System and method for load torque disturbance suppression for brushed DC motors

Abstract

A method for controlling a brushed DC motor includes determining a speed difference signal based on a difference between a speed command signal and a motor speed; determining an initial voltage command based on the speed difference signal; determining a final voltage command based on the initial voltage command; applying a DC voltage based on the final voltage command to cause the brushed DC motor to rotate the lead screw and move the load along the path; determining a disturbance torque; and counteracting the perturbation torque by at least one of: determining a feed-forward voltage command based on a position of the load along the path, and determining a final voltage command as a sum of the initial voltage command and the feed-forward voltage command; or a speed compensation signal is determined based on the disturbance torque, and a speed difference signal is further determined based on the speed compensation signal.

Description

Technical Field

[0001] The present disclosure relates to methods and systems for operating a brushed DC motor. Background Art

[0002] Brushed DC motors are used in a variety of applications. One such application is in power steering systems for vehicles. Significant advantages of brushed DC motors include low-cost components, less circuitry, simplicity, and ease of control when compared to alternatives such as AC motors.

[0003] For ergonomic purposes, the steering column is able to be adjusted in two directions, tilt and telescopic. The tilt direction allows the driver to adjust the steering column up and down, while the telescopic direction pulls the steering column towards the driver or pushes it away from the driver. These adjustments can be made manually by unlocking the tilt lever mechanism (manual column) or by DC motor actuators (electric column), in which case there is one motor for each adjustment direction. As part of the requirements of some electric columns, there is a requirement to drive these DC motors at a specific speed profile and keep that speed constant even in the presence of signal disturbances. These signal disturbances are a combination of friction and mass inertia. Therefore, the DC motor speed controller should take these disturbances into account to suppress them and maintain good control of the motor speed.

[0004] In control theory, a robust controller is a design technique that accounts for uncertainties and compensates for them in the system's response. As part of a robust controller, good disturbance rejection is a key characteristic of the controller. Disturbances can be a source of controller failure, system instability, or poor quality system response. Summary of the Invention

[0005] According to one or more embodiments, a method for controlling a brushed DC motor includes determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining an initial voltage command based on the speed difference signal; determining a final voltage command based on the initial voltage command; applying a DC voltage to the brushed DC motor based on the final voltage command to cause the brushed DC motor to rotate a lead screw and thereby move a load along a path; determining a disturbance torque acting on the brushed DC motor; and modifying at least one of the final voltage command and the speed difference signal to cause the brushed DC motor to generate a compensation torque that offsets the disturbance torque. Modifying at least one of the final voltage command and the speed difference signal may include at least one of: determining a feedforward voltage command based on a position of the load along the path and determining the final voltage command as a sum of the initial voltage command and the feedforward voltage command; or determining a speed compensation signal based on the disturbance torque and further determining the speed difference signal based on the speed compensation signal.

[0006] According to one or more embodiments, a motor control system is provided. The motor system includes: a brushed DC motor having a set of brushes and configured to rotate a lead screw and thereby move a load along a path; a voltage regulator configured to apply a DC voltage to the brushed DC motor based on a final voltage command; and a controller. The controller is configured to: determine a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determine an initial voltage command based on the speed difference signal; determine a final voltage command based on the initial voltage command; determine a disturbance torque acting on the brushed DC motor via the lead screw; and modify at least one of the final voltage command and the speed difference signal so that the brushed DC motor generates a compensation torque that offsets the disturbance torque. Modifying at least one of the final voltage command and the speed difference signal may include at least one of the following: determining a feedforward voltage command based on a position of the load along the path and determining the final voltage command as the sum of the initial voltage command and the feedforward voltage command; or determining a speed compensation signal based on the disturbance torque and further determining the speed difference signal based on the speed compensation signal.

[0007] According to one or more embodiments, a method for operating a brushed DC motor is provided. The method includes determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining an initial voltage command based on the speed difference signal; determining a final voltage command based on the initial voltage command; applying a DC voltage to the brushed DC motor based on the final voltage command; determining a disturbance torque acting on the brushed DC motor; and modifying the speed difference signal so that the brushed DC motor generates a compensation torque that offsets the disturbance torque. Modifying the speed difference signal may include determining a speed compensation signal based on the disturbance torque, and further determining the speed difference signal based on the speed compensation signal.

