Control method of multi-degree-of-freedom mechanical arm radiotherapy bed

Abstract

The invention relates to a control method for a multi-degree-of-freedom mechanical arm radiotherapy bed, and the multi-degree-of-freedom mechanical arm radiotherapy bed reduces the height of an upper bed through an articulated arm structure, achieves the six-dimensional movement through a series-parallel combined structural form, reduces the complexity of a treatment bed system, and reduces the installation difficulty. According to the control method, a safe and effective space is planned by establishing a positive and negative kinematics model of the treatment bed, real-time and accurate positioning control of a patient in a treatment area is achieved, the automation degree of equipment is improved, and differentiated treatment is conducted on different patients.

Description

Technical Field

[0001] The present invention relates to the medical field, and in particular to a control method for a multi-degree-of-freedom robotic radiotherapy couch. Background Art

[0002] The treatment couch of a radiotherapy device is a motion platform composed of multiple axes, and its main function is to accurately move the patient to the treatment position according to the requirements of the treatment plan. Currently, to solve the problem of the height of getting on the couch, most treatment couches adopt the method of digging pits in the control room to reduce the height of getting on the couch, and the mechanical design structure is complex and the wiring is cumbersome. For the radiotherapy couch with an articulated arm as the main body, the structure is simple, which can effectively reduce the height of getting on the couch and avoid digging pits in the hospital control room. Therefore, to improve the adaptability of gamma knife equipment, it is necessary to provide a control method for a multi-degree-of-freedom robotic radiotherapy couch, which realizes the six-dimensional pose adjustment of the patient through a series-parallel combined structure form to ensure the effectiveness of the treatment process and reduce the irradiation dose of the patient. Summary of the Invention

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

[0004] The technical solution of the present invention is as follows: The present invention relates to a control method for a multi-degree-of-freedom robotic arm radiotherapy couch, which is characterized in that: the multi-degree-of-freedom robotic arm radiotherapy couch includes an X-direction component, a joint arm component, a Y-direction component and a calibration component. The joint arm component is arranged on the X-direction component, and the calibration component and the Y-direction component are respectively arranged on the joint arm component. The X-direction component includes an X-direction base, an X-direction linear guide rail and an X-direction transmission component; both the X-direction linear guide rail and the X-direction transmission component are arranged on the X-direction base, and the joint arm component is arranged on the X-direction linear guide rail and the X-direction transmission component. The joint 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, a fifth-axis drive and a Y-direction connecting seat; the first robotic arm is connected to the base through the first-axis drive, the second robotic arm is connected to the first robotic arm through the second-axis drive, the third robotic arm is connected to the second robotic arm through the third-axis drive, the fourth robotic arm is connected to the third robotic arm through the fourth-axis drive, and the Y-direction connecting seat is connected to the fourth robotic arm through the fifth-axis drive. Among them, the first-axis drive connects the first robotic arm and the base to form a first rotating joint, the second-axis drive connects the first robotic arm and the second robotic arm to form a second rotating joint, the third-axis drive connects the second robotic arm and the third robotic arm to form a third rotating joint, the fourth-axis drive connects the third robotic arm and the fourth robotic arm to form a fourth rotating joint, and the fifth-axis drive connects the fourth robotic arm to form a fifth rotating joint. The control method includes the following steps:

[0005] 1) Use the improved DH method to establish a robotic arm coordinate system with multiple degrees of freedom. Determine the axial direction of each joint axis as the Z direction in sequence. According to the right-hand rule, determine the X and Y directions. The relevant parameters for the transformation relationship between two adjacent joint axes are: alpha i-1 is the angle of rotation around the X i-1 axis, from Z i-1 to Zi, a i-1 is the distance along the X i-1 axis, from Z i-1 to Z i theta i is the angle of rotation around the Z i axis, from X i-1 to X i di is the distance along the Zi axis, from X i-1 to X i Among them, a1, a2, a3, d1, d5 are determined according to the configuration design of the joints;

[0006] 2) According to the forward kinematics method of the robotic arm, obtain the end pose matrix T(p) of the multi-degree-of-freedom robotic arm through the translation and rotation of the base coordinate system. Sequentially pass through the homogeneous matrix T(i - 1,

