Predefined time preset robust force control method for pneumatic grinding device

Abstract

The application discloses a predefined time preset performance robust force control method of a pneumatic grinding device, which comprises the following steps: determining an expected force signal based on the correlation between a first force and a second force; taking the expected force signal as the input of a rate-dependent inverse hysteresis model to obtain an expected air pressure of the rate-dependent inverse hysteresis model output; constructing a practical predefined time controller based on the expected air pressure and a practical predefined time disturbance observer; and controlling the opening degree of a proportional pressure regulating valve by using the practical predefined time controller so that the first force meets the expected value of the first force. The method can still achieve satisfactory force control accuracy when the frequency of the expected force signal changes, can accurately observe external disturbances within a specified time, improve the robustness of force control, and can make the air pressure tracking error converge to a specified progress within a specified time, thereby improving the control accuracy and response speed of force control.

Description

TECHNICAL FIELD

[0001] The application relates to the field of force control of grinding robots, and in particular to a predefined time preset performance robust force control method for a pneumatic grinding device. BACKGROUND

[0002] Grinding and polishing is an indispensable part of manufacturing. With the development and progress of science and technology, the demand for high-precision grinding is increasing in high-precision fields such as automobiles, ships and aerospace. Contact force control in the grinding process is the key to achieving high-precision grinding. Since grinding and polishing is a material removal process, in order to prevent irreversible damage to the workpiece surface, the grinding device needs to have good compliance. The grinding device driven by a double-acting cylinder has been widely used in the grinding field due to its good compliance. However, the hysteresis nonlinearity between the air pressure and the contact force in the device poses a great challenge to the contact force control.

[0003] Early control schemes install a force sensor at the end of the grinding device to measure the contact force on the end of the grinding device in real time, and feed the force sensor value back to the controller to achieve closed-loop control of the force. However, in this control scheme, the output force of the grinding device needs to be taken as the controlled variable when modeling the dynamics of the system, and the high-order dynamics model established makes it difficult to design and implement the control algorithm.

[0004] The prior art research adopts a "planning + control" scheme to achieve good results for the force control of the grinding device driven by a double-acting cylinder, and does not require the installation of a force sensor during grinding, thereby reducing the hardware cost. Specifically, a non-rate-dependent hysteresis model is first used to accurately fit the hysteresis nonlinearity between the air pressure and the force as much as possible, and an inverse model of the hysteresis model is constructed. Then, the expected air pressure is planned from the inverse model according to the expected contact force, and finally the expected air pressure planned is taken as the controlled variable. However, the hysteresis nonlinearity is usually rate-dependent, and when the frequency of the expected force signal changes, the non-rate-dependent hysteresis model cannot accurately fit the hysteresis nonlinearity, which inevitably leads to deterioration of the force control accuracy. Moreover, the existing research scheme cannot achieve preset tracking performance control of the air pressure, nor can it make all signals in the closed-loop system converge to a small neighborhood of the origin within a preset time. SUMMARY

[0005] The application provides a predefined time preset performance robust force control method for a pneumatic grinding device, aiming to achieve fast and high-precision robust force control of the pneumatic grinding device.

[0006] To achieve the above-mentioned purpose, the application provides the following technical solutions:

[0007] A predefined time preset performance robust force control method of a pneumatic grinding device, comprising:

[0008] determining an expected force signal based on a correlation between a first force and a second force;

[0009] obtaining an expected air pressure based on the expected force signal as an input of a rate-dependent inverse hysteresis model, the rate-dependent inverse hysteresis model being used to compensate for a nonlinear and asymmetric hysteresis characteristic between the expected air pressure and the expected force signal;

[0010] constructing a practical predefined time controller based on the expected air pressure and a practical predefined time disturbance observer, the practical predefined time disturbance observer being used to control a disturbance observation error to converge to a specified interval within a first specified time, and the practical predefined time controller being used to control an air pressure tracking error to converge to the specified interval within a second specified time, the air pressure tracking error representing a difference between the expected air pressure and an actual air pressure, and the actual air pressure representing an inlet air pressure of a double-acting cylinder in the pneumatic grinding device;

[0011] controlling an opening degree of a proportional pressure regulating valve by using the practical predefined time controller, so that the first force meets an expected value of the first force, the proportional pressure regulating valve being used to control the inlet air pressure in response to a control signal input by the practical predefined time controller, to adjust an output force of the pneumatic grinding device.