[0008] These and other advantages and features will become more apparent from the following description taken in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The subject matter of the present disclosure is particularly pointed out and distinctly claimed in the claims at the conclusion of the specification. The foregoing and other features and advantages of the present disclosure will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in which:

[0010] Figure 1 A column position module (CPM) of a steering system in a vehicle according to aspects of the present disclosure is shown;

[0011] Figure 2 1. A schematic block diagram of a system for controlling a brushed DC motor according to aspects of the present disclosure is shown;

[0012] Figure 3AA graph showing relative pitch over time of a CPM module moving in a column downward direction according to aspects of the present disclosure;

[0013] Figure 3B a graph showing a Fast Fourier Transform (FFT) analysis of pitch versus frequency for a CPM module moving in a column downward direction;

[0014] Figure 4 shows a schematic block diagram of a motor control system for operating a DC motor according to aspects of the present disclosure;

[0015] Figures 5A to 5C Various schematic diagrams of lead screw mechanisms are shown;

[0016] Figure 6 A graph showing motor speed versus time for a DC brushed motor controlled by a PI control loop in response to a step change in speed command without torque disturbance rejection;

[0017] Figure 7 a graph showing motor speed versus time for a DC brushed motor controlled by a PI control loop in response to a step change speed command with torque disturbance rejection in accordance with aspects of the present disclosure; and

[0018] Figures 8A to 8B A flow chart listing steps in a method for operating a brushed DC motor according to aspects of the present disclosure is shown. DETAILED DESCRIPTION

[0019] Reference will now be made to the accompanying drawings, wherein the present disclosure will be described with reference to specific embodiments, rather than limiting the present disclosure, it being understood that the disclosed embodiments are merely illustrative of non-limiting embodiments of the present disclosure that may be embodied in various forms and alternatives. The drawings are not necessarily drawn to scale, and some features may be exaggerated or minimized to illustrate details of particular components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but merely as a representative basis for teaching those skilled in the art to employ the present disclosure in various ways.

[0020] As used herein, the terms module and submodule refer to one or more processing circuits (e.g., application-specific integrated circuits (ASICs), electronic circuits), processors (shared, dedicated, or grouped) and memories that execute one or more software or firmware programs, combinatorial logic circuits, and / or other suitable components that provide the described functionality. It will be understood that the submodules described below can be combined and / or further divided.

[0021] The present disclosure provides a system and method for a robust controller for a brushed DC motor. A feedforward type of control can be used to achieve the desired robustness. The goal of the method is to control the undesirable effects of a measured disturbance before they are reflected in the output of the system and to reduce the deviation of the output from the set point. In other words, it is an active method to minimize disturbances to the manipulated variable. According to the process, a feedforward block is added to the DC motor model to compensate for the load and friction torque as disturbances. Appropriate analysis of the load and friction torque results in a better speed response using the proposed control algorithm.

[0022] Referring now to the accompanying drawings, the technical solutions will be described with reference to specific embodiments, but not limited thereto. Figure 1 An exemplary embodiment of a column position module (CPM) 20 of a steering system in a vehicle is shown, which may utilize the disclosed systems and methods to control a DC motor.

[0023] The CPM 20 includes a steering shaft 22 configured to be attached to a steering wheel, which may also be referred to as a steering wheel, that a person may use to steer a vehicle. The CPM 20 includes a steering actuator 24 attached to the steering shaft. The steering actuator 24 may supplement the force applied by the person to provide a power-assisted steering function. The CPM 20 also includes a telescopic actuator motor 26 configured to control the axial position of the steering wheel by moving the steering shaft 22 in an axial direction. The CPM 20 also includes a rake actuator motor 28 configured to control the vertical position of the steering wheel by moving the end of the steering shaft in a radial direction.

[0024] Any or all of the steering actuator 24, telescopic actuator motor 26, and / or tilt actuator motor 28 may include brushed DC motors and may be controlled using the systems and methods of the present disclosure. However, the systems and methods of the present disclosure may be used with brushed DC motors in other vehicle applications, such as for window or lock actuators. The systems and methods of the present disclosure are not limited to use in vehicles, but may be used with brushed DC motors in a variety of different applications.

[0025] Figure 2 1 shows a schematic block diagram of a system 50 for controlling brushed DC motors 26, 28. Figure 2 As shown, the brushed DC motors 26, 28 include a set of brushes 30, 32 for transmitting DC current from a fixed terminal to a rotor winding. The set of brushes 30, 32 includes a first brush 30 configured to be connected to a power source to receive DC current. The set of brushes 30, 32 also includes a second brush 32 configured to be connected to a current sink (such as a ground terminal).

[0026] System 50 includes a controller 60. Controller 60 may include any suitable controller, such as an electronic control unit or other suitable controller. Controller 60 may be configured to control various functions of, for example, a steering system and / or various functions of a vehicle. Controller 60 may include a processor 62 and a memory 64. Processor 62 may include any suitable processor, such as the processors described herein. Additionally or alternatively, controller 60 may include any suitable number of processors in addition to or in addition to processor 62. Memory 64 may include a single disk or multiple disks (e.g., a hard drive) and a storage management module that manages one or more partitions within memory 64. In some embodiments, memory 64 may include flash memory, semiconductor (solid-state) memory, or the like. Memory 64 may include random access memory (RAM), read-only memory (ROM), or a combination thereof. Memory 64 may include instructions that, when executed by processor 62, cause processor 62 to control at least various aspects of the vehicle. Additionally or alternatively, memory 64 may include instructions that, when executed by processor 62, cause processor 62 to perform functions associated with the systems and methods described herein.

