Method and system for identifying rotational inertia and friction torque
By establishing a kinematic model of the controlled object and analyzing the mechanical characteristic parameters of the characteristic points, the uncertainty problems of the moment of inertia and friction torque in the early stage of control system design are solved, and the adaptive ability of the system is improved.
Patent Information
- Application Number
- CN202510803068.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-16
- Publication Date
- 2025-09-26
AI Technical Summary
In the early stages of control system design, the uncertainty of the moment of inertia and friction torque in existing technologies leads to differences between the mathematical model and the actual product, which affects the performance of the control system and even makes it uncontrollable.
By establishing a kinematic model of the controlled object, analyzing the motion speed and driving torque, identifying the moment of inertia and friction torque, and using the characteristic point analysis method to obtain the mechanical characteristic parameters, including static friction torque, inertia torque and viscous friction torque.
The accurate mechanical characteristics identification of the controlled object is achieved, and the adaptive ability of the control system to load changes is improved. The method is simple and easy and is suitable for offline identification and intelligent identification.
Smart Images
Figure CN120706068A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of mechanical characteristic parameter identification, and more specifically, to a method and system for identifying moment of inertia and friction torque. Background Art
[0002] Moment of inertia and friction torque are typical mechanical parameters of control systems. When building a mathematical model for a control system, the rotating load—the motor, reducer, and controlled object—is typically considered as a whole and treated as the controlled object. During the initial modeling phase of system design, calculated or estimated values for moment of inertia and friction torque are typically used. However, due to various uncertainties, this initial mathematical model often differs from the final product, impacting control system performance and even rendering it uncontrollable.
[0003] Identifying the mechanical characteristic parameters of the controlled object through a simple and easy method is an important part of redesigning the model parameters in the early stage of control system design and an important means of control system design. Summary of the Invention
[0004] The present invention provides a method and system for identifying moment of inertia and friction torque to solve at least one of the problems existing in the prior art.
[0005] In order to achieve the above object, the present invention adopts the following technical solutions:
[0006] A first aspect of the present invention provides a method for identifying moment of inertia and friction torque, the method comprising establishing a kinematic model of a controlled object;
[0007] Analyzing the kinematic model of the controlled object to obtain the motion speed and driving torque of the controlled object;
[0008] The rotational inertia and friction torque of the controlled object are identified according to the motion speed and driving torque of the controlled object.
[0009] Optionally, analyzing the kinematic model of the controlled object includes selecting characteristic points of the controlled object for analysis, the characteristic points including a first characteristic point, a second characteristic point and a third characteristic point, the first characteristic point being the point where the velocity of the controlled object passes through zero, the second characteristic point being the point where the velocity of the controlled object is maximum and the acceleration is reversed, and the third characteristic point being any point between the first characteristic point and the second characteristic point.
[0010] Optionally, analyzing the first characteristic point of the controlled object includes: obtaining a mechanical characteristic parameter corresponding to the first characteristic point, and obtaining a corresponding static friction torque according to the mechanical characteristic parameter corresponding to the first characteristic point.
[0011] Optionally, the static friction torque is obtained according to the mechanical characteristic parameter corresponding to the first characteristic point, and the static friction torque is
[0012]
[0013] Among them, M c is the static friction torque, M ma1- is the driving torque at the moment before the first characteristic point, M ma1+ is the driving torque at the moment after the first characteristic point.
[0014] Optionally, analyzing the second characteristic point of the controlled object includes: obtaining mechanical characteristic parameters corresponding to the second characteristic point, and obtaining the moment of inertia according to the mechanical characteristic parameters corresponding to the second characteristic point.
[0015] Optionally, the moment of inertia is obtained according to the mechanical characteristic parameter corresponding to the second characteristic point, and the moment of inertia is
[0016]
[0017] Among them, J is the moment of inertia of the controlled object, M ma2- is the driving torque at the moment before the second characteristic point, M ma2+ is the driving torque at the moment after the second characteristic point, is the acceleration of the controlled object.
