises the following steps:

[0017] The first step is to fix the lateral force state detection device of the robot bone drilling tool to the end of the robot arm of the bone drilling surgical robot, determine the relative position of the robot arm end coordinate system and the axis of the tool rotation motor, and read the spatial coordinates and axis direction of the tool rotation motor origin O at any time;

[0018] Step 2: Keep the tip of the drilling tool and the front end of the lateral force contact sleeve in the same position;

[0019] The third step is to perform bone drilling according to the surgical plan. At any time when measurement is required, the information control system can read the current drill feed rate of the drilling tool from the linear drive mechanism. fead , read the Z-axis thrust F from the axial force sensor z_origin , and torque M z_origin , read the force F in the X-axis and Y-axis directions from the lateral force sensor x_radial 、F y_radial ;

[0020] Step 4: Calculate the tip offset of the drilling tool during lateral force application based on the data read out in step 3.

[0021] In this method of use, the lateral force information during the drilling process of the bone drilling surgical robot can be directly visualized based on the data read out in the third step.

[0022] The tip offset is calculated as:

[0023] A. Replacement of sensor data to tip force data variables of drilling tool:

[0024]

[0025] In formula (1) and (2): F x_radial 、F y_radial is the lateral force on the tip of the drilling tool along the X-axis and Y-axis directions at the moment of measurement read by the lateral force sensor, F z_origin F is the axial force data of the drilling tool tip along the Z axis read by the axial force sensor; x_tip 、F y_tip 、F z_tip 、M x_tip 、M y_tip 、M z_tip are the measured values ​​of force and torque on the tip of the drilling tool along the XYZ directions, respectively. Since there is no lateral torque on the tip of the drilling tool during the drilling process, M x_tip 、M y_tip , are all 0; F x 、F y 、F z are the replaced variables, representing the forces on the drilling tool in the X, Y, and Z axis directions, which are used in subsequent calculations;

[0026] B. Calculation of axial equivalent moment and moment of inertia of drilling tool tip:

[0027] Equivalent axial moment M of the drilling tool tip zd for:

[0028] M zd =M z +θ x M y +θ y M x (3)

[0029] In formula (3): θ x ,θ y are the deformation angles of the drilling tool tip in the XYZ coordinate system;

[0030]

[0031] In formula (4): I is the moment of inertia, D is the diameter of the drilling tool, and π is the pi;

[0032] C. Variable normalization calculation:

[0033] The measured values ​​are normalized according to the following formula:

[0034]

[0035] In formula (5): E is the Young's modulus of the drilling tool, m x 、m y 、m zd is the normalized torque, f x 、f y 、f z is the normalized force, u x 、u y 、u z is the normalized drilling tool tip displacement, l = l fead +s, where l is the length from the tip of the drilling tool to the constraint point where the annular protrusion is located, l fead is the drilling tool feed rate, s is the length from the lateral force contact sleeve to the constraint point where the annular protrusion is located;

[0036] D. Calculation of normalized drilling tool tip lateral deformation, rotation angle, and axial deformation

[0037] Let variable g = [f y m x f x m y ] T 、v=[u y θ x u x θ y ] T , then the relationship between the lateral deformation vector v of the drilling tool and the lateral force vector g of the drilling tool is:

[0038]

[0039] The axial deformation relationship of the drilling tool is:

[0040]

[0041] Formula (6) is a linear equation system. With g as input, the lateral deformation vector v of the drilling tool is calculated according to formula (8). Substituting v into formula (7) can directly solve the axial deformation u of the drilling tool. z ;

[0042]

[0043] In formulas (6) and (7): k′ 33 、k 44 And H1, H2, H3, H4, H5, H6, H7 are all calculation coefficients; k'33 、k 44 Preferred: in, G is the shear modulus of the drilling tool material;

[0044]

[0045] E. Calculation and recovery of absolute values ​​of lateral deformation, angular and axial deformation of the drilling tool tip:

[0046] According to the value of the lateral deformation vector v of the drilling tool and the axial deformation u of the drilling tool calculated in step D z The value of is substituted into the relationship (5) to solve the actual offset of the drilling tool tip U x =u x l、U y =u y l、U z =u z l, where U x 、U y That is, the lateral displacement of the drilling tool tip relative to the ideal position under the action of lateral force during the bone drilling process. Based on this lateral displacement value, the lateral deformation value of the drilling tool during the deep bone drilling process of the robot can be calculated.