[0012] Optionally, determining an expected force signal based on a correlation between a first force and a second force, comprises:

[0013] obtaining the correlation between the first force and the second force based on a dynamic model of the pneumatic grinding device, the first force representing a contact force between a tool head of the pneumatic grinding device and a workpiece, and the second force representing a sum of an output force of the pneumatic grinding device and a friction force on a surface of the workpiece;

[0014] determining an expected force corresponding to an expected value of the first force based on the correlation;

[0015] determining the expected force signal based on the expected force.

[0016] Optionally, the rate-dependent inverse hysteresis model comprises a multi-stage multiplication structure, the multi-stage multiplication structure comprising a rate-dependent play operator, a dead zone operator and a high-order polynomial, wherein the rate-dependent play operator is used to describe a rate-dependent nonlinear hysteresis characteristic between the expected air pressure and the expected force signal, and the dead zone operator and the high-order polynomial are both used to describe an asymmetric hysteresis characteristic between the expected air pressure and the expected force signal.

[0017] Optionally, in the multi-stage multiplication structure, the rate-dependent play operator and the dead-zone operator form a series structure, and the high-order polynomial and the series structure form a parallel structure.

[0018] A predefined time preset performance robust force control device of a pneumatic grinding device, comprising:

[0019] A signal determination unit is configured to determine an expected force signal based on a correlation between a first force and a second force;

[0020] A gas pressure planning unit is configured to obtain an expected gas pressure output by a rate-dependent inverse hysteresis model based on the expected force signal as an input of the rate-dependent inverse hysteresis model; the rate-dependent inverse hysteresis model is used to compensate for a nonlinear and asymmetric hysteresis characteristic between the expected gas pressure and the expected force signal;

[0021] A controller configuration unit is configured to configure a practical predefined time controller based on the expected gas pressure in combination with a practical predefined time disturbance observer; the practical predefined time disturbance observer is used to control a disturbance observation error to converge to a specified interval within a first specified time; the practical predefined time controller is used to control a gas pressure tracking error to converge to the specified interval within a second specified time; the gas pressure tracking error represents a difference between the expected gas pressure and an actual gas pressure; the actual gas pressure represents an inlet pressure of a double-acting cylinder in the pneumatic grinding device;

[0022] An opening degree control unit is configured to control an opening degree of a proportional pressure regulating valve by using the practical predefined time controller, so that the first force meets an expected value of the first force; the proportional pressure regulating valve is used to control the inlet pressure in response to a control signal input by the practical predefined time controller, so as to adjust an output force of the pneumatic grinding device.

[0023] Optionally, the signal determination unit is specifically configured to:

[0024] obtain a correlation between a first force and a second force based on a dynamics model of the pneumatic grinding device; the first force represents a contact force between a tool head of the pneumatic grinding device and a workpiece; the second force represents a sum of an output force of the pneumatic grinding device and a friction force on a surface of the workpiece;

[0025] determine an expected force corresponding to an expected value of the first force based on the correlation;

[0026] determine the expected force signal based on the expected force.

[0027] Optionally, the rate-dependent inverse hysteresis model adopted by the air pressure planning unit comprises a multi-stage multiplication structure, the multi-stage multiplication structure comprising a rate-dependent play operator, a dead-zone operator and a high-order polynomial; wherein the rate-dependent play operator is used to describe the rate-dependent nonlinear hysteresis characteristic between the expected air pressure and the expected force signal; the dead-zone operator and the high-order polynomial are both used to describe the asymmetric hysteresis characteristic between the expected air pressure and the expected force signal.

[0028] Optionally, in the multi-stage multiplication structure, the rate-dependent play operator and the dead-zone operator form a series structure, and the high-order polynomial and the series structure form a parallel structure.

[0029] A storage medium comprising a stored program, wherein the program, when executed by a processor, performs the predefined time preset performance robust force control method of the pneumatic grinding device.

[0030] A pneumatic grinding device comprising a processor, a memory and a bus; the processor is connected with the memory through the bus;

[0031] The memory is used to store a program, and the processor is used to run the program, wherein the program, when executed by the processor, performs the predefined time preset performance robust force control method of the pneumatic grinding device.

