Motion sensing diagnostics for permanent magnet DC motor drives

Abstract

The invention relates to motion sensing diagnostics for permanent magnet DC motor drivers. Technical solutions for diagnosing sensor errors in an actuator having a permanent magnet DC (PMDC) motor are described, including: measuring, by a position sensor, a measured position of the PMDC motor; determining an estimated motor speed based on the measured position; measuring, by a current sensor, a measurement current in the PMDC motor; determining a voltage command for the PMDC motor based on the measured current in the PMDC motor; determining an observed speed of the PMDC motor based on the measured current and voltage commands and using a motor speed observer; determining a differential speed as a difference between the estimated motor speed and the observed speed; determining a sensor error based on the differential velocity; and performing an action in response to determining the sensor error.

Description

Background Technology

[0001] This disclosure relates to methods and systems for diagnosing motion sensors used in permanent magnet DC motors (such as brushed DC motors).

[0002] Permanent magnet DC motors (such as brushed DC motors) are used in a variety of applications. One such application is in power steering systems for vehicles. Column adjustment actuators provide the ability to dynamically adjust the spatial orientation of the steering wheel to enhance driver comfort and safety. This dual-track control is achieved by separately adjusting the translational positions of tilt and telescopic actuators for vertical and horizontal motion. Typically, a permanent magnet DC (PMDC) motor driver coupled to a lead screw mechanism is used to generate the necessary force, which is then determined by a position controller that acts partly on an estimated translational position signal. In cost-optimized applications, a single rotary position encoder is included to measure the motor position, making the entire mechanism susceptible to single-point failure, which can sometimes be dangerous. Summary of the Invention

[0003] According to one or more embodiments, a method for diagnosing sensor errors in an actuator having a permanent magnet DC (PMDC) motor includes: measuring a measured position of the PMDC motor by a position sensor; determining an estimated motor speed based on the measured position; measuring a measured current in the PMDC motor by a current sensor; determining a voltage command for the PMDC motor based on the measured current in the PMDC motor; determining an observed speed of the PMDC motor based on the measured current and voltage command and using a motor speed observer; determining a differential speed as the difference between the estimated motor speed and the observed speed; determining a sensor error based on the differential speed; and performing an action in response to determining the sensor error.

[0004] According to one or more embodiments, a motor control system includes: a position sensor configured to measure a measured position of a PMDC motor; a current sensor configured to measure a measured current in the PMDC motor; and a controller. The controller is configured to: determine an estimated motor speed based on the measured position; determine a voltage command for the PMDC motor based on the measured current in the PMDC motor; determine an observed speed of the PMDC motor based on the measured current and voltage command and using a motor speed observer; determine a differential speed as the difference between the estimated motor speed and the observed speed; determine a sensor error based on the differential speed; and perform an action in response to determining the sensor error.

[0005] According to one or more embodiments, a motor control system includes: a position sensor configured to measure a measured position of a PMDC motor; a current sensor configured to measure a measured current in the PMDC motor; a processor; and a memory. The memory includes instructions that, when executed by the processor, cause the processor to: determine an estimated motor speed based on the measured position; determine a voltage command for the PMDC motor based on the measured current in the PMDC motor; determine an observed speed of the PMDC motor based on the measured current and the voltage command and using a motor speed observer; determine a differential speed as the difference between the estimated motor speed and the observed speed; determine a sensor error based on the differential speed; and perform an action in response to determining the sensor error.

[0006] These and other advantages and features will become more apparent from the following description taken in conjunction with the accompanying drawings. Attached Figure Description

[0007] The subject matter of this disclosure is specifically pointed out and clearly stated in the claims at the end of the specification. The foregoing and other features and advantages of this disclosure will become apparent from the following detailed description taken in conjunction with the accompanying drawings, wherein:

[0008] Figure 1 A column position module (CPM) of a steering system in a vehicle according to various aspects of this disclosure is shown;

[0009] Figure 2 A schematic block diagram of a motor control system for controlling a brushed permanent magnet direct current (PMDC) motor according to various aspects of this disclosure is shown.

[0010] Figure 3 An electrical schematic diagram of a control system for a brushed DC motor according to various aspects of this disclosure is shown.

[0011] Figure 4 A schematic block diagram of a motion sensing diagnostic controller for a PMDC motor is shown according to various aspects of this disclosure;

[0012] Figure 5 A schematic block diagram of a PMDC motor according to various aspects of this disclosure is shown;

[0013] Figure 6 A block diagram illustrating the structure and data flow of an indication state observer according to various aspects of this disclosure is shown;

[0014] Figure 7 A schematic block diagram of a motor control system with a disturbance state observer and a speed estimator according to various aspects of this disclosure is shown.

[0015] Figure 8A schematic block diagram of a motor control system with a disturbance state observer and a speed estimator according to various aspects of this disclosure is shown.

[0016] Figure 9 A graph illustrating the actual and estimated motor positions over time according to various aspects of this disclosure is shown;

[0017] Figure 10 Graphs illustrating the actual speed, observed speed, and estimated motor speed of a PMDC motor according to various aspects of this disclosure are shown.

