Respiratory motion compensation method and system based on master-slave force feedback

Abstract

The invention discloses a breathing motion compensation method and system based on master-slave force feedback. The breathing motion compensation method comprises the following steps that firstly, slave end acting force of breathing of a patient on a puncture needle is measured; 2, if the slave end acting force is equal to 0, directly returning to the step 1, otherwise, transmitting the slave end acting force to the master hand according to a preset proportion; 3, if the feedback force of the master hand is increased, the motion acceleration of the master hand is increased, so that the motion acceleration of the puncture needle is increased, and the step 1 continues to be executed; if the feedback force of the master hand is reduced, the motion acceleration of the master hand is reduced, so that the motion acceleration of the puncture needle is reduced, and the first step is continued; and if the feedback force of the master hand is not changed, directly returning to the step 1. According to the breathing motion compensation method, breathing motion compensation is introduced in the master-slave lung puncture operation process, so that a patient can continue to puncture under breathing, and the force of the master hand is accurately fed back to the slave end mechanical arm.

Description

Technical Field

[0001] The present invention belongs to the technical field of master-slave lung puncture medical robots, and in particular relates to a respiratory motion compensation method and system based on master-slave force feedback. Background Art

[0002] Prior art discloses a human-machine interactive control system for remote puncture surgery. This system, based on a dual-constraint mechanism, combines a posture constraint mode with a needle insertion constraint mode to effectively regulate the operator's behavior during remote operation. In posture constraint mode, the system monitors in real time whether the end of the simulated puncture rod deviates from an arc-shaped area centered on the RCM point and with the current needle insertion depth as the radius. If deviation occurs, a constraint force is applied to guide the return. In needle insertion constraint mode, the system detects deviations in the propulsion direction and applies force feedback to ensure that the puncture action proceeds in the predetermined direction, avoiding the risks of rotation or posture errors. This solution also incorporates spatial mapping technology using multi-coordinate system fusion to accurately map the operator's control actions to the CT image of the surgical area, achieving a what-you-see-is-what-you-get control effect. A terminal force sensor is also equipped to sense the puncture resistance and feedback it to the operator, providing a realistic tactile simulation experience. This three-in-one control method not only improves operational safety but also provides technical support for precise control of minimally invasive interventional surgery under remote image guidance. It is particularly suitable for clinical scenarios requiring high-precision control, such as tumor ablation and puncture sampling.

[0003] The specific solution for respiratory motion compensation in existing master-slave lung punctures is a hybrid force-position control framework for robotic thoracoabdominal punctures for respiratory motion compensation. This framework combines respiratory gating technology with adaptive admittance control to achieve precise puncture under a single CT scan. The respiratory phase is identified in real time using surface markers; based on this, a segmented control strategy is designed, whereby position control is used to advance the needle along the planned path during the last 20% of the respiratory cycle window at the end of inspiration. For the remaining respiratory phases, the system switches to an admittance control mode based on force feedback, driving the needle to follow the movement of the organ. However, this solution only involves the admittance control of the slave-side robotic arm for respiratory motion compensation and does not integrate control with the master-side master hand.

[0004] Therefore, the master-slave lung puncture system lacks effective respiratory motion compensation methods and technologies. The existing respiratory motion compensation technology cannot be well integrated into the master-slave lung puncture device, and cannot fully utilize the advantages of the slave end's strong position control capability and the master end's strong force rendering capability. As a result, the existing technology has the following disadvantages:

[0005] 1. During lung puncture surgery, the patient's breathing can cause target displacement. The existing master-slave lung puncture technology lacks effective respiratory motion compensation technology to compensate for puncture target displacement. The current technology will cause more harm to the patient during the lung puncture process and pose a major safety issue.

[0006] 2. The existing master-slave lung puncture technology cannot continue puncturing while the patient is breathing, and there is a problem that the force of the master hand cannot be accurately transmitted to the slave end, resulting in insufficient lung puncture force accuracy;

[0007] 3. The slave-end robotic arm of the existing master-slave lung puncture technology has a large inertia and poor real-time performance, which results in weak force control capabilities of the slave-end robotic arm. The master arm has a small inertia, strong real-time performance, and strong real-time tracking capabilities. This is the advantage of the master arm, but its position control capability is far inferior to that of the robotic arm. Summary of the Invention

[0008] The present invention provides a respiratory motion compensation method and system based on master-slave force feedback. The respiratory motion compensation method can introduce respiratory motion compensation during master-slave lung puncture surgery, allowing the patient to continue puncturing while breathing, accurately feeding back the force of the master hand to the slave robotic arm, and giving full play to the position control advantages of the slave robotic arm and the force control performance advantages of the master hand.

