ROBOT DENTAL

Abstract

A dental robot comprising a tandem positioning arm; wherein the tandem positioning arm comprises a pedestal, several positioning arms, and a sheath, the sheath being designed to hold surgical instruments; the pedestal, the several positioning arms, and the sheath being connected sequentially in series by rotary joints; and a joint angle measuring device is mounted on each of the rotary joints.

Description

Dental robot Cross-reference with related application This application claims priority over China's application no. 202010693115.9, filed on July 17, 2020, entitled "Dental Robot and Oral Navigation Method", which is incorporated herein in its entirety by reference. Field of technology This application relates to the technical field of medical devices and instruments and, in particular, to a dental robot designed to carry out an oral navigation method. Background With the application of navigation and robotic technologies in oral and maxillofacial surgical procedures, the level of digitalization in oral surgery has improved considerably. A robot-assisted oral navigation system can be of great help to dentists, thereby improving the precision of surgical procedures, reducing their difficulty, and ensuring surgical safety. In the related technique, robotic systems for dental surgery typically use general-purpose industrial mechanical arms, which entails not only a large volume and weight of the entire system, but also a high cost and poor viability. Summary The realizations of this application provide a dental robot designed to carry out an oral navigation method, in order to solve the problems associated with the high volume and weight, as well as the poor viability of traditional robotic systems for dental surgery. In one respect, one of the embodiments of the present application provides a dental robot, which includes a tandem positioning arm; where The tandem positioning arm includes a pedestal, several positioning arms, and a sheath, the sheath being designed to hold surgical instruments; The pedestal, the various positioning arms, and the sheath are connected sequentially in series by means of rotary joints; Each of the rotating joints is fitted with a joint angle measuring device. In one embodiment, the joint angle measuring device is an absolute encoder. In one embodiment, the positioning arm has a hollow structure. In one embodiment, a torque servomotor is mounted on each of the rotary joints. In one embodiment, the dental robot also includes a dental treatment chair; where A head restraint device, arranged on both sides of a dental chair headrest, has a rack and pinion locking structure; and the tandem positioning arm is fixedly mounted to a dental chair equipment base by means of the pedestal. The dental robot is designed to carry out an oral navigation method using the dental robot according to the first aspect, which includes: to determine the position in a coordinate system of a surgical instrument held by a sheath disposed on top of a tandem positioning arm of a dental robot, based on the joint angles measured by each joint angle measuring device of the tandem positioning arm; to convert the coordinate position of the surgical instrument in the coordinate system of the dental robot to the coordinate position of the surgical instrument in a three-dimensional image coordinate system; and Perform oral navigation based on the coordinate position of the surgical instrument in the three-dimensional image coordinate system and on pre-established surgical trajectories in the three-dimensional image coordinate system. In one embodiment, the conversion of the surgical instrument's coordinate position in the dental robot's coordinate system to the surgical instrument's coordinate position in a three-dimensional image coordinate system includes: convert the coordinate position of the surgical instrument in the dental robot's coordinate system to a coordinate position of the surgical instrument in the three-dimensional image coordinate system, based on a spatial mapping relationship; where the spatial mapping relationship is determined based on coordinate positions of pre-established characteristic points in the three-dimensional image in the dental robot's coordinate system. In one embodiment, after performing oral navigation based on the coordinate position of the surgical instrument in the coordinate system of the three-dimensional image and on pre-established surgical trajectories in said coordinate system, the method further includes: determine a contact stiffness of the tandem positioning arm based on a pre-established working area of ​​the surgical instrument in the three-dimensional image and on the coordinate position of the surgical instrument in the three-dimensional image coordinate system; and Adjust the torque output of the torque servo motor at each rotary joint of the tandem positioning arm based on the contact stiffness of the tandem positioning arm. In one embodiment, prior to performing oral navigation based on the coordinate position of the surgical instrument in the three-dimensional image coordinate system and on pre-established surgical trajectories in said coordinate system, the method further includes: determine a relative position between an area to be operated on and the surgical instrument based on the