Magnetorheological machining control system and machining method based on instantaneous current sensing

Abstract

The present invention relates to the field of magnetorheological technology, and specifically to a magnetorheological processing control system based on instantaneous current sensing and a processing method thereof. The system includes a polishing platform, a polishing component, a detection circuit, and a computer. The polishing component includes an industrial robot and a magnetorheological polishing module. When the magnetorheological polishing module is used to process a polishing test piece, the first instantaneous current corresponding to the magnetorheological polishing module at different operating speeds is collected, and the corresponding relationship between the operating speed of the magnetorheological polishing module and the ideal instantaneous current is calculated. The second instantaneous current is determined based on this relationship, and it is determined whether to adjust the operating speed of the magnetorheological polishing module based on the determination result. This process does not require calibration steps for parameters such as gravity compensation. The accuracy of the measurement data is only limited by the current measurement accuracy of the second instantaneous current between the magnetorheological polishing module and the polishing test piece. The measurement results are more accurate, and no force sensor is required, which reduces equipment costs.

Description

Technical Field

[0001] The present invention relates to the field of magnetorheological technology, and in particular to a magnetorheological processing control system based on instantaneous current sensing and a processing method thereof. Background Art

[0002] Magnetorheological finishing (MRF) is an advanced optical manufacturing technology that has developed in recent years. It offers numerous advantages, including stable removal function, controllable edge effects, minimal subsurface damage, no photocopying, strong reshaping capabilities, and high machining accuracy. Consequently, MRF has garnered widespread attention in high-precision optical processing. Existing MRF machining centers primarily integrate MRF modules onto CNC machine tools. However, CNC machine tools have limitations (such as low degrees of freedom, large footprint, and high cost) that limit the deviation of aspheric surfaces and hinder precise position control along the surface normal. In response to these shortcomings of CNC machine tools, researchers have introduced six-degree-of-freedom industrial robots into the field of optical processing in recent years. Six-degree-of-freedom industrial robots have the advantages of high degrees of freedom, small footprint, large processing range, and low cost, which make up for the shortcomings of CNC machine tools. Therefore, when the magnetorheological polishing module is integrated into the industrial robot, theoretically, high-precision processing of large-aperture complex curved optical components can be achieved. However, due to the influence of factors such as processing, assembly, load, trajectory planning, and reduction ratio, the robot end execution accuracy is low, and the polishing gap changes greatly during the processing. At the same time, magnetorheological polishing technology is an optical processing technology with high certainty of the removal function. During the polishing process, the requirements for the change of the polishing gap are high. Generally, the polishing gap of the magnetorheological CNC machining center changes in tens of microns (PV<0.1mm), and the trajectory accuracy of common commercial robots is generally in the sub-millimeter to millimeter range, which cannot meet the requirements of magnetorheological polishing technology for polishing gap changes during high-precision polishing.

[0003] Force-position control is currently gaining popularity as a new approach to robotic constant-force controlled polishing. A common application involves placing a force sensor between the machining tool and the robot. The force sensor is first calibrated with gravity to ensure measurement accuracy. The position error is calculated by measuring force changes. This position error is then compensated for using the robot itself or other motion compensation mechanisms to achieve constant force control. Efficient machining of large-aperture optical components requires magnetorheological (MR) machining equipment with large polishing wheels. These MR machining modules typically weigh hundreds of kilograms. However, for these MR machining modules, the force variation caused by the robot's position error is only tens of Newtons. High-precision machining requires maintaining a constant force of a few Newtons or even a fraction of a Newton. This requires measurement equipment such as force sensors to achieve an absolute accuracy of one part per ten thousand. Furthermore, the force sensor must be capable of varying speed and position. Force sensors that meet these requirements are often extremely expensive, significantly increasing the cost of the equipment. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a magnetorheological processing control system based on instantaneous current sensing and a processing method thereof. It solves the problem that the existing technology requires the use of high-precision force sensors for data collection for the control of the polishing wheel, and the high cost of high-precision force sensors, by simply adjusting the rotational speed of the polishing wheel or the liquid pump.

[0005] To achieve the above object, the technical solution created by the present invention is implemented as follows:

[0006] A magnetorheological processing control system based on instantaneous current sensing, comprising:

[0007] a polishing platform on which a test polishing element and an element to be polished are arranged;

[0008] The polishing assembly includes an industrial robot and a magnetorheological polishing module. The industrial robot is used to drive the magnetorheological polishing module to move to the location of the test polishing element or to drive the magnetorheological polishing module to move to the location of the element to be polished. The magnetorheological polishing module includes a polishing wheel, a nozzle, and a liquid pump. The liquid pump is used to supply magnetorheological fluid to the nozzle. The nozzle is used to spray the magnetorheological fluid onto the polishing wheel. The polishing wheel is used to process the test polishing element or the element to be polished. The operating speed of the magnetorheological polishing module is the speed of the liquid pump or the speed of the polishing wheel.

[0009] a detection circuit configured to output a constant voltage and, when the magnetorheological polishing module contacts the surface of the test polishing element, form a first closed loop and detect a first instantaneous current in the first closed loop in real time, or, when the magnetorheological polishing module contacts the surface of the element to be polished, form a second closed loop and detect a second instantaneous current in the second closed loop in real time;

[0010] A computer is used to calculate the correspondence between the operating speed of the magnetorheological polishing module and the ideal instantaneous current based on polishing data, the polishing data including first instantaneous current data detected by the detection circuit at different operating speeds of the magnetorheological polishing module; and the computer is used to adjust the current operating speed of the magnetorheological polishing module when it is determined that the error between the second instantaneous current detected by the detection circuit and the ideal instantaneous current corresponding to the current operating speed of the magnetorheological polishing module exceeds a preset error range, so that the error between the second instantaneous current detected by the detection circuit and the ideal instantaneous current corresponding to the current operating speed after the operating speed of the magnetorheological polishing module is adjusted is within the preset error range.

