A clamping mechanism of a surgical robot

Abstract

The application discloses a clamping mechanism of a surgical robot, which comprises a rotating shaft, two finger plates symmetrically installed on opposite sides of the rotating shaft and matched at their ends to realize synchronous opening and closing movement, a Hall sensor for collecting magnetic field intensity change and an inductance sensor for outputting induction voltage according to the insertion amount of an inner iron core on the rotating shaft, a magnet arranged at a position corresponding to the Hall sensor on the finger plate, and a connecting rod hinged to the free end of the iron core at a corresponding position on the inner side of the two finger plates, so that the iron core moves in the inductance sensor through the connecting rod when the two finger plates are opened and closed. The pinch angle of the two finger plates is calculated according to the information collected by the Hall sensor and the inductance sensor, and the final pinch angle of the two finger plates is calculated through weighted calculation. The application adopts a multi-sensor fusion method, improves the precision and linearity of the movement detection of the clamping mechanism, and prevents the risk of failure of a single sensor.

Description

Technical Field

[0001] This invention relates to the field of robotics, and more particularly to a clamping mechanism for a surgical robot. Background Technology

[0002] Minimally invasive surgery has largely replaced open surgery as the main direction of development in the field of surgical medicine. Compared with traditional open surgery, minimally invasive surgery has advantages such as less trauma, less pain, and faster recovery. With the development of robotics technology, minimally invasive surgery based on laparoscopic surgical robots has gradually matured and is being widely used.

[0003] The laparoscopic surgical robot features a master-slave teleoperation structure, comprising a master hand and a slave arm. The surgeon controls the movement of the distal end-effectors and endoscope in the slave arm by manipulating the master hand. The basic master-slave operation process is as follows: after the positions of the master hand and the distal end-effectors in the slave arm are matched, the surgeon operates the gripping mechanism of the master hand. The controller maps the position of the gripping mechanism of the master hand to the distal end-effectors in real time, and the distal end-effectors reproduce the position of the master hand in real time.

[0004] In existing technologies, Hall effect sensors are typically used to detect the movement of the master gripper mechanism in order to control the movement of the instruments at the end of the arm. However, due to the different mounting positions of the magnet and the Hall effect sensor, the relationship between the movement of the gripper mechanism and the change in the magnetic field strength detected by the Hall effect sensor is not linear. In addition, there is a certain nonlinearity between the detected magnetic field and the output voltage of the Hall effect sensor itself. In actual use, doctors cannot linearly control the movement of the end-effector when operating the gripper mechanism, resulting in a problem of low linearity. Moreover, detecting the movement of the gripper mechanism using Hall effect sensors generally has a large accuracy error, which increases the difficulty of operation for doctors in surgical scenarios requiring precise instrument manipulation. In addition, a single sensor may fail, which increases the risk during the surgical procedure. Summary of the Invention

[0005] Purpose of the invention: To address the above-mentioned shortcomings, this invention proposes a clamping mechanism for a surgical robot. It employs a multi-sensor fusion method to improve accuracy and linearity, and uses two types of sensors for mutual backup and verification to avoid the impact of a single external interference on the sampling accuracy of the system, thereby improving anti-interference capability.

[0006] Technical solution:

[0007] A clamping mechanism for a surgical robot includes:

[0008] Rotation axis;

[0009] The finger plates are two in number, symmetrically installed on opposite sides of the rotating shaft, with their ends engaging with each other to achieve synchronous opening and closing movements.

[0010] A Hall sensor for collecting changes in magnetic field strength and an inductive sensor for outputting induced voltage based on the amount of iron core inserted into the rotating shaft are provided.

[0011] A magnet is provided at the position corresponding to the Hall sensor on the finger plate. The iron core is hinged to the free end of the two finger plates at the corresponding positions on the inner side of the two finger plates through a connecting rod. When the two finger plates open and close, the iron core is driven to move inside the inductive sensor through the connecting rod.

[0012] The pinch angle of the two fingers is calculated by using the information collected by the Hall sensor and the inductor sensor, and then weighted to obtain the final pinch angle of the two fingers.

