A control method of a multi-degree-of-freedom mechanical arm radiotherapy bed

Abstract

The application relates to a control method of a multi-degree-of-freedom mechanical arm radiotherapy bed, wherein the multi-degree-of-freedom mechanical arm radiotherapy bed reduces the height of the bed through a joint arm structure and realizes six-dimensional movement through a series-parallel combined structure, so that the complexity of the radiotherapy bed system is reduced, and the installation difficulty is reduced. The control method plans a safe and effective space by establishing a forward and inverse kinematics model of the radiotherapy bed, realizes real-time accurate positioning control of a patient in a treatment area, improves the automation degree of the equipment, and carries out differential treatment for different patients.

Description

TECHNICAL FIELD

[0001] The present application relates to the medical field, and in particular to a control method of a multi-degree-of-freedom mechanical arm radiotherapy bed. BACKGROUND

[0002] The treatment bed of a radiotherapy device is a multi-axis motion platform, which is mainly used to accurately move a patient to a treatment position according to a treatment plan. At present, most treatment beds are installed in a pit in a control room to reduce the height of the bed, and the mechanical design structure is complex and the wiring is complicated. The radiotherapy bed mainly based on a joint arm has a simple structure, can effectively reduce the height of the bed, and avoids the pit in the hospital control room. Therefore, in order to improve the adaptability of the Gamma Knife device, it is necessary to provide a control method of a multi-degree-of-freedom mechanical arm radiotherapy bed, which realizes six-dimensional pose adjustment of a patient through a series-parallel combined structure, ensures the effectiveness of the treatment process, and reduces the irradiation dose of the patient. SUMMARY

[0003] To solve the above technical problems in the background art, the present application provides a new control method for a multi-degree-of-freedom mechanical arm radiotherapy bed, which reduces the height of the bed through a joint arm structure and realizes six-dimensional motion through a series-parallel combined structure, thereby reducing the complexity of the treatment bed system and the installation difficulty.

[0004] The technical solution of this invention is as follows: This invention is a control method for a multi-degree-of-freedom robotic arm radiotherapy bed, characterized in that: the multi-degree-of-freedom robotic arm radiotherapy bed includes an X-axis component, an articulated arm component, a Y-axis component, and a calibration component. The articulated arm component is disposed on the X-axis component, and the calibration component and the Y-axis component are respectively disposed on the articulated arm component. The X-axis component includes an X-axis base, an X-axis linear guide, and an X-axis transmission component; both the X-axis linear guide and the X-axis transmission component are disposed on the X-axis base, and the articulated arm component is disposed on the X-axis linear guide and the X-axis transmission component. The articulated arm component includes a base, a first robotic arm, a first axis drive, a second robotic arm, a second axis drive, a third axis drive, a third robotic arm, a fourth axis drive, a fourth robotic arm, and a fifth axis drive. The system includes a moving and Y-axis connecting seat; a first robotic arm is connected to the base via a first axis drive, a second robotic arm is connected to the first robotic arm via a second axis drive, a third robotic arm is connected to the second robotic arm via a third axis drive, a fourth robotic arm is connected to the third robotic arm via a fourth axis drive, and the Y-axis connecting seat is connected to the fourth robotic arm via a fifth axis drive. The first axis drive connects the first robotic arm and the base to form a first rotary joint, the second axis drive connects the first and second robotic arms to form a second rotary joint, the third axis drive connects the second and third robotic arms to form a third rotary joint, the fourth axis drive connects the third and fourth robotic arms to form a fourth rotary joint, and the fifth axis drive connects the fourth robotic arm to form a fifth rotary joint. The control method includes the following steps:

[0005] 1) A multi-degree-of-freedom robotic arm coordinate system is established using the improved DH method. The axis of each joint is sequentially determined as the Z direction, and the X and Y directions are determined according to the right-hand rule. The relevant parameters for the transformation relationship between two adjacent joint axes are: alpha i-1 For X i-1 Axis, from Z i-1 Rotate to the angle of Zi, a i-1 For along X i-1 Axis, from Z i-1 Move to Z i The distance, theta i To circle around Z i Axis, from X i-1 Rotate to X i The angle, di, is along the Zi axis from X i-1 Move to X i The distances, where a1, a2, a3, d1, and d5 are determined according to the joint configuration design;

[0006] 2) Based on the forward kinematics method of the robotic arm, the end-effector pose matrix T(p) of the multi-degree-of-freedom robotic arm is obtained through translation and rotation of the base coordinate system. This is then sequentially processed by the homogeneous matrices T(i-1, ..., ...) of two adjacent rotary joints.

[0007] i) = Rx(ai-1) * Dx(ai-1) * Rz(θi) * Dz(di) is obtained by multiplication, (i = 1, 2, 3, 4, 5), wherein Rx, Rz are rotation matrices, and Dx and Dz are translation matrices;

[0008] T(p) = T(0, 1) * T(1, 2) * T(2, 3) * T(3, 4) * T(4, 5) (Formula 1) is obtained according to the above formula:

[0009]

[0010] wherein S1 = sin(θ1), C 234 = cos(θ2 + θ3 + θ4), and other expressions are similar;

[0011] S1S5 + C 234 C1C5 = Nx, C5S1 - C 234 C1S5 = Ox, S 234 C1 = Ax, C 234 C5S1 - C1S5 = Ny, -C1C5 - C 234 S1S5 = Oy,

[0012] S 234 S1 = Ay, S 234 C5 = Nz, -S 234 S5 = Oz, -C 234 = Az; [N, O, A] is an attitude vector of the end of the mechanical arm; 1, C1(a1 + a3C 23 + a2C2 + d5S 234 ) = Px, S1(a1 + a3C 23 + a2C2 + d5S 234 ) = Py, d1 + a3S 23 + a2S2 - d5C 234 = Pz; [Px, Py, Pz] is a position coordinate of the end;