[0011] Furthermore, the magnetorheological polishing module also includes a magnetorheological mounting frame, a magnet, a driving wheel, a driven wheel, a synchronous belt and a drive motor; wherein, the magnetorheological mounting frame is connected to the industrial robot, the magnet, the drive motor and the polishing wheel are respectively arranged on the magnetorheological mounting frame, a bearing seat is installed on the magnetorheological mounting frame, a bearing is installed in the bearing seat, the bearing is connected to the polishing wheel, the driven wheel is mounted on the bearing, the driving wheel is mounted on the output end of the drive motor, and the synchronous belt is tensioned on the driven wheel and the driving wheel.

[0012] A magnetorheological machining control method based on polishing wheel speed regulation is implemented using the above-mentioned magnetorheological machining control system based on instantaneous current sensing. The magnetorheological machining control method includes the following steps:

[0013] The industrial robot drives the magnetorheological polishing module to move until it contacts the surface of the test polishing element. The computer sets different polishing wheel speeds to process the test polishing element. The detection circuit detects the first instantaneous current in the first closed loop in real time to obtain the corresponding relationship between the polishing wheel speed and the first instantaneous current. , Indicates the polishing wheel speed, represents the first instantaneous current, The conversion relationship between the polishing wheel rotation speed and the first instantaneous current is represented, and multiple sets of first instantaneous currents and corresponding polishing wheel rotation speeds are mapped and stored to obtain polishing data. The computer calculates the corresponding relationship between the polishing wheel rotation speed and the ideal instantaneous current based on the polishing data;

[0014] The industrial robot drives the magnetorheological polishing module to move until it contacts the surface of the element to be polished. The detection circuit detects the second instantaneous current in the second closed loop in real time. When the computer determines that the error between the second instantaneous current and the ideal instantaneous current corresponding to the current polishing wheel speed exceeds a preset error range, the polishing wheel speed is adjusted by controlling the drive motor so that the error between the second instantaneous current detected by the detection circuit and the corresponding ideal instantaneous current after the polishing wheel speed is adjusted is within the preset error range.

[0015] Furthermore, the sampling period of the detection circuit collecting the second instantaneous current is recorded as , adjust the polishing wheel speed to the maximum adjustment value ∆v max The shortest time required is recorded as , , the shortest switching time between two adjacent machining trajectory points on the component to be polished is recorded as , ;in, The fastest adjustment speed for the polishing wheel speed change. is the maximum moving speed of the industrial robot. Indicates the distance between two adjacent machining track points on the component to be polished;

[0016] The method for adjusting the sampling frequency of the detection circuit includes:

[0017] judge 、 、 Does the relationship between satisfy the formula:

[0018] ;

[0019] If it is not satisfied, the sampling frequency of the detection circuit collecting the second instantaneous current is adjusted until the formula is satisfied. The sampling frequency is .

[0020] Furthermore, by controlling the driving motor to adjust the polishing wheel speed at the current processing trajectory point Make adjustments, including:

[0021] If the second instantaneous current Does not exceed the allowable variation range When the drive motor is not controlled, the polishing wheel speed at the current processing trajectory point is maintained. constant;

[0022] If the second instantaneous current Exceeding the allowable variation range and When the drive motor is controlled, the polishing wheel speed at the current processing trajectory point is adjusted according to the following formula: To make adjustments:

[0023] ;

[0024] in, represents the ideal instantaneous current value, Indicates the adjustment amplitude of the second instantaneous current;

[0025] If the second instantaneous current Exceeding the allowable variation range and When the drive motor is controlled, the polishing wheel speed at the current processing trajectory point is adjusted according to the following formula: To make adjustments:

[0026] ;

[0027] in, Indicates the set initial speed of the polishing wheel.

[0028] A magnetorheological processing control method based on liquid pump speed regulation is implemented using the above-mentioned magnetorheological processing control system based on instantaneous current sensing. The magnetorheological processing control method includes the following steps:

[0029] The industrial robot drives the magnetorheological polishing module to move until it contacts the surface of the test polishing element. The computer sets different liquid pump speeds to process the test polishing element. The detection circuit detects the first instantaneous current in the first closed loop in real time to obtain the corresponding relationship between the liquid pump height and the first instantaneous current. , represents the first instantaneous current, Indicates the liquid pump speed, Indicates the conversion relationship between the liquid pump speed and the first instantaneous current, maps and stores multiple sets of first instantaneous currents and corresponding liquid pump speeds to obtain polishing data, and the computer calculates the corresponding relationship between the liquid pump speed and the ideal instantaneous current based on the polishing data;

[0030] The industrial robot drives the magnetorheological polishing module to move until it contacts the surface of the component to be polished. The detection circuit detects the second instantaneous current in the second closed loop in real time. When the computer determines that the error between the second instantaneous current and the ideal instantaneous current corresponding to the current liquid pump speed exceeds a preset error range, the liquid pump speed is adjusted so that the error between the second instantaneous current detected by the detection circuit and the corresponding ideal instantaneous current after the liquid pump speed is adjusted is within the preset error range.

[0031] Furthermore, the sampling period of the detection circuit collecting the second instantaneous current is recorded as , adjust the liquid pump speed to the maximum adjustment amount The shortest time required is recorded as , , the shortest switching time between two adjacent machining trajectory points on the component to be polished is recorded as , ;in, The fastest adjustment speed for the liquid pump speed change. is the maximum moving speed of the industrial robot. Indicates the distance between two adjacent machining track points on the component to be polished;

[0032] The method for adjusting the sampling frequency of the detection circuit includes:

[0033] judge 、 、 Does the relationship between satisfy the formula:

[0034] ;

[0035] If it is not satisfied, the sampling frequency of the detection circuit collecting the second instantaneous current is adjusted until the formula is satisfied. The sampling frequency is .

[0036] Furthermore, the liquid pump speed at the current processing trajectory point Make adjustments, including:

[0037] If the second instantaneous current Does not exceed the allowable variation range When the liquid pump motor is not controlled, the liquid pump speed at the current processing trajectory point is maintained. constant;

[0038] If the second instantaneous current Exceeding the allowable variation range and When the liquid pump speed at the current processing trajectory point is calculated according to the following formula: To make adjustments:

[0039] ;

[0040] in, represents the ideal instantaneous current value, Indicates the adjustment amplitude of the second instantaneous current;

[0041] If the second instantaneous current Exceeding the allowable variation range and When the liquid pump speed at the current processing trajectory point is calculated according to the following formula: To make adjustments:

[0042] ;

[0043] in, Indicates the initially set liquid pump speed.