positions of visual markers located, respectively, in the area to be operated on and on the surgical instrument; convert the relative position to a three-dimensional coordinate system to obtain a three-dimensional relative position; and Adjust a coordinate position of the area to be intervened in the three-dimensional image coordinate system based on the coordinate position of the surgical instrument in the three-dimensional image coordinate system and the relative three-dimensional position. In one embodiment, the visual markers of the area to be intervened are mounted using an oral guide that is determined based on a three-dimensional curved surface of the dentition within the area to be intervened. The embodiments described in this application comprise a dental robot. The dental robot includes a tandem positioning arm, in which a pedestal, several positioning arms, and a sheath are sequentially connected in series by rotary joints; a joint angle measuring device is mounted on each rotary joint. Thanks to the reduced weight of the tandem positioning arm, the volume and weight of the dental robotic system are reduced, and the ease of use of the dental robot in surgical procedures is improved. Brief description of the drawings To illustrate more clearly the technical solutions of the embodiments of the present application or of the prior art, the drawings necessary for describing the embodiments or of the prior art are briefly described below. The drawings in the following description clearly show some embodiments of the present application. Other drawings based on these drawings can be obtained by persons generally skilled in the art without any further creative work. FIG.1 is a schematic structural diagram of a dental robot according to an embodiment of the present application; FIG.2 is a schematic diagram of a head restraint device; FIG.3 is a schematic structural diagram of a dental robot according to an embodiment of the present application; FIG. 4 is a schematic flowchart of an oral navigation method for a dental robot; and FIG. 5 is a schematic diagram of a patient tracking device. Detailed description To illustrate the objectives, technical solutions, and advantages of the embodiments of this application more clearly, the technical solutions of the embodiments of this application shall be clearly and thoroughly described together with the accompanying drawings of the embodiments of this application. Clearly, the embodiments described are a part of the embodiments of this application, rather than all of them. All other embodiments obtained by a person skilled in the art, based on the embodiments of this application without any creative effort, shall fall within the scope of protection of this application. FIG. 1 is a schematic structural diagram of a dental robot according to an embodiment of the present application. As shown in FIG. 1, the dental robot includes a tandem positioning arm; the tandem positioning arm includes a pedestal 100, a first positioning arm 110, a second positioning arm 120, and a sheath 130, and the sheath 130 is designed to hold surgical instruments; the pedestal 100, the first positioning arm 110, the second positioning arm 120, and the sheath 130 are connected sequentially in series by means of a first rotary joint 101, a second rotary joint 102, and a third rotary joint 103; and a joint angle measuring device is mounted on each of the rotary joints. It should be noted that the embodiments described in this application are based on an example where the number of positioning arms is two, and these embodiments are part of the embodiments in this application, rather than all embodiments. In the embodiments of this application, the number of positioning arms is not specifically defined. In one embodiment, the pedestal 100, the first positioning arm 110, the second positioning arm 120, and the sleeve 130 are connected in series by rotary joints. The sleeve 130 is designed to hold surgical instruments. The tandem positioning arm has at least six degrees of freedom and can be used to position surgical instruments and adjust their position within the workspace. To make the dental robot's tandem positioning arm more flexible when moving or avoiding obstacles, the number of tandem positioning arms can also be flexibly adjusted, resulting in a structure with redundant degrees of freedom. Traditional robotic systems for oral surgery utilize general-purpose industrial robotic arms, which are controlled by motors, making surgical robots bulky and heavy. When using surgical robots, dentists must learn to operate and manage these industrial robotic arms, increasing training costs. Furthermore, unlike standardized production methods in the industry, oral surgery requires dentists to develop different surgical plans based on each patient's specific conditions. During the procedure, these plans must also be adapted based on real-time information provided by each patient. Therefore, traditional robotic systems for oral surgery are not very practical and are inefficient during surgical procedures. In the dental robot described in the embodiments of this application, the joint angle measuring device is installed on each rotary joint of the tandem positioning arm. The surgical instrument is precisely positioned by measuring the joint angle, replacing