Robot and robot zero calibration method

Abstract

The invention discloses a robot and a robot zero point calibration method, the robot comprises a receiver, a controller and a joint structure, the joint structure comprises a first joint and a second joint, the first joint is rotatably connected to the second joint, one of the first joint and the second joint is provided with a reflection type sensor, and the reflection type sensor is connected with the controller. The other one is provided with a reflecting plate; the reflective sensor is used for generating a pulse signal when receiving a reflected signal of the reflecting plate, and the pulse signal is used for triggering the controller to generate an instruction signal; the receiver is used for receiving a zero calibration instruction; the controller is used for responding to the zero calibration instruction and controlling the first joint to rotate, and the controller is further used for responding to the instruction signal and controlling the first joint to stop rotating, and zero calibration is completed.

Description

Technical Field

[0001] This application belongs to the field of robotics technology, specifically relating to a robot and a method for zero-point calibration of a robot. Background Technology

[0002] The robot's zero point is the initial position of the robot's operating model. Each robot has its zero point pre-set at the factory. The robot determines its mechanical position based on this zero point, allowing the controller to synchronously update the position information and thus control the robot's motion. In related technologies, the common method for robot zero-point calibration is to manually align the mechanical joints with the scale lines marked on them at the factory, thereby returning the robot to its zero point. However, this method relies on visual observation and manual control, resulting in low calibration accuracy. Summary of the Invention

[0003] This application aims to provide a robot and a zero-point calibration method, which at least solves one of the problems of low efficiency and low accuracy in robot zero-point calibration in the prior art.

[0004] To solve the above-mentioned technical problems, this application is implemented as follows: In a first aspect, embodiments of this application propose a robot, which includes a receiver, a controller, and a joint structure. The joint structure includes a first joint and a second joint, with the first joint rotatably connected to the second joint. One of the first joint and the second joint is provided with a reflective sensor, and the other is provided with a reflector. The reflective sensor generates a pulse signal upon receiving a reflected signal from the reflector, and the pulse signal triggers the controller to generate a command signal. The receiver receives a zero-point calibration command. The controller responds to the zero-point calibration command and controls the rotation of the first joint. The controller also responds to the command signal and controls the first joint to stop rotating, thus completing the zero-point calibration.

[0005] Optionally, the controller is further configured to control the first joint to perform multiple rotation operations, and to determine the position where the first joint stops in response to the command signal during the last rotation operation as the target zero point position.

[0006] Optionally, the robot further includes a memory for storing the position at which the robot stops in response to the command signal during each rotation operation as the expected zero-point position.

[0007] Optionally, for each of the above-mentioned rotation operations, based on the expected zero point position stored in the memory after the previous above-mentioned rotation operation, the controller is used to control the first joint to rotate at a preset speed and a preset angle in the counterclockwise / clockwise direction respectively by a preset angle; wherein, for the first above-mentioned rotation operation, the position based is the position of the first joint after the user manually rotates the first joint.

[0008] Optionally, the preset rotation angle during the Nth rotation operation is greater than the preset rotation angle during the (N+1)th rotation operation; and / or, The preset rotation speed during the Nth rotation operation is greater than the preset rotation speed during the (N+1)th rotation operation; where N is a positive integer.

[0009] Optionally, during the first rotation operation, the preset rotation angle is 45°, and the preset rotation speed is 10% of the standard rotation speed of the first joint.

[0010] Optionally, during the second rotation operation, the preset rotation angle is 25°, and the preset rotation speed is 5% of the standard rotation speed.

[0011] Optionally, during the third rotation operation, the preset rotation angle is 5°, and the preset rotation speed is 1% of the standard rotation speed.

[0012] Optionally, the aforementioned reflective sensor further includes an error display, which displays the position error value between the expected zero point position and the initial zero point position of the first joint; wherein, when the reading of the position error value is 0, the error display generates the aforementioned pulse signal and determines the position where the first joint stops at this time as the target zero point position, thus completing the zero point calibration.

[0013] Optionally, for the first rotation operation, the position is the position of the first joint after the user manually rotates it, and the position of the first joint has an angular difference of a first preset angle from the initial zero point position of the first joint.

[0014] Optionally, the axis of the first joint is perpendicular to the axis of the second joint, and the first joint is configured to rotate about the axis of the second joint.

[0015] Secondly, embodiments of this application propose a robot zero-point calibration method for zero-point calibration of a robot as described in any of the above schemes, comprising: Issue a zero-point calibration command; In response to the aforementioned zero-point calibration command, the rotation of the aforementioned first joint is controlled; The aforementioned reflective sensor generates a pulse signal when it is facing the aforementioned reflector, and the aforementioned pulse signal is used to trigger the aforementioned controller to generate a command signal; In response to the above command signal, the first joint is controlled to stop rotating, and zero-point calibration is completed.

[0016] The robot provided in the embodiments of this application, by installing a reflective sensor and a reflector plate on the first joint and the second joint respectively, and based on the reflective sensor receiving the reflected signal reflected by the reflector plate when the reflective sensor is aligned with the reflector plate, the pulse signal generated by the reflective sensor controls the stopping position after the first joint stops rotating, so that the robot can automatically perform zero-point calibration. Compared with manual calibration, it can improve the accuracy of the mechanical zero point of each axis of the robot, reduce calibration error, and does not require a lot of external equipment to assist, which can reduce the cost and process of zero-point calibration, improve the efficiency of zero-point calibration, and is applicable to robots with various signals.

[0017] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this disclosure. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a schematic diagram of the robot structure provided according to an embodiment of this application; Figure 2 This is an isometric drawing of a robot provided according to an embodiment of this application; Figure 3 yes Figure 2 A magnified view of a section at point A in the middle; Figure 4 This is an isometric view of a reflective sensor provided according to an embodiment of this application; Figure 5 This is a flowchart of the robot zero-point calibration method provided according to the embodiments of this application; Figure 6 This is a flowchart illustrating the specific steps of the robot zero-point calibration method provided in the embodiments of this application.