[0044] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0045] When a magnetorheological polishing module is used to process a polishing test piece, different operating speeds of the magnetorheological polishing module and the corresponding first instantaneous current are collected. The corresponding relationship between the operating speed of the magnetorheological polishing module and the ideal instantaneous current is then calculated based on the collected operating speed of the magnetorheological polishing module and the first instantaneous current. The second instantaneous current is then judged based on this relationship. Based on the judgment result, it is determined whether to adjust the operating speed of the magnetorheological polishing module, thereby achieving real-time adjustment of the operating speed by the computer, so that the magnetorheological fluid flow fluctuation at each processing trajectory point meets the high-precision polishing requirements and ensures the constancy of the removal function. This process does not require calibration steps for parameters such as gravity compensation, and is not affected by the weight of the magnetorheological processing module of the robotic magnetorheological processing equipment, the equipment's own operating accuracy, operating speed, posture, inertia, and other factors. The accuracy of the measurement data is only limited by the current measurement accuracy of the second instantaneous current between the magnetorheological polishing module and the polished test piece. The measurement results are more accurate, and there is no need to add high-precision force sensors and other equipment, thereby reducing equipment costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a structural diagram of the magnetorheological processing control system based on instantaneous current sensing described in an embodiment of the present invention.

[0047] Figure numerals: polishing platform 1, industrial robot 21, polishing wheel 221, nozzle 222, liquid pump 223, magnetorheological mounting frame 224, mounting frame 225, drive motor 226, active wheel 227, driven wheel 228, synchronous belt 229, current intensity controller 230, computer 3, test polishing element 4 and element to be polished 5. DETAILED DESCRIPTION

[0048] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. In the following description, identical modules are denoted by identical reference numerals. In the case of identical reference numerals, their names and functions are also identical. Therefore, their detailed description will not be repeated.

[0049] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and do not constitute a limitation of the present invention.

[0050] In the first aspect, this embodiment provides a magnetorheological processing control system based on instantaneous current sensing, the structure of the system is as follows: Figure 1As shown, it includes a polishing platform 1, a polishing assembly, a detection circuit and a computer 3. A test polishing element 4 and a to-be-polished element 5 are provided on the polishing platform 1; the polishing assembly includes an industrial robot 21 and a magnetorheological polishing module. The industrial robot 21 is used to drive the magnetorheological polishing module to move to the position of the test polishing element 4 or the position of the to-be-polished element 5, and to adjust the polishing gap between the magnetorheological polishing module and the test polishing element 4 or the polishing gap between the magnetorheological polishing module and the to-be-polished element 5; the magnetorheological polishing module includes a polishing wheel 221, a nozzle 222 and a liquid pump 223. The liquid pump 223 is used to provide magnetorheological fluid to the nozzle 222, and the nozzle 222 is used to spray magnetorheological fluid onto the polishing wheel 221; the working speed of the magnetorheological polishing module is the speed of the liquid pump 223 or the speed of the polishing wheel 221; the detection circuit is used to output a constant voltage and to detect the magnetorheological fluid when the magnetorheological polishing module contacts the surface of the test polishing element 4 When the magnetorheological polishing module contacts the surface of the element to be polished 5, a first closed loop is formed, and the first instantaneous current in the first closed loop is detected in real time, or when the magnetorheological polishing module contacts the surface of the element to be polished 5, a second closed loop is formed, and the second instantaneous current in the second closed loop is detected in real time; the computer 3 is used to calculate the correspondence between the working speed of the magnetorheological polishing module and the ideal instantaneous current according to the polishing data, and the polishing data includes the first instantaneous current data detected by the detection circuit at different working speeds of the magnetorheological polishing module; and the computer 3 is used to adjust the working speed of the current magnetorheological polishing module when it is determined that the error between the second instantaneous current detected by the detection circuit and the ideal instantaneous current corresponding to the current working speed of the magnetorheological polishing module exceeds a preset error range, so that after the working speed of the magnetorheological polishing module is adjusted, the error between the second instantaneous current detected by the detection circuit and the ideal instantaneous current corresponding to the current working speed is within the preset error range.

[0051] In this embodiment, the polishing platform 1 refers to a working platform for experiments, on which are placed a test polishing element 4, an element to be polished 5, and other polishing components, such as the magnetorheological fluid required for polishing and supporting tooling for the element to be polished. Among them, the test polishing element 4 is a reference component required for calculating the ideal instantaneous current corresponding to the operating speed, and the element to be polished 5 is a component that needs to undergo magnetorheological polishing processing.

[0052] In this embodiment, the industrial robot 21 may be a six-degree-of-freedom robotic arm, or other robots with posture adjustment functions.

[0053] The magnetorheological polishing module includes a magnetorheological mounting frame 224, a magnet (not shown), a drive motor 226, a driving wheel 227, a driven wheel 228 and a synchronous belt 229; wherein the magnetorheological mounting frame 224 is connected to the industrial robot 21, and the magnet, the drive motor 226 and the polishing wheel 221 are respectively arranged on the magnetorheological mounting frame 224, and the magnet is mounted on the magnetorheological mounting frame 224 and close to the working point of the polishing wheel 221 (in the embodiment of the present invention, the working point of the polishing wheel 221 is specified to be along the normal direction of the surface of the element 5 to be polished, and the polishing wheel 221 is closest to the surface of the element 5 to be polished). Contacts), magnets are used to generate a magnetic field, which affects the magnetorheological fluid (MRF) by the intensity of the magnetic field, thereby changing the stiffness of the MRF. A bearing seat is mounted on the MRF mounting frame 224, and a bearing is mounted within the bearing seat. The bearing is connected to the polishing wheel 221. A driven wheel 228 is mounted on the bearing, and a driving wheel 227 is mounted on the output end of the drive motor 226. A synchronous belt 229 is tensioned between the driven wheel 228 and the driving wheel 227. The polishing wheel 221 is driven by the drive motor 226 to rotate. (See Chinese Patent Publication No. CN118322074A, published on July 12, 2024.) The drive motor 226 drives the polishing wheel 221 to rotate at high speed, drawing the MRF into the magnetic field. Under the influence of the magnetic field, the MRF flows into a MR ribbon. The dimensional parameters of the MR ribbon vary with the speed of the polishing wheel 221 or the speed of the liquid pump 223.