[0018] Optionally, analyzing the third characteristic point of the controlled object includes: acquiring mechanical characteristic parameters of the third characteristic point, and acquiring the viscous friction torque of the controlled object according to the mechanical characteristic parameters corresponding to the third characteristic point.
[0019] Optionally, obtaining the viscous friction torque of the controlled object according to the mechanical characteristic parameter corresponding to the third characteristic point includes:
[0020] The viscous friction coefficient is obtained according to the mechanical characteristic parameter corresponding to the third characteristic point, and the viscous friction torque is obtained according to the viscous friction coefficient. The viscous friction torque is:
[0021]
[0022] M v '=k v 'ω a2 ,
[0023] Among them, k v ' is the viscous friction coefficient, ω a2 is the speed of the controlled object at the second characteristic point, M ma2- is the driving torque at the moment before the second characteristic point, M ma1+is the driving torque at the moment after the first characteristic point, M v ' is the viscous friction torque corresponding to the third characteristic point.
[0024] Optionally, establishing a kinematic model of the controlled object includes:
[0025] The controlled object is abstracted into a general kinematic model, and the clockwise motion direction of the controlled object is set as the positive direction. The motion equation of the control system is established according to the positive direction and the kinematic law. The motion equation of the control system is:
[0026]
[0027] Among them, M m is the driving torque of the driving motor, sign() is the sign function, M c is the static friction torque, M v is the viscous friction torque, M v =k v ω, k v is the viscous friction coefficient, ω is the speed of the object being measured, J is the moment of inertia of the controlled object, is the acceleration of the controlled object.
[0028] The second aspect of the present invention provides a system for identifying the moment of inertia and friction torque, the system comprising a model building module, an analysis module and an identification module, wherein:
[0029] The model building module is used to build a kinematic model of the controlled object;
[0030] The analysis module is used to analyze the kinematic model of the controlled object to obtain the motion speed and driving torque of the controlled object;
[0031] The identification module is used to identify the rotational inertia and friction torque of the controlled object according to the motion speed and driving torque of the controlled object.
[0032] The beneficial effects of the present invention are as follows:
[0033] The present invention abstracts the controlled object as a moving body, establishes a kinematic model of the controlled object, and accurately understands the motion of the controlled object; the method has a simple algorithm, small calculation amount, is easy to implement, has a wide range of applications, and improves the control system's ability to adapt to changes in the controlled object. BRIEF DESCRIPTION OF THE DRAWINGS
[0034] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings.
[0035] Figure 1 A flow chart showing the method for identifying the moment of inertia and friction torque of the present invention;
[0036] Figure 2 A schematic diagram of a simplified motion model of a controlled object according to the present invention is shown;
[0037] Figure 3 A diagram showing the relationship between the motion speed of the controlled object and the change in driving torque in this embodiment is shown. DETAILED DESCRIPTION
[0038] In order to more clearly illustrate the present invention, the present invention is further described below in conjunction with preferred embodiments and accompanying drawings. Similar components in the accompanying drawings are represented by the same reference numerals. It should be understood by those skilled in the art that the following detailed description is illustrative rather than restrictive and should not be used to limit the scope of protection of the present invention.
[0039] One embodiment of the present invention provides a method for identifying the moment of inertia and friction torque, comprising establishing a kinematic model of a controlled object;
[0040] Analyzing the kinematic model of the controlled object to obtain the motion speed and driving torque of the controlled object;
[0041] The rotational inertia and friction torque of the controlled object are identified according to the motion speed and driving torque of the controlled object.