[0013] 3) an inverse solution model M of the multi-degree-of-freedom mechanical arm is established 1；

[0014] T(0, 1) is obtained by multiplying the inverse matrix of T(1) on the left of formula 1 -1 * T(p) = T(2, 3) * T(3, 4) * T(4, 5) (Formula 2), P is obtained according to the matrix correspondence y cos(θ1) - P x sin(θ1) = 0, the rotation angle θ1 of the first rotation joint = arctan(Py, Px),

[0015] is obtained according to the matrix correspondence Substituting θ1, we get the rotation angle θ5 of the fifth rotation joint = arctan(-sin(θ5),-cos(θ5));

[0016] Multiplying Equation 2 by the inverse of T(4,5) on the right yields T(0,1). -1 *T(p)*T(4,5) -1 =T(1,2)*T(2,3)*T(3,4) (Equation 3), obtained according to the matrix correspondence.

[0017]

[0018] The rotation angle θ3 of the third rotary joint is arctan(s31,c3), and the second set of solutions is...

[0019] θ3 = arctan(s32, c3);

[0020] Multiply equation 3 on the left by the inverse matrix T(1,2). -1 *T(0,1) -1 *T(p)*T(4,5) -1 =T(2,3)*T(3,4), obtained according to the matrix correspondence.

[0021]

[0022] The rotation angle θ2 of the second rotary joint is θ2 = arctan(D, -sqrt(ps2 + pc2 - D2)) - arctan(pc, ps), and the second solution is θ2 = arctan(D, -sqrt(ps2 + pc2 - D2)) - arctan(pc, ps);

[0023] Multiplying equation 1 by the inverse matrices of T(0,1), T(1,2), and T(2,3) on the left yields T(2,3). -1 *T(1,2) -1 *T(0,1) -1 *T(p)=T(3,4)*T(4,5); This is obtained based on the matrix correspondence.

[0024]

[0025] The rotation angle θ4 of the fourth rotary joint is arctan(Ath4, Bth4);

[0026] 4) The Monte Carlo algorithm is used to set random working points for the robotic arm, with the number of random points N = 5,000,000;

[0027] Within the joint angle limit, a total of [N,5] rotational joint angles are randomly obtained, and the working pose set is generated using forward motion.

[0028] The pose set space is recursively divided into multiple regions, with each node representing a point in 3D space. The space is further divided into two half-spaces. The median value in the Y direction of the pose set is selected as the root node O for partitioning. Values ​​less than Oy are assigned to the left subset, and values ​​greater than Oy are assigned to the right subset. This process is repeated a second time, selecting the median value in the X direction as the root node. Values ​​less than Ox are assigned to the left subset, and values ​​greater than Ox are assigned to the right subset. A third partition is then performed, selecting the median value in the Z direction as the root node. Values ​​less than Oz are assigned to the left subset, and values ​​greater than Oz are assigned to the right subset. This process is repeated to construct the pose set search tree model M2.

[0029] The host computer control system sends the target coordinates in real time, and each target coordinate is regarded as the terminal target point P of the robotic arm. t P t =[N,O,A,Px,Py,Pz], the rotation angles of each joint are obtained by inverse solving model M1;

[0030] If no solution exists, P can be obtained using the nearest neighbor algorithm. t The nearest point P tn ;

[0031] P tn Input to the search tree model M 2；

[0032] Starting from the root node, visit each node layer by layer downwards, checking if the dividing surface of the current node is related to the node starting from P. tn Intersection judgment is performed on envelope sets centered at a radius of R, with a criterion of 0.01 ≤ R ≤ 0.05 and an upper limit of R of 0.1 mm.

[0033] Calculate P tn Calculate the perpendicular distance D to the current node's splitting plane. If D > R, search the child nodes of the subtree on the same side of the splitting plane; if D ≤ R, search the subtrees on both the left and right sides. When recursively reaching a leaf node, calculate the Euclidean distance E between all points within that node and q. d Save points whose distance is less than R to the result set;

[0034] 5) Calculate the rotational joint angles using the inverse model M1;

[0035] 6) Send the rotational joint angle to the lower-level control device for movement.

[0036] Furthermore, the X-axis transmission assembly includes an X-axis drive motor, a reducer, a first support, a lead screw, a nut seat, and a second support. The X-axis drive motor is connected to the reducer, which is mounted on the first support. The nut seat is mounted on the lead screw, and both ends of the lead screw are mounted on the first and second supports respectively via bearings. The end of the lead screw closest to the first support is connected to the reducer via a coupling. The first and second supports are mounted on the X-axis base, and the articulated arm assembly is connected to the nut seat.

[0037] Furthermore, X-axis linear guides and nut seats are respectively installed on both sides of the bottom of the base.

[0038] Furthermore, the Y-axis component includes a Y-axis drive component and a patient support component. The patient support component is mounted on the Y-axis drive component. The Y-axis drive component includes a Y-axis base, a Y-axis linear motor, a Y-axis linear guide, and a magnetic scale. The Y-axis linear motor, Y-axis linear guide, and magnetic scale are mounted on the Y-axis base. The patient support component includes a support plate assembly, a positioning bed, and a locking device. The positioning bed is placed on the support plate assembly and is connected to the support plate assembly via the locking device. The support plate assembly is mounted on the Y-axis linear guide. The Y-axis linear motor can drive the support plate assembly to move on the Y-axis linear guide. The Y-axis base is mounted on the Y-axis connecting seat.

[0039] Furthermore, the support plate assembly includes a support plate, a locking sleeve, a positioning sleeve, and a position detection switch. The locking sleeve and the positioning sleeve are mounted on the support plate, the position detection switch is mounted on the positioning sleeve, and the support plate is mounted on the Y-axis linear guide rail.