[0047] Compared with the prior art, the present invention has the following advantages:

[0048] The robot bone drilling tool lateral force state detection device of the present invention can help the bone drilling surgical robot sense the lateral force of the drilling tool and calculate the lateral deviation degree of the drilling path. When facing the minimally invasive bone cutting task of complex bone tissue deep in the human body, it can help the surgical robot better cope with the minimally invasive bone cutting task of complex bone tissue deep in the human body, enhance the robot's perception and understanding of the deformation and displacement caused by the lateral force of the drilling tool tip, and improve the safety and intelligence of the robot's complex bone drilling surgery. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Attachment Figure 1 This is a schematic diagram of the combined structure of the power part and the sensor part of the lateral force state detection device of the robot bone drilling tool of the present invention;

[0050] Attachment Figure 2 For attachment Figure 1 Schematic diagram of the cross-section structure;

[0051] Attachment Figure 3 For attachment Figure 2 Schematic diagram of the enlarged structure of part A;

[0052] Attachment Figure 4 For attachment Figure 3 Schematic diagram of the enlarged structure of part B;

[0053] Attachment Figure 5 This is a front view of the connection structure between the robot bone drilling tool lateral force state detection device and the end of the robot arm of the bone drilling surgical robot of the present invention;

[0054] Attachment Figure 6 A side view of the connection structure between the robot bone drilling tool lateral force state detection device and the end of the robot arm of the bone drilling surgical robot of the present invention;

[0055] Attachment Figure 7 Schematic diagram of the relationship between the forces on various parts and the axial force sensor and the lateral force sensor during the lateral deformation and offset process of the drilling tool in an embodiment of the present invention.

[0056] Among them: 1—Robot arm fixing flange; 2—Feed motor bracket; 3—Feed motor; 4—Screw coupling; 5—Feed screw; 6—Lateral force sensor fixing bracket; 7—Rotation motor bracket; 8—Axial force sensor; 9—Tool rotation motor; 10—Drilling tool chuck; 11—Lateral force sensor; 12—Sleeve fixing seat; 13—Lateral force transmission sleeve; 14—Lateral force contact sleeve; 15—Constraint protrusion; 16—Drilling tool. DETAILED DESCRIPTION

[0057] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0058] like Figure 1-6 As shown: A robot bone drilling tool lateral force state detection device is characterized in that: the device includes a linear drive mechanism, a tool rotating motor 9, an axial force sensor 8, and a lateral force sensor 11. The tool rotating motor 9 is driven by a linear drive mechanism. The axial force sensor 8 is set at the tail end of the tool rotating motor 9 and the lateral force sensor 11 is set at the front. The axis of the drilling tool 16 passes through the measuring axis of the axial force sensor 8, the hollow output shaft of the tool rotating motor 9, and the hollow hole of the lateral force sensor 11 from the back to the front, and the tool rotating motor 9 can drive the drilling tool 16 to rotate; the part of the drilling tool 16 passing through the lateral force sensor 11 is sleeved with a lateral force transmission mechanism whose tail end is fixed on the lateral force sensor 11, and a constraint protrusion 15 for constraining the lateral movement of the drilling tool 16 is provided on the front end inner wall of the lateral force transmission mechanism, wherein the constraint protrusion 15 is a primary constraint and the overall lateral force transmission mechanism is a secondary constraint.

[0059] The lateral force state detection device of the robotic bone drilling tool also involves a control part. The feed motor 3 and the tool rotation motor 9 in the linear drive mechanism are respectively connected to the information control system through the driver, and the axial force sensor 8 and the lateral force sensor 11 are respectively connected to the information control system through the corresponding signal acquisition cards; the information control system is also connected to the bone drilling surgical robot system to read the coordinate information of the end of the mechanical arm of the bone drilling surgical robot and control the bone drilling surgical robot system.