[0042] In a specific example, for example Figure 1 As shown in the figure, it is a flow chart of the method for identifying the moment of inertia and friction torque provided in this example. The method includes
[0043] Establish the kinematic model of the controlled object;
[0044] Based on the laws of kinematics, the controlled object is abstracted into a general kinematic model. This kinematic model generates motion due to the combined effects of the drive motor's driving torque and friction torque. The controlled object is the load. Friction includes static friction torque and viscous friction torque. The model is simplified based on engineering needs. The clockwise direction of the controlled object is set as the positive direction, and the positive directions of the drive motor's driving torque, static friction torque, and viscous friction torque are all set to be in the clockwise direction of the controlled object. The static friction torque is assumed to be uniform and essentially constant, with its direction opposite to that of the load's motion. The viscous friction torque is directly proportional to the rotational speed and its direction opposite to that of the load's motion.
[0045] For example Figure 2 The figure shows a simplified motion model of the controlled object in this example. Based on the set positive velocity direction of the controlled object and the kinematic laws, the control system motion equations are established.
[0046] Analyze the kinematic model of the controlled object and obtain the relationship between the motion speed and driving torque of the controlled object;
[0047] The rotational inertia and friction torque of the controlled object are obtained according to the motion speed and driving torque of the controlled object.
[0048] This embodiment loads a triangular wave speed signal with a zero mean of constant acceleration and deceleration into the velocity loop of the controlled object. The loaded signal and the armature current (torque) signal of the speed loop's drive motor are recorded. Feature points of the controlled object are selected based on the object's speed, and the corresponding data is obtained. The system's moment of inertia and friction characteristic parameters are derived from this data. The system's moment of inertia is the sum of the moments of inertia of its components, and the friction characteristics are static friction torque and viscous friction torque. This identification method abstracts the controlled object as a moving body, establishes its kinematic model, and accurately understands its motion. This method is simple and easy to implement, and can be applied to both offline system identification and intelligent load parameter recognition, improving the control system's ability to adapt to changes in the measured object.
[0049] In a possible implementation, establishing a kinematic model of the controlled object includes:
[0050] The controlled object is abstracted into a general kinematic model, and the clockwise motion direction of the controlled object is set as the positive velocity direction. The motion equation of the control system is established according to the positive velocity direction and the kinematic law. The motion equation of the control system is:
[0051]
[0052] Among them, M m is the driving torque of the driving motor, sign() is the sign function, M c is the static friction torque, M v is the viscous friction torque, M v =k v ω, k v is the viscous friction coefficient, ω is the speed of the object being measured, J is the moment of inertia of the controlled object, is the acceleration of the controlled object.
[0053] Continuing with the previous example, for example Figure 2 As shown in the figure, the positive direction of the controlled object's velocity is set to the clockwise direction of the controlled object. The positive directions of the drive motor's driving torque, static friction torque, and viscous friction torque are all set to the clockwise direction of the controlled object. Friction torque includes static friction torque and viscous friction torque.
[0054] According to the positive direction of the speed and the law of dynamics, the relationship between the speed of the controlled object and the driving torque and friction torque of the driving motor is obtained.
[0055] In one possible implementation, analyzing the kinematic model of the controlled object includes selecting characteristic points of the controlled object for analysis, the characteristic points including a first characteristic point, a second characteristic point, and a third characteristic point, the first characteristic point being the point where the velocity of the controlled object passes through zero, the second characteristic point being the point where the velocity of the controlled object is maximum and the acceleration is reversed, and the third characteristic point being any point between the first characteristic point and the second characteristic point.
[0056] In a specific example, for example Figure 3 As shown, according to formula (1), a schematic diagram of the change of the motion speed and driving torque of the controlled object is obtained, and characteristic points are selected according to the speed of the controlled object. The selected characteristic points are analyzed to obtain the driving torque corresponding to the characteristic points.
[0057] In a possible implementation, analyzing the first characteristic point of the controlled object includes: obtaining a mechanical characteristic parameter corresponding to the first characteristic point, and obtaining a static friction torque according to the mechanical characteristic parameter corresponding to the first characteristic point.