[0009] In order to achieve the above object, the present invention adopts the following specific technical solutions:

[0010] The present invention provides a respiratory motion compensation method based on master-slave force feedback, which is used in a master-slave lung puncture system. The master-slave lung puncture system is divided into a master end and a slave end; the master end includes a master hand; the slave end includes a mechanical arm, a puncture needle and a force sensor; the respiratory motion compensation method includes the following steps:

[0011] Step 1: measuring the force exerted by the patient's breathing on the puncture needle from the end;

[0012] Step 2: Determine whether the slave end force is equal to 0. If so, return to step 1 directly. Otherwise, transfer the slave end force to the master hand according to a predetermined ratio, and obtain the master hand feedback force at the master hand end.

[0013] Step three, determine whether the master hand feedback force increases. If so, increase the master hand's motion acceleration, thereby increasing the motion acceleration of the puncture needle, and continue to return to step one; if not, determine whether the master hand feedback force decreases. If the master hand feedback force decreases, reduce the master hand's motion acceleration, thereby reducing the motion acceleration of the puncture needle, and continue to return to step one; if the master hand feedback force remains unchanged, directly return to step one.

[0014] Furthermore, in step 2, when the slave force is transmitted to the master hand according to a predetermined ratio, the value of the predetermined ratio is determined according to the magnitude of the slave force, and the slave force and the master hand feedback force satisfy the following formula:

[0015] Fz=kFc;

[0016] In the above formula, Fz is the feedback force of the master hand, Fc is the force applied from the slave end, and k is the proportional coefficient.

[0017] Furthermore, the value of the predetermined ratio is adjusted by fuzzy control.

[0018] Furthermore, the value of the proportional coefficient and the slave force satisfy the following relationship:

[0019] When 0<Fc<1N, 0<k<0.5;

[0020] When 1N≤Fc<2N, 0.5≤k<1;

[0021] When 2N≤Fc, 1≤k<2;

[0022] In the above formula, k is the proportional coefficient, and Fc is the force exerted by the patient's breathing on the puncture needle from the end.

[0023] Furthermore, in step 1, a force sensor is used to measure the force exerted by the patient's breathing on the puncture needle from the end.

[0024] In addition, the present invention also provides a master-slave lung puncture system, which adopts the above-mentioned respiratory motion compensation method and includes a master hand, a robotic arm, a puncture needle, a force sensor and a controller; the force sensor and the puncture needle are both installed at the end of the robotic arm; the force sensor is used to measure the force exerted by the patient's breathing on the puncture needle; the controller is connected to the master hand, the robotic arm and the force sensor signal.

[0025] Compared with the prior art, the technical solution of the present invention has the following beneficial effects:

[0026] 1. Compared with the existing master-slave lung puncture system, the master-slave lung puncture system of the present invention converts the force compensation of the master hand into the position compensation of the slave end robotic arm by adding respiratory motion compensation, giving full play to the advantages of the strong force rendering capability of the master hand and the high position control accuracy of the slave end robotic arm, better ensuring the safety of lung puncture surgery, greatly improving the accuracy of puncture and motion compensation, and reducing damage to the patient by respiratory tracking of the puncture needle, thereby improving the safety and accuracy of lung puncture surgery.

[0027] 2. The respiratory motion compensation method of the present invention can perform puncture under respiratory motion by performing motion compensation, and can accurately transmit the puncture force to the slave hand.

[0028] 3. In the respiratory motion compensation method of the present invention, the use of the main hand for force control has the characteristics of high force control accuracy and good real-time performance, that is, strong force rendering capability; at the same time, since the position control accuracy of the robotic arm is good, the use of the robotic arm for position control has the characteristics of good tracking capability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic diagram of the master-slave lung puncture system of the present invention;

[0030] Figure 2 Flowchart of the respiratory motion compensation method of the present invention.