motor control and reducing the use of electronic devices related to motor control, thus allowing the dental robots to be lightweight. Furthermore, a drag-and-position operating mode is adopted to facilitate flexible operation by the dentist, better suited to their usage habits and eliminating learning costs. The embodiments described in this application comprise a dental robot, which includes a tandem positioning arm in which the pedestal, several positioning arms, and the sheath are sequentially connected in series by rotary joints; and a joint angle measuring device is mounted on each of the rotary joints. Thanks to the reduced weight of the tandem positioning arm, the volume and weight of the dental robotic system are reduced, thus improving the functionality of the dental robot in surgical procedures. Starting from any of the above embodiments, the joint angle measuring device is an absolute encoder. In one embodiment, the joint angle measuring device is an absolute encoder; for example, a photoelectric absolute encoder can be used to perform the joint angle measurement. While a relative encoder requires a relative zero point to determine the actual measured value, the absolute encoder possesses the structural characteristic that ensures the uniqueness of each measured value and does not require a reference zero point. In carrying out the present application, an absolute encoder is used, which avoids having to calibrate the zero point during use, thus simplifying the use of the tandem positioning arm. Starting from any of the above realizations, the positioning arm has a hollow structure. In one embodiment, the positioning arm body features a hollow interior, which reduces its weight and improves operational flexibility. This hollow structure also accommodates the internal electrical wiring of the dental robotic system, further reducing the overall size of the dental robot. Based on any of the above embodiments, the positioning arm is made of at least one of the following materials: engineering plastics, aluminum alloy, and carbon fiber. In one embodiment, the positioning arm can be made of lightweight, high-strength materials such as engineering plastics, aluminum alloy, or carbon fiber to reduce the body's weight. Starting from any of the above embodiments, a torque servomotor is mounted on each of the rotary joints. In one embodiment, a small torque servomotor is mounted on each rotary joint. The gravitational moment at each rotary joint can be calculated according to the robot's dynamic model, and the torque provided by the servomotor compensates for this gravitational moment, making it more flexible and convenient to move the tandem positioning arm. Based on any of the above designs, the dental robot also includes a dental treatment chair; where A head restraint device, arranged on both sides of a dental chair headrest, has a rack and pinion locking structure; and the tandem positioning arm is fixedly mounted to a dental chair equipment base by means of the pedestal. In one embodiment, the dental robot also includes a dental chair. To better secure the patient's head, the head restraint device located on either side of the dental chair's headrest features a rack and pinion locking mechanism. Figure 2 is a schematic diagram of the head restraint device. As shown in Figure 2, the head restraint device includes a pinion 201, a first rack 211, a second rack 212, a first head support 221, and a second head support 222. The pinion 201 can be rotated by means of a control to drive the first rack 211 and the second rack 212, causing them to move toward each other and adjusting the distance between the first head support 221 and the second head support 222 to secure the patient's head. Because it is rigidly fixed to the base of the dental treatment chair equipment by means of the pedestal, the tandem positioning arm moves easily to the area of ​​the patient's mouth where the intervention will be performed. Based on any of the previous designs, the dental robot also includes a visual browser; and The visual navigator is permanently mounted to the base of the dental treatment chair equipment by means of a support arm. In one embodiment, the visual navigator can track visual markers in the area to be operated on and on surgical instruments in real time, and detect their spatial positions in real time to guide the execution of dental surgery. Based on any one of the above embodiments, FIG. 3 is a schematic structural diagram of a dental robot according to an embodiment of the present application. As shown in FIG. 3, the dental robot includes a tandem positioning arm 301, a dental treatment chair 302, a visual navigator 303, and a surgical instrument 304. In one embodiment, during use, the patient lies in the dental chair, the dentist moves the tandem positioning arm 301 and uses the surgical instrument 304, held by the sheath located at the end of the tandem positioning arm 301, to perform the oral surgery. When the patient moves their head, the dentist can also use the visual navigator 303 to follow the visual markers located on the areas to be treated and on the surgical instruments, in order to perform the oral surgery. Based on any of the previous embodiments, FIG. 4 is a schematic flowchart of an oral navigation method for the dental robot. As shown in