[0020] Figure label: 11. Receiver; 12. Controller; 13. Joint structure; 130. Drive unit; 131. First joint; 132. Second joint; 141. Reflective sensor; 142. Reflector; 143. Error display; 144. Indicator light; 145. Buzzer; 146. Mounting plate; 147. Mounting hole; 15. Memory. Detailed Implementation

[0021] The embodiments of this application will now be described in detail. Examples of these embodiments are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0022] The terms "first" and "second" in the specification and claims of this application may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise stated, "multiple" means two or more. Furthermore, "and / or" in the specification and claims indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0023] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0024] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection between two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0025] like Figures 1 to 4 As shown in the figure, an embodiment of this application proposes a robot.

[0026] In the robot manufacturing process, calibration is a core step to ensure its motion accuracy and stability. Before leaving the factory, the system automatically collects robot motion data by integrating high-precision sensors or vision systems, and completes the calibration work in combination with intelligent algorithms. A typical application is a calibration scheme based on a laser tracker. After calibration, the system accurately obtains the robot's mechanical origin position, which is also the target zero point position and the factory zero point position in this embodiment.

[0027] After obtaining the zero point position, a dedicated zero-point calibration device is installed at the rotational connection of each joint structure 13. Two zero-point calibration devices are installed at the rotational points of the joint structure 13 and aligned. That is, the zero point scales mentioned above are set at the first joint 131 and the second joint 132. The aforementioned reflective sensor 141 and the transmitter plate are installed at the zero point scales respectively. After ensuring that the reflected sensing signal is stably triggered, the set of sensing signals is recorded and the reading of the error display 143 is cleared to zero. Subsequently, the set of sensing signals is used for the logical judgment of the robot and its zero-point calibration method and as a signal for the final positioning. The recording of the origin of the joint structure 13 is completed. The workflow of the remaining joint structures 13 is similar.

[0028] Figure 1 A schematic diagram of the structure of a robot provided in an exemplary embodiment of this application is given. This robot is a six-axis robot. Figure 2 for Figure 1 The enlarged view at point A shows that the joint structure 13 has zero-point markings at both ends. When the zero-point markings of the first joint 131 and the second joint 132 are aligned and coincident, it indicates that the first joint 131 is at the accurate factory zero-point position. Figure 1 Only the zero-point scale corresponding to one joint structure 13 of the robot is shown. The number of zero-point scales on the robot is not limited to this. Figure 1 The number shown is not limited to the six-axis robot shown in the figure, and the types of robots in this application are not limited to the six-axis robot shown in the figure.

[0029] Furthermore, the axis of the first joint 131 is perpendicular to the axis of the second joint 132, and the first joint 131 is configured to rotate about the axis of the second joint 132. The most typical form of the robot's joint structure 13 is given here. The first joint 131 and the second joint 132 can also be hinged, such as when the axes of the first joint 131 and the second joint 132 intersect at a point. The first joint 131 rotates around this intersection point and is connected to the second joint 132, causing a change in the angle between the axes of the first joint 131 and the second joint 132. Further details are omitted here.

[0030] like Figure 3As shown, the robot includes a receiver 11, a controller 12, and a joint structure 13. The joint structure 13 includes a first joint 131 and a second joint 132. The first joint 131 is rotatably connected to the second joint 132. One of the first joint 131 and the second joint 132 is provided with a reflective sensor 141, and the other is provided with a reflector 142. The reflective sensor 141 generates a pulse signal when it receives a reflected signal from the reflector 142. The pulse signal triggers the controller 12 to generate a command signal. The receiver 11 receives a zero-point calibration command. The controller 12 responds to the zero-point calibration command and controls the rotation of the first joint 131. The controller 12 also responds to the command signal and controls the first joint 131 to stop rotating, thus completing the zero-point calibration.

[0031] The controller 12 mentioned above can be a general-purpose processor, including a central processing unit (CPU) or a network processor (NP); it can also be a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, or discrete hardware components.

[0032] In one possible implementation, after receiving the zero-point calibration command, the robot controls the joint structure 13 to rotate at a preset rotation speed. In order to accurately calibrate and return to zero in one go, the preset rotation speed is less than the standard rotation speed in the normal working mode of the robot, for example, 1% of the standard rotation speed.

[0033] This low-speed operation mode is one of the core guarantees of zero-point calibration accuracy. At high speeds, the inertia of the mechanical system, the minute elastic deformation of transmission components, and the response delay of the control system can all introduce significant positional errors, leading to deviations in zero-point positioning. Reducing the speed to an extremely low level, such as 1% of the standard speed, can greatly suppress the influence of these dynamic factors. Robot joints are typically driven by servo motors, which output high torque through high-reduction-ratio reducers. Under low-speed conditions, the feedback resolution of the motor encoder is relatively higher, and the control system has stronger fine-tuning capabilities for position, enabling it to approach the theoretical zero point through slow, creeping motion. Furthermore, low-speed operation provides the position detection sensors mounted on the joints (such as the reflective sensor 141 described later) with more sufficient and stable response time, ensuring that the command signals they issue are triggered when the joint structure 13 precisely passes a certain physical position, rather than within a high-speed, ambiguous range. This fundamentally avoids calibration failures caused by signal jitter or false triggering. Therefore, this preset rotational speed, far below the operating speed, is a key parameter balancing calibration efficiency and accuracy, and a primary condition for achieving highly reliable zero-point reset.