[0031] Reference numerals: 1 - main hand, 2 - robotic arm, 3 - puncture needle, 4 - force sensor, 5 - patient, 6 - operating area. DETAILED DESCRIPTION

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0033] like Figure 1 As shown in the structure, an embodiment of the present invention provides a master-slave lung puncture system, which includes a master hand 1, a robotic arm 2, a puncture needle 3, a force sensor 4, and a controller. The master-slave lung puncture system is divided into a master end and a slave end. The master end includes a master hand 1, which can be a popular Omega series or Touch series master hand. The slave end includes a robotic arm 2, a puncture needle 3, and a force sensor 4. The force sensor 4 and the puncture needle 3 are both mounted at the end of the robotic arm 2. The force sensor 4 is used to measure the force exerted by the patient's breathing on the puncture needle 3 and can be a six-dimensional force sensor 4. The controller is signal-connected to the master hand 1, robotic arm 2, and force sensor 4. The robotic arm 2 can be a commercially available UR5, KUKA, or Siling robotic arm. The bottom of the puncture needle 3 is located within the surgical area 6 of the patient 5.

[0034] The master-slave lung puncture system uses a respiratory motion compensation method based on master-slave force feedback to compensate for the respiratory motion of the puncture needle 3 during the puncture process. Figure 2 As shown, the respiratory motion compensation method includes the following steps:

[0035] Step 1: Use the force sensor 4 to measure the force exerted by the patient's breathing on the puncture needle 3 from the end.

[0036] Step 2: The controller determines whether the slave force is equal to 0. If so, the controller directly returns to step 1. Otherwise, the slave force is transferred to the master hand 1 according to a predetermined ratio, and the master hand feedback force is obtained at the master hand 1 end. When the slave force is transferred to the master hand 1 according to the predetermined ratio, the value of the predetermined ratio is determined according to the magnitude of the slave force, and can be adjusted by the controller through fuzzy control. The slave force and the master hand feedback force satisfy the following formula:

[0037] Fz=kFc;

[0038] In the above formula, Fz is the master feedback force, Fc is the slave end force, and k is the proportional coefficient.

[0039] The proportional coefficient and the slave end force satisfy the following relationship:

[0040] When 0 < Fc < 1 N, 0 < k < 0.5;

[0041] When 1 N≤ Fc < 2 N, 0.5≤ k < 1;

[0042] When 2 N≤ Fc, 1≤ k < 2;

[0043] In the above formula, k is the proportional coefficient, and Fc is the slave end force of the patient's breathing on the puncture needle 3.

[0044] Step three, the controller judges whether the master feedback force is increased, if yes, the motion acceleration of the master 1 is increased, so that the motion acceleration of the puncture needle 3 is increased, and the step one is returned; if not, the controller judges whether the master feedback force is reduced, if the master feedback force is reduced, the motion acceleration of the master 1 is reduced, so that the motion acceleration of the puncture needle 3 is reduced, and the step one is returned; if the master feedback force is not changed, the step one is returned directly. When judging whether the master feedback force is increased or not, the master feedback force obtained at this moment is compared with the last master feedback force obtained at the last moment.

[0045] The above respiratory motion compensation method can be executed by the controller of the master-slave lung puncture system.

[0046] The technical scheme of the present application is explained from three parts below, the first part is not punctured, only respiratory motion, the respiratory motion compensation method of the master-slave lung puncture system; the second part is lung puncture under respiration, and the method of precise transmission of the master end force to the slave end during the puncture process; the third part applies the above two methods through an example.

[0047] The first part, the respiratory motion compensation method of the master-slave lung puncture system

[0048] Before lung puncture is performed, the patient's lung has respiratory motion. When the puncture needle 3 penetrates into the patient 5 puncture entry point, if the mechanical arm 2 does not follow the patient's respiration for servo, it may cause excessive trauma to the patient 5, resulting in safety problems in the operation. The present application aims at this technical problem, and proposes a respiratory motion compensation method for master-slave lung puncture. According to Figure 1 The force sensor 4 at the end of the mechanical arm 2 can measure the slave end force Fc caused by the patient's respiration on the puncture needle 3, and the force-acceleration relationship of the slave end is obtained by Newton's second law as follows:

[0049] Fc = mc × ac (1)

[0050] In the above formula, Fc is the force acting on the slave end, mc is the mass of the slave end, and ac is the acceleration of the slave end.