[0054] Liquid pump 223 is mounted on one side of polishing platform 1 via mounting bracket 225 to supply magnetorheological fluid to nozzle 222. Nozzle 222 is mounted on magnetorheological mounting bracket 224 along the rotation direction of polishing wheel 221. Liquid pump 223 adopts DFLD vertical multi-stage pump from Shanghai Dongfang Pump Industry Co., Ltd.

[0055] In this embodiment, the polishing principle of a test polishing element 4 is explained as follows: When the polishing wheel is operating, the magnetorheological fluid is subjected to changes in the magnetic field, changing from a liquid state to a near-solid state, forming a Bingham fluid. The rotation of the polishing wheel 221 causes the Bingham fluid to exert a shear force on the outer surface of the test polishing element 4, thereby polishing the test polishing element 4. Different rotational speeds of the polishing wheel 221 correspond to different shear forces, resulting in different polishing effects. Different rotational speeds of the liquid pump 223 also exert different shear forces on the outer surface of the test polishing element 4, achieving different polishing effects.

[0056] The magnetorheological polishing module can achieve flexible polishing of various components, especially optical components with high-precision requirements on the outer surface.

[0057] It's important to note that strong magnetism exists within the working area of ​​the MRP module. Therefore, circuit connections must be placed away from this area to prevent wires from being attracted to the module and impacting normal operation. Ideally, the fixed voltage should not exceed the human safety voltage, and the instantaneous current measured using contact resistance should not exceed the human safety current.

[0058] In this embodiment, the detection circuit is based on the principle of resistance change. Pressure exists between the magnetorheological polishing module and the test polishing element 4, and between the magnetorheological polishing module and the element to be polished 5. Different polishing gaps correspond to different pressures. Changes in pressure will cause changes in contact resistance, and thus the current flowing through the contact resistance will also change. Taking the test polishing element 4 as an example, the same principle can be applied to the element to be polished 5, as follows:

[0059] The detection circuit applies a fixed voltage between the magnetorheological polishing module and the test polishing element 4, and uses the relationship between contact resistance and pressure to calculate the resistance value caused by the pressure change. Then, based on the relationship between the fixed voltage, contact resistance and instantaneous current, the instantaneous current value is calculated using Ohm's law. The instantaneous current value in the first closed loop is the first instantaneous current. The relationship between pressure and contact resistance can be expressed by the following formula:

[0060] ;

[0061] in, is the contact resistance, is the material coefficient, is the pressure when the magnetorheological polishing module contacts the test polishing element 4, is the coefficient corresponding to the contact form (including point contact, surface contact, line contact, etc.). In this embodiment, For surface contact, .

[0062] The detection circuit can be implemented by a current intensity controller 230 . The current intensity controller 230 can adopt a Smart200 series DA conversion module of Siemens to sense the first instantaneous current between the test polishing element 4 and the polishing wheel 221 .

[0063] In this embodiment, computer 3 is configured to calculate a correspondence between different operating speeds of the magnetorheological polishing module and an ideal instantaneous current based on polishing data collected by the detection circuit at different operating speeds of the magnetorheological polishing module. The polishing data includes first instantaneous current data in a first closed loop detected by the detection circuit at different operating speeds.

[0064] The working speed of the magnetorheological polishing module can be pre-set. Different working speeds should cover the maximum polishing gap and the minimum polishing gap to which the industrial robot 21 can drive the magnetorheological polishing module. The polishing data can be collected multiple times, and finally the error between multiple sets of polishing data can be reduced by taking the mean or variance and other numerical calculation methods. The relationship between the ideal instantaneous current and the working speed of the magnetorheological polishing module is calculated based on the polishing data.

[0065] In this embodiment, the computer 3 calculates the correspondence between the different operating speeds of the magnetorheological polishing module and the ideal instantaneous current by correlating the first instantaneous current data in the first closed loop with the corresponding operating speed of the magnetorheological polishing module. Using this as a reference, when processing the polishing element 5, the computer 3 compares the difference between the second instantaneous current corresponding to the operating speed of the magnetorheological polishing module in the second closed loop of the polishing element 5 and the ideal instantaneous current at that operating speed to determine whether it is within a preset error range. If not, the operating speed of the magnetorheological polishing module is adjusted so that the second instantaneous current is the same as, or within the same preset error range as, the ideal instantaneous current corresponding to the current operating speed of the magnetorheological polishing module. This method, based on the correspondence between the operating speed of the magnetorheological polishing module and the instantaneous current, enables real-time adjustment of the operating speed of the magnetorheological polishing module during the polishing process, thereby realizing automatic compensation for the operating speed of the magnetorheological polishing module.

[0066] When processing the test polishing element 4 using the magnetorheological polishing module, the different operating speeds of the magnetorheological polishing module and the corresponding first instantaneous current are collected. The corresponding relationship between the magnetorheological polishing module's operating speed and the ideal instantaneous current is then calculated using the magnetorheological polishing module's operating speed and the first instantaneous current. This relationship is then used to determine the second instantaneous current. Based on the determination result, it is determined whether to adjust the magnetorheological polishing module's operating speed. This achieves real-time adjustment of the magnetorheological polishing module's operating speed, ensuring that the magnetorheological fluid flow fluctuation at each processing trajectory point meets high-precision polishing requirements and maintains a constant removal function. This process does not require calibration steps for parameters such as gravity compensation and is unaffected by the weight of the magnetorheological polishing module, the operating accuracy, operating speed, posture, inertia, and other factors of the robotic magnetorheological machining equipment. The accuracy of the measured data is only limited by the current measurement accuracy of the second instantaneous current between the magnetorheological polishing module and the element to be polished. This provides more accurate measurement results and eliminates the need for additional equipment such as high-precision force sensors, reducing equipment costs.