[0034] Because the first joint 131 of the robot rotates slowly during the calibration process, the user can manually adjust the first joint 131 to a position close to the zero point before the robot automatically performs zero-point calibration. That is, for the first rotation operation, the position is the position of the first joint 131 after the user manually rotates it. This position is angularly different from the initial zero-point position of the first joint 131 by a first preset angle, making the first joint 131 as close as possible to the target zero-point position, thereby reducing calibration time. This manual operation can be done by directly adjusting the joint structure 13 or by controlling it through the manual mode of the robot teach pendant.

[0035] This manual pre-adjustment step significantly optimizes the starting point of the automatic calibration process. In industrial settings, robots may deviate from their zero point due to maintenance, transportation, or accidental collisions, with deviations potentially ranging from significant. If the automatic search were to begin at a low speed directly from any arbitrary point, the time commitment would be extremely long. Allowing users to perform manual coarse adjustments essentially delegates the large-scale search task to efficient human judgment and operation. Users can quickly rotate the joint axis to a position with a small angular difference from the theoretical zero point—a first preset angle, for example, within ±10°—based on alignment marks on the mechanical structure (such as scribe lines or grooves) or by using rough readings from the joint encoders displayed on the teach pendant. Establishing this proximity defines a very small search range for subsequent automatic fine calibration, allowing the low-speed, high-precision automatic search to be performed within this limited range, thus reducing the total calibration time to an acceptable level. This human-machine collaborative calibration initialization strategy perfectly combines human macroscopic positioning capabilities with the machine's microscopic positioning accuracy, representing a significant aspect of engineering practicality.

[0036] Optionally, a communication connection is established between the robot and the robot teach pendant. The robot teach pendant is a handheld device used for manual robot operation, programming, parameter configuration, and monitoring. When it receives an activation operation for the automatic mechanical zero-point calibration function, the robot teach pendant sends a zero-point calibration command to the robot. Optionally, the controller 12 is also used to control the first joint 131 to perform multiple rotation operations, and to determine the position where the first joint 131 stops in response to the command signal during the last rotation operation as the target zero-point position.

[0037] When the user triggers the "automatic zero-point calibration" function on the teach pendant touchscreen or via a dedicated button, the software within the teach pendant generates a structured digital instruction package containing instruction codes, target joint identifiers (such as the first joint 131), and related speed and mode parameters. This instruction package is sent to the robot's main controller 12 via a communication link. After parsing the instruction, the controller 12 initiates the aforementioned low-speed motion control sequence. The strategy for multiple rotation operations is an iterative refinement algorithm. The initial rotation may be based on manual pre-adjustment to find a preliminary predicted zero-point position.

[0038] Subsequent rotation operations use this predicted position as a new starting point, and perform local fine-tuning searches with smaller movement amplitudes and potentially slower speeds. They gradually eliminate interference from factors such as sensor errors and mechanical hysteresis. By taking multiple measurements and finally converging, the position at the last and most accurate response signal is locked as the final target zero point position and written into the non-volatile memory of the controller 12 as the absolute coordinate reference for all movements of the joint.

[0039] In summary, the robot provided in this application, by installing a reflective sensor 141 and a reflector 142 on the first joint 131 and the second joint 132 respectively, and based on the reflected signal received by the reflective sensor 141 from the reflector 142 when the reflective sensor 141 is aligned with the reflector 142, the pulse signal generated by the reflective sensor 141 controls the stopping position of the first joint 131 after it stops rotating, so that the robot can automatically perform zero-point calibration. Compared with manual calibration, it can improve the accuracy of the mechanical zero point of each axis of the robot, reduce calibration error, and does not require a lot of external equipment to assist it. It can reduce the cost and process of zero-point calibration, improve the efficiency of zero-point calibration, and is applicable to robots with various signals.

[0040] Optionally, the reflective sensor 141 includes an input / output (I / O) interface, which is connected to the I / O communication port on the controller 12 via a communication bus. The reflective sensor 141 is used to send pulse signals to the controller 12 via the I / O connection line upon receiving a reflected signal, and to receive enable signals via the communication bus. The communication bus can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. This communication bus can be divided into an address bus, a data bus, and a control bus. For ease of illustration, only one thick line is used in the figure, but this does not indicate that there is only one bus or one type of bus.

[0041] When the reflective sensor 141 detects that its emitted laser signal is effectively reflected and received by the reflector 142 at the zero point position, its internal circuitry generates a digital level transition. This transition signal, acting as a pulse signal, is transmitted in real time to the digital input port of the controller 12 via the I / O connection line, typically a shielded twisted pair cable. Simultaneously, the sensor's operating status (such as on, off, or fault) may require configuration and monitoring through more complex bidirectional communication, necessitating a communication bus.

[0042] PCI or EISA buses, as mature computer expansion bus standards, feature high bandwidth and stringent electrical specifications, ensuring reliable and high-speed transmission of control commands and status data between the controller 12 and multiple sensors. The address bus specifies which sensor node the controller 12 accesses, the data bus transmits specific commands or status bytes, and the control bus carries coordination signals such as read / write operations and interrupt requests. This layered, functional communication architecture ensures both the real-time performance of trigger signals at critical locations and flexible device management capabilities for the entire zero-point detection system.

[0043] Furthermore, the robot also includes a memory 15, which stores the position at which the robot stops in response to the command signal during each rotation operation as a predicted zero-point position. The memory 15 contains a computer program and the predicted zero-point position for subsequent rotation operations, or the predicted zero-point position can be used as the final target zero-point position.

[0044] The memory 15 may include random access memory (RAM) or non-volatile memory, such as at least one disk storage device. Optionally, the memory 15 may also be at least one storage device located remotely from the aforementioned controller 12.

[0045] During iterative calibration, the predicted zero-point position found in each rotation operation is an intermediate result that needs to be temporarily stored as the reference starting point for the next rotation operation. This function is usually handled by RAM because of its fast read and write speed, suitable for frequent data updates. The final determined target zero-point position, as one of the robot's most important parameters, must be permanently saved and cannot be lost even in the event of a power outage. This requires non-volatile memory, such as Flash memory or RAM with battery backup. Disk storage, such as solid-state drives, hard disk drives, or USB flash drives, may be used to store larger calibration history logs, multiple sets of zero-point parameters, or complex compensation algorithm data.