[0058] Continuing with the previous example, for example Figure 3 As shown, the first characteristic point is the point where the velocity of the controlled object crosses zero, that is, Figure 3 At the point a1 in the middle, the relationship between the motion speed, driving torque and friction torque at this moment is analyzed according to the laws of kinematics. By comparing the change in driving torque before and after the motion speed change of the first characteristic point of the measured object, the static friction torque of the system is calculated;
[0059] When the controlled object is at position a1, according to the laws of kinematics, the direction of its acceleration remains unchanged, meaning its moment of inertia remains unchanged. The direction of its velocity changes, meaning its frictional torque also changes. The velocity of the controlled object is zero, meaning its viscous frictional torque is zero. At this point, the magnitude of the static frictional torque remains unchanged, only its direction changes. This means the system's driving torque changes by the amount of static frictional torque.
[0060] According to formula (1), the static friction torque corresponding to the first characteristic point is obtained as
[0061]
[0062] Among them, M c is the static friction torque, M ma1- is the driving torque at the moment before the first characteristic point, M ma1+ is the driving torque at the moment after the first characteristic point.
[0063] This example obtains the first characteristic point of the controlled object according to the motion of the controlled object, and obtains the driving torque and friction torque corresponding to the first characteristic point based on the parameter data corresponding to the first characteristic point, thereby obtaining the identification results of the moment of inertia and friction torque.
[0064] In a possible implementation, analyzing the second characteristic point of the controlled object includes: obtaining mechanical characteristic parameters corresponding to the second characteristic point, and obtaining the inertia moment according to the mechanical characteristic parameters corresponding to the second characteristic point.
[0065] Continuing with the previous example, Figure 3 As shown, the second characteristic point is the point where the velocity of the controlled object is the largest and the acceleration is reversed, that is, Figure 3 At the point a2 in the middle, the relationship between the motion speed, driving torque and friction torque at this moment is analyzed according to the laws of kinematics. By comparing the changes in driving torque before and after the motion speed changes, the system moment of inertia is calculated.
[0066] When the controlled object is at position a2, according to the laws of kinematics, the direction of its acceleration changes, which means the direction of its moment of inertia changes. The velocity of the controlled object remains unchanged, which means the friction torque remains unchanged. At this point, the magnitude of the moment of inertia remains unchanged, only its direction changes. This means the sudden change in the system's driving torque is the change in the moment of inertia.
[0067] According to formula (1), the inertia moment corresponding to the second characteristic point is obtained as
[0068]
[0069] Among them, J is the moment of inertia of the controlled object, M ma2- is the driving torque at the moment before the second characteristic point, M ma2+ is the driving torque at the moment after the second characteristic point, is the acceleration of the controlled object.
[0070] This example obtains the second characteristic point of the controlled object according to the motion of the controlled object, and obtains the driving torque and friction torque corresponding to the second characteristic point based on the parameter data corresponding to the second characteristic point, thereby obtaining the identification results of the moment of inertia and friction torque.
[0071] In a possible implementation, analyzing the third characteristic point of the controlled object includes: obtaining mechanical characteristic parameters of the third characteristic point, and obtaining the viscous friction torque of the controlled object according to the mechanical characteristic parameters corresponding to the third characteristic point.
[0072] Continuing with the previous example, for example Figure 3 As shown, the third feature point is any point between the first feature point and the second feature point, that is, Figure 3 For any point on the line segment corresponding to the position from a1 to a2, the relationship between the driving torque and the friction torque is analyzed according to the movement speed. According to the change of the measured driving torque, the viscous friction coefficient of the system is calculated, and the viscous friction torque is obtained according to the viscous friction coefficient.
[0073] When the controlled object is at the third characteristic point, according to the laws of kinematics, the acceleration direction of the controlled object remains unchanged, that is, the inertia moment remains unchanged; the velocity direction remains unchanged, that is, the static friction moment remains unchanged; the velocity direction changes, that is, at this moment, the change in driving torque is reflected by the change in viscous friction moment with velocity.