[0060] like Figure 1-4 As shown, in the above-mentioned device, the lateral force sensor 11 is fixed on the lateral force sensor fixing bracket 6, the L-shaped lateral force sensor fixing bracket 6 is fixed to the front end of the feed motor bracket 2 in the linear drive mechanism, and the axis of the lateral force transmission mechanism coincides with the axis of the hollow hole of the lateral force sensor 11; further, the lateral force transmission mechanism includes a long lateral force transmission sleeve 13 and a short lateral force contact sleeve 14, the tail inner wall of the lateral force contact sleeve 14 and the front outer wall of the lateral force transmission sleeve 13 are axially connected by precision threads, the tail end of the lateral force transmission sleeve 13 is fixed to the lateral force sensor 11 through the sleeve fixing seat 12, and the restraining protrusion 15 is located on the front inner wall of the lateral force contact sleeve 14.

[0061] like Figure 1-2 As shown in , 5-6, the linear drive mechanism includes a feed motor bracket 2, a feed motor 3, a screw coupling 4 and a screw feed screw 5. The feed motor bracket 2 is fixed to the end of the robot arm of the bone drilling surgical robot through the robot arm fixing flange 1 at its bottom, and the feed motor 3 is installed at the tail of the feed motor bracket 2. The feed motor 3 drives the screw feed screw 5 through the screw coupling 4 to drive the rotating motor bracket 7 to complete the feeding and retracting movement along the drilling path. The rotating motor bracket 7 and the screw feed screw 5 constitute a screw nut structure; the tail end of the tool rotating motor 9 is rigidly connected to the L-shaped rotating motor bracket 7 through the axial force sensor 8, so that the tool rotating motor 9 is in a suspended state relative to the rotating motor bracket 7. The drilling tool chuck 10 at the front end of the tool rotating motor 9 is used to fix the drilling tool 16.

[0062] A method for using a device for detecting the lateral force state of a robot bone drilling tool, the steps of the method are as follows:

[0063] The first step is to fix the lateral force state detection device of the robot bone drilling tool to the end of the robot arm of the bone drilling surgical robot, and determine the relative position of the coordinate system of the end of the robot arm and the axis of the tool rotary motor 9 by mechanical measurement or calibration. In this way, the spatial coordinates and axis direction of the origin O of the tool rotary motor 9 at any time can be directly read from the end of the robot arm;

[0064] Step 2: Adjust the position of the drilling tool 16 by the feed motor 3 so that the tip of the drilling tool 16 and the front end of the lateral force contact sleeve 14 maintain the same position;

[0065] The third step is to control the bone drilling surgical robot system, the linear drive mechanism and the tool rotation motor 9 to perform the bone drilling operation according to the surgical plan. At any time when measurement is required, the information control system can read the current drill feed rate l of the drilling tool 16 from the linear drive mechanism. fead , read the Z-axis thrust F from the axial force sensor 8 z_origin , and torque M z_origin , read the force F in the X-axis and Y-axis directions from the lateral force sensor 11 x_radial 、F y_radial ;

[0066] Step 4: Calculate the tip offset of the drilling tool 16 during lateral force based on the data read out in step 3. Also, directly visualize the lateral force information during the drilling process of the bone drilling surgical robot based on the data read out in step 3.

[0067] The tip offset in step 4 is calculated as:

[0068] A. Replacement of sensor data to tip force data variables of drilling tool:

[0069]

[0070] In formula (1) and (2): F x_radial 、F y_radial is the lateral force on the tip of the drilling tool along the X-axis and Y-axis directions at the moment of measurement read by the lateral force sensor, F z_origin F is the axial force data of the drilling tool tip along the Z axis read by the axial force sensor; x_tip 、F y_tip 、F z_tip 、M x_tip 、M y_tip 、M z_tip are the measured values ​​of force and torque on the tip of the drilling tool along the XYZ directions, respectively. Since there is no lateral torque on the tip of the drilling tool during the drilling process, M x_tip 、M y_tip , are all 0; F x 、F y 、F z are the replaced variables, representing the forces on the drilling tool in the X, Y, and Z axis directions, which are used in subsequent calculations;