[0046] Placing the memory 15 in a location far from the controller 12, such as a shop floor server, enables centralized data management and backup. This facilitates unified analysis, tracking, and recovery of zero-point data from multiple robots, which is particularly important in large-scale automated production lines. Therefore, the hierarchical design and rational configuration of the memory 15 ensures the full lifecycle management of calibration data from generation and temporary storage to final solidification and archiving, forming the basis for the repeatability and traceability of the calibration process.

[0047] Optionally, for each of the above-mentioned rotation operations, based on the expected zero point position stored in the memory 15 after the previous above-mentioned rotation operation, the controller 12 is used to control the first joint 131 to rotate at a preset speed and a preset angle in the counterclockwise / clockwise direction respectively by a preset angle; wherein, for the first above-mentioned rotation operation, the position based is the position of the first joint 131 after the user manually rotates the first joint 131.

[0048] The clockwise and counterclockwise directions mentioned above are... Figure 3In the "+" and "-" directions shown, during each rotation, the controller 12 controls the first joint 131 to first move clockwise by a preset angle, then return to the starting position, and then move counterclockwise by a preset angle. This allows the controller to search for the zero point position on both sides of the expected zero point position in a single rotation, completely covering both sides of the expected zero point position. This significantly improves zero-point search efficiency compared to rotating the joint one full circle. This method avoids the time-consuming process of rotating the joint slowly 360°, making it particularly suitable for fine calibration stages where the zero point has been limited to a small range manually or in the previous iteration. Through symmetrical search, it effectively addresses the impact of potential unidirectional backlash in mechanical transmission on zero-point positioning. By approximating bidirectionally, it obtains a midpoint position unaffected by unidirectional backlash errors, thus significantly improving calibration accuracy and efficiency.

[0049] Optionally, the preset rotation angle during the Nth rotation operation is greater than the preset rotation angle during the (N+1)th rotation operation; and / or, the preset rotation speed during the Nth rotation operation is greater than the preset rotation speed during the (N+1)th rotation operation; where N is a positive integer.

[0050] For example, during the first rotation operation, the preset rotation angle is 45°, and the preset rotation speed is 10% of the standard rotation speed of the first joint 131. During the second rotation operation, the preset rotation angle is 25°, and the preset rotation speed is 5% of the standard rotation speed. During the third rotation operation, the preset rotation angle is 5°, and the preset rotation speed is 1% of the standard rotation speed.

[0051] In this embodiment, by successively reducing the preset rotation speed and rotation angle of the first joint 131 during the rotation operation, it can gradually approach the target zero point position. That is, firstly, the zero point is searched with a larger speed and a larger range. After triggering the command signal, the first joint 131 stops. Since the signal triggering takes time and the movement of the first joint 131 has inertia, the first joint 131 cannot stop immediately, so there will be a position error of the zero point. Therefore, during the second rotation operation, the movement speed and movement angle of the first joint 131 are reduced to approach the target zero point position, gradually reducing the error between the first joint 131 and the target zero point position when it stops.

[0052] Specifically, in this embodiment, three rotation operations were performed. The third rotation had the smallest rotation speed and angle, which enabled the target zero point position to be found and the zero point calibration to be completed under the final rotation operation.

[0053] In this embodiment, as Figure 4 As shown, the reflective sensor 141 also includes an error display 143, which is used to display the position error value between the expected zero point position and the initial zero point position of the first joint 131; wherein, when the reading of the position error value is 0, the error display 143 generates the pulse signal and determines the position where the first joint 131 stops at this time as the target zero point position, thus completing the zero point calibration.

[0054] Specifically, the error display 143 is turned on during the third rotation operation. The error display 143 is used to display the position error value between the expected zero point position and the initial zero point position of the first joint 131. When the first joint 131 moves to the target zero point position, the reading of the error display 143 is zero, indicating that the position of the robot's first joint 131 after stopping is the target zero point position, which further improves the efficiency of zero point calibration.

[0055] The introduction of the error display 143 is a key step in moving the zero-point calibration process from being invisible and imprecise to being visualized and quantified. Its design logic is deeply consistent with the iterative calibration strategy: in the first two rotation operations, the deviation between the joint position and the theoretical zero point may still be large. At this time, displaying specific error values ​​may have limited meaning for the operator, and may even cause misunderstanding or anxiety due to the fluctuation of values.

[0056] Therefore, the decision to activate the error display 143 during the third and final fine-search phase is based on profound engineering considerations. At this point, after the first two iterations, the joint is within a very small neighborhood, extremely close to the true zero point, and the error value itself is already small and its changes tend to be stable. The error value displayed in real time provides the operator with a precise, digital indication of the progress. It transforms the calibration process from blind waiting into an observable convergence process. The operator can visually see the error value gradually decrease with the slightest movement of the joint until it reaches zero. This intuitive feedback not only enhances the user's confidence and sense of control over the calibration process, but more importantly, it helps determine whether the calibration is proceeding normally.

[0057] For example, if the error value fails to converge during iteration or drifts after reaching zero, the operator can immediately interrupt the process to check for abnormalities in the mechanical transmission or sensors. Therefore, the error display 143 is not only a status indicator but also a simple diagnostic tool. It confirms the final calibration result with an indisputable number 0, greatly improving the verifiability of the calibration operation and the authority of the final result, thus optimizing overall efficiency from a human-machine interaction perspective.