[0013] The inductive sensor includes a sensor coil wound axially within it to form a passage through the iron core. The sensor coil includes an excitation coil in the middle and two auxiliary coils disposed on both sides of the excitation coil.

[0014] The two connecting rods are of the same length and are installed symmetrically.

[0015] The Hall sensor consists of one unit, and the magnets are arranged symmetrically on the two finger plates with their magnetic poles facing the same direction, so that the magnetic field lines between them pass through the Hall sensor.

[0016] There are two Hall sensors, and a magnet is installed on each of the two finger plates corresponding to one Hall sensor.

[0017] The weighted calculation specifically refers to:

[0018] U = λ1u1 + λ2u2;

[0019] Where U is the final pinch angle of the finger plate, u1 and u2 are the pinch angles of the finger plate calculated using information collected by the inductive sensor and the Hall sensor, respectively, λ1 and λ2 are the weights of the corresponding pinch angles of the finger plate, and λ1+λ2=1.

[0020] λ1 and λ2 are set to 0.9 and 0.1 respectively.

[0021] Based on the fact that the change in magnetic field strength collected by the Hall sensor and the induced voltage output by the inductive sensor have the same trend, it is determined whether the two sensors are abnormal during operation, and an alarm is issued when an abnormal sensor value is detected.

[0022] Both finger plates are provided with meshing teeth at their ends. The two finger plates are installed by meshing teeth at their ends to achieve opening and closing movements with the meshing point as the axis.

[0023] A torsion spring is also provided at the meshing teeth of the two finger plates, which always applies an outward opening force to the finger plates.

[0024] Compared with the prior art, the present invention has the following specific beneficial effects:

[0025] 1. This invention employs a multi-sensor fusion method, using two types of sensors to avoid the impact of a single external interference on the sampling accuracy of the system, while also preventing the risk of a single sensor failing during surgery.

[0026] 2. This invention adopts a high linearity sensor design, and structurally improves the progress and linearity of the clamping motion of the surgical robot through a high-precision linear transformation relationship.

[0027] 3. This invention employs two types of sensor design, weighted design, and Hall calibration, which solves the problems of low accuracy and poor linearity of the end effector in the clamping mechanism. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the clamping mechanism of the present invention.

[0029] Figure 2 This is a schematic diagram of the clamping mechanism of the present invention;

[0030] Figure 3 This is a front view of the interior of the clamping mechanism of the present invention;

[0031] Figure 4 This is a perspective view of the interior of the clamping mechanism of the present invention;

[0032] Figure 5 This is a schematic diagram showing the installation of the internal sensors of the clamping mechanism of the present invention;

[0033] Figure 6 This is a top view of the sensor inside the clamping mechanism of the present invention;

[0034] Figure 7 This is a cross-sectional view showing the installation of the internal sensor of the clamping mechanism of the present invention;

[0035] Figure 8 This is a cross-sectional view of the internal sensor of the clamping mechanism of the present invention;

[0036] Figure 9 This is a cross-sectional view of the clamping mechanism of the present invention after installation.

[0037] In the diagram, 1. J7 rotating shaft, 2. toggle switch, 3. first finger plate, 4. J7 joint, 5. J7 connecting rod, 6. dust cover, 7. J7 joint motor, 8. Hall sensor, 9. mating block, 10. second finger plate, 11. meshing tooth, 12. magnet, 13. mounting bracket, 14. return spring, 15. circuit board, 16. torsion spring, 17. inductive sensor, 18. sensor core, 19. first connecting rod, 20. second connecting rod, 21. sensor coil, 22. excitation coil, 23. secondary coil. Detailed Implementation

[0038] The present invention will be further explained below with reference to the accompanying drawings and specific embodiments.

[0039] Reference Figure 1 The clamping mechanism of the present invention is installed in conjunction with the J7 joint 4 at the end of the J7 link 5, and includes a housing (not shown in the figure), a J7 rotating shaft 1, a detection component installed in the J7 rotating shaft 1, and a first finger plate 3 and a second finger plate 10 respectively symmetrically installed on opposite sides of the J7 rotating shaft 1.