[0027] The controller 60 may be operatively connected to the voltage regulator 52. The voltage regulator 52 may be configured to apply a DC voltage v to the first brush 30 of the brushed DC motor 26, 28. The voltage regulator 52 may be configured to apply a DC voltage v to the first brush 30 of the brushed DC motor 26, 28 based on the final voltage command v from the controller 60. cmd To generate a DC voltage v.

[0028] In some embodiments, as Figure 2 As shown, the system 50 may include a current sensor 54 configured to measure the DC current supplied to the brushed DC motors 26, 28 and to generate a motor current signal i m The motor current signal is transmitted to the controller 60 and represents the actual motor current in the windings of the brushed DC motors 26, 28. Additionally or alternatively, as in Figure 2 As shown, the system 50 may include a position sensor 56 configured to measure the rotational position of the brushed DC motors 26, 28 and to generate a motor position signal θ. m Transmitted to the controller 60.

[0029] In some embodiments, the controller 60 can perform the methods described herein. However, the methods described herein as being performed by the controller 60 is not intended to be limiting, and any type of software executed on a controller or processor can perform the methods described herein without departing from the scope of the present disclosure. For example, a controller (such as a processor executing software within a computing device) can perform the methods described herein.

[0030] Figure 3A A graph over time is shown of the relative pitch of the tilt actuator motor 28 moving the CPM 20 in a column-down direction. Figure 3B A graph showing a Fast Fourier Transform (FFT) analysis of pitch versus frequency for a CPM module moving in a column downward direction. Figure 3B A large spike at approximately 4 Hz is shown. This spike represents undesirable noise or vibration that a person using the CPM may perceive. Similar undesirable noise or vibration may be generated by the tilt actuator motor 28 moving in either direction or the telescopic actuator motor 26 moving in either direction. The method and system of the present disclosure are intended to minimize or eliminate such vibrations that would otherwise cause undesirable noise and vibration. Furthermore, the techniques of the present disclosure can be applied to reduce noise or vibration in any brushed DC motor application.

[0031] Figure 4 A schematic block diagram of a motor control system 70 for operating a DC motor according to aspects of the present disclosure is shown. The motor control system 70 is configured as a speed-torque controller. However, the principles of the present disclosure can be applied to other controller configurations.

[0032] The motor control system 70 includes a first subtractor 72 configured to reduce the speed command signal ω ref Subtract the motor speed ω and calculate the speed command signal ω ref The speed difference signal ω is the difference between the speed of the motor ω diff The first subtractor 72 also adds the first modified signal 97 to the speed command signal ω ref The speed error signal E(s) is calculated by adding them.

[0033] The motor control system 70 also includes a voltage command generator 74 that is configured to generate an initial voltage command signal V(s). The voltage command generator 74 may use a proportional-integral (PI) control loop to generate the initial voltage command signal V(s). However, other control techniques, such as a proportional-integral-derivative (PID) control loop or a lookup table, may be used. In some embodiments, the initial voltage command signal V(s) may be directly used as the final voltage command V(s) for the voltage regulator 52. cmd Alternatively, the initial voltage command signal V(s) may be modified to determine the final voltage command v cmd .

[0034] The motor control system 70 also includes a DC motor model 80 that represents the brushed DC motors 26, 28. The DC motor model 80 includes a second subtractor 82 that determines an applied voltage signal 83 by subtracting the back EMF voltage signal 93 from the initial voltage command signal V(s). The DC motor model 80 also includes a first transform 84 that takes the applied voltage signal 83 and generates the applied voltage signal 83 by dividing the applied voltage signal 83 by L(s). s +R to calculate the first intermediate signal 85, where L s is the inductance value, and R is the resistance value. The DC motor model 80 further includes a first multiplier 86 configured to multiply the first intermediate signal 85 by the motor torque constant K m are multiplied together to determine the resulting torque signal 87 .

[0035] The DC motor model 80 further includes a third subtractor 88 that generates a torque signal by subtracting the disturbance torque T dist The DC motor model 80 also includes a second transformation 90 that takes the total torque signal 89 and calculates the total torque signal 89 by dividing it by J. s +b to calculate the motor speed signal ω, where J s is the moment of inertia, s is the Laplace domain variable, and b is the motor viscous friction constant.

[0036] In some embodiments, as Figure 4 As shown, the motor control system 70 includes a feedforward controller 96 configured to generate a signal based on the disturbance torque T dist To generate the first modified signal 97, and to make the brushed DC motors 26, 28 generate a counteracting disturbance torque T dist The feedforward controller 96 may be labeled G1(s), and its operation will be described in further detail below.

[0037] The present disclosure provides a method for compensating or counteracting the disturbance torque T dist The first method is to model the load-friction torque (profile). The relationship between torque and voltage is given in equation (1):

[0038]

[0039] Where τ represents the motor torque, i is the motor current, K is the electromotive force constant, v is the DC input voltage, ω is the motor speed (in rad / sec), R is the resistance, L is the inductance, and s is the Laplace complex variable.

