A control method of a polishing robot with motion trajectory self-learning
The grinding robot system, which learns its motion trajectory, uses spindle current monitoring and position monitoring units to control the grinding wheel spindle in stages for full and re-grinding. This solves the problem of insufficient grinding accuracy at locations where the cutting resistance on the workpiece surface increases, and achieves a highly efficient and precise grinding effect.
Patent Information
- Application Number
- CN202311289780.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-10-08
- Publication Date
- 2026-02-27
- Estimated Expiration
- 2043-10-08
AI Technical Summary
In existing technologies, it is impossible to perform targeted re-grinding at locations where the cutting resistance on the workpiece surface increases, resulting in insufficient grinding accuracy.
The grinding robot system adopts motion trajectory self-learning. The spindle current monitoring unit monitors the working current in real time. Combined with the spindle position monitoring unit and control unit, it controls the grinding wheel spindle to perform full grinding and re-grinding in stages, and plans the re-grinding path to improve grinding efficiency and accuracy.
It enables precise re-grinding of the workpiece surface at locations where cutting resistance increases, improving grinding efficiency and accuracy, and ensuring that the workpiece surface meets the predetermined accuracy requirements.
Smart Images
Figure CN117207192B_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the technical field of intelligent polishing, in particular to a control method of a polishing robot with self-learning motion trajectory. BACKGROUND
[0002] In actual polishing process, the spindle will adjust the size of working current to ensure the stability of power, and the cutting resistance of the workpiece surface in contact with the grinding wheel will affect the working current of the spindle. The greater the cutting resistance, the greater the working current of the spindle, and vice versa.
[0003] However, the part with increased cutting resistance cannot be polished specifically, and only multiple comprehensive polishing can be used to ensure the polishing accuracy of the workpiece surface, without regrinding the surface of the position with increased resistance.
[0004] Therefore, the present application provides a polishing robot system with self-learning motion trajectory and a control method. SUMMARY
[0005] The present application aims to provide a control method of a polishing robot with self-learning motion trajectory to solve the problem of regrinding the surface of the position with increased resistance.
[0006] To achieve the above-mentioned purpose, one of the purposes of the present application is to provide a polishing robot system with self-learning motion trajectory, which comprises:
[0007] A grinding wheel mounting unit for mounting a grinding wheel spindle, the end of the grinding wheel spindle is provided with a grinding wheel, the grinding wheel is driven to rotate by the rotation of the grinding wheel spindle, and the grinding wheel is in contact with the workpiece surface to realize polishing;
[0008] A spindle current monitoring unit for monitoring the working current output to the grinding wheel spindle in real time to perceive the cutting resistance of the workpiece surface through the size of the working current;
[0009] A spindle position monitoring unit for monitoring the position of the grinding wheel spindle in real time;
[0010] And a control unit for controlling the grinding wheel mounting unit to drive the grinding wheel to polish the workpiece surface;
[0011] Wherein, the monitoring threshold of the working current is set in advance, and the spindle position monitoring unit sends the position of the grinding wheel spindle to the control unit when the working current is greater than the monitoring threshold, to prepare for the regrinding of the control unit.
[0012] As a further improvement of the technical solution, the control unit controls the grinding wheel mounting unit twice, the first time is to drive the grinding wheel to polish the surface of the workpiece, and determine the position needing re-polishing at the same time; the second time is to drive the grinding wheel to polish the position needing re-polishing on the surface of the workpiece.
[0013] As a further improvement of the technical solution, the control unit controls the grinding wheel mounting unit three times, the first time is to drive the grinding wheel to polish the surface of the workpiece, and determine the position needing re-polishing at the same time; the second time is to drive the grinding wheel to polish the position needing re-polishing on the surface of the workpiece; the third time is to control the grinding wheel mounting unit after re-polishing, and drive the grinding wheel to polish the surface.
[0014] As a further improvement of the technical solution, the control unit is installed in the electric control cabinet.
[0015] The spindle current monitoring unit is arranged in the electric control cabinet, and the spindle current monitoring unit obtains the working current of the polishing grinding wheel spindle through the frequency converter.
[0016] As a further improvement of the technical solution, a current sensor is installed in the circuit of the output end of the frequency converter or the input end of the spindle motor.
[0017] As a further improvement of the technical solution, a PLC control panel is arranged on the electric control cabinet, the monitoring threshold A0 of the grinding wheel spindle is set through the PLC, the PLC reads the current value A1 changing on the grinding wheel spindle in real time through the frequency converter, and compares the current value A1 with the monitoring threshold A0: when A1 is greater than A0, the spindle position monitoring unit sends the position of the grinding wheel spindle to the control unit, and then the control unit plans a re-polishing path, and the grinding wheel mounting unit drives the grinding wheel to polish the position needing re-polishing on the surface of the workpiece according to the re-polishing path.