[0074] According to formula (1), the viscous friction coefficient corresponding to the third characteristic point is obtained:
[0075] M ma2- -M ma1+ =k v '(ω a2 -ω a1 ),
[0076] Among them, ω a1 is the velocity corresponding to the first characteristic point, ω a1 is zero, ω a2 is the velocity corresponding to the second feature point, k v ' is the viscous friction coefficient corresponding to the third characteristic point;
[0077] The viscous friction coefficient corresponding to the third characteristic point is The viscous friction torque corresponding to the third characteristic point is M v '=k v 'ω a2 .
[0078] This example obtains the third characteristic point of the controlled object according to the motion of the controlled object, and obtains the driving torque and friction torque corresponding to the third characteristic point based on the parameter data corresponding to the third characteristic point, thereby obtaining the identification results of the moment of inertia and friction torque.
[0079] In a possible implementation, the corresponding sudden change amount of the driving torque is obtained according to the change of the driving torque before and after the motion speed of the controlled object changes.
[0080] Identify mechanical characteristic parameters according to the speed of the controlled object:
[0081] If the controlled object is at the position of the first characteristic point, the static friction torque of the system is obtained according to the parameters corresponding to the first characteristic point by comparing the changes in the driving torque before and after the speed change;
[0082] If the controlled object is at the position of the second characteristic point, by comparing the changes in the driving torque before and after the speed change, the inertia moment of the system is obtained according to the parameters corresponding to the second characteristic point, and the rotational inertia of the system is obtained according to the inertia moment;
[0083] If the controlled object is at the position of the third characteristic point, by comparing the changes in the driving torque before and after the speed change, the viscous friction coefficient of the system is obtained according to the parameters corresponding to the third characteristic point, and the viscous friction torque of the system is obtained according to the viscous friction coefficient.
[0084] This embodiment extracts characteristic point data during the motion of the controlled object to obtain the torque parameters and friction characteristic parameters of the control system. This method implements a method for testing the load mechanical characteristic parameters based on a triangular wave signal with a zero mean value of constant acceleration and constant deceleration in a given controlled object speed loop. This method is simple and easy to implement and can be used for both offline identification of the system and intelligent identification of load parameters, thereby improving the control system's ability to adapt to load changes.
[0085] The second aspect of the present invention provides a system for identifying the moment of inertia and friction torque, the system comprising a model building module, an analysis module and an identification module, wherein:
[0086] The model building module is used to build a kinematic model of the controlled object;
[0087] The analysis module is used to analyze the kinematic model of the controlled object to obtain the motion speed and driving torque of the controlled object;
[0088] The identification module is used to identify the rotational inertia and friction torque of the controlled object according to the motion speed and driving torque of the controlled object.
[0089] In a specific example, the controlled object is abstracted into a universal kinematic model. The kinematic equations of the control system are established based on the set positive velocity direction of the controlled object and the kinematic laws. The controlled object is the load. Based on the kinematic equations of the control system, the relationship between the controlled object's motion velocity and driving torque is established. Feature points are selected based on the velocity of the controlled object during its motion. The data corresponding to these feature points is analyzed, and the relationship between the motion velocity, driving torque, and friction torque corresponding to each feature point is resolved to obtain identification results for the moment of inertia and friction torque.
[0090] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "upper" and "lower" is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. Unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be internal communication between two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.
[0091] It should also be noted that, in the description of the present invention, relational terms such as first and second, etc., are used only 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 these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or device comprising the element.
[0092] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not limitations on the implementation methods of the present invention. For ordinary technicians in the relevant field, other different forms of changes or modifications can be made based on the above description. It is impossible to list all the implementation methods here. All obvious changes or modifications derived from the technical solution of the present invention are still within the scope of protection of the present invention.