[0040] Because the disturbance caused by the load friction torque is combined with the feedforward term (such as v ff) is added to the voltage command equation to correlate the related terms, so equation (1) can be written as equation (2):

[0041]

[0042] In the time domain, this equation can be written as equation (3):

[0043]

[0044] The brushed DC motors 26, 28 of the CPM 20 are relatively small, and R>>L. Therefore, equation (3) can be simplified to equation (4).

[0045]

[0046] Therefore, the feedforward voltage term v ff can be added to the output v of a speed controller (such as a classic PID) ctrl To offset the disturbance torque T dist .

[0047] v cmd =v ctrl +v ff (5)

[0048] The present disclosure also provides a method for compensating or counteracting the disturbance torque T dist The second method. If the disturbance torque T can be measured or otherwise determined dist , then the feedforward transfer function G1(s) can be used to offset the disturbance effect at the output of the system, such as Figure 4 shown.

[0049] Figure 4 The motor control system 70 can be described by equations (6)-(8):

[0050]

[0051] V(s)=E(s)D(s) (7)

[0052] E(s)=ω ref (s)-ω(s)+G1(s)T dist (8)

[0053] Equations (6)-(8) can be combined into equation (9):

[0054]

[0055] In order to eliminate the disturbance torque T dist The terms of equation (9) can be set as described in the following equations (10)-(11):

[0056]

[0057] In some cases, the disturbance torque T can be estimated from the current and motor speed measurements according to the following state equations (12)-(15): dist .

[0058]

[0059] The disturbance torque T can be calculated using the Luenberger Observer dist The estimated value of , as stated in equations (16)-(17).

[0060]

[0061] where x e is the state estimator, and G is the observer gain matrix. Therefore, equation (16) can be rewritten as equation (18).

[0062]

[0063] Observer Term A obs 、B obs 、C obs 、D obs can be determined as set out in equation group (19):

[0064]

[0065] Figures 5A to 5C Various schematic diagrams of a lead screw mechanism 40 are shown. The lead screw mechanism 40 may be used in the CPM 20 to convert the rotational force from one of the brushed DC motors 26, 28 into linear motion, thereby moving the CPM 20 with corresponding telescopic or tilting movements. dist The power may be transmitted to the brushed DC motors 26 , 28 and affected by the lead screw mechanism 40 .

[0066] As shown, the lead screw mechanism 40 includes a lead screw 42 having external threads and engaged with a lead nut 44 .

[0067] For a lead screw mechanism 40 having an Acme thread, as shown, including a lead screw 42 having threads having a trapezoidal cross-section to define a ramp 43 that engages a lead nut 44, the torque T on the lead screw can be related to the force F exerted by the lead nut 44 as set forth in equation (20):

[0068]

[0069] where d m is the average diameter of the lead screw 42, l is the lead and is equal to the pitch P for a lead screw 42 having a single thread configuration, and secα is the secant of the thread angle α.

[0070] Figure 6 A graph showing motor speed versus time for a DC brushed motor controlled by a PI control loop in response to a step change in speed command without torque disturbance rejection is shown. Figure 6 Including showing the speed command signal ω ref A first graph 100 of a velocity reference (also referred to as a speed reference) with a step change to 362.5 rad / sec at time 0.1 s. Figure 6 Also included is a second graph 102 showing the motor speed ω, which increases after time 0.1 s to approach the speed command signal ω. ref rad / sec and exhibited variable oscillations until approximately time = 3.0 seconds.

[0071] Figure 7 A graph showing motor speed versus time for a DC brushed motor controlled by a PI control loop in response to a step change speed command with torque disturbance rejection in accordance with aspects of the present disclosure. Figure 7 Including showing the speed command signal ω ref A third graph 110 of φ(t) (also referred to as the speed reference) with a step change to 362.5 rad / sec at time 0.1 s. Figure 7 Also included is a fourth graph 112 showing the motor speed ω, which increases after time 0.1 s to approach the speed command signal ω. ref 362.5rad / sec and exhibits some oscillation until about time 2.5s, but with Figure 6 Compared to the oscillations of the second graph 102 , the oscillations in the fourth graph are greatly reduced.

[0072] Figures 8A to 8B 1 is a flow chart outlining the steps in a method 200 for controlling a brushed DC motor according to aspects of the present disclosure. The method 200 may be performed by the motor control system 70 of the present disclosure. It will be understood from the present disclosure that the order of operations within the method is not limited to the following. Figures 8A to 8B Rather, the steps are not performed in the order illustrated in the accompanying drawings, but may be performed in one or more altered orders where applicable and in accordance with the present disclosure.

[0073] At 202, method 200 determines a speed difference signal based on the difference between the speed command signal and the motor speed of the brushed DC motor. For example, processor 62 may execute instructions to implement subtractor 72 to calculate a speed difference signal representing the speed command signal ω. ref and motor speed ω m The speed difference signal ω diff .