[0032] The technical scheme provided in the application determines the expected force signal based on the correlation between the first force and the second force. The expected force signal is used as the input of the rate-dependent inverse hysteresis model to obtain the expected air pressure output by the rate-dependent inverse hysteresis model. Based on the expected air pressure, a practical predefined time disturbance observer is combined to construct a practical predefined time controller. The opening of the proportional pressure regulating valve is controlled by the practical predefined time controller to make the first force meet the expected value of the first force. The application can still achieve satisfactory force control accuracy when the frequency of the expected force signal changes, can accurately observe external disturbances within a specified time, improve the robustness of force control, and can make the air pressure tracking error converge to a specified progress within a specified time, improve the control accuracy and response speed of force control. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiment or prior art description. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other drawings can also be obtained without creative labor based on these drawings.

[0034] Figure 1A flowchart of a predefined time preset performance robust force control method of a pneumatic grinding device provided by an embodiment of the present application is shown in the figure;

[0035] Figure 2 A flowchart of another predefined time preset performance robust force control method of a pneumatic grinding device provided by an embodiment of the present application is shown in the figure;

[0036] Figure 3 A force analysis diagram of a pneumatic grinding device provided by an embodiment of the present application is shown in the figure;

[0037] Figure 4 A schematic diagram of a multi-stage multiplication structure provided by an embodiment of the present application is shown in the figure;

[0038] Figure 5 A logical architecture diagram of a "planning + control" provided by an embodiment of the present application is shown in the figure;

[0039] Figure 6 An architecture diagram of a predefined time preset performance robust force control device of a pneumatic grinding device provided by an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0040] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only some of the embodiments of the present application, but not all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the scope of protection of the present application.

[0041] In the present application, the relationship terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between the entities or operations, the term "comprising", "including" or any other variant thereof is intended to cover non-exclusive inclusion, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed or inherent to such process, method, article or device. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of another identical element in the process, method, article or device including the element.

[0042] The existing force control method of the grinding equipment driven by the double-acting cylinder shown in the background art has the following disadvantages: (1) in the "planning part", the existing technology is based on a non-rate-dependent hysteresis model, when the frequency of the desired force signal changes, the force control accuracy of the existing technology will deteriorate; (2) in terms of disturbance rejection effect in the "control" part, the observation error of the disturbance of the existing technology is often uniformly ultimately bounded or asymptotically stable, and cannot accurately observe the external disturbance within a human-specified time; (3) in terms of tracking effect in the "control" part, a practical predefined time controller based on preset performance design can make the air pressure tracking error converge to a human-specified accuracy within a human-specified time.

[0043] In summary, the embodiment of the present application provides a predefined time preset performance robust force control method for a pneumatic grinding equipment, which is used to solve the following technical problems: (1) unable to compensate the rate-dependent hysteresis nonlinearity between air pressure (i.e. intake pressure of double-acting cylinder) and contact force; (2) unable to effectively observe and compensate external disturbance within a specified time; (3) unable to make air pressure tracking error converge within a specified accuracy within a human-specified time.

[0044] As Figure 1 shown, a flowchart of a predefined time preset performance robust force control method for a pneumatic grinding equipment provided by the embodiment of the present application is shown, which includes the following steps.

[0045] S101: determining a desired force signal based on the correlation between the first force and the second force.

[0046] The correlation between the first force and the second force can be determined based on the mechanical analysis of the pneumatic grinding equipment when grinding the workpiece.

[0047] Optionally, the implementation process of determining the desired force signal based on the correlation between the first force and the second force can be referred to the steps shown in Figure 2 and the corresponding explanation.

[0048] S102: obtaining a desired air pressure based on the desired force signal as the input of the rate-dependent inverse hysteresis model.

[0049] The rate-dependent inverse hysteresis model is used to compensate the nonlinear and asymmetric hysteresis characteristics between the desired air pressure and the desired force signal.

[0050] Optionally, the rate-dependent inverse hysteresis model comprises a multi-stage multiplication structure, the multi-stage multiplication structure comprises a rate-dependent play operator, a dead-zone operator and a high-order polynomial, wherein the rate-dependent play operator is used to describe a rate-dependent nonlinear hysteresis characteristic between the desired air pressure and the desired force signal, and the dead-zone operator and the high-order polynomial are used to describe an asymmetric hysteresis characteristic between the desired air pressure and the desired force signal.

[0051] Optionally, in the multi-stage multiplication structure, the rate-dependent play operator and the dead-zone operator form a series structure, and the high-order polynomial and the series structure form a parallel structure.