FIG. 4, the method includes: In step 410, determine the coordinate position in a coordinate system of a surgical instrument held by the sheath disposed on top of the tandem positioning arm of a dental robot, based on the joint angles measured by each joint angle measuring device of the tandem positioning arm. In one embodiment, the coordinate system of the dental robot is established based on the robot's structural parameters, and the pedestal of the tandem positioning arm can be selected as the origin of the coordinate system. The embodiments of this application do not specifically define the choice of the origin of the dental robot's coordinate system. Based on the articulation angles measured by each articulation angle measuring device on the tandem positioning arm, the Denavit-Hartenberg (DH) method of robotic kinematics can be used to calculate the position of the sleeve on top of the tandem positioning arm in real time. Therefore, the sleeve's position can be accurately determined when the tandem positioning arm moves to perform surgical procedures within its workspace. The surgical instrument can be, specifically, a medical-dental instrument, such as a dental implant handpiece, a repair handpiece, and similar instruments. The sheath allows for the attachment of various surgical instruments for oral surgery. After undergoing position and posture calibration, the surgical instrument is mounted in the sheath of the tandem positioning arm. The coordinate position of the surgical instrument within the dental robot's coordinate system can be determined based on the instrument's calibration parameters relative to the sheath of the tandem positioning arm. In step 420, the coordinate position of the surgical instrument in the dental robot's coordinate system is converted to the coordinate position of the surgical instrument in a three-dimensional image coordinate system. In one embodiment, the three-dimensional image can be a three-dimensional image of the patient's oral cavity obtained using CBCT (cone-beam computed tomography, or X-ray tomography) technology, also called cone-beam CT. The three-dimensional image coordinate system can be established based on this three-dimensional image of the patient's oral cavity. Based on the spatial mapping relationship between the dental robot's coordinate system and the three-dimensional imaging coordinate system, the surgical instrument's coordinate position in the dental robot's coordinate system can be converted to the surgical instrument's coordinate position in the three-dimensional imaging coordinate system. This spatial mapping relationship can be pre-calibrated. In stage 430, oral navigation is performed based on the coordinate position of the surgical instrument in the three-dimensional image coordinate system and on pre-established surgical trajectories in the three-dimensional image coordinate system. In one embodiment, the pre-setting of the surgical path refers to planning surgical interventions in advance within the three-dimensional image coordinate system, as well as determining the movement path of the surgical instrument within that three-dimensional image coordinate system. During oral surgery, the tandem positioning arm is moved to align the coordinate position of the surgical instrument in the three-dimensional image coordinate system with the pre-established surgical trajectory in the three-dimensional image coordinate system, in order to obtain the real-time position error of the surgical instrument, thus guiding the dentist to perform the oral surgery operations. In the oral navigation method of a dental robot, the surgical instrument's coordinate position is converted from the robot's coordinate system to its coordinate position in a three-dimensional imaging coordinate system. This is then compared to a pre-established surgical trajectory in the three-dimensional imaging coordinate system. This ensures the instrument's movement path is well-defined during oral surgery, guiding the dentist and reducing the difficulty of the procedure while guaranteeing surgical safety. Furthermore, this oral navigation method avoids problems such as visual occlusion associated with optical navigation instruments. Starting from any one of the previous realizations, stage 420 includes: convert the coordinate position of the surgical instrument in the dental robot's coordinate system to the coordinate position of the surgical instrument in the three-dimensional image coordinate system, based on a spatial mapping relationship; where the spatial mapping relationship is determined based on coordinate positions of pre-set feature points in the three-dimensional image in the dental robot's coordinate system. In one embodiment, the spatial mapping relation is a position conversion relation of a coordinate point from the dental robot's coordinate system to the three-dimensional image coordinate system, which can be determined by the coordinate position of the preset feature points in the three-dimensional image in the dental robot's coordinate system. Preset reference points are predetermined positioning points whose coordinate positions in the three-dimensional image have been determined using markers. The number of preset reference points is at least three. The position of each preset reference point in the dental robot's