[0071] B. Calculation of axial equivalent moment and moment of inertia of drilling tool tip:

[0072] Equivalent axial moment M of the drilling tool tip zd for:

[0073] M zd =M z +θ x M y +θ y M x (3)

[0074] In formula (3): θ x ,θ y are the deformation angles of the drilling tool tip in the XYZ coordinate system;

[0075]

[0076] In formula (4): I is the moment of inertia, D is the diameter of the drilling tool, and π is the pi;

[0077] C. Variable normalization calculation:

[0078] The measured values ​​are normalized according to the following formula:

[0079]

[0080] In formula (5), E is the Young's modulus of the drilling tool, l is the drilling tool feed rate, m x 、m y 、m zd is the normalized torque, f x 、f y 、f z is the normalized force, u x 、u y 、u z is the normalized drilling tool tip displacement, l = l fead +s is the length from the tip of the drilling tool to the constraint point where the circular protrusion is located;

[0081] D. Calculation of normalized drilling tool tip lateral deformation, rotation angle, and axial deformation

[0082] Let variable g = [f y m x f x m y ] T 、v=[u y θ x u x θ y ] T , then the relationship between the lateral deformation vector v of the drilling tool and the lateral force vector g of the drilling tool is:

[0083]

[0084] The axial deformation relationship of the drilling tool is:

[0085]

[0086] Formula (6) is a linear equation system. With g as input, the lateral deformation vector v of the drilling tool is calculated according to formula (8). Substituting v into formula (7) can directly solve the axial deformation u of the drilling tool. z ;

[0087] In formulas (6) and (7): k′ 33 、k 44 And H1, H2, H3, H4, H5, H6, H7 are all calculation coefficients; k' 33 、k 44 Preferred: in, G is the shear modulus of the drilling tool material;

[0088]

[0089] E. Calculation and recovery of absolute values ​​of lateral deformation, angular and axial deformation of the drilling tool tip:

[0090] According to the value of the lateral deformation vector v of the drilling tool and the axial deformation u of the drilling tool calculated in step D z The value of is substituted into the relationship (5) to solve the actual offset of the drilling tool tip U x =u x l、U y =u y l、U z =u z l, where U x 、U y That is, the lateral displacement of the drilling tool tip relative to the ideal position under the action of lateral force during the bone drilling process. Based on this lateral displacement value, the lateral deformation value of the drilling tool during the deep bone drilling process of the robot can be calculated.

[0091] Example

[0092] like Figure 1-6 As shown, the present invention provides a device for detecting the lateral force state of a robot bone drilling tool. The device as a whole is composed of a bone drilling power part, a bone drilling force sensing part and an information control part.