[0052] In some examples, the multi-stage multiplication structure can refer to Figure 4 In the architecture shown in Figure 4 In the architecture shown in is a design parameter.

[0053] In some examples, the expression of the rate-dependent inverse hysteresis model can refer to formula (5) shown.

[0054] (5)

[0055] In formula (5), is a high-order polynomial, is a weight, , is a dead-zone operator and is defined as formula (6).

[0056] (6)

[0057] In formula (6), is a threshold of the dead-zone operator, is a constant, wherein, is a rate-dependent play operator and is defined as formula (7).

[0058] (7)

[0059] In formula (7), is a threshold of the rate-dependent play operator, , and are all constants.

[0060] It can be understood that through the rate-dependent inverse hysteresis model shown in formula (5), in the “planning” part, when the frequency of the desired force signal changes, satisfactory force control accuracy can still be achieved.

[0061] S103: Based on the desired air pressure, a practical predefined time controller is constructed in combination with a practical predefined time disturbance observer.

[0062] Among them, the practical predefined time disturbance observer is used to control the disturbance observation error to converge to the specified interval within the first specified time, and the practical predefined time controller is used to control the air pressure tracking error to converge to the specified interval within the second specified time. The air pressure tracking error represents the difference between the expected air pressure and the actual air pressure, and the actual air pressure represents the intake pressure of the double-acting cylinder in the pneumatic grinding equipment.

[0063] In some examples, the expression for a practical predefined time perturbation observer can be found in Equation (8).

[0064] (8)

[0065] In formula (8), , , , , , , , , , , , , , , All of these can be considered as design parameters.

[0066] It should be noted that, based on the practical predefined time perturbation observer shown in formula (8), the perturbation observation error can be minimized. The small neighborhood (i.e., the specified interval) that converges to the origin within the specified time (i.e., the first specified time). It can be configured by technicians according to the actual situation.

[0067] It is understandable that, through the practical predefined time disturbance observer shown in formula (8), accurate observation of external disturbances can be achieved within a manually specified time in terms of the disturbance rejection effect of the "control" part.

[0068] In some examples, the expression for a practical predefined time controller can be found in formula (9).

[0069] (9)

[0070] In formula (9), , , , , , , , , , , , , , , , , , , , , may be regarded as design parameters, and The expression of (10) can also refer to formula (10).

[0071] (10)

[0072] In formula (10), , Further, let The designed practical pre-defined time controller can make the air pressure tracking error Converge to a small neighborhood of the origin (i.e. the specified interval) within Time (i.e. the second specified time), and when The air pressure tracking error Can always be constrained within the specified precision .

[0073] It can be understood that the practical pre-defined time controller shown in formula (9) can realize the convergence of the air pressure tracking error to the human-specified precision within the human-specified time in terms of the tracking effect of the "control" part.

[0074] S104: Use the practical pre-defined time controller to control the opening of the proportional pressure regulating valve, so that the first acting force meets the expected value of the first acting force.

[0075] Wherein, the proportional pressure regulating valve is used to respond to the control signal input by the practical pre-defined time controller, control the inlet air pressure, and adjust the output force of the aerodynamic grinding equipment. It can be understood that by adjusting the output force of the aerodynamic grinding equipment, the first acting force will also change indirectly, so that the first acting force meets the expected value of the first acting force.

[0076] In some examples, the expected value of the first acting force is an empirical value formulated by humans in the grinding process to meet the best grinding effect.

[0077] In some examples, after obtaining the expected force signal, the expected force signal is taken as an input of a rate-dependent inverse hysteresis model, an expected air pressure is planned, and a practical predefined time controller is constructed based on the expected air pressure, a practical predefined time disturbance observer, and a preset performance technique in a control part, and then the practical predefined time controller acts on the proportional pressure regulating valve to realize control of the intake air pressure.

[0078] In possible embodiments, the "planning + control" logical architecture shown in the embodiments of the present application can be seen from Figure 5 .

[0079] The processes shown in S101-S104 can use the rate-dependent inverse hysteresis model to enable the control method to still achieve satisfactory force control accuracy when the frequency of the expected force signal changes, use the practical predefined time disturbance observer to enable accurate observation of external disturbances within a human-specified time, improve the robustness of force control, and use the practical predefined time controller to enable the air pressure tracking error to converge to a specified accuracy within a human-specified time, improve the control accuracy and response speed of force control.