[0040] like Figure 2 , 3 As shown, the J7 rotating shaft 1 is connected to the J7 joint motor 7 inside the J7 joint 4, and is driven to rotate by the J7 joint motor 7. The first finger plate 3 and the second finger plate 10 are rotatably mounted in the housing relative to the two sides of the J7 rotating shaft 1, and both have meshing teeth 11 at the ends away from the J7 joint motor 7. The two finger plates are installed by meshing teeth 11 at their ends to achieve synchronous movement, specifically opening and closing movement with the meshing teeth 11 at their ends as the axis. A torsion spring 16 is also provided at the meshing teeth 11 of the two finger plates. The elastic force of the torsion spring 16 always applies an outward force to the two finger plates, so that even when the operator's pinching force disappears, an outward opening force is applied to the two finger plates, thereby causing the two finger plates to open.

[0041] Specifically, the meshing teeth 11 at the ends of the two finger plates are connected to the housing via a rotating shaft, and the torsion spring 16 is mounted on its rotating shaft.

[0042] More specifically, the shell has slots corresponding to the shape of the two finger plates at the positions corresponding to the two finger plates, so as to accommodate the two finger plates when they are pinched together.

[0043] like Figure 2-4 As shown, the J7 rotating shaft 1 includes a mounting bracket 13 for mounting a detection component and a dust cover 6 for protecting the detection component. The dust cover 6 is fitted over the mounting bracket 13, and the mounting bracket 13 has a mounting groove for mounting the detection component. The detection component includes an inductive sensor 17 and a sensor core 18 passing through the hollow structure of the inductive sensor 17, as shown. Figure 7 ,8 As shown, the sensor core 18 always passes through the hollow structure of the inductor sensor 17 during its movement stroke, with its end extending out of the inductor sensor 17. The inductor sensor 17 includes a sensor coil 21, which is axially wound inside the inductor sensor 17 to form a passage for the sensor core 18. Further, the sensor coil 21 is axially wound on the inner wall of the hollow structure of the inductor sensor 17; see reference... Figure 7 , 8 The sensor coil 21 includes an excitation coil 22 and two auxiliary coils 23. The excitation coil 22 is located in the middle of the inductive sensor 17, and the two auxiliary coils 23 are located on both sides of the excitation coil 22.

[0044] The excitation coil 22 is excited by alternating current at a fixed frequency and voltage. Since the excitation source voltage and frequency are constant, the cross-sectional area of ​​the sensor coil is constant. The voltage induced by the secondary coil 23 is only related to the magnetic flux, that is, to the position of the sensor core 18, and is linear. The design of the two secondary coils 23 being set on both sides of the excitation coil 22 makes it so that when the position of the sensor core 18 changes, the induced voltage output by the inductive sensor 17 is in a differential form with one increasing and one decreasing, which can be input to the industrial control computer through a differential amplifier.

[0045] like Figure 4 , 5As shown, two connecting rods, namely the first connecting rod 19 and the second connecting rod 20, are rotatably mounted on the end of the sensor core 18. The other ends of the two connecting rods are rotatably connected to the inner side of the end of the two finger plates away from the J7 joint motor, thereby forming a scissor mechanism. In this invention, the two connecting rods are of the same length and are symmetrically installed. The end of the inductive sensor 17 near the J7 joint motor 7 is fitted with a mating block 9. Specifically, a through hole is provided on the mating block 9 along the axial direction, and the mating block 9 is slidably sleeved on the outside of one end of the inductive sensor 17 through its through hole. A return spring 14 is also sleeved on the outside of the inductive sensor 17. The two ends of the return spring 14 abut against the end face of the mating block 9 and the inner wall of the dustproof shell 6, respectively, and it is always in a contracted state. A scissor mechanism is formed on the mating block 9 along the direction perpendicular to the opening and closing direction of the two finger plates. A mating hole is provided in the direction of the J7 rotation axis. This mating hole mates with a toggle switch 2 that is slidably installed along the length of the J7 rotation axis. The toggle switch 2 drives the mating block 9 to move, and when the toggle force of the toggle switch 2 is lost, the spring force of the return spring 14 returns it to its initial state. Specifically, the toggle switch 2 can be used as a clutch. It is connected to the IO control board of the main hand. The IO control board is connected to the system controller. The doctor toggles the toggle switch 2, thereby sending the toggle signal to the controller through the IO control board. The controller controls the synchronous movement of the instrument at the end of the arm disconnecting from the main hand. After the doctor releases the toggle switch 2, the toggle switch 2 returns to its initial position under the force of the return spring 14, and the controller controls the synchronous movement of the instrument at the end of the arm opening from the main hand.