[0007] It 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;

[0008] 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:

[0009]

[0010] Among them, 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 the attitude vector of the end of the robotic 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] are the end position coordinates;

[0013] 3) Establish the inverse solution model M of the multi - degree - of - freedom robotic arm 1；

[0014] Multiply the left side of Equation 1 by the inverse matrix of T(1) to get T(0, 1) -1 * T(p) = T(2, 3) * T(3, 4) * T(4, 5) (Equation 2), and according to the matrix correspondence, we get P y cos(θ1) - P x sin(θ1) = 0, the rotation angle θ1 of the first rotation joint = arctan(Py, Px),

[0015] According to the matrix correspondence, we get Substitute θ1, and the rotation angle θ5 of the fifth rotating joint is obtained as θ5 = arctan(-sin(θ5), -cos(θ5));

[0016] Right - multiply the right - hand side of Equation 2 by the inverse matrix of T(4,5) to get T(0,1) -1 *T(p)*T(4,5) -1 = T(1,2)*T(2,3)*T(3,4) (Equation 3), and according to the matrix correspondence relationship,

[0017]

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

[0019] θ3 = arctan(s32, c3);

[0020] Left - multiply the left - hand side of Equation 3 by the inverse matrix T(1,2) of T(1,2) -1 *T(0,1) -1 *T(p)*T(4,5) -1 = T(2,3)*T(3,4), and according to the matrix correspondence relationship,

[0021]

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

[0023] Left - multiply the left - hand side of Equation 1 by the inverse matrices of T(0,1), T(1,2), and T(2,3) to get T(2,3) -1 *T(1,2) -1 *T(0,1) -1 *T(p) = T(3,4)*T(4,5); and according to the matrix correspondence relationship,

[0024]

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

[0026] 4) Use the Monte Carlo algorithm to set the random working points of the robotic arm, and the number of random points N = 5000000;

[0027] Randomly obtain a total of [N, 5] rotation joint angles within the joint angle limit range, and use forward kinematics to generate the working pose set;

[0028] The pose set space is recursively divided into multiple regions. Each node represents a point in three-dimensional space. Meanwhile, the space is divided into two half-spaces. The median value in the Y direction of the pose set is selected as the root node O for splitting. The left subset is less than Oy, and the right subset is greater than Oy. The above subsets are further divided. The median value in the X direction is selected as the root node. The left subset is less than Ox, and the right subset is greater than Ox. The above subsets are divided for the third time. The median value in the Z direction is selected as the root node. The left subset is less than Oz, and the right subset is greater than Oz. The above process is continuously repeated to construct the pose set search tree model M2.

[0029] The host computer control system issues the target coordinates in real time. Each target coordinate is regarded as the target point P at the end of the robotic arm. t , P t = [N, O, A, Px, Py, Pz]. The rotation angles of each joint are obtained through the inverse solution model M1.

[0030] If the solution does not exist, the nearest point P of P is obtained through the nearest neighbor calculation method. t of tn ;

[0031] P tn is input into the search tree model M 2；

[0032] Starting from the root node, visit the nodes layer by layer downward. Judge whether the splitting plane of the current node intersects with the envelope set centered on P tn with a radius of R. Set 0.01 ≤ R ≤ 0.05, and the upper limit of R is 0.1 mm.

[0033] Calculate the vertical distance D from P tn to the splitting plane of the current node. If D > R, search for the child nodes of the subtree on the same side of the splitting plane. If D ≤ R, search for the subtrees on both sides; when recursively reaching the leaf node, calculate the Euclidean distance E between all points in the node and q d , and save the points with a distance less than R into the result set.

[0034] 5) Calculate the rotation joint angles through the inverse solution model M1.

[0035] 6) Issue the rotation joint angles to the lower computer control device to control the movement.

[0036] Furthermore, the X-direction transmission component includes an X-direction driving motor, a reducer, a first support, a lead screw, a nut seat, and a second support. The X-direction driving motor is connected to the reducer. The reducer is arranged on the first support. The nut seat is arranged on the lead screw. Both ends of the lead screw are respectively arranged on the first support and the second support through bearings. One end of the lead screw close to the first support is connected to the reducer through a coupling. The first support and the second support are arranged on the X-direction base. The joint arm component is connected to the nut seat.