[0018] The second object of the present application is to provide a re-polishing path determination method, which comprises the following method steps:
[0019] S1, an x-y-z axis coordinate system is established, wherein the x-y plane is used to represent the coordinates of the position of the grinding wheel spindle, and the y axis is used to represent the working current of the grinding wheel spindle;
[0020] S2, a monitoring plane M2 is determined according to the monitoring threshold A0, and the monitoring plane M2=(x, y, A0);
[0021] S3, the current value A1 changing on the grinding wheel spindle is obtained, and then the x-y-z axis coordinate system only retains the points above the monitoring plane M2;
[0022] S4, a re-polishing path is planned in the x-y-z axis coordinate system according to the retained points.
[0023] As a further improvement of the technical solution, the remaining points are sequentially connected, the connection is the regrinding path, and the average of all points is taken as the initial current of regrinding.
[0024] As a further improvement of the technical solution, the grinding level is determined according to the condition of the grinding wheel, the points belonging to the same grinding level are sequentially connected, the connection is the regrinding path, and the average of all points on the regrinding path is taken as the initial current of regrinding.
[0025] As a further improvement of the technical solution, a precision threshold is set, a precision plane M1 is obtained in the x-y-z axis coordinate system with the precision threshold as the height, then a comprehensive grinding is performed, and the initial current is half of the height value of the monitoring plane M2 and the precision plane M1, so that the workpiece surface approaches the precision plane M1.
[0026] Compared with the prior art, the beneficial effects of the present application are:
[0027] In the control method of the polishing robot with motion trajectory self-learning, when the working current is greater than the monitoring threshold, the spindle position monitoring unit sends the position of the grinding wheel spindle to the control unit, and the control unit controls the mechanical arm twice, the first time is to drive the grinding wheel to polish the workpiece surface comprehensively, and determine the position needing regrinding at the same time, and the second time is to drive the grinding wheel to polish the position needing regrinding on the workpiece surface, thereby improving the polishing efficiency. BRIEF DESCRIPTION OF DRAWINGS
[0028] Figure 1 It is a schematic diagram of the module structure of the system of the present application;
[0029] Figure 2 It is a schematic diagram of the regrinding path planning principle of the present application.
[0030] The meanings of various labels in the figure are:
[0031] 100, grinding wheel mounting unit; 200, spindle current monitoring unit; 300, spindle position monitoring unit; 400, control unit. DETAILED DESCRIPTION
[0032] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.
[0033] In actual polishing process, the spindle will adjust the size of working current to ensure the stability of power, and the cutting resistance of the workpiece surface in contact with the grinding wheel will affect the working current of the spindle. The greater the cutting resistance, the greater the working current of the spindle, and vice versa. Based on this principle, the application provides a polishing robot system with self-learning motion trajectory, as shown in Figure 1 The grinding wheel carrying unit 100 is used to carry the grinding wheel spindle, and the grinding wheel is arranged at the end of the grinding wheel spindle. The grinding wheel is driven to rotate by the rotation of the grinding wheel spindle, and the grinding wheel is in contact with the workpiece surface to realize polishing. The relevant principle is known to those skilled in the art, and will not be described here. However, the grinding wheel carrying unit 100 usually selects a movable mechanical arm, and the grinding wheel spindle is arranged on the mechanical arm. The grinding wheel spindle is driven to displace by the mechanical arm, so that the workpiece surface is polished by the grinding wheel.
[0034] The spindle current monitoring unit 200 monitors the working current output to the grinding wheel spindle in real time during the grinding process of the grinding wheel, so as to perceive the cutting resistance of the workpiece surface through the size of the working current. At the same time, the spindle position monitoring unit 300 also monitors the position of the grinding wheel spindle in real time to improve the accuracy of the polishing path. Furthermore, a monitoring threshold of working current is set in advance. When the working current is greater than the monitoring threshold, it indicates that the cutting resistance of the workpiece surface is large. At this time, only one polishing will produce burrs, so it needs to be polished again. Therefore, when the working current is greater than the monitoring threshold, the spindle position monitoring unit 300 sends the position of the grinding wheel spindle to the control unit 400. The control unit 400 controls the mechanical arm twice. The first time, the mechanical arm drives the grinding wheel to polish the workpiece surface comprehensively, and determines the position needing to be polished again while polishing. The second time, the mechanical arm drives the grinding wheel to polish the position needing to be polished again on the workpiece surface.