[0018] Figure 11 Examples are shown in the context of... Figure 10 A chart showing the difference in speed over the same time period;

[0019] Figure 12 A flowchart is shown outlining the steps of a method for diagnosing sensor errors in an actuator with a PMDC motor, according to various aspects of this disclosure. Detailed Implementation

[0020] The present disclosure will now be described with reference to the accompanying drawings, in which specific embodiments will be shown, and not to be limited thereto. It should be understood that the disclosed embodiments are merely illustrative of non-limiting embodiments of the present disclosure embodied in various forms and alternative forms. The drawings are not necessarily drawn to scale, and some features may be enlarged or reduced to show details of specific components. Therefore, the specific structural and functional details disclosed herein should not be construed as limiting, but are merely a representative basis for teaching those skilled in the art to employ the present disclosure in various ways.

[0021] 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 executing one or more software or firmware programs, combinational 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 subdivided.

[0022] This disclosure provides a motion sensing diagnostic scheme that uses an observer to estimate the speed of a permanent magnet DC (PMDC) motor in an actuator. The observed speed is compared with the estimated motor speed calculated from a position sensor, and adaptive threshold adjustment is used to detect position sensor faults, thereby improving system safety.

[0023] An adaptive threshold can be implemented to prevent false detections of faults that might trigger faults under certain conditions. For example, at very low speeds, the actuator's estimated speed may be inaccurate, so the adaptive threshold can be set relatively high to prevent false alarms that might otherwise occur. Additionally or alternatively, inaccurate resistance and / or inductance estimates may lead to inaccuracies in speed observations during certain conditions, and the adaptive threshold can be configured to prevent corresponding false alarms that might otherwise occur.

[0024] Referring now to the accompanying drawings, the technical solutions will be described with reference to specific embodiments, but are not limited thereto.

[0025] Figure 1 An exemplary embodiment of a column position module (CPM) 20 of a steering system in a vehicle is shown, which can control a PMDC motor using the disclosed systems and methods.

[0026] CPM 20 includes a steering shaft 22 configured to be attached to a steering wheel, also referred to as a steering wheel, which a person can use to steer the vehicle. CPM 20 includes a steering actuator 24 attached to the steering shaft. The steering actuator 24 can supplement the force applied by the person to provide power-assisted steering functionality. CPM 20 also includes a rake actuator motor 26 configured to control the vertical position of the steering wheel by moving the end of the steering shaft in the radial direction. CPM 20 also includes a telescopic actuator motor 28. Figure 1 (Not shown in the image), the telescopic actuator motor is configured to control the axial position of the steering wheel by moving the steering shaft 22 in the axial direction.

[0027] Any or all of the steering actuator 24, tilt actuator motor 26, and / or telescopic actuator motor 28 may comprise a brushed DC motor and can be controlled using the systems and methods of this disclosure. However, the systems and methods of this disclosure can be used with brushed DC motors in other applications of vehicles, such as steering actuators for electric power steering (EPS) systems. The systems and methods of this disclosure are not limited to use in vehicles but can be used with PMDC motors in a variety of different applications.

[0028] Figure 2 A schematic block diagram of a motor control system 50 for controlling PMDC motors 26, 28 is shown. In some embodiments, such as Figure 2As shown, PMDC motors 26 and 28 are brushed DC motors having groups of brushes 30 and 32 for transferring DC current from fixed terminals to rotor windings of the PMDC motors 26 and 28. The group of brushes 30 and 32 includes a first brush 30 configured to be connected to a power supply to receive DC current. The group of brushes 30 and 32 also includes a second brush 32 configured to be connected to a current sink (such as a ground terminal).

[0029] The motor control system 50 includes a controller 60. The controller 60 may include any suitable controller, such as an electronic control unit or other suitable controller. The controller 60 may be configured to control various functions, such as steering systems and / or various functions of the vehicle. The controller 60 may include a processor 62 and a memory 64. The processor 62 may include any suitable processor, such as the processor described herein. Alternatively or additionally, in addition to or excluding the processor 62, the controller 60 may include any suitable number of processors. The memory 64 may include a single disk, multiple disks (e.g., a hard disk drive), and / or an electronic non-volatile computer memory storage medium (e.g., a flash memory device). In some embodiments, the memory 64 may include flash memory, semiconductor (solid-state) memory, etc. The memory 64 may include random access memory (RAM), read-only memory (ROM), or a combination thereof. The memory 64 may include instructions that, when executed by the processor 62, cause the processor 62 to control at least various aspects of the vehicle. Alternatively or additionally, the memory 64 may include instructions that, when executed by the processor 62, cause the processor 62 to perform functions associated with the systems and methods described herein.

[0030] The controller 60 can be operatively connected to the voltage regulator 52. The voltage regulator 52 can be configured to apply a DC voltage v to the first brush 30 of the PMDC motors 26, 28. The voltage regulator 52 can be based on a voltage command V from the controller 60. * To generate DC voltage v.

[0031] In some embodiments, such as Figure 2 As shown, the motor control system 50 may include a current sensor 54, which is configured to measure the DC current supplied to the PMDC motors 26, 28 and transmit the motor current signal. The motor current signal, transmitted to controller 60, represents the actual motor current in the windings of PMDC motors 26 and 28. Alternatively, it may be as follows: Figure 2 As shown, the motor control system 50 may include a position sensor 56, which is configured to measure the rotational position of the PMDC motors 26, 28 and transmit the motor position signal. Transmitted to controller 60.