[0093] The bone drilling power unit has two degrees of freedom: feed and rotation. The feed degree of freedom consists of a feed motor 3, a screw coupling 4, a screw feed screw 5, and a rotary motor bracket 2. The feed motor 3 and screw feed screw 5 are mounted on the feed motor bracket 2, with the screw coupling 4 mounted between the output shaft of the feed motor 3 and the screw feed screw 5. The feed motor 3 is a servo motor. The feed motor 3 drives the screw feed screw 5 through the screw coupling 4, driving the rotary motor bracket 2 to complete the feed and retract motion along the drilling path. The rotational freedom is composed of a rotating motor bracket 2, an axial force sensor 8, a tool rotating motor 9 with a hollow shaft, and a drilling tool chuck 10. The rotating motor bracket 2 and the tail end of the tool rotating motor 9 are rigidly connected by the axial force sensor 8, and the rotation axis of the tool rotating motor 9 coincides with the measuring axis of the axial force sensor 8; the measuring axis of the axial force sensor 8 is parallel to the feed motion direction of the rotating motor bracket 2, so that the axial thrust and torque exerted on the tool rotating motor 9 during the rotation process can be measured by the axial force sensor 8; the output shaft of the tool rotating motor 9 is a hollow shaft with an inner diameter greater than 5mm, and the drilling tool 16 (drill bit or Kirschner wire) can pass through the hollow shaft of the above-mentioned tool rotating motor 9, and the two are fixed by the drilling tool chuck 10; the clamping diameter of the drilling tool chuck 10 is adjustable, and the adjustment range is 0 to 5mm. ; The other end of the drilling tool 16 is laterally constrained by a lateral force transmission mechanism composed of a lateral force transmission sleeve 13 and a lateral force contact sleeve 14, wherein the lateral force transmission sleeve 13 is hollow and its inner diameter is more than 1 mm larger than the diameter of the drilling tool 16, one end of the lateral force transmission sleeve 13 is rigidly connected to the lateral force sensor 11 through a sleeve fixing seat 12, and the other end is axially connected to the lateral force contact sleeve through a precision thread, the lateral force sensor 11 is fixed to the feed motor bracket 2 through a lateral force sensor fixing bracket 6, the lateral force sensor 11 is a hollow six-axis sensor (the measuring axes in the three directions of XYZ are orthogonal, and the intersection is located on the hollow axis), the inner diameter of the hollow hole of the lateral force sensor 11 is greater than 5 mm, and the axis of the hollow hole of the lateral force sensor 11 coincides with one of the force-bearing lateral axes (the Z axis is selected in this scheme). The axis of the lateral force transmission sleeve 13 coincides with the axis of the hollow hole of the lateral force sensor 11; the inner diameter of the lateral force contact sleeve 14 is consistent with the inner diameter of the lateral force transmission sleeve 13, and a circular constraint protrusion 15 is arranged on the inner wall of the lateral force contact sleeve 14 close to the tip of the drilling tool 16. The constraint protrusion 15 and the drilling tool 16 are clearance fit (recommended fit F8 / h7), so that the drilling tool 16 can perform axial feed rotation under the constraint of the circular constraint protrusion 15, but the lateral movement of the drilling tool 16 is constrained by the constraint protrusion 15; the distance between the constraint protrusion 15 and the end of the lateral force contact sleeve 14 is in the range of 2-5mm, requiring that when the drilling tool 16 produces the maximum deformation within the allowable range, it can still ensure that the front end side wall only contacts the constraint protrusion 15, and does not contact the inner wall of the end of the lateral force contact sleeve 14.The entire bone drilling power part is fixed to the end of the robotic arm through the robotic arm fixing flange 1.

[0094] The bone drilling force sensing part is composed of an axial force sensor 8 and a lateral force sensor 11. The arrangement of the axial force sensor 8 and the lateral force sensor 11 has been described in the bone drilling power part. The force information of the robot's drilling tool 16 is measured separately by two sensors. Among them, the axial force sensor 8 is responsible for measuring the axial thrust and torque information of the drilling tool 16 during the drilling process. The axial force of the drilling tool 16 is transmitted to the axial force sensor 8 by the drilling tool 16, the drilling tool chuck 10, and the tool rotation motor 9. The lateral force sensor 11 is responsible for measuring the lateral force information of the drilling tool 16. The lateral force information of the drilling tool 16 is transmitted to the lateral force sensor 11 by the constraint protrusion 15 of the drilling tool 16 and the lateral force contact sleeve 14, the lateral force transmission sleeve 13, and the sleeve fixing seat 12. Based on the designed structure and sensor arrangement, the force applied to the tip of the drilling tool 16 in the XYZ directions during the bone drilling process can be directly measured by the axial force sensor 8 and the lateral force sensor 11 .

[0095] The information control system consists of a computer or other computing device. The feed motor 3 and tool rotation motor 9 in the linear drive mechanism are connected to the information control system via drivers. The axial force sensor 8 and lateral force sensor 11 are connected to the information control system via corresponding signal acquisition cards. The information control system can read the feed and rotation value changes caused by the motor movement in the power system, as well as the sampled data from the sensors. The information control system is also connected to the bone drilling surgical robot system to read the coordinate information of the robot's robotic arm and control the bone drilling surgical robot system.