[0035] The control unit 400 is installed in the electric control cabinet to control the mechanical arm and control the power supply to output the working current to the grinding wheel spindle. Therefore, the spindle current monitoring unit 200 is also arranged in the electric control cabinet. Then the working current of the polishing grinding wheel spindle is obtained through the frequency converter. The specific principle is as follows:
[0036] The frequency converter receives the input AC voltage and processes it through rectification and filtering to obtain DC voltage. The inverter inside the frequency converter converts the DC voltage into an adjustable AC voltage. This AC voltage is then regulated by the frequency converter's control module by changing the frequency and voltage. The frequency converter supplies the regulated AC voltage to the drive motor of the grinding wheel spindle, thereby driving the grinding wheel spindle to rotate. Because the grinding wheel spindle may face different load variations during machining, such as different hardness or surface roughness of the cutting material, the frequency converter precisely controls the torque output of the spindle motor based on the real-time load conditions. This allows the grinding wheel spindle to better cope with load changes and maintain stable machining results. As the grinding wheel spindle rotates, current flows through it; therefore, a current sensor is installed in the circuit at the output of the frequency converter or the input of the spindle motor to measure the current magnitude, thereby indirectly obtaining the magnitude of the cutting resistance.
[0037] In addition, to facilitate the setting of monitoring thresholds during use, a PLC control panel (hereinafter referred to as PLC) is installed on the electrical control cabinet. The upper limit of the grinding wheel spindle current value is set to A0 through the PLC. The PLC reads the changing current value A1 on the grinding wheel spindle through the frequency converter and compares A1 with the preset upper limit value A0 (i.e., the monitoring threshold). When A1 is greater than A0, the spindle position monitoring unit 300 sends the position of the grinding wheel spindle to the control unit 400. Then, the control unit 400 plans the re-grinding path and causes the robotic arm to drive the grinding wheel to grind the workpiece surface at the re-grinding position according to the re-grinding path.
[0038] The planning steps for the regrinding path are as follows:
[0039] S1. Establish the xyz axis coordinate system ( Figure 2 As shown in the figure, the xy plane is used to represent the coordinates of the position of the grinding wheel spindle, and the y-axis is used to represent the working current of the grinding wheel spindle. In this way, the working current of the grinding wheel spindle can be reflected in the xyz axis coordinate system through the y-axis.
[0040] S2. Determine the monitoring plane M2 based on the monitoring threshold A0, M2 = (x, y, A0);
[0041] S3. Obtain the changing current value A1 on the grinding wheel spindle, and then keep only the points on the monitoring plane M2 in the xyz axis coordinate system.
[0042] S4. In the xyz axis coordinate system, plan the re-grinding path based on the retained points, and then move the grinding wheel along the re-grinding path to achieve re-grinding of the workpiece surface.
[0043] There are several implementation methods for planning the re-grinding path in S4:
[0044] One, the remaining points are connected in turn, and the connection is the regrinding path, and the average of all points is used as the initial current of regrinding, that is:
[0045]
[0046]
[0047] In the formula, is the initial current; is the number of remaining points.
[0048] Suppose the remaining points are d1, d2, d3, d4, d5 and d6, and their corresponding current values are y1, y2, y3, y4, y5 and y6, then In this way, the grinding wheel can adapt to the surface at all point positions during regrinding, and there will be no problem of excessive grinding or insufficient grinding intensity, so that the surface of the regrinded workpiece approaches the monitoring plane M2;
[0049] Second, different grinding levels are determined according to the condition of the grinding wheel, and then the points belonging to the same grinding level (the level is divided according to the working current, because different working currents represent different surface roughness, so different grinding precision grinding wheels need to be selected) are connected in turn, thereby forming multiple regrinding paths, and different regrinding paths use grinding wheels of different precision. Suppose the remaining points are d1, d2, d3, d4, d5 and d6, wherein d1, d2 and d3 belong to the same grinding level, and d4, d5 and d6 belong to the same grinding level, and then the average of all points on the regrinding path is used as the initial current of regrinding, so the initial current of the first regrinding path is ; the initial current of the second regrinding path is The initial current obtained in this way is more representative and can make the surfaces at more point positions approach the monitoring plane M2.
[0050] Further, when A1 is less than A0, the mechanical arm moves at an accelerated speed; when A1 is greater than A0, the mechanical arm moves at a reduced speed to finely grind the surface of the workpiece; when A1 is equal to A0, the moving speed of the mechanical arm remains unchanged; at the same time, the establishment of the x-y-z axis coordinate system and the real-time monitoring of the position of the grinding wheel spindle are realized through self-learning of the neural network, and laser recognition technology is usually used.
[0051] Further, as shown in Figure 2 , a precision threshold is set, and a precision plane M1 is obtained in the x-y-z axis coordinate system with the precision threshold as the height, and then a comprehensive grinding is performed to make the surface of the workpiece approach the precision plane M1 to achieve the predetermined precision requirement, and the half of the height values of M2 and M1 is used as the initial current for comprehensive grinding.