[0040] Furthermore, the positioning sleeve includes a body positioning sleeve and a head positioning sleeve, the locking sleeve includes a body locking sleeve and a head locking sleeve, and the position detection switch includes a body position detection switch and a head position detection switch. The body positioning sleeve is located at the front of the support plate, the head positioning sleeve is located in the middle of the support plate, the body locking sleeve is located between the head positioning sleeve and the body positioning sleeve, and the head locking sleeve is located at the rear of the support plate to the right of the head positioning sleeve. The body position detection switch is located on the body positioning sleeve, and the head position detection switch is located on the head positioning sleeve.

[0041] Furthermore, there are three body positioning sleeves, arranged in a triangular shape on the upper part of the support plate, and three head positioning sleeves, arranged in a triangular shape in the middle of the support plate.

[0042] Furthermore, the calibration assembly includes a fixed base, a rotating arm, a drive motor, a Z-axis ranging sensor, and a Y-axis ranging sensor. The drive motor is mounted on the fixed base, the rotating arm is connected to the drive motor, and both the Z-axis and Y-axis ranging sensors are mounted on the rotating arm. The fixed base is mounted on the first robotic arm of the articulated arm assembly.

[0043] This invention provides a control method for a multi-degree-of-freedom robotic arm radiotherapy bed. The multi-degree-of-freedom robotic arm radiotherapy bed reduces the height of the bed through an articulated arm structure and achieves six-dimensional motion through a series-parallel combined structure, thereby reducing the complexity of the treatment bed system and simplifying installation. The control method plans a safe and effective space by establishing a forward and inverse kinematic model of the treatment bed, enabling real-time and precise positioning control of the patient in the treatment area, improving the automation level of the equipment, and providing differentiated treatment for different patients. Attached Figure Description

[0044] Figure 1 This is a schematic diagram of the structure of the multi-degree-of-freedom robotic arm radiotherapy bed of the present invention;

[0045] Figure 2 This is a schematic diagram of the X-axis component of the present invention;

[0046] Figure 3 This is a schematic diagram of the X-axis transmission assembly of the present invention;

[0047] Figure 4 This is a schematic diagram of the articulated arm assembly of the present invention;

[0048] Figure 5 This is a schematic diagram of the Y-axis component of the present invention;

[0049] Figure 6 This is a schematic diagram of the Y-axis drive component of the present invention;

[0050] Figure 7 This is a schematic diagram of the patient support component of the present invention;

[0051] Figure 8 This is a schematic diagram of the structure of the support plate assembly of the present invention;

[0052] Figure 9 These are schematic diagrams of specific embodiments of the support plate assembly of the present invention;

[0053] Figure 10 This is a schematic diagram of the structure of the calibration component of the present invention;

[0054] Figure 11 This is a schematic diagram of the treatment bed coordinate system established by the MDH method of the present invention;

[0055] Figure 12 This is the MDH parameter table of the present invention.

[0056] The annotations in the attached figures are explained as follows:

[0057] 1. X-axis assembly; 2. Articulated arm assembly; 3. Y-axis assembly; 4. Calibration assembly;

[0058] 1.1 X-axis base; 1.2 X-axis linear guide; 1.3 X-axis transmission assembly;

[0059] 1.3.1 X-axis drive motor; 1.3.2 Reducer; 1.3.3 First support; 1.3.4 Lead screw; 1.3.5 Nut seat; 1.3.6 Second support;

[0060] 2.1 Base; 2.2 First robotic arm; 2.3 First axis drive; 2.4 Second robotic arm; 2.5 Second axis drive; 2.6 Third axis drive; 2.7 Third robotic arm; 2.8 Fourth axis drive; 2.9 Fourth robotic arm; 2.10 Fifth axis drive; 2.11 Y-axis connecting seat;

[0061] 3.1 Y-axis drive component; 3.2 Patient support component;

[0062] 3.1.1 Y-axis base; 3.1.2 Y-axis linear motor; 3.1.3 Y-axis linear guide; 3.1.4 Magnetic scale;

[0063] 3.2.1 Support plate assembly; 3.2.2 Positioning bed; 3.2.3 Locking device;

[0064] 3.2.1.1 Support plate; 3.2.1.2 Locking sleeve; 3.2.1.3 Positioning sleeve; 3.2.1.4 Position detection switch;

[0065] 3.2.1.2.1 Head locking sleeve; 3.2.1.2.2 Body locking sleeve; 3.2.1.3.1 Head positioning sleeve; 3.2.1.3.2 Body positioning sleeve; 3.2.1.4.1 Head position detection switch; 3.2.1.4.2 Body position detection switch;

[0066] 4.1 Fixed base; 4.2 Rotating arm; 4.3 Drive motor; 4.4 Z-axis distance sensor; 4.5 Y-axis distance sensor. Detailed Implementation

[0067] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0068] See Figure 1 , 2 The structure of the multi-degree-of-freedom robotic arm radiotherapy bed of the present invention includes an X-axis component 1, an articulated arm component 2, a Y-axis component 3, and a calibration component 4. The articulated arm component 2 is disposed on the X-axis component 1, and the calibration component 4 and the Y-axis component 3 are respectively disposed on the articulated arm component 2; wherein, as shown... Figure 2 As shown, the X-axis assembly 1 includes an X-axis base 1.1, an X-axis linear guide rail 1.2, and an X-axis transmission assembly 1.3; the X-axis linear guide rail 1.2 and the X-axis transmission assembly 1.3 are both mounted on the X-axis base 1.1, and the articulated arm assembly 2 is mounted on the X-axis linear guide rail 1.2 and the X-axis transmission assembly 1.3.