[0074] At 204 , method 200 determines an initial voltage command based on the speed difference signal. For example, processor 62 may execute instructions to implement voltage command generator 74 to calculate the initial voltage command signal V(s).

[0075] At 206, method 200 determines a final voltage command based on the initial voltage command. For example, processor 62 may execute instructions to determine a final voltage command v based on the initial voltage command signal V(s). cmd In some embodiments, the initial voltage command signal V(s) may be directly used as the final voltage command v for the voltage regulator 52. cmd Alternatively, the initial voltage command signal V(s) may be modified to determine the final voltage command v cmd .

[0076] At 208, method 200 applies a DC voltage to the brushed DC motor based on the final voltage command to cause the brushed DC motor to rotate the lead screw and thereby move the load along the path. For example, the voltage regulator 52 may generate a DC voltage v and apply it to the first brush 30 of the brushed DC motor 26, 28, wherein the DC voltage v is based on the final voltage command v from the controller 60. cmd .

[0077] At 210 , method 200 determines the disturbance torque acting on the brushed DC motor. For example, processor 62 may execute instructions to measure or estimate the disturbance torque T dist , as described in this disclosure.

[0078] At 212 , method 200 modifies at least one of the final voltage command and the speed difference signal to cause the brushed DC motor to generate a compensation torque that counteracts the disturbance torque.

[0079] Step 212 may include determining a feed-forward voltage command based on the position of the load along the path at step 212A, and determining the final voltage command as the sum of the initial voltage command and the feed-forward voltage command. For example, the processor 62 may execute instructions to calculate the feed-forward voltage command v ff , and by adding the feedforward voltage command v ff To modify the initial voltage command signal V(s) to determine the final voltage command v cmd .

[0080] Alternatively or in addition, step 212 may include determining a speed compensation signal based on the disturbance torque at step 212B, and further determining a speed difference signal based on the speed compensation signal. For example, the processor 62 may execute instructions to implement the first subtractor 72 to add the first modification signal 97 to the speed command signal ω ref To calculate the speed error signal E(s).

[0081] In some embodiments, determining the feed-forward voltage command at step 212A includes determining the feed-forward voltage command based on To determine the feedforward voltage command v ff , where R is the resistance of the brushed DC motor, K is the electromotive force constant, θ is the position of the load along the path, and τ LF (θ) is the disturbance torque as a function of the position θ of the load.

[0082] In some embodiments, determining the speed compensation signal at step 212B includes determining the speed compensation signal according to To determine the speed compensation signal ω(s), where T dist is the disturbance torque, L is the inductance of the brushed DC motor, s is the Laplace domain variable, R is the resistance of the brushed DC motor, D(s) is the transfer function describing the relationship between the speed difference signal and the final voltage command, and K m is the motor torque constant.

[0083] In some embodiments, determining the disturbance torque at step 210 includes measuring the disturbance torque.

[0084] In some embodiments, determining the disturbance torque at step 210 includes estimating the disturbance torque based on a motor current in the brushed DC motor and a motor speed of the brushed DC motor.

[0085] In some embodiments, estimating the disturbance torque includes: To calculate the estimated disturbance torque, where J is the moment of inertia, is the derivative of the motor speed for a brushed DC motor, K m is the motor torque constant, i is the motor current in a brushed DC motor, b is the motor viscous friction constant, ω is the motor speed of a brushed DC motor, and T dist is the disturbance torque.

[0086] In some embodiments, estimating the disturbance torque includes using a Lundberg observer according to To calculate the disturbance torque, where is the derivative of the state estimator, x eis the state estimator, G is the observer gain matrix, and where:

[0087]

[0088] u is the DC voltage applied to the brushed DC motor, J is the moment of inertia, L is the inductance of the brushed DC motor, R is the resistance of the brushed DC motor, K b is the motor back EMF constant, K m is the motor torque constant, i is the motor current in a brushed DC motor, b is the motor viscous friction constant,

[0089] ω is the motor speed of the brushed DC motor, and T dist is the disturbance torque.

[0090] The present disclosure provides a method for controlling a brushed DC motor. The method includes determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining an initial voltage command based on the speed difference signal; determining a final voltage command based on the initial voltage command; applying a DC voltage to the brushed DC motor based on the final voltage command so that the brushed DC motor rotates a lead screw and thereby moves a load along a path; determining a disturbance torque acting on the brushed DC motor; and modifying at least one of the final voltage command and the speed difference signal so that the brushed DC motor generates a compensation torque that offsets the disturbance torque. In some embodiments, modifying at least one of the final voltage command and the speed difference signal includes at least one of the following: determining a feedforward voltage command based on a position of the load along the path and determining the final voltage command as the sum of the initial voltage command and the feedforward voltage command; or determining a speed compensation signal based on the disturbance torque and further determining the speed difference signal based on the speed compensation signal.