coordinate system is obtained by moving the tandem positioning arm and using the tip of the surgical instrument, or the attached calibration probe, to touch the parts of the patient's tooth that correspond, point by point, to the positions of the preset reference points in the three-dimensional image. The positions of the preset reference points in the dental robot's coordinate system and in the coordinate system of the three-dimensional image are mapped and recorded, respectively, to obtain the spatial mapping relationship. The mapping log algorithm can be the ICP (iterative nearest point) algorithm, and the selection of the log algorithm is not specifically defined in the realizations of this application. Starting from any one of the above realizations, after step 430, the method additionally includes: determine the contact stiffness of the tandem positioning arm based on a pre-established working area of ​​the surgical instrument in the three-dimensional image and on the coordinate position of the surgical instrument in the three-dimensional image coordinate system; and Adjust the output torque of the torque servo motor at each rotary joint of the tandem positioning arm based on the contact stiffness of the tandem positioning arm. In one scenario, for oral surgery, an intervention area can be pre-planned in the three-dimensional image to obtain a pre-established working area. For example, for molar restoration surgery, the milling and unmilled areas can be pre-planned in the three-dimensional image. When handling the surgical instrument during the procedure, the positional relationship between the instrument and the pre-established work area is evaluated based on the instrument's coordinate position in the three-dimensional imaging coordinate system, and the contact stiffness of the tandem positioning arm is determined. Contact stiffness is the sensitivity of the tandem positioning arm when it is dragged. For example, when the surgical instrument is in the milling area, the contact stiffness is zero and it can be dragged freely; when the surgical instrument is near the non-milling area, the contact stiffness is not zero and increases as the distance from the non-milling area decreases, thus requiring some dragging force. Based on the contact stiffness of the tandem positioning arm, the output torque of the torque servomotor is adjusted at each rotary joint of the tandem positioning arm, so that the dentist can obtain information about the force exerted when dragging the tandem positioning arm, thereby improving the precision of the surgical intervention and the safety during the operation, avoiding damage to healthy tissues. The torque output of the torque servomotor is adjusted by calculating the torque that each torque servomotor should generate during drag, based on preset parameters such as contact stiffness and damping, allowing the sensitivity of the tandem positioning arm to be dynamically varied and providing the dentist with different force feedback responses. In the dental robot's oral navigation method, the output torque of the torque servomotor at each rotary joint is adjusted based on the preset working area of ​​the surgical instrument in the three-dimensional image and the coordinate position of the surgical instrument in the three-dimensional image coordinate system, thus providing the dentist with information on the applied force and improving the safety of the oral surgery intervention. Starting from any one of the above realizations, before step 430, the method additionally includes: determine the relative position between the area to be operated on and the surgical instrument based on the positions of visual markers located, respectively, in the area to be operated on and on the surgical instrument; convert the relative position to a three-dimensional coordinate system to obtain a three-dimensional relative position; and Adjust a coordinate position of the area to be intervened in the three-dimensional image coordinate system based on the coordinate position of the surgical instrument in the three-dimensional image coordinate system and the relative three-dimensional position. In one instance, in some procedures where precision significantly influences the outcome of the surgery, such as dental implant surgery, even though the patient's head and jaw are immobilized by the fixation device, slight positional changes can occur, and prolonged restraint and fixation can cause discomfort to the patient. Visual markers can be placed in the area of ​​the patient's oral cavity to be operated on and on the surgical instrument, respectively. The visual markers present in the field of vision can be tracked using the visual navigation system, and the positions of the visual markers in the intervention area and on the surgical instrument can be detected in real time. Based on the positions of the visual markers arranged respectively in the area to be operated on and on the surgical instrument, the relative position between the area to be operated on and the surgical instrument is determined, and this relative position is converted to a three-dimensional coordinate system to obtain a three-dimensional relative position. Based on the coordinate position of the surgical instrument in the three-dimensional image coordinate system and the relative