[0069] See Figure 3The structure of the X-axis transmission assembly 1.3 of the present invention includes an X-axis drive motor 1.3.1, a reducer 1.3.2, a first support 1.3.3, a lead screw 1.3.4, a nut seat 1.3.5, and a second support 1.3.6. The X-axis drive motor 1.3.1 is connected to the reducer 1.3.2, which is mounted on the first support 1.3.3. The nut seat 1.3.5 is mounted on the lead screw 1.3.4, and the lead screw 1.3.4 has two ends... The bearings are mounted on the first support 1.3.3 and the second support 1.3.6. The end of the lead screw 1.3.4 near the first support 1.3.3 is connected to the reducer 1.3.2 via a coupling. The first support 1.3.3 and the second support 1.3.6 are mounted on the X-axis base 1.1. The articulated arm assembly 2 is connected to the nut seat 1.3.5. The position of the articulated arm assembly 2 in the X-axis direction can be adjusted via the X-axis linear guide 1.2 and the X-axis transmission assembly 1.3.

[0070] See Figure 4 The articulated arm assembly 2 of the present invention comprises a base 2.1, a first robotic arm 2.2, a first axis drive 2.3, a second robotic arm 2.4, a second axis drive 2.5, a third axis drive 2.6, a third robotic arm 2.7, a fourth axis drive 2.8, a fourth robotic arm 2.9, a fifth axis drive 2.10, and a Y-axis connecting seat 2.11. The first robotic arm 2.2 is connected to the base 2.1 via the first axis drive 2.3, the second robotic arm 2.4 is connected to the first robotic arm 2.2 via the second axis drive 2.5, the third robotic arm 2.7 is connected to the second robotic arm 2.4 via the third axis drive 2.6, the fourth robotic arm 2.9 is connected to the third robotic arm 2.7 via the fourth axis drive 2.8, and the Y-axis connecting seat 2.11 is connected to the fourth robotic arm 2.9 via the fifth axis drive 2.10. An X-axis linear guide rail 1.2 and a nut seat 1.3.5 are respectively provided on both sides of the bottom of the base 2.1.

[0071] The specific connection method is as follows: The first axis drive 2.3, second axis drive 2.5, third axis drive 2.6, fourth axis drive 2.8, and fifth axis drive 2.10 each consist of a motor and a reducer, with the motor output shaft connected to the reducer input shaft. The first reducer of the first axis drive 2.3 has its two end faces fixed to the base 2.1 and the first robotic arm 2.2, respectively. The first motor is fixed to the first robotic arm 2.2. During movement, the first motor drives the first reducer to rotate, thereby moving the first robotic arm 2.2 and achieving the movement of the first joint. The second reducer of the second axis drive 2.5 has its two end faces fixed to the first robotic arm 2.2 and the second robotic arm 2.4, respectively. The second motor is fixed to the second robotic arm 2.4. During movement, the second motor drives the second reducer to rotate, thereby moving the second robotic arm and achieving the movement of the second joint. The third reducer of the third axis drive 2.6 has its two end faces fixed to the second robotic arm 2.4 and the third robotic arm 2.7, respectively. The third motor is fixed to the second robotic arm 2.4. During the movement, the third motor drives the third reducer to rotate, which in turn drives the third robotic arm 2.7 to move, thus realizing the movement of the third joint. The two ends of the fourth reducer of the fourth axis drive 2.8 are fixed to the third robotic arm 2.7 and the fourth robotic arm 2.9, respectively. The fourth motor is fixed on the third robotic arm 2.7. During the movement, the fourth motor drives the fourth reducer to rotate, which in turn drives the fourth robotic arm 2.9 to move, thus realizing the movement of the fourth joint. The two ends of the fifth reducer of the fifth axis drive 2.10 are fixed to the fourth robotic arm 2.9 and the Y-axis connecting seat 2.11, respectively. The fifth motor is fixed on the fourth robotic arm 2.9. During the movement, the fifth motor drives the fifth reducer to rotate, which in turn drives the Y-axis connecting seat 2.11 to move, thus realizing the movement of the fifth joint.

[0072] See Figure 5 The structure of the Y-direction component 3 in a specific embodiment of the present invention includes a Y-direction driving component 3.1 and a patient support component 3.2. The patient support component 3.2 is disposed on the Y-direction driving component 3.1, and the displacement of the patient support component 3.2 in the Y direction can be controlled by the Y-direction driving component 3.1.

[0073] See Figure 6 The structure of the Y-axis drive assembly 3.1 of the present invention includes a Y-axis base 3.1.1, a Y-axis linear motor 3.1.2, a Y-axis linear guide rail 3.1.3, and a magnetic scale 3.1.4. The Y-axis linear motor 3.1.2, the Y-axis linear guide rail 3.1.3, and the magnetic scale 3.1.4 are all mounted on the Y-axis base 3.1.1. The magnetic scale 3.1.4 provides position feedback for the movement of the linear motor.

[0074] See Figure 7The structure of the patient support component 3.2 of the present invention includes a support plate component 3.2.1, a positioning bed 3.2.2, and a locking device 3.2.3. The positioning bed 3.2.2 is placed on the support plate component 3.2.1 and is connected to the support plate component 3.2.1 through the locking device 3.2.3. The support plate component 3.2.1 is mounted on a Y-axis linear guide rail 3.1.3. A Y-axis linear motor 3.1.2 can drive the support plate component 3.2.1 to move on the Y-axis linear guide rail 3.1.3. A Y-axis base 3.1.1 is mounted on a Y-axis connecting seat 2.11.

[0075] 3.2. Positioning bed. An existing positioning bed that can achieve patient positioning can be used, or the positioning bed with the authorization announcement number CN221358234 and the name "A positioning bed with patient protection device" can be used.

[0076] The locking device 3.2.3 between the positioning bed 3.2. and the support plate assembly 3.2.1 of the present invention can be an existing electromagnet adsorption method or a mechanical rotation locking method, etc.