[0051] When the force sensor 4 at the end of the slave manipulator 2 detects a force, its slave force Fc is transmitted to the master hand 1 with a proportional coefficient k, that is, the master hand feedback force is Fz:

[0052] Fz = k × Fc (2)

[0053] Similarly, the force-acceleration relationship at the master end is:

[0054] Fz = mz × az (3)

[0055] In the above formula, Fz is the feedback force of the master hand, mz is the mass of the master end, and az is the motion acceleration of the master end.

[0056] Since the force detected by the force sensor 4 at the end of the slave manipulator 2 and the force transmitted to the master hand 1 are proportional, then:

[0057] Mz × az = k × mc × ac (4)

[0058] ac = (mz × az) / (k × mc) (5)

[0059] Let mz / (k×mc)=i, then formula (5) becomes:

[0060] Ac = iaz (6)

[0061] From the above formula (6), it can be seen that the motion acceleration ac of the slave end is proportional to the motion acceleration az of the master end.

[0062] To compensate for respiratory motion, the goal is to minimize the force exerted on the puncture needle 3 by respiratory motion, as detected by the force sensor 4 of the slave manipulator 2, to zero, i.e., Fc = 0. With Fc = 0 as the target, by adjusting k, the force Fz transmitted from the slave manipulator 2 to the master hand 1 will change. First, Fc is the upward force exerted on the puncture needle 3 by the needle entry point caused by respiratory motion. Assuming that adjusting k increases Fz, it can be seen from formula (3) that mz is a constant value, and an increase in Fz will cause an increase in az; thus, it can be seen from formula (6) that an increase in az will cause an increase in ac, and an increase in ac will cause the end of the robot 2 to move upward faster. From formula (1), mc is a constant value, so the Fc detected by the robot 2 will decrease faster; when Fc decreases, k can be appropriately adjusted to reduce Fz. From formula (3), it can be seen that mz is a constant value, and a decrease in Fz will cause a decrease in az; thus, it can be seen from formula (6) that a decrease in az will cause a decrease in ac, and a decrease in ac will cause the end of the robot 2 to move upward slower. From formula (1), mc is a constant value, so the Fc detected by the robot 2 will decrease slower, thereby achieving respiratory motion compensation by detecting the magnitude of the force exerted on the puncture needle 3, thereby forming a closed-loop control to achieve the goal of Fc=0. According to the above process, respiratory motion compensation of the master-slave lung puncture system can be achieved.

[0063] Part 2: Master-slave lung puncture system for puncturing under breathing and accurately transmitting the master hand's force to the slave end

[0064] The lung puncture method of the present invention does not require the patient to hold his breath, and accurate puncture can be performed under the patient's respiratory movement. When the lung puncture begins, that is, the doctor needs to apply force Fs to the master hand 1, then substitute formulas (2) and (3), and the resultant force-acceleration relationship at the slave end is:

[0065] kFc + Fs = mz × az (7)

[0066] Substituting formula (5) into formula (7) yields:

[0067] ac = (kFc + Fs) / mz (8)

[0068] Therefore, ac has a proportional relationship with (kFc+Fs), and 1 / mz is a constant. As mentioned in the first part, Fc=0 can be made by adjusting the proportional coefficient k, that is, the movement of the robotic arm 2 during lung puncture is actually achieved by adjusting the master end. The force applied by the doctor on the master hand 1 can be directly fed back as the acceleration of the end of the slave robotic arm 2 according to a certain proportion, thereby achieving position control of the end of the robotic arm 2 by controlling the force of the master end. In addition, the lung puncture process is not affected by respiratory movement, and precise puncture can continue under breathing, which not only ensures the safety of lung puncture but also ensures the precise transmission of puncture force.

[0069] Part III: Example of respiratory motion compensation in the master-slave lung puncture system

[0070] Both the first and second parts are based on the relationship between the force Fc detected by the slave robotic arm 2 and the force Fz exerted by the master hand 1. Fc and Fz can be a simple proportional relationship or a complex relationship such as Fc = kFz + bv, where v represents the velocity of the slave robotic arm 2 and b is a parameter that regulates the velocity. However, this paper only uses the simplest model for illustration.