[0091] In some embodiments, the method further comprises determining a feed-forward voltage command based on a position of the load along the path, and modifying at least one of the final voltage command and the speed difference signal comprises determining the final voltage command as a sum of the initial voltage command and the feed-forward voltage command.

[0092] In some embodiments, determining the feed-forward voltage command includes determining the feed-forward voltage command based on To determine the feedforward voltage command v ff , where R is the resistance of the brushed DC motor, K is the electromotive force constant, θ is the position of the load along the path, and τ LF (θ) is the disturbance torque as a function of the position θ of the load.

[0093] In some embodiments, the method further includes: determining a speed compensation signal based on the disturbance torque to enable the brushed DC motor to generate a compensation torque to offset the disturbance torque, and modifying at least one of the final voltage command and the speed difference signal includes: further determining the speed difference signal based on the speed compensation signal.

[0094] In some embodiments, determining the speed compensation signal includes determining the speed compensation signal based on To determine the speed compensation signal ω(s), where T dist is the disturbance torque, Ls is the inductance of the brushed DC motor, R is the resistance of the brushed DC motor, D(s) is the transfer function describing the relationship between the speed difference signal and the final voltage command, and K m is the motor torque constant.

[0095] In some embodiments, determining the disturbance torque includes measuring the disturbance torque.

[0096] In some embodiments, determining the disturbance torque includes estimating the disturbance torque based on a motor current in the brushed DC motor and a motor speed of the brushed DC motor.

[0097] In some embodiments, estimating the disturbance torque includes: To calculate the estimated disturbance torque, where J is the moment of inertia, is the derivative of the motor speed for a brushed DC motor, K m is the motor torque constant, i is the motor current in a brushed DC motor, b is the motor viscous friction constant, ω is the motor speed of a brushed DC motor, and T dist is the disturbance torque.

[0098] In some embodiments, estimating the disturbance torque includes using a Lundberg observer according to To calculate the disturbance torque, where is the derivative of the state estimator, x e is the state estimator, G is the observer gain matrix, and where: u is the DC voltage applied to the brushed DC motor, J is the moment of inertia, L is the inductance of the brushed DC motor, R is the resistance of the brushed DC motor, K b is the motor back EMF constant, K m is the motor torque constant, i is the motor current in a brushed DC motor, b is the motor viscous friction constant, ω is the motor speed of a brushed DC motor, and T dist is the disturbance torque.

[0099] The present disclosure also provides a motor control system. The motor control system includes: a brushed DC motor having a set of brushes and configured to rotate a lead screw and thereby move a load along a path; a voltage regulator configured to apply a DC voltage to the brushed DC motor based on a final voltage command; and a controller. The controller is configured to: determine a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determine an initial voltage command based on the speed difference signal; determine a final voltage command based on the initial voltage command; determine a disturbance torque acting on the brushed DC motor via the lead screw; and modify at least one of the final voltage command and the speed difference signal so that the brushed DC motor generates a compensation torque that offsets the disturbance torque. Modifying at least one of the final voltage command and the speed difference signal includes at least one of the following: determining a feedforward voltage command based on a position of the load along the path, and determining the final voltage command as the sum of the initial voltage command and the feedforward voltage command; or determining a speed compensation signal based on the disturbance torque, and further determining the speed difference signal based on the speed compensation signal.

[0100] In some embodiments, the controller is further configured to determine a feed-forward voltage command based on a position of the load along the path, and modifying at least one of the final voltage command and the speed difference signal includes determining the final voltage command as a sum of the initial voltage command and the feed-forward voltage command.

[0101] In some embodiments, determining the feed-forward voltage command includes determining the feed-forward voltage command based on To determine the feedforward voltage command v ff , where R is the resistance of the brushed DC motor, K is the electromotive force constant, θ is the position of the load along the path, and τ LF (θ) is the disturbance torque as a function of the position θ of the load.

[0102] In some embodiments, the controller is further configured to determine a speed compensation signal based on the disturbance torque, and cause the brushed DC motor to generate a compensation torque to offset the disturbance torque, and modifying at least one of the final voltage command and the speed difference signal includes: further determining the speed difference signal based on the speed compensation signal.

[0103] In some embodiments, determining the speed compensation signal includes determining the speed compensation signal based on To determine the speed compensation signal ω(s), where T dist is the disturbance torque, Ls is the inductance of the brushed DC motor, R is the resistance of the brushed DC motor, D(s) is the transfer function describing the relationship between the speed difference signal and the final voltage command, and K m is the motor torque constant.

[0104] In some embodiments, determining the disturbance torque includes measuring the disturbance torque.

[0105] In some embodiments, determining the disturbance torque includes estimating the disturbance torque based on a motor current in the brushed DC motor and a motor speed of the brushed DC motor.

[0106] In some embodiments, estimating the disturbance torque includes determining the value of the disturbance torque based on: To calculate the estimated disturbance torque, where J is the moment of inertia, is the derivative of the motor speed for a brushed DC motor, K m is the motor torque constant, i is the motor current in a brushed DC motor, b is the motor viscous friction constant, ω is the motor speed of a brushed DC motor, and T dist is the disturbance torque.