[0046] like Figure 3 , 4 As shown in Figure 9, magnets 12 are fixedly installed at the ends of the two finger plates near the joint motor 7 of J7, and the magnetic poles of the two magnets 12 are installed in the same direction, so that the magnetic field lines between them pass through the Hall sensor 8. A circuit board 15 is installed inside the J7 rotation shaft 1 at the position corresponding to the magnets 12 on the two finger plates, and the Hall sensor 8 is fixedly installed on the circuit board 15. This design makes a magnetic field that passes through the Hall sensor 8 be generated between the two magnets 12 of the two finger plates. The magnetic field strength is collected in real time to calculate the magnetic field strength of the current finger plate position, thereby obtaining the position of the two finger plates at the current moment.

[0047] In this invention, a single Hall sensor 8 is designed, and the positions of the two magnets 12 on the two finger plates need to correspond or even be symmetrical, so as to calculate the current position of the two finger plates by real-time acquisition of the magnetic field strength generated by the two magnets 12 passing through the Hall sensor 8. However, this invention is not limited to this. This invention can design two Hall sensors 8 inside the J7 rotating shaft 1, and install a magnet on each of the two finger plates corresponding to one Hall sensor 8. The position of each finger plate at the current moment can be calculated by real-time acquisition of the magnetic field strength generated by the magnet when the finger plates move through the Hall sensor 8.

[0048] In this invention, only one magnet 12 can be set on any finger plate, and correspondingly, the number of Hall sensors is also one.

[0049] In this invention, magnet 12 is a cylindrical magnet.

[0050] Furthermore, the circuit board 15 is mounted on the dustproof housing 6 or the mounting bracket 13.

[0051] The working principle of this invention is as follows:

[0052] The operator pinches the two finger plates together with their fingers. The two finger plates move inward synchronously around their meshing point through their meshing teeth, thus closing the plates. At the same time as the two finger plates move inward, the ends of the two connecting rods that rotate with them also move inward. This, in turn, pushes the sensor core 18 to move within the inductive sensor 17 through the scissor mechanism formed by the two connecting rods. This changes the mutual inductance between the coils, thereby changing the voltage value of the secondary coil 23. Based on its transformer principle, the current insertion depth of the sensor core 18 can be calculated very accurately, thus precisely calculating the current position of the finger plates.

[0053] Meanwhile, the Hall sensor of the present invention outputs different voltages according to the magnitude of the magnetic field strength passing through it. Since the magnetic field strength is different due to the different distances between the magnet 12 and the Hall sensor 8, it is related to the component of the magnetic field lines passing through the Hall sensor and is also affected by the distance change. Therefore, the pinch angle-Hall output voltage curve is obtained by fitting algorithm. By filtering and curve fitting algorithm, it is fitted to a near linear relationship. Thus, the pinch angle of the finger plate is obtained by combining the pinch angle-Hall output voltage curve and the magnitude of the output voltage of the Hall sensor.

[0054] Because the magnetic field lines of the magnet are unevenly distributed, and the relative positions of the magnet and the Hall sensor change continuously during the pinching process of the finger plate, it is impossible to accurately calculate the actual pinching angle based on the voltage value of the Hall sensor. Therefore, this invention performs a weighted calculation on the pinching angle of the finger plate obtained by the inductive sensor and the Hall sensor to obtain the final pinching angle of the finger plate, specifically:

[0055] U = λ1u1 + λ2u2;

[0056] Wherein, U is the final pinch angle of the finger plate, u1 and u2 are the pinch angles of the finger plate obtained by the inductive sensor and the Hall sensor, respectively, λ1 and λ2 are the weights of the pinch angles of the finger plate obtained by the inductive sensor and the Hall sensor, respectively, and λ1+λ2=1; in this invention, λ1 and λ2 are taken as 0.9 and 0.1, respectively.