[0037] Further, X-direction linear guide rails and nut seats are respectively arranged on both sides of the bottom of the base.

[0038] Further, the Y-direction component includes a Y-direction driving component and a patient support component. The patient support component is arranged on the Y-direction driving component. The Y-direction driving component includes a Y-direction base, a Y-direction linear motor, a Y-direction linear guide rail and a magnetic grating ruler. The Y-direction linear motor, the Y-direction linear guide rail and the magnetic grating ruler are arranged on the Y-direction base. The patient support component includes a support plate component, a positioning bed and a locking device. The positioning bed is placed on the support plate component. The positioning bed is connected to the support plate component through the locking device. The support plate component is arranged on the Y-direction linear guide rail. The Y-direction linear motor can drive the support plate component to move on the Y-direction linear guide rail. The Y-direction base is arranged on the Y-direction connecting seat.

[0039] Further, the support plate component 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 rail.

[0040] Further, 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 in 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.

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

[0042] Further, the calibration component includes 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 to the driving motor. The Z-direction distance measuring sensor and the Y-direction distance measuring sensor are both arranged on the rotating arm. The fixed seat is arranged on the first robotic arm of the articulated arm assembly.

[0043] A control method for a multi-degree-of-freedom robotic arm radiotherapy bed provided by the present invention. The multi-degree-of-freedom robotic arm radiotherapy bed reduces the height of getting on the bed through an articulated arm structure, and realizes six-dimensional motion through a series-parallel combined structure form, thereby reducing the complexity of the treatment bed system and the installation difficulty. Its control method plans a safe and effective space by establishing a forward and inverse kinematic model of the treatment bed, realizes real-time and accurate positioning control of the patient in the treatment area, improves the automation degree of the equipment, and performs differential treatment for different patients. Description of the Drawings

[0044] Figure 1 It is a schematic structural diagram of the multi-degree-of-freedom robotic arm radiotherapy couch of the present invention;

[0045] Figure 2 It is a schematic structural diagram of the X-direction component of the present invention;

[0046] Figure 3 It is a schematic structural diagram of the X-direction drive component of the present invention;

[0047] Figure 4 It is a schematic structural diagram of the articulated arm component of the present invention;

[0048] Figure 5 It is a schematic structural diagram of the Y-direction component of the present invention;

[0049] Figure 6 It is a schematic structural diagram of the Y-direction drive component of the present invention;

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

[0051] Figure 8 It is a schematic structural diagram of the support plate component of the present invention;

[0052] Figure 9 It is a separate schematic diagram of a specific embodiment of the support plate component of the present invention;

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

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

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

[0056] The description of the reference numerals is as follows:

[0057] 1. X-direction component; 2. Articulated arm component; 3. Y-direction component; 4. Calibration component;

[0058] 1.1. X-direction base; 1.2. X-direction linear guide rail; 1.3. X-direction drive component;

[0059] 1.3.1. X-direction 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-direction connection seat

[0061] 3.1, Y-direction drive assembly; 3.2, Patient support assembly

[0062] 3.1.1, Y-direction base; 3.1.2, Y-direction linear motor; 3.1.3, Y-direction linear guide rail; 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 seat; 4.2, Rotating arm; 4.3, Drive motor; 4.4, Z-direction distance measuring sensor; 4.5, Y-direction distance measuring sensor Detailed implementation manners

[0067] The present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments

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

[0069] See Figure 3, the structure of the specific embodiment of the X-direction drive assembly 1.3 of the present invention includes an X-direction drive motor 1.3.1, a speed 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-direction drive motor 1.3.1 is connected to the speed reducer 1.3.2. The speed reducer 1.3.2 is arranged on the first support 1.3.3. The nut seat 1.3.5 is arranged on the lead screw 1.3.4. Both ends of the lead screw 1.3.4 are respectively arranged on the first support 1.3.3 and the second support 1.3.6 through bearings. One end of the lead screw 1.3.4 close to the first support 1.3.3 is connected to the speed reducer 1.3.2 through a coupling. The first support 1.3.3 and the second support 1.3 are arranged on the X-direction base 1.1. The articulated arm assembly 2 is connected to the nut seat 1.3.5. Through the X-direction linear guide 1.2 and the X-direction drive assembly 1.3, the position of the articulated arm assembly 2 in the X direction can be adjusted.