[0107] In some embodiments, estimating the disturbance torque includes using a Lundberg observer according to To calculate the disturbance torque, where is the derivative of the state estimator, x e is the state estimator, G is the observer gain matrix, and where: u is the DC voltage applied to the brushed DC motor, J is the moment of inertia, L is the inductance of the brushed DC motor, R is the resistance of the brushed DC motor, K b is the motor back EMF constant, K m is the motor torque constant, i is the motor current in a brushed DC motor, b is the motor viscous friction constant, ω is the motor speed of a brushed DC motor, and T dist is the disturbance torque.

[0108] The present disclosure also provides a method for controlling a brushed DC motor. The method includes determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining an initial voltage command based on the speed difference signal; determining a final voltage command based on the initial voltage command; applying a DC voltage to the brushed DC motor based on the final voltage command; determining a disturbance torque acting on the brushed DC motor; and modifying the speed difference signal so that the brushed DC motor generates a compensation torque that offsets the disturbance torque.

[0109] Modifying the speed difference signal includes determining a speed compensation signal based on the disturbance torque, and further determining the speed difference signal based on the speed compensation signal.

[0110] In some embodiments, determining the speed compensation signal includes determining the speed compensation signal based on To determine the speed compensation signal ω(s), where T distis the disturbance torque, Ls is the inductance of the brushed DC motor, R is the resistance of the brushed DC motor, D(s) is the transfer function describing the relationship between the speed difference signal and the final voltage command, and K m is the motor torque constant.

[0111] Although the present disclosure has been described in detail with reference to only a limited number of embodiments, it should be readily understood that the present disclosure is not limited to these disclosed embodiments. Rather, the present disclosure may be modified to include any number of variations, alterations, substitutions, or equivalent arrangements not previously described but commensurate with the scope of the present disclosure. Additionally, although various embodiments of the present disclosure have been described, it should be understood that aspects of the present disclosure may include only some of the described embodiments or combinations of various embodiments. Therefore, the present disclosure should not be considered to be limited by the foregoing description.

Claims

1. A method for controlling a brushed DC motor, the method comprising: determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining an initial voltage command based on the speed difference signal; determining a final voltage command based on the initial voltage command; applying a DC voltage to the brushed DC motor based on the final voltage command to cause the brushed DC motor to rotate a lead screw and thereby move a load along a path; determining a disturbance torque acting on the brushed DC motor; and modifying at least one of the final voltage command and the speed difference signal so that the brushed DC motor generates a compensation torque that offsets the disturbance torque, Wherein, modifying at least one of the final voltage command and the speed difference signal comprises at least one of the following: determining a feed-forward voltage command based on a position of the load along the path, and determining the final voltage command as a sum of the initial voltage command and the feed-forward voltage command; or A speed compensation signal is determined based on the disturbance torque, and the speed difference signal is determined further based on the speed compensation signal.

2. The method according to claim 1, further comprising: determining the feed-forward voltage command based on a position of the load along the path, and Wherein, modifying at least one of the final voltage command and the speed difference signal includes: determining the final voltage command as a sum of the initial voltage command and the feed-forward voltage command.

3. The method according to claim 2, wherein: Determining the feedforward voltage command includes: To determine the feedforward voltage command v ff , where R is the resistance of the brushed DC motor, K is the electromotive force constant, θ is the position of the load along the path, and τ LF (θ) is the disturbance torque as a function of the position θ of the load.

4. The method according to claim 1, further comprising: determining the speed compensation signal based on the disturbance torque so that the brushed DC motor generates a compensation torque to offset the disturbance torque, and Wherein, modifying at least one of the final voltage command and the speed difference signal includes: determining the speed difference signal further based on the speed compensation signal.

5. The method according to claim 4, wherein Determining the speed compensation signal includes: To determine the speed compensation signal ω(s), where T dist is the disturbance torque, L is the inductance of the brushed DC motor, s is a Laplace domain variable, R is the resistance of the brushed DC motor, D(s) is a transfer function describing the relationship between the speed difference signal and the final voltage command, and K m is the motor torque constant.

6. The method according to claim 1, wherein Determining the disturbance torque includes measuring the disturbance torque.

7. The method according to claim 1, wherein Determining the disturbance torque includes estimating the disturbance torque based on a motor current in the brushed DC motor and a motor speed of the brushed DC motor.

8. The method according to claim 7, wherein: Estimating the disturbance torque includes: To calculate the estimated disturbance torque, where J is the moment of inertia, is the derivative of the motor speed of the brushed DC motor, K m is the motor torque constant, i is the motor current in the brushed DC motor, b is the motor viscous friction constant, ω is the motor speed of the brushed DC motor, and T dist is the disturbance torque.