[0032] In some embodiments, controller 60 may perform the methods described herein. However, the methods described herein performed by controller 60 are not intended to be limiting, and any type of software executing on the controller or processor may perform the methods described herein without departing from the scope of this disclosure. For example, a controller (such as a processor executing software within a computing device) may perform the methods described herein.

[0033] Figure 3 An electrical schematic diagram of a control system for PMDC motors 26 and 28 is shown. As shown, the controller 60 and PMDC motors 26 and 28 define a voltage loop with a supply current of i. S And defines the battery voltage V between the two terminals of the power source (not shown). BATT The controller power supply voltage V between the two ends of the controller 60 ECU .like Figure 3 As shown, the voltage loop includes the battery harness resistor R in the current path between the battery and the controller 60. BH The voltage loop also includes the controller input resistor R within the controller 60. C Its relationship with the battery harness resistance R BH Series connection. PMDC motors 26 and 28 in Figure 3 The diagram is shown as including an inductor, a resistor, and a voltage source connected in series, representing the winding inductance, the coil resistance, and the back electromotive force, respectively.

[0034] Figure 4 A schematic block diagram of a motion sensing diagnostic controller 70 for a PMDC motor is shown. The motion sensing diagnostic controller 70 can be implemented in software, hardware, or a combination of both. In some embodiments, a processor 62 can execute instructions to implement the motion sensing diagnostic controller 70. The motion sensing diagnostic controller 70 processes motor position signals from a position sensor 56. and motor current signal from current sensor 54 As input.

[0035] The motion sensing diagnostic controller 70 includes a position estimator 72 configured to base its position on a motor position signal from the position sensor 56. To determine the estimated motor position For example, the position estimator 72 can apply a scaling factor and / or offset to the motor position signal. To calculate the estimated motor position The motion sensing diagnostic controller 70 includes a current estimator 82 configured to base its signal on a motor current signal from a current sensor 54. To determine the estimated motor current For example, the current estimator 82 can apply a scaling factor and / or offset to the motor current signal. To calculate the estimated motor current

[0036] The motion sensing diagnostic controller 70 also includes a speed estimator 74, which is configured to base its speed on the estimated motor position. To determine the estimated motor speed For example, the speed estimator 74 can calculate the estimated motor speed. As estimated motor position The derivative over time.

[0037] In some cases, when the PMDC motors 26 and 28 have relatively low speeds, the motor position signal... It may have relatively low resolution. For example, in the case where position sensor 56 includes a position encoder, the position signal... The resolution may be low at lower speeds. Therefore, the estimated motor speed... It may exhibit significant quantization noise. Using a simple derivative operator consisting of pure derivatives along with a low-pass filter reduces the velocity noise, but at the cost of degraded estimated dynamics. The velocity error threshold can be adjusted based on the rotational speed of the PMDC motors 26 and 28 to avoid incorrect indications of sensor errors. It can also be based on the observed velocity. To adjust the velocity error threshold. For example, when observing velocity. When the speed is below the low speed threshold, the speed error threshold can be increased or the speed error threshold can be set to a predetermined value.

[0038] The motion sensing diagnostic controller 70 also includes a motor speed observer 84, which is configured to base its speed on an estimated motor current. To determine the observer-based velocity, which can also be referred to as the observation velocity. For example, the motor speed observer 84 can use a disturbance observer based on the motor electromagnetic model to calculate the observed speed. However, different observer designs can be used to calculate the observation rate. The motion sensing diagnostic controller 70 also includes a motor current controller 86, which is configured to base its decisions on the estimated motor current. Determine the voltage command V * The voltage command V can be used. * The voltage is sent to voltage regulator 52 to generate the DC voltage to be applied to PMDC motors 26, 28. In some embodiments, such as Figure 4 As shown, the voltage command V will also be applied. *The signal is sent to the motor speed observer 84, and the motor speed observer further bases the signal on the voltage command V. * Determine the observation speed

[0039] The motion sensing diagnostic controller 70 also includes a motion sensing diagnostic component 76, which is configured to perform motion sensing diagnostics based on observed velocity. and estimated motor speed To selectively indicate sensor errors. The motion sensing diagnostic component 76 includes a velocity difference calculator 90, which is configured to determine the difference velocity Δω as the observed velocity. With the estimated motor speed The motion sensing diagnostic component 76 also includes a motion sensing error detector 94, which is configured to selectively generate a fault signal F when the differential velocity Δω exceeds a velocity error threshold. For example, the motion sensing error detector 94 may include a comparator configured to compare whether the differential velocity Δω exceeds the value of the velocity error threshold. Therefore, the fault signal F may indicate a failure of the position sensor 56.

[0040] One or more actions can be performed based on the fault signal F. For example, controller 60 can generate a diagnostic fault code (DTC) and / or generate a warning message to notify the operator of the sensor error. In some embodiments, controller 60 can communicate the message about the fault signal F to an external controller (such as a supervisory controller). In some embodiments, controller 60 can perform one or more actions to mitigate the effects of the sensor error, such as operating the PMDC motor in a reduced capacity manner, replacing the PMDC motors 26 and 28 with redundant motors, or based on observed speed. To control the operation of PMDC motors 26 and 28.

[0041] In some embodiments, such as Figure 4 As shown, the motion sensing diagnostic component 76 also includes an adaptive threshold calculator 92 configured to adjust a speed error threshold. For example, the adaptive threshold calculator 92 can dynamically adjust the speed error threshold based on the operating conditions of the actuator. Since the expected speed error at any given time depends on the type of position sensor, the structure of the speed estimator 74, and the characteristics of the motor speed observer 84, the speed error threshold can be determined based on available signals that provide such information.