[0067] In a second aspect, this embodiment further provides a magnetorheological machining control method based on polishing wheel speed regulation, which is implemented using the above-mentioned magnetorheological machining control system based on instantaneous current sensing. The magnetorheological machining control method includes the following steps:

[0068] The industrial robot drives the magnetorheological polishing module to move until it contacts the surface of the test polishing element. The computer sets different polishing wheel speeds to process the test polishing element. The detection circuit detects the first instantaneous current in the first closed loop in real time to obtain the corresponding relationship between the polishing wheel speed and the first instantaneous current. , Indicates the polishing wheel speed, represents the first instantaneous current, The conversion relationship between the polishing wheel rotation speed and the first instantaneous current is represented, and multiple sets of first instantaneous currents and corresponding polishing wheel rotation speeds are mapped and stored to obtain polishing data. The computer calculates the corresponding relationship between the polishing wheel rotation speed and the ideal instantaneous current based on the polishing data;

[0069] The industrial robot drives the magnetorheological polishing module to move until it contacts the surface of the element to be polished. The detection circuit detects the second instantaneous current in the second closed loop in real time. When the computer determines that the error between the second instantaneous current and the ideal instantaneous current corresponding to the current polishing wheel speed exceeds a preset error range, the polishing wheel speed is adjusted by controlling the drive motor so that the error between the second instantaneous current detected by the detection circuit and the corresponding ideal instantaneous current after the polishing wheel speed is adjusted is within the preset error range.

[0070] In this embodiment, the correspondence between the ideal instantaneous current and the polishing wheel speed must first be obtained. The industrial robot drives the magnetorheological polishing module until it contacts the surface of the test polishing element. The portion where the polishing wheel contacts the test polishing element is recorded as the first processing trajectory point. This first processing trajectory point remains unchanged during the measurement of the same set of polishing data. Optionally, when measuring multiple sets of polishing data, different first processing trajectory points can be selected on the test polishing element to improve the accuracy of the correspondence between the ideal instantaneous current and the polishing wheel speed.

[0071] During the process of the polishing wheel processing the test polishing element, the computer controls the drive motor to set different polishing wheel speeds, collects the first instantaneous current in the first closed loop corresponding to different polishing wheel speeds, maps and stores multiple groups of first instantaneous currents with the corresponding polishing wheel speeds to obtain polishing data, and the computer calculates the corresponding relationship between the polishing wheel speed and the ideal instantaneous current based on the polishing data.

[0072] After obtaining the correspondence between the ideal instantaneous current and the polishing wheel speed, when processing the polishing element, the polishing wheel speed can be adjusted according to this correspondence so that the second instantaneous current corresponding to the current polishing wheel speed and the ideal instantaneous current are within the same preset error range.

[0073] In some embodiments, the correspondence between the polishing wheel speed and the ideal instantaneous current is a function curve relationship, which is characterized by the correspondence between the polishing wheel speed and the first instantaneous current. The correspondence between the polishing wheel speed and the first instantaneous current is obtained by fitting based on multiple discrete values ​​of the polishing wheel speed and the first instantaneous current.

[0074] In this embodiment, a plurality of polishing wheel rotational speeds correspond to a plurality of first instantaneous currents. Both the polishing wheel rotational speeds and the first instantaneous currents are discrete values. Therefore, the discrete values ​​need to be fitted.

[0075] Fitting process: The discrete data is imported into Matlab software, and the data fitting is completed with the help of Matlab software's polyfit fitting command to solve the corresponding relationship between the polishing wheel speed and the current parameters. ; Polyfit fitting command is a basic general command of Matlab software. Finally, the polishing wheel speed is obtained With the first instantaneous current The corresponding relationship between them is:

[0076] .

[0077] This method can more intuitively show the corresponding relationship between the ideal instantaneous current and the polishing wheel speed. Based on this, the components to be polished under the same polishing conditions can be processed and the automatic compensation effect of the polishing wheel speed can be achieved.

[0078] In some embodiments, the sampling period of the detection circuit collecting the second instantaneous current is recorded as , adjust the polishing wheel speed to the maximum adjustment value ∆v max The shortest time required is recorded as , , the shortest switching time between two adjacent machining trajectory points on the component to be polished is recorded as , ;in, The fastest adjustment speed for the polishing wheel speed change. is the maximum moving speed of the industrial robot. Indicates the distance between two adjacent machining track points on the component to be polished;

[0079] The method for adjusting the sampling frequency of the detection circuit includes:

[0080] judge 、 、 Does the relationship between satisfy the formula:

[0081] ;

[0082] If it is not satisfied, the sampling frequency of the detection circuit collecting the second instantaneous current is adjusted until the formula is satisfied. The sampling frequency is .

[0083] In this embodiment, the above formula gives the corresponding relationship between the three time elements, namely: within a single sampling cycle, the industrial robot can adjust the magnetorheological polishing module so that it moves to the polishing wheel speed corresponding to the ideal instantaneous current before performing the next sampling, thereby avoiding the sampling cycle being too long resulting in the sampling frequency being too slow, so that the sampling frequency does not match the adjustment speed of the polishing wheel speed, and the adjustment is not timely, resulting in the inability to know the current state of the second instantaneous current, affecting the automatic compensation function of the polishing wheel speed.

[0084] In some embodiments, if the current polishing wheel speed is Adjust to the second instantaneous current With the current polishing wheel speed When the error of the corresponding ideal instantaneous current is equal to or greater than the upper threshold of the preset error range, the current polishing wheel speed is The corresponding adjustment range is , current polishing wheel speed The corresponding second instantaneous current The value of , represents the ideal instantaneous current value, Indicates the adjustment amplitude of the second instantaneous current;

[0085] If the current polishing wheel speed Adjust to the second instantaneous current With the current polishing wheel speed When the error of the corresponding ideal instantaneous current is equal to or greater than the lower limit threshold of the preset error range, the current polishing wheel speed is The corresponding adjustment range is , current polishing wheel speed The corresponding second instantaneous current The value of ;

[0086] By controlling the driving motor to adjust the polishing wheel speed at the current processing trajectory point Make adjustments, including:

[0087] If the second instantaneous current Does not exceed the allowable variation range When the drive motor is not controlled, the polishing wheel speed at the current processing trajectory point is maintained. constant;

[0088] If the second instantaneous current Exceeding the allowable variation range and When the drive motor is controlled, the polishing wheel speed at the current processing trajectory point is adjusted according to the following formula: To make adjustments:

[0089] ;

[0090] in, represents the ideal instantaneous current value, Indicates the adjustment amplitude of the second instantaneous current;

[0091] If the second instantaneous current Exceeding the allowable variation range and When the drive motor is controlled, the polishing wheel speed at the current processing trajectory point is adjusted according to the following formula: To make adjustments:

[0092] ;

[0093] in, Indicates the set initial speed of the polishing wheel.