three-dimensional position, the coordinate position of the area to be operated on in the three-dimensional image coordinate system is adjusted so that the adjusted intervention area can adapt to changes in the position of the patient's head and jaw, in order to continue guiding the dentist to perform the oral surgery intervention. In the dental robot's oral navigation method, visual markers located respectively in the area to be operated on and on the surgical instrument are tracked by a visual navigator, and the position of the area to be operated on in the three-dimensional image coordinate system is adjusted in real time, thereby improving the accuracy of the oral surgery intervention. Starting from any of the above realizations, the visual marker of the area to be intervened is placed by means of an oral guide that is determined based on a three-dimensional curved surface of the dentition within the area to be treated. In one embodiment, in order to perform the surgical intervention accurately even when the patient moves their head, a tracking device can be placed on the patient's jaw. Figure 5 is a schematic diagram of a patient tracking device. As shown in Figure 5, the patient tracking device includes an oral guide 501, a connecting rod 502, and a visual marker 503 of the area to be treated. The visual marker 503 is connected to the oral guide 501 by the connecting rod 502. The patient tracking device can be manufactured rapidly using 3D printing and other methods. The 501 oral guide is determined based on a three-dimensional curved surface of the dentition within the area to be operated on in the patient's oral cavity and can be installed to fit the patient's dentition precisely. In oral surgery, once the patient has become accustomed to the device, the patient's jaw position can be detected in real time using the visual navigation instrument. The device implementations mentioned above are merely illustrative. Units described as independent components may or may not be physically separate, and components shown as units may or may not be physical units; that is, they may be located in a single place or distributed across multiple network units. Some or all of the modules can be selected according to the actual needs to achieve the purpose of the implementations. Those with a general understanding of the subject matter can grasp and implement them without requiring any significant creative effort. Through the preceding description of the implementations, those generally versed in the subject can clearly understand that the various implementations can be implemented using software and a necessary general hardware platform, and of course, using hardware. Based on this understanding, the above technical solutions, in their essence, or a part thereof that contributes to the above technique, can be realized in the form of software products. Computer software products can be stored on computer-readable storage media, such as ROM / RAM, magnetic disk, compact disc, and include various instructions for causing a computing device (which may be a personal computer, a server, a network device, or the like) to perform the methods described in various embodiments or in part thereof. Finally, it should be noted that the prior embodiments are intended solely to illustrate, rather than limit, the technical solutions of the present application; although the present application has been described in detail with reference to prior embodiments, those skilled in the art should understand that the technical solutions documented in prior embodiments may still be modified, or parts of their technical features may be substituted in an equivalent manner; and such modifications or substitutions do not separate the substance of the corresponding technical solutions from the spirit and scope of the technical solutions of various embodiments of the present application. Reference numbers 100 pedestal 110 first positioning arm 120 second positioning arm 101 first rotary joint 102 second rotary joint 103 third rotary joint 130 case 201 pinion 211 first zipper 212 second zipper 221 first head support 222 second head support 301 tandem positioning arm 302 dental treatment chair 303 visual browser 304 surgical instrument 501 oral guide 502 connecting rod 503 visual marker

Claims

1. A dental robot comprising a tandem positioning arm; wherein the tandem positioning arm comprises a pedestal, several positioning arms, and a sheath, the sheath being designed to hold surgical instruments; the pedestal, the several positioning arms, and the sheath being connected sequentially in series by rotary joints; and a joint angle measuring device is mounted on each of the rotary joints.

2. The dental robot of claim 1, wherein the joint angle measuring device is an absolute encoder.

3. The dental robot of claim 1, wherein the positioning arm has a hollow structure.

4. The dental robot of claim 1, wherein a torque servomotor is mounted on each of the rotary joints. 5.The dental robot of claim 1, further comprising a dental treatment chair; wherein a head-holding device, arranged on both sides of a headrest of the dental treatment chair, has a rack and pinion locking structure; and the tandem positioning arm is fixedly mounted on an equipment base of the dental treatment chair by means of the pedestal.