[0042] The observer is susceptible to errors in motor parameter estimation, which in turn depend on motor current and temperature. Therefore, a scheme to adjust the speed error threshold using appropriate signals can be adopted to enhance diagnostic robustness.

[0043] In sensor-based speed estimation techniques, the measured motor position is utilized. To determine the estimated motor speed like Figure 4 As shown. The motor position signal can be based on the position signal from position sensor 56. And using the derivative with a low-pass filter To determine the estimated motor speeds of PMDC motors 26 and 28. The derivative term can be approximated using different techniques and can be written as equation (1):

[0044]

[0045] The low-pass filter frequency, which approximates the derivative, must be carefully selected to attenuate noise in the estimated signal. The low-pass filter frequency can be determined by performing a sensitivity analysis for a given application.

[0046] This disclosure provides a method for using current sensor information and command voltage V. * Determine the observation speed Observer-based estimation methods, such as Figure 4 As shown. This article references... Figure 8 One method is described in which a disturbance observer is implemented to estimate the motor speed. The disturbance observer can be implemented using equation (2). However, different observer designs can be used to calculate the observed speed.

[0047]

[0048] in and These represent the estimated results for the motor resistance and inductance, respectively. V * I a and These represent the observed disturbance, command voltage, actual motor current, and estimated motor current, respectively, with L1 and L2 representing the observer gain. Observed disturbance It can represent back electromotive force and brush voltage drop. The combination of .

[0049] Subsequently, observation speed Equation (3) can be used to extract:

[0050]

[0051] in and The estimated results of the brush voltage drop and the back electromotive force constant of the motor are represented, respectively. These two speed estimates are then used to calculate the differential speed Δ in real time, as shown in equation (4). This helps to indicate faults caused by position sensor failure, because the observed speed... It is unrelated to the measurement results from the position sensor.

[0052]

[0053] Where the difference velocity Δω represents the observation velocity With the estimated motor speed The estimated motor speed is the difference between the speed and the sensor values, based on measurements from the sensor. Under normal operation, the speed difference Δω should be within a speed error threshold. However, during position sensor failure, Δω may exceed the speed error threshold. The speed error threshold can depend on the type of position sensor, the type of speed estimation technique, and / or the observer design. In some embodiments, the speed error threshold can be dynamically adjusted.

[0054] Figure 5 A schematic block diagram of a controlled body model of a brushed PMDC motor 200 according to various aspects of the present disclosure is shown, which may represent PMDC motors 26, 28 of CPM 20.

[0055] The controlled body model of the electrical subsystem of the brushed PMDC motor 200 is partially represented by the controlled body module 210. In one or more examples, the controlled body module 210 models the electrical subsystems of the PMDC motors 26 and 28. The controlled body module 210 receives a voltage signal 220 (V) as input and generates a current signal 230 (I). a As output. In one or more examples, the disturbance estimation result 240(D) ​​affects the voltage signal 220, as shown in the figure. The disturbance estimation result 240 can be BEMF and brush voltage drop v. B The sum of all components. In one or more examples, the PMDC motor 200 includes additional components such as a delay compensation module.

[0056] Typically, observer design is performed by utilizing a model of the controlled entity from which its state variables are to be extracted. In the case of PMDC motors 26 and 28, the controlled entity is the electrical subsystem of the PMDC motor, which can be modeled using equations (5) to (6):

[0057]

[0058] T e =K e i a (6)

[0059] Where Ke R and L are the BEMF constant, resistance, and inductance of the motor, respectively; V and i a and T e For the motor's voltage input, current, and electromagnetic torque, v B For the brush voltage drop, and ω m This represents the motor speed.

[0060] Brush voltage drop v B It can be nonlinear and can be described as in equation (7):

[0061]

[0062] Among them, σ(i) a () refers to the symbol for current, and the quantities V0 and I0 are state variables of the function.

[0063] The disturbance term d is defined as the back electromotive force K. e ω m Term and brush voltage drop v B The negative value of the sum of the terms is shown in equation (8):

[0064] d=-(K e ω m +v B (8)

[0065] In addition, the electrical parameters of PMDC motors 26 and 28 (i.e., back electromotive force constant or torque constant K) e The resistance R and inductance L change dynamically with the operating conditions of the PMDC motors 26 and 28. For a given magnet temperature θ... Tm The parameter change control equation can be expressed as equation (9):

[0066]

[0067] in To account for the scaling factor of magnetic saturation, and for the motor current i a The function is α. Furthermore, α is a constant representing the thermal coefficient of the permanent magnet material used in motors 26 and 28.

[0068] Furthermore, the inductance L of PMDC motors 26 and 28 can be described by equation (10):

[0069] L = γ L L n (10)

[0070] Where γ L The scaling factor of the inductance is based on the magnetic saturation characteristics of PMDC motors 26 and 28, and the motor current I is... a The function.

[0071] Furthermore, the motor circuit resistance R can be described by equation (11):

[0072] R = R FET (1+α si (θ TSi -θ n ))+R m (1+α Cu (θ TCu -θ n (11)

[0073] Where R FET α is the nominal value of the FET resistance. Si θ is a constant representing the thermal coefficient of silicon. TSi θ represents the temperature of the FET under operating conditions. n To measure R below FET The nominal temperature, R m α is the nominal value of the motor resistance. Cu θ is a constant representing the thermal coefficient of the copper winding. TCu θ represents the temperature of the winding under operating conditions. n To measure R below m The nominal temperature.