[0058] Furthermore, the reflective sensor 141 and the reflector 142 are respectively mounted at the zero-point scale of the first joint 131 and the second joint 132. Specifically, the reflective sensor 141 is mounted on the second joint 132, and the reflector 142 is mounted on the first joint 131. The design and installation details of the mounting plate 146 are fundamental to ensuring the long-term stable operation of the sensor and often determine the final accuracy and reliability of the calibration system. The mounting plate 146 is typically made of materials with sufficient rigidity and dimensional stability, such as aluminum alloy or steel. Its function is not only to connect but also to provide a rigid, finely adjustable mounting reference surface.

[0059] This cross-joint mounting configuration is a classic and reliable mechanical layout for achieving absolute zero-point detection. Its core principle lies in defining the absolute zero point of the first joint 131 using the relative positional relationship between two adjacent first joints 131 and second joint 132. The reflector 142, as a passive optical marker, is precisely fixed to the mechanical structure of the first joint 131, and its installation position is rigorously calibrated to precisely correspond to the theoretical mechanical zero point of the first joint 131. The reflective sensor 141, as an active detection unit, is mounted on the second joint 132 and moves with it. When the robot executes the zero-point calibration procedure and controls the rotation of the first joint 131, the posture of the second joint 132 in space remains fixed.

[0060] Only when the first joint 131 rotates to its specific zero-point angle will the reflector 142 fixed thereon fall precisely within the effective detection range of the sensor mounted on the second joint 132, thus being detected by the sensor and triggering a signal. This design cleverly avoids the wiring difficulties or coaxial installation complexities associated with mounting both the sensor and the target on the same rotating component. It establishes a clear and stable spatial geometric triggering condition by detecting the position of one joint from the position of another. This triggering condition uniquely corresponds to an absolute angular position of the first joint 131, i.e., its mechanical zero point. This mounting method has a clear structure, and the signal triggering position depends only on the relative geometric relationship between the two joints, independent of the robot's overall pose in space, thus resulting in extremely high zero-point reproducibility.

[0061] The design of the mounting holes 147 at the four corners ensures that the force between the mounting plate 146 and the connecting surface of the second joint 132 is uniform. The pre-tightening force generated by the fastening bolts can effectively resist the vibration and torque generated during the robot's movement, preventing the mounting plate 146 from loosening or undergoing micro-deformation.

[0062] In this embodiment, the reflective sensor 141 is mounted on the second joint 132 via a mounting plate 146. The mounting plate 146 has multiple mounting holes 147, specifically, each corner of the mounting plate 146 has a mounting hole 147. Connectors such as bolts pass through the mounting holes 147 to mount the mounting plate 146 and the reflective sensor 141 on the second joint 132.

[0063] Mounting hole 147 can be designed as an elongated hole or equipped with adjustment shims, which allows for post-installation fine-tuning of the sensor. During initial installation, the sensor's orientation and detection distance can be adjusted by slightly loosening the bolts and gently moving the mounting plate 146 to ensure that the reflector 142 is precisely located in the optimal sensing zone at the center of the sensor spot when the first joint 131 is at its theoretical zero point.

[0064] After adjustment, tighten the bolts completely to lock them in place. This adjustability is crucial for compensating for accumulated tolerances during robot assembly. Furthermore, the structure of the mounting plate 146 also considers the routing and securing of sensor cables, typically incorporating cable channels or cable tie holes to prevent cables from dangling, swaying, or being scratched by moving parts. Therefore, a seemingly simple mounting plate 146 actually integrates multiple functions such as mechanical interface, precision adjustment, anti-loosening and vibration protection, and cable management, serving as a key carrier for the reliable integration of sensors from individual components into the system.

[0065] Furthermore, the reflective sensor 141 is also equipped with a buzzer 145 and an indicator light 144. When the first joint 131 completes a rotation operation without being stopped by a trigger command signal, the buzzer 145 emits an alarm sound, and the indicator light 144 lights up red to indicate to the user to perform a second zero-point calibration operation. When the first joint 131 completes the final rotation operation and the reading of the error display 143 is 0, the buzzer 145 emits a prompt sound, and the indicator light 144 lights up green to remind the user that the calibration is complete.

[0066] The audible and visual alarm system, composed of buzzer 145 and indicator light 144, constructs a multi-layered, multi-modal human-machine interaction closed loop, greatly improving the user-friendliness, safety, and status identifiability of the calibration process. In noisy or variable industrial environments, relying solely on screen displays or single prompts may lead to operator oversights. The combined audible and visual alarm follows the principle of redundant prompts in ergonomics.

[0067] If the sensor is not triggered after the first rotation operation, it means that the zero point marker has not been found within the current search range. At this time, the buzzer 145 emits a unique, possibly intermittent, alarm sound, or directly announces that the zero point cannot be found, while the red indicator light 144 illuminates or flashes. This combination of sound and light alarms immediately and clearly informs the operator that the first stage of the search has failed and that the next round of calibration work needs to be started according to the procedure. Red, in industry practice, often represents a warning, caution, or incomplete status. This prevents the operator from waiting for a long time due to not noticing the screen log.

[0068] Conversely, when the entire calibration process is successfully completed and the error display 143 returns to zero, the buzzer 145 will emit a different tone, and the green indicator light 144 will remain constantly lit. Green represents safety, normal operation, and completion. This combination of sound and light provides the operator with a clear and unambiguous success signal. The operator does not need to check the teach pendant; they can confirm that the calibration has been successfully completed solely by hearing and seeing the green light, and can safely proceed with subsequent operations.

[0069] This design conveys the status of key process nodes to users through the most intuitive sensory channels, reducing the cognitive load on users, preventing misoperation, and ensuring that the calibration process can be correctly and efficiently advanced step by step until completion. It is a concrete manifestation of intelligent and human-centered design in industrial equipment.

[0070] like Figure 5 As shown, in a second aspect, embodiments of this application propose a robot zero-point calibration method for zero-point calibration of a robot as described in any of the above schemes, comprising: Step 1: Issue a zero-point calibration command.