[0057] In this invention, because the change in magnetic field strength collected by the Hall sensor and the induced voltage output by the inductive sensor have the same trend, when the output voltage of the Hall sensor increases, the output voltage of the inductive sensor will also increase, and when the output voltage of the Hall sensor decreases, the output voltage of the inductive sensor will also decrease. Using this principle, the two sensors can be mutually verified to check whether there is any abnormality, thereby improving the safety of sensor operation. When an abnormal sensor value is detected, the system will issue an alarm to avoid dangerous situations caused by sensor malfunction.

[0058] This invention uses a fusion algorithm to calculate the position of the finger plate, thereby controlling the end effector with high precision and linearity. Due to the high precision and linearity of the inductive sensor, it can accurately and linearly reflect the operator's speed and displacement when manipulating the finger plate, making surgical control more precise and linear, improving surgical accuracy and reducing the difficulty of delicate operations. Simultaneously, the two types of sensors provide mutual backup and verification, ensuring good accuracy even under single external interference, improving anti-interference capabilities. The mutual backup and verification of the two types of sensors also ensures the reliability of the system.

[0059] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details of the above embodiments. Within the scope of the technical concept of the present invention, various equivalent transformations (such as quantity, shape, position, etc.) can be made to the technical solution of the present invention, and these equivalent transformations all fall within the protection scope of the present invention.

Claims

1. A gripping mechanism of a surgical robot characterized by comprising: include: Rotation axis; The finger plates are two in number, symmetrically installed on opposite sides of the rotating shaft, with their ends engaging with each other to achieve synchronous opening and closing movements. A Hall sensor for collecting changes in magnetic field strength and an inductive sensor for outputting induced voltage based on the amount of iron core inserted into the rotating shaft are provided. A magnet is provided at the position corresponding to the Hall sensor on the finger plate, and magnets with the same magnetic poles are provided at the positions corresponding to the Hall sensor on the two finger plates. The two finger plates are hinged to the free end of the iron core through a connecting rod at the corresponding positions on the inner side. When the two finger plates open and close, the iron core is driven to move inside the inductive sensor through the connecting rod. The pinch angle of the two-finger pads is calculated by using information collected by the Hall sensor and the inductive sensor, and then weighted to obtain the final pinch angle of the two-finger pads. U Specifically: U = λ 1 u 1+ λ 2 u 2； wherein, u 1, u 2 are the pinch angles of the finger plate calculated from the information collected by the inductive sensor and the Hall sensor, respectively, λ 1, λ 2 are the weights of the corresponding pinch angles of the finger plate, λ 1+ λ 2 = 1.

2. The clamping mechanism of claim 1, wherein The inductive sensor includes a sensor coil wound axially within it to form a passage through the iron core. The sensor coil includes an excitation coil in the middle and two auxiliary coils disposed on both sides of the excitation coil.

3. The clamping mechanism of claim 1, wherein The two connecting rods are of the same length and are installed symmetrically.

4. The chucking mechanism of claim 1, wherein The Hall sensor consists of one unit, and the magnets are arranged symmetrically on the two finger plates.

5. The chucking mechanism of claim 1, wherein There are two Hall sensors, and a magnet is installed on each of the two finger plates corresponding to one Hall sensor.

6. The chucking mechanism of claim 1, wherein λ 1、 λ 2 take 0.9 and 0.1 respectively.

7. The clamping mechanism according to claim 1, characterized in that, Based on the fact that the change in magnetic field strength collected by the Hall sensor and the induced voltage output by the inductive sensor have the same trend, it is determined whether the two sensors are abnormal during operation, and an alarm is issued when an abnormal sensor value is detected.

8. The chucking mechanism of claim 1, wherein Both finger plates are provided with meshing teeth at their ends. The two finger plates are installed by meshing teeth at their ends to achieve opening and closing movements with the meshing point as the axis.

9. The chucking mechanism of claim 1, wherein, A torsion spring is also provided at the meshing teeth of the two finger plates, which always applies an outward opening force to the finger plates.

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