[0077] See Figure 8 The structure of the support plate assembly 3.2.1 of the present invention includes a support plate 3.2.1.1, a locking sleeve 3.2.1.2, a positioning sleeve 3.2.1.3, and a position detection switch 3.2.1.4. The locking sleeve 3.2.1.2 and the positioning sleeve 3.2.1.3 are disposed on the support plate 3.2.1.1, the position detection switch 3.2.1.4 is disposed on the positioning sleeve 3.2.1.3, and the support plate 3.2.1.1 is disposed on the Y-direction linear guide rail 3.1.3.

[0078] See Figure 9In a preferred embodiment of the support plate assembly 3.2.1 of the present invention, the positioning sleeve includes a body positioning sleeve 3.2.1.3.2 and a head positioning sleeve 3.2.1.3.1, the locking sleeve includes a body locking sleeve 3.2.1.2.2 and a head locking sleeve 3.2.1.2.1, the position detection switch includes a body position detection switch 3.2.1.4.2 and a head position detection switch 3.2.1.4.1, the body positioning sleeve 3.2.1.3.2 is located at the front of the support plate 3.2.1.1, and the head positioning sleeve 3.2.1.3. 1. Located in the middle of support plate 3.2.1.1, body locking sleeve 3.2.1.2 is located between body positioning sleeve 3.2.1.3.2 and head positioning sleeve 3.2.1.3.1. The head locking sleeve 3.2.1.2.1 is located at the rear of support plate 3.2.1.1 to the right of head positioning sleeve 3.2.1.3.1. Body position detection switch 3.2.1.4.2 is located on body positioning sleeve 3.2.1.3.2, and head position detection switch 3.2.1.4.1 is located on head positioning sleeve 3.2.1.3.1. In this embodiment, there are three body positioning sleeves 3.2.1.3.2, arranged in a "T" shape on the upper part of support plate 3.2.1.1, and there are also three head positioning sleeves 3.2.1.3.1, arranged in a "T" shape in the middle of support plate 3.2.1.1.

[0079] During treatment, the position of the positioning bed 3.2.2 on the support plate assembly 3.2.1 is selected according to the location of the patient's tumor. Treatment can only begin when the positioning bed 3.2.2 is in the corresponding position according to the treatment plan and triggers the corresponding position detection switch 3.2.1.4. Otherwise, the system will activate the safety model and cannot execute the treatment plan to protect the patient from mistreatment. The positioning bed 3.2.2 is positioned relative to the support plate assembly 3.2.1 using positioning pins and positioning sleeves 3.2.1.3, and is securely locked to the support plate assembly 3.2.1 using a locking device 3.2.3. The positioning pins and locking device 3.2.3 ensure the consistency of hardware for the patient in each treatment session.

[0080] See Figure 10 In a preferred embodiment of the calibration component 4 of the present invention, it includes a fixed base 4.1, a rotating arm 4.2, a drive motor 4.3, a Z-axis ranging sensor 4.4, and a Y-axis ranging sensor 4.5. The drive motor is mounted on the fixed base 4.1, the rotating arm 4.2 is connected to the drive motor 4.3, and both the Z-axis ranging sensor 4.4 and the Y-axis ranging sensor 4.5 are mounted on the rotating arm 4.2. The fixed base 4.1 is mounted on the first robotic arm 2.2 of the articulated arm assembly 2.

[0081] The articulated arm assembly 2 is fixed to the linear guide rail 1.2 of the X-axis assembly 1 via the base 2.1 and is connected to the nut seat 1.3.5; the Y-axis assembly 3 is fixed to the Y-axis connecting seat 2.11 of the articulated arm assembly 2; the calibration assembly 4 is set on the first robotic arm 2.2 of the articulated arm assembly 2.

[0082] In application of this invention, the multi-degree-of-freedom robotic arm radiotherapy bed is connected to the main unit of the radiotherapy equipment. After CT positioning is completed, the positioning bed 3.2.2 is positioned on the support plate assembly 3.2.1 according to the location of the patient's tumor. The positioning bed 3.2.2 is fixed to the support plate assembly 3.2.1 by the locking device 3.2.3, and a treatment plan is made. When treatment begins, after the patient is placed on the positioning bed 3.2.2, the multi-degree-of-freedom robotic arm radiotherapy bed first moves to the marked position through the X-axis assembly 1, the articulated arm assembly 2, and the Y-axis assembly 3. Then, the drive motor 4.3 drives the rotating arm 4.2 to move 90 degrees. The Z-axis ranging sensor 4.4 and the Y-axis ranging sensor 4.5 calibrate the Z and Y axes respectively, feeding back the errors caused by deformation and transmission to the control system. After judgment, the control system provides a correction value for position correction, and then begins to execute the treatment plan for treatment.

[0083] This invention provides a control method for a multi-degree-of-freedom robotic arm radiotherapy bed. In the articulated arm assembly, a first axis drives and connects the first robotic arm and the base to form a first rotary joint; a second axis drives and connects the first and second robotic arms to form a second rotary joint; a third axis drives and connects the second and third robotic arms to form a third rotary joint; a fourth axis drives and connects the third and fourth robotic arms to form a fourth rotary joint; and a fifth axis drives and connects the fourth robotic arm to form a fifth rotary joint. The control method includes the following steps:

[0084] 1) A multi-degree-of-freedom robotic arm coordinate system is established using the improved DH method. The axis of each joint is sequentially determined as the Z-direction, and the X and Y directions are determined according to the right-hand rule, such as... Figure 11 As shown, the relevant parameters for the transformation relationship between two adjacent joint axes are: alpha i-1 For X i-1 Axis, from Z i-1 Rotate to the angle of Zi, a i-1 For along X i-1 Axis, from Z i-1 Move to Z i The distance, theta i To circle around Z i Axis, from X i-1 Rotate to X i The angle, di, is along the Zi axis from X i-1 Move to X i The distances, where a1, a2, a3, d1, and d5 are determined according to the joint configuration design; the MDH parameter table is as follows.Figure 12 As shown;

[0085] 2) Based on the forward kinematics method of the robotic arm, the end-effector pose matrix T(p) of the multi-degree-of-freedom robotic arm is obtained through translation and rotation of the base coordinate system. This is then sequentially processed by the homogeneous matrices T(i-1, ..., ...) of two adjacent rotary joints.