[0071] Specifically, optionally, a communication connection is established between the robot and the robot teach pendant. The robot teach pendant is a handheld device used for manual operation, programming, parameter configuration, and monitoring of the robot. When it receives an activation operation for the automatic mechanical zero-point calibration function, the robot teach pendant sends a zero-point calibration command to the robot. Optionally, the controller 12 is also used to control the first joint 131 to perform multiple rotation operations, and to determine the position where the first joint 131 stops in response to the command signal during the last rotation operation as the target zero-point position.

[0072] Step 2: In response to the above zero-point calibration command, control the rotation of the first joint 131.

[0073] In one optional implementation, after receiving a zero-point calibration command, the robot controls the joint structure 13 to rotate at a preset rotation speed. To ensure accurate calibration and a one-time return to zero, this preset rotation speed is less than the standard rotation speed in the robot's normal operating mode, for example, 1% of the standard rotation speed. Since the first joint 131 rotates slowly during calibration, the user can manually adjust the first joint 131 to a position close to the zero point before the robot automatically performs zero-point calibration. That is, for the first rotation operation, the position is based on the position of the first joint 131 after the user manually rotates it. The position of the first joint 131 is angularly different from its initial zero-point position by a first preset angle, thereby reducing calibration time. This manual operation can be achieved by directly adjusting the joint structure 13 or by controlling it through the manual mode of the robot teach pendant.

[0074] Optionally, for each of the above-mentioned rotation operations, based on the expected zero point position stored in the memory 15 after the previous above-mentioned rotation operation, the controller 12 is used to control the first joint 131 to rotate at a preset speed and a preset angle in the counterclockwise / clockwise direction respectively by a preset angle; wherein, for the first above-mentioned rotation operation, the position based is the position of the first joint 131 after the user manually rotates the first joint 131.

[0075] The clockwise and counterclockwise directions mentioned above are... Figure 3 As shown in the "+" and "-" directions, in each rotation operation, the controller 12 controls the first joint 131 to first move clockwise by a preset angle, then return to the starting position and then move counterclockwise by a preset angle, thereby finding the zero point position on both sides of the expected zero point position. In one rotation, it can completely cover all positions on both sides of the expected zero point position, thus fully finding the zero point. Compared with the method of rotating one full circle to find the zero point position, it can improve the zero point finding efficiency.

[0076] Optionally, the preset rotation angle during the Nth rotation operation is greater than the preset rotation angle during the (N+1)th rotation operation; and / or, the preset rotation speed during the Nth rotation operation is greater than the preset rotation speed during the (N+1)th rotation operation; where N is a positive integer.

[0077] For example, during the first rotation operation, the preset rotation angle is 45°, and the preset rotation speed is 10% of the standard rotation speed of the first joint 131. During the second rotation operation, the preset rotation angle is 25°, and the preset rotation speed is 5% of the standard rotation speed. During the third rotation operation, the preset rotation angle is 5°, and the preset rotation speed is 1% of the standard rotation speed.

[0078] Step 3: The above-mentioned reflective sensor 141 generates a pulse signal when it is facing the above-mentioned reflector 142.

[0079] Step 4: The pulse signal is used to trigger the controller 12 to generate the command signal.

[0080] Optionally, the reflective sensor 141 includes an input / output (I / O) interface, which is connected to the I / O communication port on the controller 12 via a communication bus. The reflective sensor 141 is used to send pulse signals to the controller 12 via the I / O connection line upon receiving a reflected signal, and to receive enable signals via the communication bus. The communication bus can be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus. This communication bus can be divided into an address bus, a data bus, and a control bus. For ease of illustration, only one thick line is used in the figure, but this does not indicate that there is only one bus or one type of bus.

[0081] Furthermore, the robot also includes a memory 15, which stores the position at which the robot stops in response to the command signal during each rotation operation as a predicted zero-point position. The memory 15 contains a computer program and the predicted zero-point position for subsequent rotation operations, or the predicted zero-point position can be used as the final target zero-point position.

[0082] Specifically, the error display 143 is turned on during the third rotation operation. The error display 143 is used to display the position error value between the expected zero point position and the initial zero point position of the first joint 131. When the first joint 131 moves to the target zero point position, the reading of the error display 143 is zero, indicating that the position of the robot's first joint 131 after stopping is the target zero point position, which further improves the efficiency of zero point calibration.

[0083] The introduction of the error display 143 is a key step in moving the zero-point calibration process from being invisible and imprecise to being visualized and quantified. Its design logic is deeply consistent with the iterative calibration strategy: in the first two rotation operations, the deviation between the joint position and the theoretical zero point may still be large. At this time, displaying specific error values ​​may have limited meaning for the operator, and may even cause misunderstanding or anxiety due to the fluctuation of values.

[0084] Therefore, the decision to activate the error display 143 during the third and final fine-search phase is based on profound engineering considerations. At this point, after the first two iterations, the joint is within a very small neighborhood, extremely close to the true zero point, and the error value itself is already small and its changes tend to be stable. The error value displayed in real time provides the operator with a precise, digital indication of the progress. It transforms the calibration process from blind waiting into an observable convergence process. The operator can visually see the error value gradually decrease with the slightest movement of the joint until it reaches zero. This intuitive feedback not only enhances the user's confidence and sense of control over the calibration process, but more importantly, it helps determine whether the calibration is proceeding normally.

[0085] For example, if the error value fails to converge during iteration or drifts after reaching zero, the operator can immediately interrupt the process to check for abnormalities in the mechanical transmission or sensors. Therefore, the error display 143 is not only a status indicator but also a simple diagnostic tool. It confirms the final calibration result with an indisputable number 0, greatly improving the verifiability of the calibration operation and the authority of the final result, thus optimizing overall efficiency from a human-machine interaction perspective.