[0070] See Figure 4 , the structure of the specific embodiment of the articulated arm assembly 2 of the present invention includes 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-direction connection seat 2.11; the first robotic arm 2.2 is connected to the base 2.1 through the first axis drive 2.3, the second robotic arm 2.4 is connected to the first robotic arm 2.2 through the second axis drive 2.5, the third robotic arm 2.7 is connected to the second robotic arm 2.4 through the third axis drive 2.6, the fourth robotic arm 2.9 is connected to the third robotic arm 2.7 through the fourth axis drive 2.8, the Y-direction connection seat 2.11 is connected to the fourth robotic arm 2.9 through the fifth axis drive 2.10. Both sides of the bottom of the base 2.1 are respectively arranged on the X-direction linear guide 1.2 and the nut seat 1.3.5.

[0071] The specific connection method is as follows: The first-axis drive 2.3, the second-axis drive 2.5, the third-axis drive 2.6, the fourth-axis drive 2.8, and the fifth-axis drive 2.10 are each composed of a motor and a speed reducer. The output shaft of the motor is connected to the input shaft of the speed reducer. The two end faces of the first speed reducer of the first-axis drive 2.3 are respectively fixed to the base 2.1 and the first robotic arm 2.2. The first motor is fixed on the first robotic arm 2.2. During the movement, the first motor drives the first speed reducer to rotate, thereby driving the first robotic arm 2.2 to move, so as to realize the movement of the first joint; The two end faces of the second speed reducer of the second-axis drive 2.5 are respectively fixed to the first robotic arm 2.2 and the second robotic arm 2.4. The second motor is fixed on the second robotic arm 2.4. During the movement, the second motor drives the second speed reducer to rotate, thereby driving the second robotic arm to move, so as to realize the movement of the second joint; The two end faces of the third speed reducer of the third-axis drive 2.6 are respectively fixed to the second robotic arm 2.4 and the third robotic arm 2.7. The third motor is fixed on the second robotic arm 2.4. During the movement, the third motor drives the third speed reducer to rotate, thereby driving the third robotic arm 2.7 to move, so as to realize the movement of the third joint; The two end faces of the fourth speed reducer of the fourth-axis drive 2.8 are respectively fixed to the third robotic arm 2.7 and the fourth robotic arm 2.9. The fourth motor is fixed on the third robotic arm 2.7. During the movement, the fourth motor drives the fourth speed reducer to rotate, thereby driving the fourth robotic arm 2.9 to move, so as to realize the movement of the fourth joint; The two end faces of the fifth speed reducer of the fifth-axis drive 2.10 are respectively fixed to the fourth robotic arm 2.9 and the Y-direction connecting seat 2.11. The fifth motor is fixed on the fourth robotic arm 2.9. During the movement, the fifth motor drives the fifth speed reducer to rotate, thereby driving the Y-direction connecting seat 2.11 to move, so as to realize the movement of the fifth joint.

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

[0073] See Figure 6 , the structure of the specific embodiment of the Y-direction drive component 3.1 of the present invention includes a Y-direction base 3.1.1, a Y-direction linear motor 3.1.2, a Y-direction linear guide rail 3.1.3, and a magnetic grating ruler 3.1.4. The Y-direction linear motor 3.1.2, the Y-direction linear guide rail 3.1.3, and the magnetic grating ruler 3.1.4 are all arranged on the Y-direction base 3.1.1. The function of the magnetic grating ruler 3.1.4 is to provide position feedback for the movement of the linear motor.

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

[0075] The positioning bed 3.2. can adopt an existing positioning bed that can realize patient positioning, or can also adopt the positioning bed with the authorization announcement number CN221358234 and the name of "a positioning bed with a patient protection device" applied by the applicant.