[0074] The resistance equations described above provide the resistance of the motor circuit, not just the resistance of the motor windings. In one or more examples, the aforementioned parameter variation model is used to continuously estimate motor parameters in real-time or near real-time, enabling improved estimation of the signals used by the motor control system.

[0075] Furthermore, a piecewise observer structure can be used to transform the nonlinear brush voltage drop term v B Linearization is used for specific applications in motor control systems. Alternatively, as previously mentioned, the brush voltage drop term v B Together with BEMF, it can be cumulatively calculated as a disturbance term d240, which can be directly estimated using estimation techniques. It should be noted that the disturbance value d can be calculated in the presence of integral control for current regulation.

[0076] Therefore, by calculating the brush voltage drop term, the technical solution presented in this paper further facilitates the determination of the observer's behavior in terms of dynamic response, accuracy, and convergence speed estimation.

[0077] The previously proposed time-domain model of the PMDC motor can be transformed into the s-domain, as shown in equation (12):

[0078] V(s)=(Ls+R)I a (s)+D(s), (12)

[0079] Another representation of the controlled body model of the electrical subsystem of PMDC motors 26 and 28 using state space representation is given in continuous time by equations (13) to (14).

[0080]

[0081] y = Cx (14)

[0082] Where x is a state vector including the values ​​of the current state of EPS system 12, u is an input vector including the measurable (and controllable) inputs of EPS system 12, and D is a disturbance estimation result 240, including uncontrollable measurable values, and is generally nonlinear in nature. Furthermore, y is an output vector based on the current state x of EPS system 12. A, B, C, and E are configurable matrices set up to model the PMDC motors 26, 28 of EPS system 12. In one or more examples, the matrices may be pre-configured.

[0083] Figure 6 One or more components and data flows of a state observer module according to one or more embodiments are illustrated. Observer module 300 includes a state estimator 310 that calculates or estimates one or more state variables of a controlled body model. As shown, state estimator 310 uses the same control signal input applied to controlled body module 210 to drive the controlled body model 320 of the brushed PMDC motor 200 and updates the state variables of state estimator 310 until the state estimator output is driven to become equal to the measured system output. State estimator 310 receives the measured system output or intermediate signals via one or more sensors 330. The estimated state variables can then be used for any purpose within the PMDC motor control system. In one or more examples, state estimator 310 models a disturbance d 240 as a state variable.

[0084] In the described model, L is a matrix that includes the observer gain and is modified to achieve desired observer characteristics, such as bandwidth. For example, for a linear observer, the gain is a scalar value and acts on the difference between the measured system output and the estimated system output. However, it should be noted that this disclosure is not limited to such observers, and other observer structures, such as nonlinear estimators, may also be employed. For example, a sliding-mode observer may be used, in which the state variables are updated according to a scalar gain acting on the sign of the output error. Furthermore, reduced-order implementations of linear and nonlinear observers can also be used to estimate disturbance terms and motor speeds.

[0085] Furthermore, the disturbance estimate 240 is considered to be the state of system 12 with unknown initial conditions. Under this assumption, the derivative of the unknown step function is zero, and therefore the modified controlled volume model can be written as equation (15):

[0086]

[0087] Furthermore, the linear model of the perturbation observer module 410 is given by equation (16):

[0088]

[0089] in For the estimated current, For the estimated disturbance, For the estimated motor circuit resistance, L1 and L2 are the observer gains, representing the estimated inductance. Several different gain tuning strategies (including linear quadratic Gaussian (LQG) estimators, pole placement, etc.) can be used to obtain the observer gain. However, the technique described in this paper implements observer gain scheduling to facilitate improved tuning capability, thereby producing a single adjustable parameter. Specifically, the gain is selected such that the observer poles are scalar x times faster than the controlled volume poles. For example, the observer error estimation results are given by equations (17) to (18):

[0090]

[0091] For example, when the estimated parameters are the same as the actual parameters, the error dynamics between the controlled body and the observer are obtained, as shown in equation (19):

[0092]

[0093] The characteristic equation of the error dynamics matrix is ​​compared with the root ratio of the controlled body poles. Comparing the characteristic equations of x times faster, the observer gains L1 and L2 are given by equations (20) to (21):

[0094]

[0095] Therefore, the observer equation is given by equation (22):

[0096]

[0097] The stability and achievable bandwidth of an observer can be limited by the sampling time of the control loop that implements the observer. Therefore, the calculation of the worst-case scalar k, which could destabilize the observer, is performed offline and used to limit the adjustable value of k to prevent instability. Furthermore, it should be noted that the scalar k can also be scheduled as a function of multiple signals in the system, such as measured current, velocity estimates, vehicle speeds, etc.

[0098] Figure 7A block diagram of an example motor control system 400 with improvements facilitated by the technical features described herein is shown. As shown, in addition to the controlled body module 210, the motor control system 400 includes components such as a disturbance observer module 410 and a current controller 420. In one or more examples, the disturbance observer module 410 is referred to as... Figure 6 The state estimator 310. In one or more examples, components such as the disturbance observer module 410 include hardware components such as ASICs, FPGAs, etc. Alternatively or additionally, the module includes computer-executable instructions embedded in memory that can be executed by a processing unit such as the control module 40.