[0086] i) is obtained by multiplying Rx(αi-1)*Dx(ai-1)*Rz(θi)*Dz(di), (i = 1, 2, 3, 4, 5), where Rx and Rz are rotation matrices, and Dx and Dz are translation matrices;

[0087] T(p) = T(0,1)*T(1,2)*T(2,3)*T(3,4)*T(4,5) (Equation 1); Calculated according to the above formula:

[0088]

[0089] Where S1=sin(θ1),C 234 =cos(θ2+θ3+θ4), other expressions are similar;

[0090] S1S5+C 234 C1C5=Nx,C5S1-C 234 C1S5=Ox,S 234 C1=Ax,C 234 C5S1-C1S5=Ny,-C1C5-C 234 S1S5=Oy,

[0091] S 234 S1=Ay,S 234 C5=Nz,-S 234 S5=Oz,-C 234 =Az; [N,O,A] is the attitude vector of the robotic arm's end effector; 2, C1(a1+a3C 23 +a2C2+d5S 234 )=Px,S1(a1+a3C 23 +a2C2+d5S 234 )=Py,d1+a3S 23 +a2S2-d5C 234 =Pz; [Px,Py,Pz] are the coordinates of the end position;

[0092] 3) Establish the inverse kinematic model M of the multi-degree-of-freedom robotic arm 1；

[0093] Multiplying equation 1 by the inverse of T(1) on the left yields T(0,1). -1*T(p)=T(2,3)*T(3,4)*T(4,5) (Equation 2), P is obtained according to the matrix correspondence. y cos(θ1)-P x sin(θ1)=0, the rotation angle of the first rotary joint is θ1=arctan(Py,Px).

[0094] Based on the matrix correspondence, we obtain Substituting θ1, we get the rotation angle θ5 of the fifth rotation joint = arctan(-sin(θ5),-cos(θ5));

[0095] Multiplying Equation 2 by the inverse of T(4,5) on the right yields T(0,1). -1 *T(p)*T(4,5) -1 =T(1,2)*T(2,3)*T(3,4) (Equation 3), obtained according to the matrix correspondence.

[0096]

[0097] The rotation angle θ3 of the third rotary joint is arctan(s31,c3), and the second set of solutions is...

[0098] θ3 = arctan(s32, c3);

[0099] Multiply equation 3 on the left by the inverse matrix T(1,2). -1 *T(0,1) -1 *T(p)*T(4,5) -1 =T(2,3)*T(3,4), obtained according to the matrix correspondence.

[0100]

[0101] The rotation angle θ2 of the second rotary joint is θ2 = arctan(D, -sqrt(ps2 + pc2 - D2)) - arctan(pc, ps), and the second solution is θ2 = arctan(D, -sqrt(ps2 + pc2 - D2)) - arctan(pc, ps);

[0102] Multiplying equation 1 by the inverse matrices of T(0,1), T(1,2), and T(2,3) on the left yields T(2,3). -1 *T(1,2) -1 *T(0,1) -1 *T(p)=T(3,4)*T(4,5); This is obtained based on the matrix correspondence.

[0103]

[0104] The rotation angle θ4 of the fourth rotary joint is arctan(Ath4, Bth4);

[0105] 4) The Monte Carlo algorithm is used to set random working points for the robotic arm, with the number of random points N = 5,000,000;

[0106] Within the joint angle limit, a total of [N,5] rotational joint angles are randomly obtained, and the working pose set is generated using forward motion.

[0107] The pose set space is recursively divided into multiple regions, with each node representing a point in 3D space. The space is further divided into two half-spaces. The median value in the Y direction of the pose set is selected as the root node O for partitioning. Values ​​less than Oy are assigned to the left subset, and values ​​greater than Oy are assigned to the right subset. This process is repeated a second time, selecting the median value in the X direction as the root node. Values ​​less than Ox are assigned to the left subset, and values ​​greater than Ox are assigned to the right subset. A third partition is then performed, selecting the median value in the Z direction as the root node. Values ​​less than Oz are assigned to the left subset, and values ​​greater than Oz are assigned to the right subset. This process is repeated to construct the pose set search tree model M2.

[0108] The host computer control system sends the target coordinates in real time, and each target coordinate is regarded as the terminal target point P of the robotic arm. t P t =[N,O,A,Px,Py,Pz], the rotation angles of each joint are obtained by inverse solving model M1;

[0109] If no solution exists, P can be obtained using the nearest neighbor algorithm. t The nearest point P tn ;

[0110] P tn Input to the search tree model M 2；

[0111] Starting from the root node, visit each node layer by layer downwards, checking if the dividing surface of the current node is related to the node starting from P. tn Intersection judgment is performed on envelope sets centered at a radius of R, with a criterion of 0.01 ≤ R ≤ 0.05 and an upper limit of R of 0.1 mm.

[0112] Calculate P tn Calculate the perpendicular distance D to the current node's splitting plane. If D > R, search the child nodes of the subtree on the same side of the splitting plane; if D ≤ R, search the subtrees on both the left and right sides. When recursively reaching a leaf node, calculate the Euclidean distance E between all points within that node and q. d Save points whose distance is less than R to the result set;

[0113] 5) Calculate the rotational joint angles using the inverse model M1;

[0114] 6) Send the rotational joint angle to the lower-level control device for movement.