[0086] Step 5: Respond to the above command signal and control the first joint 131 to stop rotating, and complete the zero-point calibration.

[0087] When the robot receives the enable signal, it ends the runnable state and controls the joint structure 13 to stop rotating. The current mechanical position of the joint structure 13 is the calibrated zero point position.

[0088] In summary, the robot zero-point calibration method provided in this application, by installing a reflective sensor 141 and a reflector 142 on the first joint 131 and the second joint 132 respectively, and based on the reflected signal received by the reflective sensor 141 from the reflector 142 when the reflective sensor 141 is aligned with the reflector 142, the pulse signal generated by the reflective sensor 141 controls the stopping position of the first joint 131 after it stops rotating, so that the robot can automatically perform zero-point calibration. Compared with manual calibration, it can improve the accuracy of the mechanical zero point of each axis of the robot, reduce calibration error, and does not require a lot of external equipment to assist, which can reduce the cost and process of zero-point calibration, improve the efficiency of zero-point calibration, and is applicable to robots with various signals.

[0089] In the robot manufacturing process, calibration is a core step to ensure its motion accuracy and stability. Before leaving the factory, the system automatically collects robot motion data by integrating high-precision sensors or vision systems, and completes the calibration work in combination with intelligent algorithms. A typical application is a calibration scheme based on a laser tracker. After calibration, the system accurately obtains the robot's mechanical origin position, which is also the target zero point position and the factory zero point position in this embodiment.

[0090] After obtaining the zero point position, a dedicated zero-point calibration device is installed at the rotational connection of each joint structure 13. Two zero-point calibration devices are installed at the rotational points of the joint structure 13 and aligned. That is, the zero point scales mentioned above are set at the first joint 131 and the second joint 132. The aforementioned reflective sensor 141 and the transmitter plate are installed at the zero point scales respectively. After ensuring that the reflected sensing signal is stably triggered, the set of sensing signals is recorded and the reading of the error display 143 is cleared to zero. Subsequently, the set of sensing signals is used for the logical judgment of the robot and its zero-point calibration method and as a signal for the final positioning. The recording of the origin of the joint structure 13 is completed. The workflow of the remaining joint structures 13 is similar.

[0091] like Figure 6 As shown, a more specific robot zero-point calibration method is given here in this embodiment: When the robot loses its zero point due to malfunction or maintenance, the robot teach pendant is equipped with a standardized zero-return function interface, providing clear operation guidance to guide technicians to perform the zero-return process in a standardized manner, and operators to strictly follow the prompts on the zero-return interface.

[0092] Step 201: First, swing each joint structure 13 in manual mode. After confirming that there is no risk of collision during robot operation, adjust the first joint 131 of the joint structure 13 that needs to be calibrated to the approximate position so that the first joint 131 is as close as possible to the zero point position.

[0093] In step 202, under the posture of this position, the automatic positioning program is started. The reflective sensor 141 is interconnected with the robot controller 12 and automatically takes over the robot, driving the first joint 130 to move, thereby driving the first joint 131 to perform zero-point calibration. The drive unit 130 slowly performs positioning movements in sequence.

[0094] Taking the robot and its joint structure 13 in this embodiment as an example, the robot's first joint 131 first rotates 45° clockwise at 10% of its running speed and then stops, setting it as the starting point for positioning. Then it rotates 90° counterclockwise as the ending point, making it perform a fan-shaped motion for wide-range positioning. When the reflective sensor 141 moves with the first joint 131, the emitted laser beam generates a reflection signal with the reflector 142 fixed to the other side of the first joint 131, triggering the reflective sensor 141. The robot stops moving and sets the current position as the expected zero point position. If the forward and reverse positioning does not trigger the reflective sensor 141, the indicator light 144 displays a red light and a buzzer is activated, indicating "position is in an unmeasurable position". At this time, the zero point calibration work is restarted.

[0095] Step 203: Then, the robot will slow down, using the current expected zero point position as a reference, and rotate 25° clockwise at 5% of its running speed before stopping, setting this as the starting point for positioning. Then, it will rotate 50° counterclockwise as the ending point, making it perform a fan-shaped motion. When the reflective sensor 141 moves with the first joint 131, the emitted laser beam generates a reflection signal with the reflector 142 fixed to the other side of the first joint 131, triggering the reflective sensor 141. The robot stops moving and further narrows down the positioning range. If the forward and reverse positioning does not trigger the reflective sensor 141, the indicator light 144 will display a red light and start a buzzer, indicating "position is in an unmeasurable position". At this time, the zero point calibration work will restart.

[0096] Step 204: Finally, the robot will further reduce its speed. The robot will stop after turning 5° clockwise at 1% of its running speed, which will be set as the starting point for positioning. Then, it will turn 10° counterclockwise as the ending point, making it perform a fan-shaped motion. When the reflective sensor 141 moves with the first joint 131, the emitted laser beam will generate a reflection signal with the reflector 142 fixed to the first joint 131 on the other side, triggering the reflective sensor 141. The robot will then stop moving and further narrow down the positioning range.

[0097] Step 205: When the laser signal emitted by the reflective sensor 141 enters the range of the reflector 142, the error display 143 on the reflective sensor 141 displays the deviation value from the factory zero point position. When the error display 143 on the reflective sensor 141 displays 0, it indicates that the laser signal has finally converged to the target zero point position.

[0098] Step 206: At this point, indicator light 144 will display a green light and emit a work completion tone. Otherwise, continue with the third rotation operation. After more than five third rotation operations, a positioning failure will be displayed, requiring the user to confirm on-site whether any other problems have occurred. Only after confirming that there are no abnormalities should the zero-point calibration process be executed.

[0099] Step 207: After the zero-point calibration function is completed, each axis of the robot will return to its original factory position and stop, ready for subsequent use.