[0094] It should be noted that the polishing wheel speed at the current processing trajectory point and the current polishing wheel speed have the same meaning.

[0095] The polishing wheel speed at the current processing trajectory point After adjustment, the polishing wheel speed at the next processing track point is The corresponding second instantaneous current Return to the allowed variation range Within, the polishing gap change requirements of magnetorheological high-precision machining are met.

[0096] When the above technical solution uses the magnetorheological polishing module to process the test polishing element, different polishing wheel speeds and their corresponding first instantaneous currents are collected. The corresponding relationship between the polishing wheel speed and the ideal instantaneous current is then calculated based on the collected polishing wheel speed and the first instantaneous current. The second instantaneous current is then judged based on this relationship. Based on the judgment result, it is decided whether to adjust the polishing wheel speed, thereby achieving real-time adjustment and compensation of the polishing wheel speed, so that the magnetorheological fluid flow fluctuation at each processing trajectory point meets the high-precision polishing requirements and ensures the constancy of the removal function. This process does not require calibration steps for parameters such as gravity compensation, and is not affected by the weight of the magnetorheological processing module of the robotic magnetorheological processing equipment, the equipment's own operating accuracy, operating speed, posture, inertia, and other factors. The accuracy of the measurement data is only limited by the current measurement accuracy of the second instantaneous current between the magnetorheological polishing module and the element to be polished. The measurement results are more accurate, and there is no need to add high-precision force sensors and other equipment, which reduces equipment costs.

[0097] In a third aspect, this embodiment further provides a magnetorheological processing control method based on liquid pump speed regulation, which is implemented using the above-mentioned magnetorheological processing control system based on instantaneous current sensing. The magnetorheological processing control method includes the following steps:

[0098] The industrial robot drives the magnetorheological polishing module to move until it contacts the surface of the test polishing element. The computer sets different liquid pump speeds to process the test polishing element. The detection circuit detects the first instantaneous current in the first closed loop in real time to obtain the corresponding relationship between the liquid pump height and the first instantaneous current. , represents the first instantaneous current, Indicates the liquid pump speed, Indicates the conversion relationship between the liquid pump speed and the first instantaneous current, maps and stores multiple sets of first instantaneous currents and corresponding liquid pump speeds to obtain polishing data, and the computer calculates the corresponding relationship between the liquid pump speed and the ideal instantaneous current based on the polishing data;

[0099] The industrial robot drives the magnetorheological polishing module to move until it contacts the surface of the component to be polished. The detection circuit detects the second instantaneous current in the second closed loop in real time. When the computer determines that the error between the second instantaneous current and the ideal instantaneous current corresponding to the current liquid pump speed exceeds a preset error range, the liquid pump speed is adjusted so that the error between the second instantaneous current detected by the detection circuit and the corresponding ideal instantaneous current after the liquid pump speed is adjusted is within the preset error range.

[0100] In this embodiment, the correspondence between the ideal instantaneous current and the liquid pump speed must first be obtained. The industrial robot drives the magnetorheological polishing module until it contacts the surface of the test polishing element. The portion where the polishing wheel contacts the test polishing element is recorded as the first machining trajectory point. This first machining trajectory point remains unchanged during the measurement of the same set of polishing data. Optionally, when measuring multiple sets of polishing data, different first machining trajectory points can be selected on the test polishing element to improve the accuracy of the correspondence between the ideal instantaneous current and the liquid pump speed.

[0101] During the process of the polishing wheel processing the test polishing element, the computer controls the drive motor to set different liquid pump speeds, collects the first instantaneous current in the first closed loop corresponding to different liquid pump speeds, maps and stores multiple groups of first instantaneous currents with the corresponding liquid pump speeds to obtain polishing data, and the computer calculates the corresponding relationship between the liquid pump speed and the ideal instantaneous current based on the polishing data.

[0102] After obtaining the correspondence between the ideal instantaneous current and the liquid pump speed, when processing the polishing element, the liquid pump speed can be adjusted according to this correspondence so that the second instantaneous current corresponding to the current liquid pump speed is within the same preset error range as the ideal instantaneous current.

[0103] In some embodiments, the correspondence between the liquid pump speed and the ideal instantaneous current is a function curve relationship, which is characterized by the correspondence between the liquid pump speed and the first instantaneous current. The correspondence between the liquid pump speed and the first instantaneous current is obtained by fitting based on multiple discrete values ​​of the liquid pump speed and the first instantaneous current.

[0104] In this embodiment, the liquid pump speed and the first instantaneous current have a one-to-one correspondence, and both the liquid pump speed and the first instantaneous current are discrete values. Therefore, the discrete values ​​need to be fitted.

[0105] Fitting process: The discrete data is imported into Matlab software, and the data fitting is completed with the help of Matlab software's polyfit fitting command to solve the corresponding relationship between the liquid pump speed and current parameters. ;Polyfit fitting command is a basic general command of MATLAB software. Finally, the liquid pump speed is obtained With the first instantaneous current The corresponding relationship between them is:

[0106] .

[0107] This method can more intuitively show the corresponding relationship between the ideal instantaneous current and the liquid pump speed. Based on this, the components to be polished under the same polishing conditions can be processed and the automatic compensation effect of the liquid pump speed can be achieved.

[0108] In some embodiments, the sampling period of the detection circuit collecting the second instantaneous current is recorded as , adjust the liquid pump speed to the maximum adjustment amount The shortest time required is recorded as , , the shortest switching time between two adjacent machining trajectory points on the component to be polished is recorded as , ;in, The fastest adjustment speed for the liquid pump speed change. is the maximum moving speed of the industrial robot. Indicates the distance between two adjacent machining track points on the component to be polished;

[0109] The method for adjusting the sampling frequency of the detection circuit includes:

[0110] judge 、 、 Does the relationship between satisfy the formula:

[0111] ;

[0112] If it is not satisfied, the sampling frequency of the detection circuit collecting the second instantaneous current is adjusted until the formula is satisfied. The sampling frequency is .