[0096] Calculation Case

[0097] The detection device provided by the present invention is installed on the end of the robot arm of the bone drilling surgical robot, and the angle is set to drill towards a certain bone block, and the drilling tool completes the drilling. At a certain moment, the lateral force sensor 11 measures the lateral thrust to be: F x_radial =0.5N, F y_radial =4.5N, the Z-axis thrust F obtained from the axial force sensor 8 z_origin =10N, torque is M z_origin =0.3N·m, the diameter of the drilling tool D = 3mm; the feed rate of the drilling tool l fead = 80 mm; the distance s between the restraining protrusion 15 and the end of the lateral force contact sleeve 14 is 4 mm; the Young's modulus of the drilling tool is E = 194 × 10 9 Pa.

[0098] The tool offset calculation can be completed according to the method for calculating the tip offset of the drilling tool provided by the present invention:

[0099] A. Replacement of sensor data to tip force data variables of drilling tool:

[0100]

[0101] B. Calculation of axial equivalent moment and moment of inertia of drilling tool tip:

[0102] Equivalent axial moment M of the drilling tool tip zd for:

[0103] M zd =M z +θ x M y +θ y M x =M z =0.3N·m (3);

[0104] The moment of inertia I is:

[0105]

[0106] C. Variable normalization calculation:

[0107] The measured values ​​are normalized according to the following formula:

[0108] The length from the tool tip to the constraint point where the annular protrusion is located is l = l fead +s=80mm+4mm=54mm,

[0109]

[0110] D. Calculation of normalized drilling tool tip lateral deformation, rotation angle, and axial deformation

[0111] From the above, we can know that the lateral force vector of the drilling tool is g = [f y m x f x m y ] T =[0.2084 0 0.2547 0], Taking g as input, the lateral deformation vector v of the drilling tool is calculated according to formula (8) = [u y θ x u x θ y ] T=[0.013, 0.020, 0.017, -0.025], where the lateral deformations are 0.013 and 0.017, and the lateral rotation angles are -0.0251 and 0.0196 respectively;

[0112]

[0113] Substitute the above values ​​into the following formula:

[0114]

[0115] The calculation shows that the axial deformation of the drilling tool is about -0.0002. Note that all calculation results in this section are normalized values ​​without units.

[0116] E. Calculation and recovery of absolute values ​​of lateral deformation, angular and axial deformation of the drilling tool tip:

[0117] According to the value of the lateral deformation vector v of the drilling tool and the axial deformation u of the drilling tool calculated in step D z The value of is substituted into equation (5) to solve the actual offset of the drilling tool tip:

[0118] U x =u x l = 0.0014m ≈ 1.4mm (lateral offset in the x direction),

[0119] U y =u y l = 0.0011m ≈ 1.1mm (lateral offset in the y direction),

[0120] U z =u z l = -1.26 × 10 -5 m≈-1.26×10 -2 mm (axial offset in z direction).

[0121] The above is a calculation case of the present invention in one situation. The calculation results are only used to demonstrate the use process of the technical solution of the invention. The specific numerical results have no practical significance in specific situations.

[0122] The robot bone drilling tool lateral force state detection device of the present invention can help the bone drilling surgical robot sense the lateral force of the drilling tool and calculate the lateral deviation degree of the drilling path. When facing the minimally invasive bone cutting task of complex bone tissue deep in the human body, it can help the surgical robot better cope with the minimally invasive bone cutting task of complex bone tissue deep in the human body, enhance the robot's perception and understanding of the deformation and displacement caused by the lateral force of the drilling tool tip, and improve the safety and intelligence of the robot's complex bone drilling surgery.

[0123] The above embodiments are only for illustrating the technical ideas of the present invention and cannot be used to limit the scope of protection of the present invention. Any changes made on the basis of the technical solutions in accordance with the technical ideas proposed by the present invention fall within the scope of protection of the present invention; any technologies not involved in the present invention can be implemented by existing technologies.