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

[0077] See Figure 8 , the structure of the specific embodiment 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 arranged on the support plate 3.2.1.1. The position detection switch 3.2.1.4 is arranged on the positioning sleeve 3.2.1.3. The support plate 3.2.1.1 is arranged on the Y-direction linear guide rail 3.1.3.

[0078] See Figure 9, in 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, the head positioning sleeve 3.2.1.3.1 is located in the middle of the support plate 3.2.1.1, the body locking sleeve 3.2.1.2.2 is located between the body positioning sleeve 3.2.1.3.2 and the head positioning sleeve 3.2.1.3.1, the head locking sleeve 3.2.1.2.1 is located at the rear of the support plate 3.2.1.1 on the right side of the head positioning sleeve 3.2.1.3.1. The body position detection switch 3.2.1.4.2 is arranged on the body positioning sleeve 3.2.1.3.2, and the head position detection switch 3.2.1.4.1 is arranged on the head positioning sleeve 3.2.1.3.1. In this embodiment, there are three body positioning sleeves 3.2.1.3.2, which are arranged in a triangular shape on the upper part of the support plate 3.2.1.1, and there are also three head positioning sleeves 3.2.1.3.1, which are arranged in a triangular shape in the middle of the support plate 3.2.1.1.

[0079] During the treatment process, select the position of the fixed bed 3.2.2 on the support plate assembly 3.2.1 according to the tumor position of the patient. When the fixed bed 3.2.2 is in the corresponding working position according to the treatment plan and triggers the corresponding position detection switch 3.2.1.4, the treatment can start. Otherwise, the system will activate the safety model and cannot execute the treatment plan to protect the patient from being mis-treated. The fixed bed 3.2.2 ensures its position with the support plate assembly 3.2.1 through the positioning pin and the positioning sleeve 3.2.1.3, and is firmly locked with the support plate assembly 3.2.1 through the locking device 3.2.3. Through the positioning pin and the locking device 3.2.3, the hardware consistency of the patient during each fractionated treatment can be ensured.

[0080] See Figure 10 , in a preferred embodiment of the calibration assembly 4 of the present invention, it includes a fixed seat 4.1, a rotating arm 4.2, a driving motor 4.3, a Z-direction distance measuring sensor 4.4 and a Y-direction distance measuring sensor 4.5. The driving motor is arranged on the fixed seat 4.1, the rotating arm 4.2 is connected to the driving motor 4.3, and both the Z-direction distance measuring sensor 4.4 and the Y-direction distance measuring sensor 4.5 are arranged on the rotating arm 4.2. The fixed seat 4.1 is arranged on the first robotic arm 2.2 of the articulated arm assembly 2.

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

[0082] When the present invention is applied, the multi-degree-of-freedom robotic arm radiotherapy couch is connected to the radiotherapy equipment host. After CT positioning is completed, the station of the positioning couch 3.2.2 on the support plate assembly 3.2.1 is selected according to the position of the patient's tumor. The positioning couch 3.2.2 is fixed on the support plate assembly 3.2.1 through the locking device 3.2.3, and a treatment plan is made. When starting the treatment, after the patient gets on the positioning couch 3.2.2, the multi-degree-of-freedom robotic arm radiotherapy couch first moves to the marking position through the X-direction assembly 1, the articulated arm assembly 2 and the Y-direction assembly 3, and then the driving motor 4.3 drives the rotating arm 4.2 to move 90 degrees. The Z-direction ranging sensor 4.4 and the Y-direction ranging sensor 4.5 respectively calibrate the Z direction and the Y direction, and feed back the errors caused by deformation and transmission to the control system. After judgment by the control system, a correction value is given for position correction, and then the treatment plan is executed for treatment.