[0080] As Figure 2 shown, another flowchart of a predefined time preset performance robust force control method of a pneumatic grinding device provided by the embodiments of the present application is shown, which includes the following steps.

[0081] S201: Obtain a correlation between a first force and a second force based on a dynamic model of the pneumatic grinding device.

[0082] The first force represents the contact force between the tool head and the workpiece of the pneumatic grinding device, and the second force represents the sum of the output force of the pneumatic grinding device and the friction force on the workpiece surface.

[0083] In some examples, when the pneumatic grinding device grinds the workpiece, the force condition of the pneumatic grinding device can be seen from Figure 3 shown. In Figure 3 the scenario shown, represents the contact force, represents the output force of the pneumatic grinding device, represents the friction force, and both represent the mass of the tool head component, represents the angle between the contact force and the gravity, represents the intake air pressure (which can be understood as the air cylinder pressure), represents the exhaust air pressure (which can be understood as the air cylinder exhaust pressure), represents the displacement amount of the air cylinder piston.

[0084] In possible implementations, based on the force condition of the pneumatic grinding device, the proportional pressure regulating valve can be modeled as formula (1) using a second-order transfer function.

[0085] (1)

[0086] In formula (1), is a transfer function, is a system output (i.e., an inlet pressure), is a system input, is a complex variable in frequency, , and are design parameters. The design parameters can be understood as a series of design requirements and technical parameters specified according to the purpose and performance index of the pneumatic grinding device in the production process of the pneumatic grinding device.

[0087] Further, in the case of considering external disturbance , in combination with formula (1) and Figure 3 the scenario shown in formula (2), the dynamics of the pneumatic grinding device is modeled as formula (2).

[0088] (2)

[0089] In some examples, let , , formula (2) can be converted to formula (3).

[0090] (3)

[0091] In formula (3), . Further, based on formula (2) and formula (3), the dynamics model of the pneumatic grinding device can be determined, and according to the dynamics model, the relationship between the first force and the second force can be obtained.

[0092] S202: Based on the relationship, determine the expected force corresponding to the expected value of the first force.

[0093] Wherein, after obtaining the relationship between the first force and the second force, the planning formula of the expected force can be determined based on the relationship, which can be seen from formula (4).

[0094] (4)

[0095] In formula (4), represents the expected force, represents the expected value of the first force (which can be understood as the expected value of the contact force).

[0096] S203: determining a desired force signal based on the desired force.

[0097] wherein the desired force calculated by formula (4) is determined as the desired force signal, which is obviously rate-dependent, and the so-called rate-dependence can be understood as that the frequency of the desired force signal is not a certain fixed frequency, but changes with the change of the scene or the application range.

[0098] The above-mentioned processes of S201-S203 can obtain the rate-dependent desired force signal through the dynamics model of the pneumatic grinding device, and provide an effective input signal for subsequent development of the "planning" related hysteresis model.

[0099] As Figure 6 shown, the architecture schematic diagram of the predefined time preset performance robust force control device of the pneumatic grinding device provided by the embodiment of the present application includes the following modules.

[0100] The signal determination unit 100 is configured to determine the desired force signal based on the correlation between the first force and the second force.

[0101] Optionally, the signal determination unit 100 is specifically configured to: obtain the correlation between the first force and the second force based on the dynamics model of the pneumatic grinding device; the first force represents the contact force between the tool head of the pneumatic grinding device and the workpiece; the second force represents the sum of the output force of the pneumatic grinding device and the friction force on the surface of the workpiece; determine the desired force corresponding to the desired value of the first force based on the correlation; and determine the desired force signal based on the desired force.

[0102] The air pressure planning unit 200 is configured to take the desired force signal as the input of the rate-dependent inverse hysteresis model to obtain the desired air pressure output by the rate-dependent inverse hysteresis model; and the rate-dependent inverse hysteresis model is used to compensate the nonlinear and asymmetric hysteresis characteristics between the desired air pressure and the desired force signal.

[0103] Optionally, the rate-dependent inverse hysteresis model used by the air pressure planning unit 200 includes a multi-stage multiplication structure, and the multi-stage multiplication structure includes a rate-dependent play operator, a dead zone operator and a high-order polynomial; wherein the rate-dependent play operator is used to describe the rate-dependent nonlinear hysteresis characteristics between the desired air pressure and the desired force signal; and the dead zone operator and the high-order polynomial are both used to describe the asymmetric hysteresis characteristics between the desired air pressure and the desired force signal.