Claims

1. A device for detecting the lateral force state of a robot bone drilling tool, characterized by: The device comprises a linear drive mechanism, a tool rotating motor (9), an axial force sensor (8), and a lateral force sensor (11). The tool rotating motor (9) is driven by the linear drive mechanism. The axial force sensor (8) is arranged at the tail end of the tool rotating motor (9), and the lateral force sensor (11) is arranged at the front. The axis of the drilling tool (16) passes through the measuring shaft of the axial force sensor (8), the hollow output shaft of the tool rotating motor (9), and the hollow hole of the lateral force sensor (11) in sequence from the rear to the front. The tool rotating motor (9) can drive the drilling tool (16) to rotate. The drilling tool passing through the lateral force sensor (11) The tool (16) is partially sleeved with a lateral force transmission mechanism whose tail end is fixed on the lateral force sensor (11); a restraining protrusion (15) for restraining the lateral movement of the drilling tool (16) is provided on the front inner wall of the lateral force transmission mechanism; the restraining protrusion (15) and the drilling tool (16) are clearance-matched, so that the drilling tool (16) can perform axial feed rotational movement under the restraint of the annular restraining protrusion (15), but the lateral movement of the drilling tool (16) is restrained by the restraining protrusion (15); it is required that when the drilling tool (16) produces the maximum deformation within the allowable range, it is still ensured that the front side wall is only in contact with the restraining protrusion (15); The restraining protrusion (15) is a primary restraint, and the entire lateral force transmission mechanism is a secondary restraint; the axis of the lateral force transmission mechanism coincides with the axis of the hollow hole of the lateral force sensor (11); the lateral force transmission mechanism comprises a long lateral force transmission sleeve (13) and a short lateral force contact sleeve (14); the rear inner wall of the lateral force contact sleeve (14) and the front outer wall of the lateral force transmission sleeve (13) are axially connected by a precision thread; the rear end of the lateral force transmission sleeve (13) is fixed to the lateral force sensor (11) by a sleeve fixing seat (12); the restraining protrusion (15) is located on the front inner wall of the lateral force contact sleeve (14); The steps for using the device are as follows: The first step is to fix the lateral force state detection device of the robot bone drilling tool to the end of the robot arm of the bone drilling surgical robot, determine the relative position of the coordinate system of the end of the robot arm and the axis of the tool rotating motor (9), and read the spatial coordinates and axis direction of the origin O of the tool rotating motor (9) at any time; Step 2: Keep the tip of the drilling tool (16) and the front end of the lateral force contact sleeve (14) in the same position; Step 3: At any time when measurement is required, the information control system can read the current drill feed rate l of the drilling tool (16) from the linear drive mechanism. fead , read the Z-axis thrust F from the axial force sensor (8) z_origin , and torque M z_origin , read the force F in the X-axis and Y-axis directions from the lateral force sensor (11) x_radial 、F y_radial ; Step 4: Calculate the tip offset of the drilling tool (16) during the lateral force process based on the data read out in step 3; The tip offset is calculated as: A. Replacement of sensor data to tip force data variables of drilling tool: In formula (1) and (2): F x_radial 、F y_radial is the lateral force on the tip of the drilling tool along the X-axis and Y-axis directions at the moment of measurement read by the lateral force sensor, F z_origin F is the axial force data of the drilling tool tip along the Z axis read by the axial force sensor; x_tip 、F y_tip 、F z_tip 、M x_tip 、M y_tip 、M z_tip are the measured values ​​of force and torque on the tip of the drilling tool along the XYZ axis. Since there is no lateral torque on the tip of the drilling tool during the drilling process, M x_tip 、M y_tip , are all 0; F x 、F y 、F z are the replaced variables, representing the forces on the drilling tool in the XYZ axis directions; B. Calculation of axial equivalent moment and moment of inertia of drilling tool tip: Equivalent axial moment M of the drilling tool tip zd for: M zd =M z +θ x M y +θ y M x (3) In formula (3): θ x ,θ y are the deformation angles of the drilling tool tip in the XYZ coordinate system; In formula (4): I is the moment of inertia, D is the diameter of the drilling tool, and π is the pi; C. Variable normalization calculation: The measured values ​​are normalized according to the following formula: In formula (5): E is the Young's modulus of the drilling tool, m x 、m y 、m zd is the normalized torque, f x 、f y 、f z is the normalized force, u x 、u y 、u z is the normalized drilling tool tip displacement, l = l fead +s, where l is the length from the tip of the drilling tool to the constraint point where the annular protrusion is located, l fead is the drilling tool feed rate, s is the length from the lateral force contact sleeve to the constraint point where the annular protrusion is located; D. Calculation of normalized drilling tool tip lateral deformation, rotation angle, and axial deformation Let variable g = [f y m x f x m y ] T 、v=[u y θ x u x θ y ] T , then the relationship between the lateral deformation vector v of the drilling tool and the lateral force vector g of the drilling tool is: The axial deformation relationship of the drilling tool is: Formula (6) is a linear equation system. With g as input, the lateral deformation vector v of the drilling tool is calculated according to formula (8). Substituting v into formula (7) can directly solve the axial deformation u of the drilling tool. z ; In formula (6) and (7): k' 33 、k 44 and H1, H2, H3, H4, H5, H6, and H7 are all calculation coefficients; k' 33 、k 44 Pick: in, G is the shear modulus of the drilling tool material; E. Calculation and recovery of absolute values ​​of lateral deformation, angular and axial deformation of the drilling tool tip: According to the value of the lateral deformation vector v of the drilling tool and the axial deformation u of the drilling tool calculated in step D z The value of is substituted into the relationship (5) to solve the actual offset of the drilling tool tip U x =u x l、U y =u y l、U z =u z l, where U x 、U y That is, the lateral displacement of the drilling tool tip relative to the ideal position under the action of lateral force during the bone drilling process. Based on this lateral displacement value, the lateral deformation value of the drilling tool during the deep bone drilling process of the robot can be calculated.