[0083] For a control method of a multi-degree-of-freedom robotic arm radiotherapy couch provided by the present invention, in the articulated arm assembly, the first axis is drivingly connected to the first robotic arm and the base to form a first rotary joint, the second axis is drivingly connected to the first robotic arm and the second robotic arm to form a second rotary joint, the third axis is drivingly connected to the second robotic arm and the third robotic arm to form a third rotary joint, the fourth axis is drivingly connected to the third robotic arm and the fourth robotic arm to form a fourth rotary joint, and the fifth axis is drivingly connected to the fourth robotic arm to form a fifth rotary joint. The control method includes the following steps:

[0084] 1) Use the improved DH method to establish a robotic arm coordinate system with multiple degrees of freedom, and sequentially determine the axial direction of each joint axis as the Z direction. According to the right-hand rule, determine the X and Y directions. As Figure 11 shown, the relevant parameters of the transformation relationship between two adjacent joint axes are: alpha i-1 is the angle of rotation around the X i-1 axis from Z i-1 to Zi, a i-1 is the distance along the X i-1 axis from Z i-1 to Z i , theta i is the angle of rotation around the Z i axis from X i-1 to X i , and di is the distance along the Zi axis from X i-1 to X i . Among them, a1, a2, a3, d1, and d5 are determined according to the configuration design of the joint. The MDH parameter table is asFigure 12 as shown;

[0085] 2) According to the forward kinematics method of the robotic arm, the end pose matrix T(p) of the multi-degree-of-freedom robotic arm is obtained through the translation and rotation of the base coordinate system, and is successively obtained by multiplying the homogeneous matrices T(i - 1,

[0086] i) = 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), and 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 end of the robotic arm; 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 end position coordinates;

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

[0093] Multiply the left side of Equation 1 by the inverse matrix of T(1) to get T(0,1) -1*T(p) = T(2,3) * T(3,4) * T(4,5) (Equation 2), and P is obtained according to the matrix correspondence y cos(θ1) - P x sin(θ1) = 0, and the rotation angle θ1 of the first rotating joint is θ1 = arctan(Py, Px),

[0094] Obtained according to the matrix correspondence Substitute θ1 into it, and the rotation angle θ5 of the fifth rotating joint is θ5 = arctan(-sin(θ5), -cos(θ5));

[0095] Multiply the right side of Equation 2 by the inverse matrix of T(4,5) to get T(0,1) -1 *T(p) * T(4,5) -1 = T(1,2) * T(2,3) * T(3,4) (Equation 3), and obtained according to the matrix correspondence

[0096]

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

[0098] θ3 = arctan(s32, c3);

[0099] Multiply the left side of Equation 3 by the inverse matrix T(1,2) of T(1,2) -1 *T(0,1) -1 *T(p) * T(4,5) -1 = T(2,3) * T(3,4), and obtained according to the matrix correspondence

[0100]

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

[0102] Multiply the left side of Equation 1 by the inverse matrices of T(0,1), T(1,2), and T(2,3) to get T(2,3) -1 *T(1,2) -1 *T(0,1) -1 *T(p) = T(3,4) * T(4,5); and obtained according to the matrix correspondence

[0103]

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

[0105] 4) Use the Monte Carlo algorithm to set the random working points of the robotic arm, and the number of random points N = 5000000;

[0106] Randomly obtain a total of [N, 5] rotary joint angles within the joint angle limit range, and use forward kinematics to generate the working pose set;

[0107] Recursively divide the pose set space into multiple regions. Each node represents a point in three-dimensional space. At the same time, divide the space into two half-spaces. Select the median value in the Y direction of the pose set as the root node O for splitting. The left subset is less than Oy, and the right subset is greater than Oy. Perform secondary partitioning on the above subsets respectively. Select the median value in the X direction as the root node. The left subset is less than Ox, and the right subset is the opposite of Ox. Perform the third partitioning on the above subsets. Select the median value in the Z direction as the root node. The left subset is less than Oz, and the right subset is the opposite of Oz. Continuously repeat the above process to construct the pose set search tree model M2.