[0099] In one or more examples, the current controller 420 is a PI controller that controls the input voltage signal V220 applied to the PMDC motors 26, 28 to generate a current I. A 230, and subsequently controls the PMDC motors 26 and 28 to operate at the desired speed. The current controller 420 receives the current signal I. R It serves as the input and also receives the output current I. A 230 serves as feedback to calculate the error term and control the input voltage signal V 220. As described herein, the current controller 420 has adjusted the input current reference or command I based on the feedback. R Subsequently, the disturbance D240 affects the input voltage signal 220.

[0100] Therefore, in order to determine the disturbance D240, the disturbance observer module 410 receives the voltage signal 220 and the output current I. A 230. As shown in the figure, the transfer matrix for the motor control system 200 is given by equation (23):

[0101]

[0102] Therefore, based on the above equation (23), the disturbance observer module 410 determines the disturbance value D 240 based on the values ​​input to the gain matrices L and L2. As previously described, by using a linear observer, the gain matrix can be tuned to a single parameter. Thus, the gain scheduling of the linear observer improves the ability of the motor control system to determine the disturbance value D 240, thereby producing the single scalar adjustable parameter x described herein. Compared to a motor control system using a state observer module without estimating the disturbance estimate 240, the disturbance observer module 410 facilitates improved dynamic performance while maintaining similar steady-state sensitivity to modeling errors.

[0103] Figure 8An example motor control system 400 is shown, according to one or more embodiments, using a calculated disturbance estimation result 240 to estimate a motor speed signal. In addition to components described elsewhere, the brushed PMDC motor 200 also includes a speed module 510. The speed module 510 receives the calculated (or observed) output of the disturbance observer module 410 and extracts and outputs the motor speed. As previously described, the perturbation estimate 240 is estimated based on equation (8).

[0104] Therefore, the speed module 510 uses the model-based (feedforward type) brush voltage drop estimation result along with K e The estimated motor speed is extracted from the estimation results. As illustrated in equation (24):

[0105]

[0106] in and The state variables are estimates of the function. It should be noted that, as used throughout this document, the “corner cap” (^) indicates an estimated version of the true parameters.

[0107] Figure 9 A graph illustrating the actual and estimated motor positions over time according to various aspects of this disclosure is shown. Figure 9 This includes a first graph 602 showing the actual motor position and a graph showing the motor position signal corresponding to the position sensor 56. The second curve 604 shows the estimated position. Motor position signal. The resolution may depend on the type of device used for the position sensor 56.

[0108] Figure 10 The diagram shows a first curve 612 illustrating the actual velocity and an example of the observed velocity. The second speed curve, Figure 614, and the example of the estimated motor speed. The third graph, 616, shows each graph on a common timescale of 0 to 10 seconds. As shown, the observation velocity... The speed is tracked so closely that the corresponding curves 612 and 614 are almost indistinguishable.

[0109] Figure 11 A graph with a fourth curve 618 is shown, which illustrates the relationship with... Figure 10 The difference velocity Δω on the same common time scale in the graph. For example... Figures 10 to 11 As shown, the estimated motor speed The descent begins at time 5.0 seconds, indicating a failure of position sensor 56. From the same time, the differential velocity Δω increases rapidly. This increase in differential velocity Δω can be used to determine the failure of position sensor 56.

[0110] Figure 12 A flowchart is shown outlining the steps of a method 700 for diagnosing sensor errors in an actuator with a PMDC motor according to various aspects of this disclosure. Method 700 may be performed at least in part by a motor control system 50 of this disclosure. It will be understood from this disclosure that the sequence of operations within this method is not limited to... Figure 12 The execution may not be performed in the order illustrated herein, but may be performed in one or more different orders as applicable and in accordance with this disclosure.

[0111] In some embodiments, the PMDC motor includes a brushed PMDC motor having brushes for transferring DC current from a fixed terminal to a rotor winding.

[0112] In some embodiments, the PMDC motor may be an actuator motor configured to control the position of the steering wheel in a vehicle's steering system. However, method 700 may be implemented for other PMDC motors in other applications.

[0113] At point 702, method 700 measures the position of the PMDC motor using a position sensor. For example, position sensor 56 can measure the rotational position of PMDC motors 26 and 28 and transmit the motor position signal. Transmitted to controller 60.

[0114] At 704, method 700 determines the estimated motor speed based on the measured position. For example, processor 62 can execute instructions to implement position estimator 72 and speed estimator 74 to determine the estimated motor speed based on the motor position signal. To calculate the estimated motor speed

[0115] At 706, method 700 measures the current in the PMDC motor using a current sensor. For example, current sensor 54 can measure the DC current supplied to PMDC motors 26, 28 and transmit the motor current signal. The motor current signal, transmitted to controller 60, represents the actual motor current in the windings of PMDC motors 26 and 28.

[0116] At 708, method 700 determines the voltage command for the PMDC motor based on the measured current in the PMDC motor. For example, processor 62 can execute instructions to implement motor current controller 86 to determine the voltage command based on the estimated motor current. Determine the voltage command V * .