2. The device for detecting the lateral force state of a robot bone drilling tool according to claim 1, characterized in that: The lateral force sensor (11) is fixed on a lateral force sensor fixing frame (6), and the L-shaped lateral force sensor fixing frame (6) is fixed to the front end of a feed motor bracket (2) in the linear drive mechanism.

3. The device for detecting the lateral force state of a robot bone drilling tool according to claim 1, wherein: The tail end of the tool rotary motor (9) is rigidly connected to the L-shaped rotary motor bracket (7) via an axial force sensor (8), so that the tool rotary motor (9) is in a suspended state relative to the rotary motor bracket (7); the drilling tool chuck (10) at the front end of the tool rotary motor (9) is used to fix the drilling tool (16).

4. The device for detecting the lateral force state of a robot bone drilling tool according to claim 1 or 3, characterized in that: The linear drive mechanism comprises a feed motor bracket (2), a feed motor (3), a screw coupling (4) and a screw advance screw (5); the feed motor (3) is mounted at the tail of the feed motor bracket (2); the feed motor (3) drives the screw advance screw (5) through the screw coupling (4) to drive the rotating motor bracket (7) to complete the feed and retract motion along the drilling path; the rotating motor bracket (7) and the screw advance screw (5) constitute a screw nut structure.

5. The device for detecting the lateral force state of a robot bone drilling tool according to claim 4, characterized in that: The feed motor bracket (2) is fixed to the end of the robotic arm of the bone drilling surgical robot via the robotic arm fixing flange (1) at the bottom thereof.

6. The device for detecting the lateral force state of a robot bone drilling tool according to claim 1, characterized in that: The feed motor (3) and the tool rotation motor (9) in the linear drive mechanism are respectively connected to the information control system via a driver, and the axial force sensor (8) and the lateral force sensor (11) are respectively connected to the information control system via corresponding signal acquisition cards; the information control system is also connected to a bone drilling surgical robot system to read the coordinate information of the end of the mechanical arm of the bone drilling surgical robot and control the bone drilling surgical robot system.

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