[0071] Assume that Fc and Fz are in the simplest proportional relationship, that is:

[0072] Fc = k × Fz (9)

[0073] according to Figure 1 As shown, analysis starts from the end. When the patient 5 produces respiratory movement, the end of the robot arm 2 detects Fc, and the direction of Fc is upward. At this time, the proportional coefficient k is adjusted to decrease. At this moment, Fc remains unchanged, and Fz increases. According to formula (3), Fz increases, az increases, and thus ac increases according to formula (6), so that the robot arm 2 moves upward faster. When the end of the robot arm 2 compensates for respiratory movement, the Fc detected by the end of the robot arm 2 decreases. Then the proportional coefficient k can be adjusted to increase a little, so that Fz is smaller, which will reduce a little, and thus ac is reduced a little, and the compensation speed of the robot arm 2 is slower, thereby linearly compensating for respiratory movement and achieving the purpose of Fc=0. The specific control logic is as follows: Figure 2 shown.

[0074] The proportional coefficient k can be adjusted and controlled through fuzzy control. For example, when 0 < Fc < 1N, Fc is considered a small force, so 0 < k < 0.5 is set; when 1 ≤ Fc < 2, Fc is considered a medium force, so 0.5 ≤ k < 1 is set; when Fc ≥ 2N, Fc is considered a large force, so 1 ≤ k < 2 is set. The proportional coefficient k is adjusted accordingly based on the range of the slave force Fc detected by the slave robot arm 2.

[0075] Obviously, those skilled in the art may make various changes and modifications to the embodiments of the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A respiratory motion compensation method based on master-slave force feedback, characterized in that: The respiratory motion compensation method is used in a master-slave lung puncture system, which is divided into a master end and a slave end; the master end includes a master hand; the slave end includes a robotic arm, a puncture needle, and a force sensor; the respiratory motion compensation method includes the following steps: Step 1: measuring the force exerted by the patient's breathing on the puncture needle from the end; Step 2: Determine whether the slave end force is equal to 0. If so, return to step 1 directly. Otherwise, transfer the slave end force to the master hand according to a predetermined ratio, and obtain the master hand feedback force at the master hand end. Step three, determine whether the master hand feedback force increases. If so, increase the master hand's motion acceleration, thereby increasing the motion acceleration of the puncture needle, and continue to return to step one; if not, determine whether the master hand feedback force decreases. If the master hand feedback force decreases, reduce the master hand's motion acceleration, thereby reducing the motion acceleration of the puncture needle, and continue to return to step one; if the master hand feedback force remains unchanged, directly return to step one.

2. The respiratory motion compensation method according to claim 1, wherein: In step 2, when the slave force is transmitted to the master hand according to a predetermined ratio, the value of the predetermined ratio is determined according to the magnitude of the slave force, and the slave force and the master hand feedback force satisfy the following formula: Fz=kFc; In the above formula, Fz is the feedback force of the master hand, Fc is the force applied from the slave end, and k is the proportional coefficient.

3. The respiratory motion compensation method according to claim 2, wherein: The value of the predetermined ratio is adjusted by fuzzy control.

4. The respiratory motion compensation method according to claim 3, wherein: The value of the proportional coefficient and the slave end force satisfy the following relationship: When 0<Fc<1N, 0<k<0.5; When 1N≤Fc<2N, 0.5≤k<1; When 2N≤Fc, 1≤k<2; In the above formula, k is the proportional coefficient, and Fc is the force exerted by the patient's breathing on the puncture needle from the end.

5. The respiratory motion compensation method according to any one of claims 1 to 4, wherein: In step 1, a force sensor is used to measure the force exerted by the patient's breathing on the puncture needle from the end.

6. A master-slave lung puncture system, characterized in that: The master-slave lung puncture system adopts the respiratory motion compensation method according to any one of claims 1 to 5, and comprises a master hand, a robotic arm, a puncture needle, a force sensor, and a controller; the force sensor and the puncture needle are both mounted at the end of the robotic arm; The force sensor is used to measure the force exerted by the patient's breathing on the puncture needle; the controller is connected to the main hand, the robotic arm and the force sensor signal.

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