[0100] In another embodiment provided in this disclosure, a computer-readable storage medium is also provided, which stores instructions that, when executed on a computer, cause the computer to perform the robot zero-point calibration method described in the above embodiments.

[0101] In yet another embodiment provided in this disclosure, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to perform the robot zero-point calibration method described in the above embodiments.

[0102] In the above embodiments, implementation can be achieved, in whole or in part, by software, hardware, firmware, or any combination thereof. When implemented in software, it can be implemented, in whole or in part, as a computer program product. A computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, all or part of the flow or function according to the embodiments of this disclosure is generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wired (e.g., coaxial cable, fiber optic, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave) means. The computer-readable storage medium can be any available medium that a computer can access or a server, data center, or other data storage device that integrates one or more available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium (e.g., a solid-state disk (SSD)). The various embodiments in the specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0103] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the present invention.

[0104] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The device embodiments described above are merely illustrative. For example, the division of units is only a logical functional division, and in actual implementation, there may be other division methods, such as: multiple units or components can be combined, or integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the various components shown or discussed can be through some interfaces, and the indirect coupling or communication connection between devices or units can be electrical, mechanical, or other forms.

[0105] The units described above as separate components may or may not be physically separate. The components shown as units may or may not be physical units. They may be located in one place or distributed across multiple network units. Some or all of the units may be selected to achieve the purpose of this embodiment according to actual needs.

[0106] In addition, each functional unit in the various embodiments of this application can be integrated into one processing unit, or each unit can be a separate unit, or two or more units can be integrated into one unit; the integrated unit can be implemented in hardware or in the form of hardware plus software functional units.

[0107] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media that can store program code, such as mobile storage devices, read-only memory (ROM), magnetic disks, or optical disks.

[0108] Alternatively, if the integrated units described above are implemented as software functional modules and sold or used as independent products, they can also be stored in a computer-readable storage medium. Based on this understanding, the technical solutions of the embodiments of this application, or the parts that contribute to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a controller to execute all or part of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as mobile storage devices, ROMs, magnetic disks, or optical disks.

[0109] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0110] The present invention has been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A robot, characterized in that, The robot comprises a receiver (11), a controller (12) and a joint structure (13), the joint structure (13) comprises a first joint (131) and a second joint (132), the first joint (131) is rotationally connected to the second joint (132), one of the first joint (131) and the second joint (132) is provided with a reflective sensor (141), and the other is provided with a reflective plate (142); The reflective sensor (141) is used to generate a pulse signal in the case of receiving a reflected signal of the reflective plate (142), and the pulse signal is used to trigger the controller (12) to generate an instruction signal; The receiver (11) is used to receive a zero-point calibration instruction; The controller (12) is used to control the first joint (131) to rotate in response to the zero-point calibration instruction, and the controller (12) is also used to control the first joint (131) to stop rotating in response to the instruction signal, and complete zero-point calibration.

2. The robot of claim 1, wherein, The controller (12) is also used to control the first joint (131) to perform a plurality of rotation operations, and determine the position of the first joint (131) stopped in response to the instruction signal in the last rotation operation as a target zero-point position.

3. The robot of claim 2, wherein, The robot further comprises a memory (15), which is used to store the position stopped in response to the instruction signal in each rotation operation as a predicted zero-point position.

4. The robot of claim 3, wherein, For each rotation operation, based on the predicted zero-point position stored by the memory (15) after the last rotation operation, the controller (12) is used to control the first joint (131) to rotate at a preset speed and a preset angle in the counterclockwise / clockwise direction by a preset angle respectively; Wherein, for the first rotation operation, the position based on is the position of the first joint (131) after the user manually rotates the first joint (131).

5. The robot of claim 4, wherein, The preset rotation angle in the process of the Nth rotation operation is greater than the preset rotation angle in the process of the N+1th rotation operation; And / or, The preset rotation speed in the process of the Nth rotation operation is greater than the preset rotation speed in the process of the N+1th rotation operation; wherein N is a positive integer.

6. The robot of claim 5, wherein, The preset rotation angle in the process of the first rotation operation is 45°, and the preset rotation speed in the process of the first rotation operation is 10% of the standard rotation speed of the first joint (131).

7. The robot of claim 6, wherein, The preset rotation angle in the process of the second rotation operation is 25°, and the preset rotation speed in the process of the second rotation operation is 5% of the standard rotation speed.

8. The robot of claim 7, wherein, The preset rotation angle in the process of the third rotation operation is 5°, and the preset rotation speed in the process of the third rotation operation is 1% of the standard rotation speed.

9. The robot of claim 3, wherein, The reflective sensor (141) further comprises an error display (143) for displaying a position error value of the predicted zero point position and an initial zero point position of the first joint (131); wherein when the indication of the position error value is 0, the error display (143) generates the pulse signal, and determines the position of the first joint (131) at this time as the target zero point position, thereby completing zero point calibration.

10. The robot of claim 4, wherein, For the first-mentioned rotating operation, the position based on which is the position of the first joint (131) after the user manually rotates the first joint (131), at which time the position of the first joint (131) has an angle difference of a first preset angle from the target zero point position of the first joint (131).

11. The robot according to any of claims 1-10, characterized in that, The axis of the first joint (131) is perpendicular to the axis of the second joint (132), and the first joint (131) is configured to rotate around the axis of the second joint (132).

12. A robot zero calibration method, characterized by, Zero point calibration for a robot as claimed in any one of claims 1-11, comprising: issuing a zero point calibration instruction; in response to the zero point calibration instruction, controlling the first joint (131) to rotate; the reflective sensor (141) generates a pulse signal opposite the reflective plate (142), which is used to trigger the controller (12) to generate an instruction signal; in response to the instruction signal and controlling the first joint (131) to stop rotating, completing zero point calibration.

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