9. The method according to claim 7, wherein: Estimating the disturbance torque includes using a Lundberg observer according to To calculate the disturbance torque, is the derivative of the state estimator, x e is the state estimator, G is the observer gain matrix, and where: u is the DC voltage applied to the brushed DC motor, J is the moment of inertia, L is the inductance of the brushed DC motor, R is the resistance of the brushed DC motor, K b is the motor back EMF constant, K m is the motor torque constant, i is the motor current in the brushed DC motor, b is the motor viscous friction constant, ω is the motor speed of the brushed DC motor, and T dist is the disturbance torque.

10. A motor control system comprising: a brushed DC motor having sets of brushes and configured to rotate a lead screw and thereby move a load along a path; a voltage regulator configured to apply a DC voltage to the brushed DC motor based on a final voltage command; as well as The controller is configured as: determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining an initial voltage command based on the speed difference signal; determining the final voltage command based on the initial voltage command; determining a disturbance torque acting on the brushed DC motor via the lead screw; as well as modifying at least one of the final voltage command and the speed difference signal so that the brushed DC motor generates a compensation torque that offsets the disturbance torque, Wherein, modifying at least one of the final voltage command and the speed difference signal comprises at least one of the following: determining a feed-forward voltage command based on a position of the load along the path, and determining the final voltage command as a sum of the initial voltage command and the feed-forward voltage command; or A speed compensation signal is determined based on the disturbance torque, and the speed difference signal is determined further based on the speed compensation signal.

11. The motor control system according to claim 10, wherein: The controller is further configured to determine the feed-forward voltage command based on a position of the load along the path, and Wherein, modifying at least one of the final voltage command and the speed difference signal includes: determining the final voltage command as a sum of the initial voltage command and the feed-forward voltage command.

12. The motor control system according to claim 11, wherein: Determining the feedforward voltage command includes: To determine the feedforward voltage command v ff , where R is the resistance of the brushed DC motor, K is the electromotive force constant, θ is the position of the load along the path, and τ LF (θ) is the disturbance torque as a function of the position θ of the load.

13. The motor control system according to claim 10, wherein: The controller is further configured to determine the speed compensation signal based on the disturbance torque, and enable the brushed DC motor to generate a compensation torque to offset the disturbance torque, and Wherein, modifying at least one of the final voltage command and the speed difference signal includes: determining the speed difference signal further based on the speed compensation signal.

14. The motor control system according to claim 13, wherein: Determining the speed compensation signal includes: To determine the speed compensation signal ω(s), where T dist is the disturbance torque, L is the inductance of the brushed DC motor, s is a Laplace domain variable, R is the resistance of the brushed DC motor, D(s) is a transfer function describing the relationship between the speed difference signal and the final voltage command, and K m is the motor torque constant.

15. The motor control system according to claim 10, wherein: Determining the disturbance torque includes measuring the disturbance torque.

16. The motor control system according to claim 10, wherein: Determining the disturbance torque includes estimating the disturbance torque based on a motor current in the brushed DC motor and a motor speed of the brushed DC motor.

17. The motor control system according to claim 16, wherein: Estimating the disturbance torque includes: To calculate the estimated disturbance torque, where J is the moment of inertia, is the derivative of the motor speed of the brushed DC motor, K m is the motor torque constant, i is the motor current in the brushed DC motor, b is the motor viscous friction constant, ω is the motor speed of the brushed DC motor, and T dist is the disturbance torque.

18. The motor control system according to claim 16, wherein: Estimating the disturbance torque includes using a Lundberg observer according to To calculate the disturbance torque, is the derivative of the state estimator, x e is the state estimator, G is the observer gain matrix, and where: u is the DC voltage applied to the brushed DC motor, J is the moment of inertia, L is the inductance of the brushed DC motor, R is the resistance of the brushed DC motor, K b is the motor back EMF constant, K m is the motor torque constant, i is the motor current in the brushed DC motor, b is the motor viscous friction constant, ω is the motor speed of the brushed DC motor, and T dist is the disturbance torque.

19. A method for controlling a brushed DC motor, the method comprising: determining a speed difference signal based on a difference between a speed command signal and a motor speed of the brushed DC motor; determining an initial voltage command based on the speed difference signal; determining a final voltage command based on the initial voltage command; applying a DC voltage to the brushed DC motor based on the final voltage command; determining a disturbance torque acting on the brushed DC motor; as well as modifying the speed difference signal so that the brushed DC motor generates a compensation torque that offsets the disturbance torque, Wherein, modifying the speed difference signal comprises: determining a speed compensation signal based on the disturbance torque, and further determining the speed difference signal based on the speed compensation signal.

20. The method according to claim 19, wherein Determining the speed compensation signal includes: To determine the speed compensation signal ω(s), where T dist is the disturbance torque, L is the inductance of the brushed DC motor, s is a Laplace domain variable, R is the resistance of the brushed DC motor, D(s) is a transfer function describing the relationship between the speed difference signal and the final voltage command, and K m is the motor torque constant.

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