[0052] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above-mentioned embodiments, and the above-mentioned embodiments and descriptions in the specification are only preferred examples of the present application and are not intended to limit the present application. Various changes and improvements can be made to the present application without departing from the spirit and scope of the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.
Claims
1. A control method for a grinding robot with self-learning motion trajectory, characterized in that, The methods and steps include the following: S1. Establish an xyz axis coordinate system, where the xy plane is used to represent the coordinates of the position of the grinding wheel spindle, and the y axis is used to represent the working current of the grinding wheel spindle; S2. Determine the monitoring plane M2 based on the monitoring threshold A0. The monitoring plane M2 = (x, y, A0). S3. Obtain the changing current value A1 on the grinding wheel spindle, and then keep only the points on the monitoring plane M2 in the xyz axis coordinate system. S4. Plan the re-grinding path in the xyz axis coordinate system based on the retained points; Connect the remaining points sequentially to form the re-grinding path, and use the average value of all points as the initial current for re-grinding. This control method uses a grinding robot system that learns motion trajectories on the spot, which includes: A grinding wheel mounting unit (100) is used to mount a grinding wheel spindle. A grinding wheel is provided at the end of the grinding wheel spindle. The grinding wheel is rotated by the rotation of the grinding wheel spindle, and then the grinding wheel contacts the surface of the workpiece to achieve grinding. Spindle current monitoring unit (200) is used to monitor the working current output to the grinding wheel spindle in real time, so as to sense the cutting resistance of the workpiece surface by the magnitude of the working current; Spindle position monitoring unit (300), the spindle position monitoring unit (300) is used to monitor the position of the grinding wheel spindle in real time; And a control unit (400) for controlling the grinding wheel mounting unit (100) to drive the grinding wheel to grind the surface of the workpiece; Among them, a monitoring threshold for the working current is preset. When the working current is greater than the monitoring threshold, the spindle position monitoring unit (300) sends the position of the grinding wheel spindle to the control unit (400) to prepare for the grinding wheel regrinding by the control unit (400). The control unit (400) is installed inside the electrical control cabinet; The spindle current monitoring unit (200) is installed in the electrical control cabinet. The spindle current monitoring unit (200) obtains the working current of the grinding wheel spindle through the frequency converter. The electrical control cabinet is equipped with a PLC control panel. The monitoring threshold A0 of the grinding wheel spindle is set by the PLC. The PLC reads the changing current value A1 on the grinding wheel spindle in real time through the frequency converter and compares the current value A1 with the monitoring threshold A0. When A1 is greater than A0, the spindle position monitoring unit (300) sends the position of the grinding wheel spindle to the control unit (400). Then, the control unit (400) plans the re-grinding path, and the grinding wheel mounting unit (100) drives the grinding wheel to grind the workpiece surface at the re-grinding position according to the re-grinding path.
2. The control method for a grinding robot with self-learning motion trajectory according to claim 1, characterized in that, The control unit (400) controls the grinding wheel mounting unit (100) twice. The first control of the grinding wheel mounting unit (100) is to drive the grinding wheel to perform full grinding on the surface of the workpiece, and at the same time determine the position that needs to be re-grinded. The second control of the grinding wheel mounting unit (100) is to drive the grinding wheel to grind the position on the surface of the workpiece that needs to be re-grinded.
3. The control method for a grinding robot with self-learning motion trajectory according to claim 1, characterized in that, The control unit (400) controls the grinding wheel mounting unit (100) three times. The first time, the control unit (100) drives the grinding wheel to perform a full grinding of the workpiece surface and determines the position that needs to be re-grinded at the same time. The second time, the control unit (100) drives the grinding wheel to perform a grinding of the position on the workpiece surface that needs to be re-grinded. The third time, the control unit (100) is used after the re-grinding to drive the grinding wheel to perform a full grinding.
4. The control method for a grinding robot with self-learning motion trajectory according to claim 3, characterized in that, A current sensor is installed in the circuit at the output terminal of the frequency converter or the input terminal of the spindle motor.
5. The control method for a grinding robot with self-learning motion trajectory according to claim 4, characterized in that, Determine the grinding grade based on the condition of the grinding wheel, connect the points belonging to the same grinding grade sequentially, use this line as the re-grinding path, and use the average value of all points on the re-grinding path as the initial current for re-grinding.
6. The control method for a grinding robot with self-learning motion trajectory according to claim 5, characterized in that, Set a precision threshold, obtain the precision plane M1 with the precision threshold as the height in the xyz axis coordinate system, then perform a full grinding, and use half the height value of the monitoring plane M2 and the precision plane M1 as the initial current to make the workpiece surface approach the precision plane M1.
Citation Information
Patent Citations
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