[0117] At 710, method 700 determines the observed speed of the PMDC motor based on measured current and voltage commands and using a motor speed observer. For example, processor 62 can execute instructions to implement motor speed observer 84 to determine the observed speed of the PMDC motor based on the estimated motor current from current estimator 82. and voltage command V from motor current controller 86 * Determine the observation speed

[0118] At 712, method 700 determines the differential speed as the difference between the estimated motor speed and the observed speed. For example, processor 62 can execute instructions to implement speed difference calculator 90 to determine the differential speed Δω as the observed speed. With the estimated motor speed The difference between them.

[0119] At 714, method 700 determines the sensor error based on the differential velocity. For example, processor 62 can execute instructions to implement motion sensing error detector 94 to compare the differential velocity with a velocity error threshold and selectively generate a fault signal F when the differential velocity Δω exceeds the velocity error threshold. Thus, generating the fault signal F can represent the determination result of the sensor error.

[0120] In some embodiments, the method further includes adjusting a speed error threshold based on the operating conditions of the actuator. For example, processor 62 may execute instructions to implement an adaptive threshold calculator 92 to adjust the speed error threshold.

[0121] In some embodiments, adjusting the velocity error threshold includes further adjusting the velocity error threshold based on the observed velocity. In some embodiments, adjusting the velocity error threshold includes increasing the velocity error threshold based on the observed velocity being less than a low velocity threshold.

[0122] At 716, method 700 performs an action in response to determining a sensor error. For example, processor 62 may execute instructions to implement motion sensing error detector 94 to compare the differential velocity with a velocity error threshold and selectively generate a fault signal F when the differential velocity Δω exceeds the velocity error threshold. Additionally or alternatively, processor 62 may also generate and / or store diagnostic fault codes (DTCs), notify the operator of the sensor error, communicate the sensor error, and / or perform actions to mitigate the effects of the sensor error.

[0123] This disclosure provides a method for diagnosing sensor errors in an actuator having a permanent magnet DC (PMDC) motor. The method includes: measuring a measured position of the PMDC motor by a position sensor; determining an estimated motor speed based on the measured position; measuring a measured current in the PMDC motor by a current sensor; determining a voltage command for the PMDC motor based on the measured current; determining an observed speed of the PMDC motor based on the measured current and voltage command and using a motor speed observer; determining a differential speed as the difference between the estimated motor speed and the observed speed; determining a sensor error based on the differential speed; and performing an action in response to determining the sensor error.

[0124] In some embodiments, determining the sensor error further includes comparing the differential speed with a speed error threshold, and the method further includes adjusting the speed error threshold based on the operating condition of the actuator.

[0125] In some embodiments, adjusting the velocity error threshold includes: further adjusting the velocity error threshold based on the observed velocity.

[0126] In some embodiments, adjusting the velocity error threshold includes increasing the velocity error threshold based on the observed velocity being less than a low velocity threshold.

[0127] In some embodiments, the PMDC motor includes a brushed PMDC motor having brushes for transferring DC current from a fixed terminal to a rotor winding.

[0128] In some embodiments, a PMDC motor is an actuator motor configured to control the position of the steering wheel in a vehicle's steering system.

[0129] In some embodiments, performing an action in response to determining a sensor error includes at least one of the following: generating a diagnostic fault code; and notifying an operator of the sensor error.

[0130] In some embodiments, performing an action in response to determining a sensor error includes performing an action to mitigate the effect of the sensor error.

[0131] This disclosure provides a motor control system. The motor control system includes: a position sensor configured to measure a measured position of a PMDC motor; a current sensor configured to measure a measured current in the PMDC motor; and a controller. The controller is configured to: determine an estimated motor speed based on the measured position; determine a voltage command for the PMDC motor based on the measured current in the PMDC motor; determine an observed speed of the PMDC motor based on the measured current and voltage command and using a motor speed observer; determine a differential speed as the difference between the estimated motor speed and the observed speed; determine a sensor error based on the differential speed; and perform an action in response to determining the sensor error.

[0132] In some embodiments, the controller is also configured to: compare the differential speed with a speed error threshold; and adjust the speed error threshold based on the operating conditions of the PMDC motor.

[0133] In some embodiments, the controller is configured to further adjust the velocity error threshold based on the observed velocity.

[0134] In some embodiments, the controller is configured to increase the speed error threshold based on the observed speed being less than a low speed threshold.

[0135] In some embodiments, the PMDC motor includes a brushed PMDC motor having brushes for transferring DC current from a fixed terminal to a rotor winding.

[0136] In some embodiments, a PMDC motor is an actuator motor configured to control the position of the steering wheel in a vehicle's steering system.

[0137] In some embodiments, performing an action in response to determining a sensor error includes the controller performing at least one of the following: generating a diagnostic fault code; and notifying the operator of the sensor error.

[0138] In some embodiments, performing an action in response to determining a sensor error includes: the controller performing an action to mitigate the effects of the sensor error.

[0139] This disclosure provides a motor control system. The motor control system includes: a position sensor configured to measure a measured position of a PMDC motor; a current sensor configured to measure a measured current in the PMDC motor; a processor; and a memory. The memory includes instructions that, when executed by the processor, cause the processor to: determine an estimated motor speed based on the measured position; determine a voltage command for the PMDC motor based on the measured current in the PMDC motor; determine an observed speed of the PMDC motor based on the measured current and the voltage command and using a motor speed observer; determine a differential speed as the difference between the estimated motor speed and the observed speed; determine a sensor error based on the differential speed; and perform an action in response to determining the sensor error.