[0113] In this embodiment, the above formula gives the corresponding relationship between the three time elements, namely: within a single sampling cycle, the industrial robot can adjust the magnetorheological polishing module so that it moves to the liquid pump speed corresponding to the ideal instantaneous current before performing the next sampling, thereby avoiding the sampling cycle being too long, resulting in the sampling frequency being too slow, so that the sampling frequency does not match the adjustment speed of the liquid pump speed, resulting in untimely adjustment, and the inability to know the current state of the second instantaneous current, affecting the automatic compensation function of the liquid pump speed.

[0114] In some embodiments, if the current liquid pump speed Adjust to the second instantaneous current and current liquid pump speed When the error of the corresponding ideal instantaneous current is equal to or greater than the upper threshold of the preset error range, the current liquid pump speed The corresponding adjustment range is , current liquid pump speed The corresponding second instantaneous current The value of , represents the ideal instantaneous current value, Indicates the adjustment amplitude of the second instantaneous current;

[0115] If the current liquid pump speed Adjust to the second instantaneous current and current liquid pump speed When the error of the corresponding ideal instantaneous current is equal to or greater than the lower limit threshold of the preset error range, the current liquid pump speed The corresponding adjustment range is , current liquid pump speed The corresponding second instantaneous current The value of ;

[0116] Liquid pump speed for the current processing trajectory point Make adjustments, including:

[0117] If the second instantaneous current Does not exceed the allowable variation range When the liquid pump motor is not controlled, the liquid pump speed at the current processing trajectory point is maintained. constant;

[0118] If the second instantaneous current Exceeding the allowable variation range and When the liquid pump speed at the current processing trajectory point is calculated according to the following formula: To make adjustments:

[0119] ;

[0120] in, represents the ideal instantaneous current value, Indicates the adjustment amplitude of the second instantaneous current;

[0121] If the second instantaneous current Exceeding the allowable variation range and When the liquid pump speed at the current processing trajectory point is calculated according to the following formula: To make adjustments:

[0122] ;

[0123] in, Indicates the initially set liquid pump speed.

[0124] It should be noted that the liquid pump speed at the current processing trajectory point and the current liquid pump speed have the same meaning.

[0125] The liquid pump speed at the current processing trajectory point After adjustment, the liquid pump speed at the next processing trajectory point is The corresponding second instantaneous current A i Return to the allowed variation range Within, the polishing gap change requirements of magnetorheological high-precision machining are met.

[0126] The above technical solution uses a magnetorheological polishing module to process a test polishing element. It collects different liquid pump speeds and their corresponding first instantaneous currents. The collected liquid pump speeds and the first instantaneous current are then used to calculate the corresponding relationship between the liquid pump speed and the ideal instantaneous current. This relationship is then used to determine the second instantaneous current. Based on the determination result, it is determined whether to adjust the liquid pump speed, thereby achieving real-time adjustment and compensation of the liquid pump speed. This ensures that the magnetorheological fluid flow fluctuations at each processing trajectory point meet the requirements of high-precision polishing and ensures the constancy of the removal function. This process does not require calibration steps for parameters such as gravity compensation and is not affected by the weight of the magnetorheological machining module of the robotic magnetorheological machining equipment, the equipment's own operating accuracy, operating speed, posture, inertia, and other factors. The accuracy of the measurement data is only limited by the current measurement accuracy of the second instantaneous current between the magnetorheological polishing module and the element to be polished. The measurement results are more accurate, and there is no need to add high-precision force sensors and other equipment, thereby reducing equipment costs.

[0127] It should be understood that the various forms of the processes shown above can be used to reorder, add, or delete steps. For example, the steps described in the present disclosure can be performed in parallel, sequentially, or in a different order, as long as the desired results of the technical solutions disclosed in the present disclosure can be achieved. This is not limited herein.

[0128] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A magnetorheological processing control system based on instantaneous current sensing, characterized in that: include: a polishing platform on which a test polishing element and an element to be polished are arranged; The polishing assembly includes an industrial robot and a magnetorheological polishing module. The industrial robot is used to drive the magnetorheological polishing module to move to the location of the test polishing element or to drive the magnetorheological polishing module to move to the location of the element to be polished. The magnetorheological polishing module includes a polishing wheel, a nozzle, and a liquid pump. The liquid pump is used to supply magnetorheological fluid to the nozzle. The nozzle is used to spray the magnetorheological fluid onto the polishing wheel. The polishing wheel is used to process the test polishing element or the element to be polished. The operating speed of the magnetorheological polishing module is the speed of the liquid pump or the speed of the polishing wheel. a detection circuit configured to output a constant voltage and, when the magnetorheological polishing module contacts the surface of the test polishing element, form a first closed loop and detect a first instantaneous current in the first closed loop in real time, or, when the magnetorheological polishing module contacts the surface of the element to be polished, form a second closed loop and detect a second instantaneous current in the second closed loop in real time; A computer is used to calculate the correspondence between the operating speed of the magnetorheological polishing module and the ideal instantaneous current based on polishing data, the polishing data including first instantaneous current data detected by the detection circuit at different operating speeds of the magnetorheological polishing module; and the computer is used to adjust the current operating speed of the magnetorheological polishing module when it is determined that the error between the second instantaneous current detected by the detection circuit and the ideal instantaneous current corresponding to the current operating speed of the magnetorheological polishing module exceeds a preset error range, so that the error between the second instantaneous current detected by the detection circuit and the ideal instantaneous current corresponding to the current operating speed after the operating speed of the magnetorheological polishing module is adjusted is within the preset error range.

2. The magnetorheological processing control system based on instantaneous current sensing according to claim 1 is characterized in that: The magnetorheological polishing module also includes a magnetorheological mounting frame, a magnet, a driving wheel, a driven wheel, a synchronous belt and a drive motor; wherein, the magnetorheological mounting frame is connected to the industrial robot, the magnet, the drive motor and the polishing wheel are respectively arranged on the magnetorheological mounting frame, a bearing seat is installed on the magnetorheological mounting frame, a bearing is installed in the bearing seat, the bearing is connected to the polishing wheel, the driven wheel is mounted on the bearing, the driving wheel is mounted on the output end of the drive motor, and the synchronous belt is tensioned on the driven wheel and the driving wheel.