[0104] Optionally, in the multi-stage multiplication structure, the rate-dependent play operator and the dead zone operator form a series structure, and the high-order polynomial and the series structure form a parallel structure.

[0105] The controller configuration unit 300 is configured to configure a practical pre-defined time controller based on the desired air pressure and in combination with a practical pre-defined time disturbance observer, the practical pre-defined time disturbance observer being configured to control a disturbance observation error to converge to a specified interval within a first specified time, and the practical pre-defined time controller being configured to control an air pressure tracking error to converge to a specified interval within a second specified time, the air pressure tracking error representing a difference between the desired air pressure and an actual air pressure, and the actual air pressure representing an intake pressure of a double-acting cylinder in the pneumatic grinding device.

[0106] The opening degree control unit 400 is configured to control an opening degree of a proportional pressure regulating valve by using the practical pre-defined time controller, so that the first acting force meets a desired value of the first acting force, and the proportional pressure regulating valve is configured to control the intake pressure in response to a control signal input by the practical pre-defined time controller, so as to adjust an output force of the pneumatic grinding device.

[0107] The above-mentioned various modules can achieve satisfactory force control precision when a frequency of the desired force signal changes by using the rate-dependent inverse hysteresis model, can accurately observe external disturbances within a human-specified time by using the practical pre-defined time disturbance observer, and can make the air pressure tracking error converge to a specified progress within a human-specified time by using the practical pre-defined time controller, thereby improving robustness of force control and improving control precision and response speed of force control.

[0108] The application further provides a computer-readable storage medium, which comprises a stored program, wherein the program executes the pre-defined time preset performance robust force control method of the pneumatic grinding device provided in the application.

[0109] The application further provides a pneumatic grinding device, which comprises a processor, a memory and a bus. The processor is connected to the memory through the bus, the memory is configured to store a program, and the processor is configured to run the program, wherein the program executes the pre-defined time preset performance robust force control method of the pneumatic grinding device provided in the application when running.

[0110] In addition, the functions described above in the embodiments of the application can be performed at least in part by one or more hardware logic components. For example, non-limiting examples of exemplary types of hardware logic components that can be used include field programmable gate arrays (FPGAs), application specific integrated circuits (ASICs), application specific standard products (ASSPs), system on a chip (SOCs), complex programmable logic devices (CPLDs), and so on.

[0111] While several inventive embodiments have been described above, it should be appreciated that many modifications can be made of these embodiments in light of the above disclosure. Therefore, the disclosed embodiments are not intended to limit the scope of the application to the particular embodiments disclosed herein but can be practiced with modifications and changes by those having ordinary skill in the art without departing from the scope of the following claims.

[0112] The above description is merely illustrative of the application and the application should not be limited to the specific embodiments that have been described, which are to be regarded as illustrative rather than restrictive. Variations and modifications and other implementations can be possible. The order or sequence of any process or method can be different from that as described. Various "steps" as recited in the process or method claims can be carried out simultaneously or in another order than as described. Such variation and modifications are considered as possible embodiments of the present application. For example, substitutions of equivalent form or function can be made, which changes can occur within the same "class", "family", "type", or "kind" of elements.

Claims

1. A robust force control method for a predefined time preset performance of a pneumatic grinding device, characterized in that, The method comprises the following steps: determining an expected force signal based on a correlation between a first force and a second force; wherein the determination of the expected force signal comprises: obtaining the correlation between the first force and the second force based on a dynamic model of the aerodynamic grinding device; the first force represents a contact force between a tool head of the aerodynamic grinding device and a workpiece; the second force represents a sum of an output force of the aerodynamic grinding device and a friction force on a surface of the workpiece; determining an expected force corresponding to an expected value of the first force based on the correlation; and determining the expected force signal based on the expected force; using the expected force signal as an input of a rate-dependent inverse hysteresis model to obtain an expected air pressure output by the rate-dependent inverse hysteresis model; the rate-dependent inverse hysteresis model is used to compensate for a nonlinear and asymmetric hysteresis characteristic between the expected air pressure and the expected force signal; constructing a practical predefined time controller based on the expected air pressure and a practical predefined time disturbance observer; the practical predefined time disturbance observer is used to control a disturbance observation error to converge to a specified interval within a first specified time; the practical predefined time controller is used to control an air pressure tracking error to converge to the specified interval within a second specified time; the air pressure tracking error represents a difference between the expected air pressure and an actual air pressure; the actual air pressure represents an inlet air pressure of a double-acting pneumatic cylinder in the aerodynamic grinding device; controlling an opening degree of a proportional pressure regulating valve by using the practical predefined time controller, so that the first force meets the expected value of the first force; the proportional pressure regulating valve is used to control the inlet air pressure in response to a control signal input by the practical predefined time controller, so as to adjust the output force of the aerodynamic grinding device.