[0108] The host computer control system issues the target point coordinates in real time, and each target point coordinate is regarded as the end target point P of the robotic arm t ,P t =[N, O, A, Px, Py, Pz], and obtain the rotation angles of each joint through the inverse solution model M1;

[0109] If the solution does not exist, obtain the nearest point P of P t through the nearest neighbor calculation method; tn ;

[0110] P tn is input into the search tree model M 2；

[0111] Starting from the root node, visit the nodes layer by layer downwards, and judge whether the splitting plane of the current node intersects with the envelope set centered on P tn with a radius of R. Set 0.01 ≤ R ≤ 0.05, and the upper limit of R is 0.1 mm;

[0112] Calculate the vertical distance D from P tn to the splitting plane of the current node. 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 sides; when recursively reaching the leaf node, calculate the Euclidean distance E between all points in the node and q d , and save the points with a distance less than R to the result set;

[0113] 5) Calculate the rotary joint angles through the inverse solution model M1;

[0114] 6) Send the rotary joint angles to the lower computer control device to move.

[0115] The technical content not specifically described in the present invention content and the above embodiments is the same as the prior art.

[0116] The above is only the specific implementation manner disclosed by the present invention, but the protection scope disclosed by the present invention is not limited thereto. The protection scope disclosed by the present invention shall be subject to the protection scope of the claims.

Claims

1. A control method for a multi-degree-of-freedom robotic arm radiotherapy couch, characterized in that: The multi-degree-of-freedom robotic arm radiotherapy couch includes an X-direction component, an articulated arm component, a Y-direction component, and a calibration component. The articulated arm component is arranged on the X-direction component, and the calibration component and the Y-direction component are respectively arranged on the articulated arm component. The X-direction component includes an X-direction base, an X-direction linear guide rail, and an X-direction transmission component; the X-direction linear guide rail and the X-direction transmission component are both arranged on the X-direction base, and the articulated arm component is arranged on the X-direction linear guide rail and the X-direction 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, a fifth-axis drive, and a Y-direction connecting seat; The first robotic arm is connected to the base through the first-axis drive, the second robotic arm is connected to the first robotic arm through the second-axis drive, the third robotic arm is connected to the second robotic arm through the third-axis drive, the fourth robotic arm is connected to the third robotic arm through the fourth-axis drive, and the Y-direction connecting seat is connected to the fourth robotic arm through the fifth-axis drive. Among them, the first-axis drive connects the first robotic arm and the base to form a first rotating joint, the second-axis drive connects the first robotic arm and the second robotic arm to form a second rotating joint, the third-axis drive connects the second robotic arm and the third robotic arm to form a third rotating joint, the fourth-axis drive connects the third robotic arm and the fourth robotic arm to form a fourth rotating joint, and the fifth-axis drive connects the fourth robotic arm to form a fifth rotating joint. The control method includes the following steps: 1) The coordinate system of the robotic arm with multiple degrees of freedom is established using the improved DH method. The axial direction of each joint axis 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 is the angle of rotation about the X i-1 axis, from Z i-1 to Zi, a i-1 is the distance along the X i-1 axis, from Z i-1 to Z i , theta i is the angle of rotation about the Z i axis, from X i-1 to X i , and di is the distance along the Zi axis, from X i-1 to X i . Among them, a1, a2, a3, d1, and d5 are determined according to the configuration design of the joints; 2) According to the forward kinematics method of the robotic arm, the end pose matrix T(p) of the multi-degree-of-freedom robotic arm is obtained through the translation and rotation of the base coordinate system, and is successively obtained by multiplying the homogeneous matrices T(i - 1, i) = Rx(αi - 1) * Dx(ai - 1) * Rz(θi) * Dz(di) of two adjacent rotating joints, (i = 1, 2, 3, 4, 5), where 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) (Equation 1); According to the above formula, it is calculated that: where, S1 = sin(θ1), C 234 = cos(θ2 + θ3 + θ4), and other expressions are similar; 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 attitude vector of the end of the robotic 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] are the end position coordinates; 3) Establish the inverse kinematics model M of the multi-degree-of-freedom robotic arm 1； Left-multiply the inverse matrix of T(1) to Equation 1 to obtain T(0,1). -1 *T(p) = T(2,3)*T(3,4)*T(4,5) (Equation 2), and P is obtained according