3. A magnetorheological machining control method based on polishing wheel speed regulation, implemented using the magnetorheological machining control system based on instantaneous current sensing according to claim 2, characterized in that: The magnetorheological processing control method comprises the following steps: The industrial robot drives the magnetorheological polishing module to move until it contacts the surface of the test polishing element. The computer sets different polishing wheel speeds to process the test polishing element. The detection circuit detects the first instantaneous current in the first closed loop in real time to obtain the corresponding relationship between the polishing wheel speed and the first instantaneous current. , Indicates the polishing wheel speed, represents the first instantaneous current, The conversion relationship between the polishing wheel rotation speed and the first instantaneous current is represented, and multiple sets of the first instantaneous current and the corresponding polishing wheel rotation speed are mapped and stored to obtain polishing data. The computer calculates the corresponding relationship between the polishing wheel rotation speed and the ideal instantaneous current based on the polishing data; The industrial robot drives the magnetorheological polishing module to move until it contacts the surface of the element to be polished. The detection circuit detects the second instantaneous current in the second closed loop in real time. When the computer determines that the error between the second instantaneous current and the ideal instantaneous current corresponding to the current polishing wheel speed exceeds a preset error range, the polishing wheel speed is adjusted by controlling the drive motor so that the error between the second instantaneous current detected by the detection circuit and the corresponding ideal instantaneous current after the polishing wheel speed is adjusted is within the preset error range.

4. The magnetorheological machining control method based on polishing wheel speed regulation according to claim 3, characterized in that: The sampling period of the detection circuit collecting the second instantaneous current is recorded as , adjust the polishing wheel speed to the maximum adjustment value ∆v max The shortest time required is recorded as , , the shortest switching time between two adjacent machining trajectory points on the component to be polished is recorded as , ;in, The fastest adjustment speed for the polishing wheel speed change. is the maximum moving speed of the industrial robot. Indicates the distance between two adjacent machining track points on the component to be polished; The method for adjusting the sampling frequency of the detection circuit includes: judge 、 、 Does the relationship between satisfy the formula: ； If it is not satisfied, the sampling frequency of the detection circuit collecting the second instantaneous current is adjusted until the formula is satisfied. The sampling frequency is .

5. The magnetorheological machining control method based on polishing wheel speed regulation according to claim 4, characterized in that: By controlling the driving motor to adjust the polishing wheel speed at the current processing trajectory point Make adjustments, including: If the second instantaneous current Does not exceed the allowable variation range When the drive motor is not controlled, the polishing wheel speed at the current processing trajectory point is maintained. constant; If the second instantaneous current Exceeding the allowable variation range and When the drive motor is controlled, the polishing wheel speed at the current processing trajectory point is adjusted according to the following formula: To make adjustments: ； in, represents the ideal instantaneous current value, Indicates the adjustment amplitude of the second instantaneous current; If the second instantaneous current Exceeding the allowable variation range and When the drive motor is controlled, the polishing wheel speed at the current processing trajectory point is adjusted according to the following formula: To make adjustments: ； in, Indicates the set initial speed of the polishing wheel.

6. A magnetorheological processing control method based on liquid pump speed regulation, implemented using the magnetorheological processing control system based on instantaneous current sensing according to claim 1, characterized in that: The magnetorheological processing control method comprises the following steps: The industrial robot drives the magnetorheological polishing module to move until it contacts the surface of the test polishing element. The computer sets different liquid pump speeds to process the test polishing element. The detection circuit detects the first instantaneous current in the first closed loop in real time to obtain the corresponding relationship between the liquid pump speed and the first instantaneous current. , represents the first instantaneous current, Indicates the liquid pump speed, Indicates the conversion relationship between the liquid pump speed and the first instantaneous current, maps and stores multiple sets of first instantaneous currents and corresponding liquid pump speeds to obtain polishing data, and the computer calculates the corresponding relationship between the liquid pump speed and the ideal instantaneous current based on the polishing data; The industrial robot drives the magnetorheological polishing module to move until it contacts the surface of the component to be polished. The detection circuit detects the second instantaneous current in the second closed loop in real time. When the computer determines that the error between the second instantaneous current and the ideal instantaneous current corresponding to the current liquid pump speed exceeds a preset error range, the liquid pump speed is adjusted so that the error between the second instantaneous current detected by the detection circuit and the corresponding ideal instantaneous current after the liquid pump speed is adjusted is within the preset error range.

7. The magnetorheological processing control method based on liquid pump speed regulation according to claim 6 is characterized in that: The sampling period of the detection circuit collecting the second instantaneous current is recorded as , adjust the liquid pump speed to the maximum adjustment amount The shortest time required is recorded as , , the shortest switching time between two adjacent machining trajectory points on the component to be polished is recorded as , ;in, The fastest adjustment speed for the liquid pump speed change. is the maximum moving speed of the industrial robot. Indicates the distance between two adjacent machining track points on the component to be polished; The method for adjusting the sampling frequency of the detection circuit includes: judge 、 、 Does the relationship between satisfy the formula: ； If it is not satisfied, the sampling frequency of the detection circuit collecting the second instantaneous current is adjusted until the formula is satisfied. The sampling frequency is .

8. The magnetorheological processing control method based on liquid pump speed regulation according to claim 7 is characterized in that: Liquid pump speed for the current processing trajectory point Make adjustments, including: If the second instantaneous current Does not exceed the allowable variation range When the liquid pump motor is not controlled, the liquid pump speed at the current processing trajectory point is maintained. constant; If the second instantaneous current Exceeding the allowable variation range and When the liquid pump speed at the current processing trajectory point is calculated according to the following formula: To make adjustments: ； in, represents the ideal instantaneous current value, Indicates the adjustment amplitude of the second instantaneous current; If the second instantaneous current Exceeding the allowable variation range and When the liquid pump speed at the current processing trajectory point is calculated according to the following formula: To make adjustments: ； in, Indicates the initially set liquid pump speed.

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