[0115] The technical contents of this invention and those not specifically described in the above embodiments are the same as those in the prior art.

[0116] The above are merely specific embodiments disclosed in this invention, but the scope of protection disclosed in this invention is not limited thereto. The scope of protection disclosed in this invention should be determined by the scope of the claims.

Claims

1. A control method of a multi-degree-of-freedom robotic arm radiotherapy couch, characterized in that: The multi-degree-of-freedom mechanical arm radiotherapy bed comprises an X-direction assembly, a joint arm assembly, a Y-direction assembly and a calibration assembly, the joint arm assembly is arranged on the X-direction assembly, the calibration assembly and the Y-direction assembly are arranged on the joint arm assembly respectively, the X-direction assembly comprises an X-direction base, an X-direction linear guide rail and an X-direction transmission assembly; the X-direction linear guide rail and the X-direction transmission assembly are arranged on the X-direction base, and the joint arm assembly is arranged on the X-direction linear guide rail and the X-direction transmission assembly; the joint arm assembly comprises a base, a first mechanical arm, a first shaft drive, a second mechanical arm, a second shaft drive, a third shaft drive, a third mechanical arm, a fourth shaft drive, a fourth mechanical arm, a fifth shaft drive and a Y-direction connecting seat; The first mechanical arm is connected with the base through the first shaft drive, the second mechanical arm is connected with the first mechanical arm through the second shaft drive, the third mechanical arm is connected with the second mechanical arm through the third shaft drive, the fourth mechanical arm is connected with the third mechanical arm through the fourth shaft drive, and the Y-direction connecting seat is connected with the fourth mechanical arm through the fifth shaft drive, wherein the first shaft drive connects the first mechanical arm and the base to form a first rotary joint, the second shaft drive connects the first mechanical arm and the second mechanical arm to form a second rotary joint, the third shaft drive connects the second mechanical arm and the third mechanical arm to form a third rotary joint, the fourth shaft drive connects the third mechanical arm and the fourth mechanical arm to form a fourth rotary joint, and the fifth shaft drive connects the fourth mechanical arm to form a fifth rotary joint, and the control method comprises the following steps: 1) A multi-degree-of-freedom robotic arm coordinate system is established using the improved DH method. The axis of each rotary joint is sequentially determined as the Z-direction, and the X and Y directions are determined according to the right-hand rule. The relevant parameters for the transformation relationship between two adjacent joint axes are: alpha i-1 For X i-1 Axis, from Z i-1 Rotate to Z i Angle, a i-1 For along X i-1 Axis, from Z i-1 Move to Z i The distance, theta i To circle around Z i Axis, from X i-1 Rotate to X i The angle, di, is along Z. i Axis, from X i-1 Move to X i The distances, where a1, a2, a3, d1, and d5 are determined according to the joint configuration design; 2) According to the mechanical arm forward kinematics method, the end position and posture matrix T(p) of the multi-degree-of-freedom mechanical arm is obtained through the translation and rotation of the base coordinate system, and is obtained by multiplying the homogeneous matrices T(i-1, i) = Rx(ai-1)*Dx(ai-1)*Rz(θi)*Dz(di) of two adjacent rotary joints in sequence (i = 1, 2, 3, 4, 5), wherein Rx and Rz are rotation matrices, and Dx and Dz are translation matrices; T(p) = T(0,1)*T(1,2)*T(2,3)*T(3,4)*T(4,5) (Formula 1); according to the above formula, the following is obtained: where S1 = sin(θ1), C1 = cos(θ1), S2 = sin(θ2), C2 = cos(θ2), S3 = sin(θ3), C3 = cos(θ3), S4 = sin(θ4), and C4 = cos(θ4). 234 = cos( S1S5 + C 234 C1C5 = Nx, C5S1 - C 234 C1S5 = Ox, S 234 C1 = Ax, C 234 C5S1 - C1S5 = Ny, -C1C5 - C 234 S1S5 = Oy, S 234 S1 = Ay, S 234 C5 = Nz, -S 234 S5 = Oz, -C 234 = Az; [N, O, A] is the pose vector of the end of the robot arm; C1(a1+a3C 23 +a2C2+d5S 234 ) = Px, S1(a1+a3C 23 +a2C2+d5S 234 ) = Py, d1+a3S 23 +a2S2-d5C 234 = Pz; [Px, Py, Pz] is the end position coordinates; 3) A multi-degree-of-freedom mechanical arm inverse solution model M1 is established; T(0,1) = T(1) * T(0) -1 T(p) = T(2,3) * T(3,4) * T(4,5) (Equation 2), P is obtained according to the matrix correspondence y cos(θ1) - P x sin(θ1) = 0, the rotation angle θ1 of the first rotation joint = arctan(Py, Px), According to the matrix correspondence relationship, we have Substituting θ1 into the equation, we obtain the rotation angle θ5 of the fifth rotation joint, θ5 = arctan(-sin(θ5), -cos(θ5)). T(0,1) = T(2,3) * T(3,4) * T(4,5) (Equation 2) -1 T(0,1) = T(2,3) * T(3,4) * T(4,5) (Equation 2) -1 T(0,1) = T(2,3) * T(3,4) * T(4,5) (Equation 2) The rotation angle θ3 of the third rotary joint is arctan(s31, c3), and the second group of solutions is θ3 = arctan(s32, c3); T(1,2) * T(1,2) = T(0,1) -1 T(1,2) * T(0,1) = T(1,2) -1 T(1,2) * T(4,5) = T(2,3) -1 T(2,3) * T(3,4) = T(1,2) according to the matrix correspondence The rotation angle θ2 of the second rotary joint is arctan(D, -sqrt(ps2+pc2-D2))-arctan(pc, ps), and the second group of solutions is T(2,3) = T(0,1) * T(1,2) * T(2,3) * T(3,4) * T(4,5) -1 T(1,2) = T(0,1) * T(1,2) * T(2,3) * T(3,4) * T(4,5) -1 T(0,1) = T(0,1) * T(1,2) * T(2,3) * T(3,4) * T(4,5) -1 T(3,4) = T(0,1) * T(1,2) * T(2,3) * T(3,4) * T(4 The rotation angle θ4 of the fourth rotary joint is arctan(Ath4, Bth4); 4) A Monte Carlo algorithm is used to set a random working point of the mechanical arm, and the random point number N = 5000000; Randomly obtain [N, 5] rotary joint angles within the joint angle limit range, and generate a working posture set by using forward kinematics. The pose set space is recursively divided into multiple regions, each node represents a point in three-dimensional space, while the space is divided into two half spaces, the median value in Y direction of the pose set is selected as the root node O for cutting, less than Oy left subset, greater than Oy right subset, the above subsets are divided twice, the median value in X direction is selected as the root node, less than Ox left subset, otherwise Ox right subset, the above subsets are divided for the third time, the median value in Z direction is selected as the root node, less than Oz left subset, otherwise Oz right subset, the above process is repeated to construct the pose set search tree model M2, The host computer control system issues target point coordinates in real time, and each target point coordinate is regarded as a terminal target point P of the mechanical arm t , P t = [N, O, A, Px, Py, Pz], and each joint rotation angle is obtained through the inverse solution model M1. If the solution does not exist, the nearest point P is obtained by the proximal computation method t of the nearest point P tn ; P tn input to the lookup tree model M2; From the root node, access the nodes layer by layer downwards, determine whether the split surface of the current node intersects with the envelope set with P tn as the center and R as the radius, set 0.01≤R≤0.05, and the upper limit of R is 0.1mm; Compute P tn Vertical distance D from the current node to the split plane, if D > R, search the child node of the same side of the split plane, if D ≤ R, search the left and right child nodes; when recursion to the leaf node, compute the Euclidean distance E of all points in the node to q d Save the points with distance less than R to the result set; 5) calculate the rotation joint angle by inverse solution model M1; 6) the rotation joint angle is sent to the lower computer control device to move.