[0140] In some embodiments, these instructions also cause the processor to: compare the differential speed with a speed error threshold; and adjust the speed error threshold based on the operating conditions of the PMDC motor.

[0141] In some embodiments, these instructions also enable the processor to further adjust the velocity error threshold based on the observed velocity.

[0142] In some embodiments, these instructions also cause the processor to increase the speed error threshold based on the observed speed being less than a low speed threshold.

[0143] While this disclosure has been described in detail with reference to only a limited number of embodiments, it should be readily understood that this disclosure is not limited to these disclosed embodiments. Rather, this disclosure may be modified to include any number of variations, alterations, substitutions, or equivalent arrangements not previously described but equivalent in scope to this disclosure. Furthermore, although various embodiments of this disclosure have been described, it should be understood that aspects of this disclosure may include only some embodiments or combinations of various embodiments described. Therefore, this disclosure should not be considered as limited to the foregoing description.

Claims

1. A method for diagnosing sensor errors in an actuator with a permanent magnet DC (PMDC) motor, comprising: The position of the PMDC motor is measured by a position sensor; The estimated motor speed is determined based on the measured location; The measured current in the PMDC motor is measured by a current sensor; The voltage command for the PMDC motor is determined based on the measured current in the PMDC motor. The observed speed of the PMDC motor is determined based on the measured current and the voltage command, and using a motor speed observer. The differential speed is defined as the difference between the estimated motor speed and the observed speed; The sensor error is determined based on the differential velocity. as well as An action is performed in response to determining the sensor error.

2. The method according to claim 1, wherein, Determining the sensor error further includes: comparing the differential velocity with a velocity error threshold, and The method further includes adjusting the speed error threshold based on the operating status of the actuator.

3. The method according to claim 2, wherein, Adjusting the velocity error threshold includes further adjusting the velocity error threshold based on the observed velocity.

4. The method according to claim 3, wherein, Adjusting the velocity error threshold includes increasing the velocity error threshold based on the observed velocity being less than a low velocity threshold.

5. The method according to claim 1, wherein, The PMDC motor includes a brushed PMDC motor having brushes for transferring DC current from a fixed terminal to a rotor winding.

6. The method according to claim 1, wherein, The PMDC motor is an actuator motor configured to control the position of the steering wheel in the steering system of a vehicle.

7. The method according to claim 1, wherein, Performing the action in response to determining the sensor error includes at least one of the following: generating a diagnostic fault code; as well as Inform the operator of the sensor error.

8. The method according to claim 1, wherein, Performing the action in response to determining the sensor error includes: performing an action to mitigate the effect of the sensor error.

9. A motor control system, comprising: A position sensor is configured to measure the position of the PMDC motor; A current sensor is configured to measure the current in the PMDC motor. as well as The controller is configured as follows: The estimated motor speed is determined based on the measured location; The voltage command for the PMDC motor is determined based on the measured current in the PMDC motor. The observed speed of the PMDC motor is determined based on the measured current and the voltage command, and using a motor speed observer. The differential speed is defined as the difference between the estimated motor speed and the observed speed; The sensor error is determined based on the differential velocity. as well as An action is performed in response to determining the sensor error.

10. The motor control system according to claim 9, wherein, The controller is also configured to: The differential speed is compared with a speed error threshold, and The speed error threshold is adjusted based on the operating status of the PMDC motor.

11. The motor control system according to claim 10, wherein, The controller is configured to further adjust the velocity error threshold based on the observed velocity.

12. The motor control system according to claim 11, wherein, The controller is configured to increase the speed error threshold based on the observed speed being less than a low speed threshold.

13. The motor control system according to claim 9, wherein, The PMDC motor includes a brushed PMDC motor having brushes for transferring DC current from a fixed terminal to a rotor winding.

14. The motor control system according to claim 9, wherein, The PMDC motor is an actuator motor configured to control the position of the steering wheel in the steering system of a vehicle.

15. The motor control system according to claim 9, wherein, Responding to determining the sensor error by performing the action includes the controller performing at least one of the following: generating a diagnostic fault code; and notifying the operator of the sensor error.

16. The motor control system according to claim 9, wherein, Responding to determining the sensor error and performing the action includes: the controller performing an action to mitigate the effect of the sensor error.

17. A motor control system, comprising: A position sensor is configured to measure the position of the PMDC motor; A current sensor is configured to measure the current in the PMDC motor. Processor; and The memory includes instructions that, when executed by the processor, cause the processor to: The estimated motor speed is determined based on the measured location; The voltage command for the PMDC motor is determined based on the measured current in the PMDC motor. The observed speed of the PMDC motor is determined based on the measured current and the voltage command, and using a motor speed observer. The differential speed is defined as the difference between the estimated motor speed and the observed speed; The sensor error is determined based on the differential velocity. as well as An action is performed in response to determining the sensor error.

18. The motor control system according to claim 17, wherein, The instruction also causes the processor to: The differential speed is compared with a speed error threshold, and The speed error threshold is adjusted based on the operating status of the PMDC motor.

19. The motor control system according to claim 18, wherein, The instruction also causes the processor to further adjust the velocity error threshold based on the observed velocity.

20. The motor control system according to claim 19, wherein, The instruction also causes the processor to increase the speed error threshold based on the observation speed being less than a low speed threshold.

Images