2. The method of claim 1, wherein, The rate-dependent inverse hysteresis model comprises a multi-stage multiplication structure, the multi-stage multiplication structure comprises a rate-dependent play operator, a dead zone operator and a high-order polynomial; wherein the rate-dependent play operator is used to describe a rate-dependent nonlinear hysteresis characteristic between the expected air pressure and the expected force signal; the dead zone operator and the high-order polynomial are both used to describe an asymmetric hysteresis characteristic between the expected air pressure and the expected force signal.

3. The method of claim 2, wherein, In the multi-stage multiplication structure, the rate-dependent play operator and the dead zone operator form a series structure, and the high-order polynomial and the series structure form a parallel structure.

4. A robust force control device for a predefined time preset performance of a pneumatic grinding apparatus, characterized by The method comprises the following steps: a signal determination unit is configured to determine an expected force signal based on a correlation between a first force and a second force; wherein the signal determination unit is specifically configured to determine the expected force signal in the following manner: obtaining the correlation between the first force and the second force based on a dynamic model of the aerodynamic grinding device; the first force represents a contact force between a tool head of the aerodynamic grinding device and a workpiece; the second force represents a sum of an output force of the aerodynamic grinding device and a friction force on a surface of the workpiece; determining an expected force corresponding to an expected value of the first force based on the correlation; and determining the expected force signal based on the expected force; a pressure planning unit configured to obtain a desired pressure based on the desired force signal as an input of a rate-dependent inverse hysteresis model, the rate-dependent inverse hysteresis model configured to compensate for a nonlinear and asymmetric hysteresis characteristic between the desired pressure and the desired force signal; a controller configuration unit configured to configure a practical pre-defined time controller based on the desired pressure in combination with a practical pre-defined time disturbance observer, the practical pre-defined time disturbance observer configured to control a disturbance observation error to converge to a specified interval within a first specified time, the practical pre-defined time controller configured to control a pressure tracking error to converge to the specified interval within a second specified time, the pressure tracking error representing a difference between the desired pressure and an actual pressure, the actual pressure representing an inlet pressure of a double-acting cylinder in a pneumatic grinding device; an opening control unit configured to control an opening of a proportional pressure regulating valve using the practical pre-defined time controller, such that the first force meets a desired value of the first force, the proportional pressure regulating valve configured to control the inlet pressure in response to a control signal input by the practical pre-defined time controller, to adjust an output force of the pneumatic grinding device.

5. The apparatus of claim 4, wherein, The rate-dependent inverse hysteresis model used by the pressure planning unit includes a multi-stage multiplication structure, the multi-stage multiplication structure including a rate-dependent play operator, a dead-zone operator, and a high-order polynomial, wherein the rate-dependent play operator is configured to describe a rate-dependent nonlinear hysteresis characteristic between the desired pressure and the desired force signal, the dead-zone operator and the high-order polynomial are both configured to describe an asymmetric hysteresis characteristic between the desired pressure and the desired force signal.

6. The apparatus of claim 5, wherein, In the multi-stage multiplication structure, the rate-dependent play operator and the dead-zone operator form a series structure, and the high-order polynomial and the series structure form a parallel structure.

7. A storage medium, characterized by The storage medium includes a stored program, wherein the program is executed by the processor to perform the pre-defined time pre-set performance robust force control method of the pneumatic grinding device according to any one of claims 1-3.

8. A pneumatic grinding device, characterized in that comprising: a processor, a memory, and a bus; the processor and the memory are connected through the bus; the memory is configured to store a program, and the processor is configured to run the program, wherein the program is executed by the processor to perform the pre-defined time pre-set performance robust force control method of the pneumatic grinding device according to any one of claims 1-3.

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