2. The control method of the multi-degree-of-freedom robotic arm radiotherapy couch according to claim 1, characterized in that: The X-direction transmission assembly includes an X-direction drive motor, a speed reducer, a first support, a lead screw, a nut seat and a second support. The X-direction drive motor is connected with the speed reducer. The speed reducer is arranged on the first support. The nut seat is arranged on the lead screw. The lead screw is arranged on the first support and the second support through bearings at both ends respectively. The lead screw is connected with the speed reducer through a shaft coupling at one end close to the first support. The first support and the second support are arranged on an X-direction base. The joint arm assembly is connected with the nut seat.

3. The control method of the multi-degree-of-freedom robotic arm radiotherapy couch according to claim 2, characterized in that: The Y-direction connecting seat is connected with the fourth mechanical arm through the fifth shaft drive. X-direction linear guides and nut seats are arranged on both sides of the base bottom.

4. The control method of the multi-degree-of-freedom robotic arm radiotherapy couch according to claim 3, characterized in that: The Y-direction assembly includes a Y-direction drive assembly and a patient support assembly. The patient support assembly is arranged on the Y-direction drive assembly. The Y-direction drive assembly includes a Y-direction base, a Y-direction linear motor, a Y-direction linear guide and a magnetic scale. The Y-direction linear motor, the Y-direction linear guide and the magnetic scale are arranged on the Y-direction base. The patient support assembly includes a support plate assembly, a positioning bed and a locking device. The positioning bed is placed on the support plate assembly. The positioning bed is connected with the support plate assembly through the locking device. The support plate assembly is arranged on the Y-direction linear guide. The Y-direction linear motor can drive the support plate assembly to move on the Y-direction linear guide. The Y-direction base is arranged on the Y-direction connecting seat.

5. The control method of the multi-degree-of-freedom robotic arm radiotherapy couch according to claim 4, characterized in that: The support plate assembly includes a support plate, a locking sleeve, a positioning sleeve and a position detection switch. The locking sleeve and the positioning sleeve are arranged on the support plate. The position detection switch is arranged on the positioning sleeve. The support plate is arranged on the Y-direction linear guide.

6. The control method of the multi-degree-of-freedom robotic arm radiotherapy couch according to claim 5, characterized in that: The positioning sleeve includes a body positioning sleeve and a head positioning sleeve. The locking sleeve includes a body locking sleeve and a head locking sleeve. The position detection switch includes a body position detection switch and a head position detection switch. The body positioning sleeve is located at the front of the support plate. The head positioning sleeve is located at the middle of the support plate. The body locking sleeve is located between the head positioning sleeve and the body positioning sleeve. The head locking sleeve is located at the rear of the support plate on the right side of the head positioning sleeve. The body position detection switch is arranged on the body positioning sleeve. The head position detection switch is arranged on the head positioning sleeve.

7. The control method of the multi-degree-of-freedom robotic arm radiotherapy couch according to claim 6, characterized in that: The head positioning sleeve is three, arranged in the middle of the support plate in the shape of a product character.

8. The control method of the multi-degree-of-freedom robotic arm radiotherapy couch according to any one of claims 3 to 7, characterized in that: The calibration assembly comprises a fixed seat, a rotating arm, a driving motor, a Z-direction distance measuring sensor and a Y-direction distance measuring sensor, the driving motor is arranged on the fixed seat, the rotating arm is connected with the driving motor, the Z-direction distance measuring sensor and the Y-direction distance measuring sensor are both arranged on the rotating arm, and the fixed seat is arranged on the first mechanical arm of the joint arm assembly.

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