Claims
1. A method for identifying moment of inertia and friction torque, characterized in that: The method includes: Establish the kinematic model of the controlled object; Analyzing the kinematic model of the controlled object to obtain the motion speed and driving torque of the controlled object; The rotational inertia and friction torque of the controlled object are identified according to the motion speed and driving torque of the controlled object.
2. The method according to claim 1, characterized in that Analyzing the kinematic model of the controlled object includes selecting characteristic points of the controlled object for analysis, the characteristic points including a first characteristic point, a second characteristic point, and a third characteristic point. The first characteristic point is a point where the velocity of the controlled object passes through zero, the second characteristic point is a point where the velocity of the controlled object is maximum and the acceleration is reversed, and the third characteristic point is any point between the first characteristic point and the second characteristic point.
3. The method according to claim 2, characterized in that Analyzing the first characteristic point of the controlled object includes: obtaining mechanical characteristic parameters corresponding to the first characteristic point, and obtaining static friction torque according to the mechanical characteristic parameters corresponding to the first characteristic point.
4. The method according to claim 3, characterized in that The static friction torque is obtained according to the mechanical characteristic parameters corresponding to the first characteristic point, and the static friction torque is Among them, M c is the static friction torque, M ma1- is the driving torque at the moment before the first characteristic point, M ma1+ is the driving torque at the moment after the first characteristic point.
5. The method according to claim 2, characterized in that Analyzing the second characteristic point of the controlled object includes: obtaining mechanical characteristic parameters corresponding to the second characteristic point, and obtaining the inertia moment according to the mechanical characteristic parameters corresponding to the second characteristic point.
6. The method according to claim 5, characterized in that The moment of inertia is obtained according to the mechanical characteristic parameter corresponding to the second characteristic point, and the moment of inertia is Among them, J is the moment of inertia of the controlled object, M ma2- is the driving torque at the moment before the second characteristic point, M ma2+ is the driving torque at the moment after the second characteristic point, is the acceleration of the controlled object.
7. The method according to claim 2, characterized in that Analyzing the second characteristic point of the controlled object includes: obtaining mechanical characteristic parameters of the third characteristic point, and obtaining the viscous friction torque of the controlled object according to the mechanical characteristic parameters corresponding to the third characteristic point.
8. The method according to claim 7, characterized in that The step of obtaining the viscous friction torque of the controlled object according to the mechanical characteristic parameter corresponding to the third characteristic point includes: The viscous friction coefficient is obtained according to the mechanical characteristic parameter corresponding to the third characteristic point, and the viscous friction torque is obtained according to the viscous friction coefficient. The viscous friction torque is: M v '=k v Oh a2 , Among them, k v ' is the viscous friction coefficient, ω a2 is the speed of the controlled object at the second characteristic point, M ma2- is the driving torque at the moment before the second characteristic point, M ma1+ is the driving torque at the moment after the first characteristic point, M v ' is the viscous friction torque corresponding to the third characteristic point.
9. The method according to claim 1, characterized in that The kinematic model of the controlled object is established by The controlled object is abstracted into a general kinematic model, and the clockwise motion direction of the controlled object is set as the positive direction. The motion equation of the control system is established according to the positive direction and the kinematic law. The motion equation of the control system is: Among them, M m is the driving torque of the driving motor, sign() is the sign function, M c is the static friction torque, M v is the viscous friction torque, M v =k v ω, k v is the viscous friction coefficient, ω is the speed of the object being measured, J is the moment of inertia of the controlled object, is the acceleration of the controlled object.
10. A system for identifying moment of inertia and friction torque, characterized in that: The system includes a model building module, an analysis module and an identification module, wherein: The model building module is used to build a kinematic model of the controlled object; The analysis module is used to analyze the kinematic model of the controlled object to obtain the motion speed and driving torque of the controlled object; The identification module is used to identify the rotational inertia and friction torque of the controlled object according to the motion speed and driving torque of the controlled object.