to the matrix correspondence relationship. y cos(θ1) - P x sin(θ1) = 0, and the rotation angle θ1 of the first rotating joint is θ1 = arctan(Py, Px). Obtained according to the matrix correspondence Substitute θ1, and obtain the rotation angle θ5 of the fifth rotating joint as θ5 = arctan(-sin(θ5), -cos(θ5)); Right-multiply the expression 2 by the inverse matrix of T(4,5) to obtain T(0,1). -1 *T(p)*T(4,5) -1 = T(1,2)*T(2,3)*T(3,4) (Equation 3), and according to the matrix correspondence, we get The rotation angle θ3 of the third rotating joint = arctan(s31, c3), and the second set of solutions is θ3 = arctan(s32, c3); Pre - multiply the left side of Equation 3 by the inverse matrix \(T(1,2)\) of \(T(1,2)\) -1 * \(T(0,1)\) -1 * \(T(p)*T(4,5)\) -1 = \(T(2,3)*T(3,4)\), obtained according to the matrix correspondence The rotation angle θ2 of the second rotating joint = arctan(D, -sqrt(ps2 + pc2 - D2)) - arctan(pc, ps), and the second set of solutions is θ2 = arctan(D, -sqrt(ps2 + pc2 - D2)) - arctan(pc, ps); Left-multiply the inverse matrices of \(T(0,1)\), \(T(1,2)\), and \(T(2,3)\) to Equation 1 to obtain \(T(2,3)\). -1 * \(T(1,2)\) -1 * \(T(0,1)\) -1 * \(T(p)=T(3,4)*T(4,5)\); Obtained according to the matrix correspondence relationship The rotation angle θ4 of the fourth rotating joint = arctan(Ath4, Bth4); 4) Use the Monte Carlo algorithm to set the random working points of the robotic arm, and the number of random points N = 5000000; Randomly obtain a total of [N, 5] rotating joint angles within the joint angle limit range, and use forward kinematics to generate a working pose set; The pose set space is recursively divided into multiple regions, and each node represents a point in three-dimensional space. Meanwhile, the space is divided into two half-spaces. The median value in the Y direction of the pose set is selected as the root node O for splitting. The left subset is less than Oy, and the right subset is greater than Oy. The above subsets are respectively divided again. The median value in the X direction is selected as the root node. The left subset is less than Ox, and the right subset is the opposite of Ox. The above subsets are divided for the third time. The median value in the Z direction is selected as the root node. The left subset is less than Oz, and the right subset is the opposite of Oz. The above process is continuously repeated to construct the pose set search tree model M2. The host computer control system issues the target coordinates in real time, and each target coordinate is regarded as the target point P at the end of the robotic arm t , P t = [N, O, A, Px, Py, Pz], and the rotation angles of each joint are obtained through the inverse solution model M1; If no solution exists, the nearest point P of t is obtained through the nearest neighbor calculation method; t tn ​​ P tn Input to the search tree model M 2； Starting from the root node, visit the nodes layer by layer from top to bottom, and determine whether the splitting plane of the current node intersects with the envelope set centered at P tn with a radius of R. Set 0.01 ≤ R ≤ 0.05, and the upper limit of R is 0.1 mm; Calculate P tn The vertical distance D from the current node's splitting plane. If D > R, search for 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 the leaf node, calculate the Euclidean distance E between all the points within the node and q d , and save the points with a distance less than R to the result set; 5) Calculate the rotational joint angles through the inverse solution model M1. 6) Send the rotational joint angles to the lower computer to control the movement of the device.

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 component includes an X-direction driving motor, a reducer, a first support, a lead screw, a nut seat, and a second support. The X-direction driving motor is connected to the reducer. The reducer is arranged on the first support. The nut seat is arranged on the lead screw. Both ends of the lead screw are respectively arranged on the first support and the second support through bearings. One end of the lead screw close to the first support is connected to the reducer through a coupling. The first support and the second support are arranged on the X-direction base. The joint arm component is connected to 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 to the fourth robotic arm through a fifth-axis drive. Both sides of the bottom of the base are respectively arranged on the X-direction linear guide rail and the nut seat.

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

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 in 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. According to the control method of the multi-degree-of-freedom robotic arm radiotherapy bed described in claim 6, the body positioning sleeves are three and are arranged in a triangular shape in the middle of the support plate.

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 includes a fixed base, 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 base, the rotating arm is connected to 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 base is arranged on the first robotic arm of the articulated arm assembly.

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