Stepper motors and their motion control methods

Abstract

This invention discloses a stepper motor and its motion control method. The method includes the following steps: S1, setting the target position of the stepper motor; S2, determining the current motion state of the stepper motor; S3, determining the motor motion control strategy based on the current motion state of the stepper motor; S4, controlling the stepper motor to move to reach the target position according to the control strategy. This invention proposes different control strategies for different motor operating conditions, making the control strategy more targeted, significantly improving the positioning accuracy of the stepper motor, mitigating the influence of motor inertia, and further improving the stability and reliability of the adaptive high and low beam lighting system.

Description

Technical Field

[0001] This invention relates to the field of vehicle lighting motor control technology, and in particular to a stepper motor and its motion control method. Background Technology

[0002] Vehicle lights are tools used to illuminate roads at night and to signal various driving conditions. Vehicle lights are generally divided into headlights, taillights, turn signals, etc.

[0003] An adaptive high beam system is a system consisting of a sensor array, transmission path, processor, and actuators (such as a stepper motor). Adaptive high beam systems play a significant role in improving nighttime driving safety. They utilize cameras located in the rearview mirrors to detect vehicles ahead, with a detection range of up to 400 meters. If an oncoming vehicle is detected, the system selectively blocks the high beam, directing it away from the oncoming traffic. This ensures the driver's clear vision without affecting the oncoming vehicle, eliminating the need for the driver to frequently switch between high and low beams to avoid glare. When the system detects no vehicles ahead, it automatically switches back to high beam.

[0004] For example, adaptive high beam lighting systems can adjust the cutoff line of high and low beams by controlling the extension and retraction of stepper motors, thereby adjusting the illumination range. Stepper motors typically require acceleration, deceleration, and reversal during operation. However, in actual use, stepper motors often experience overcharging or step loss due to inertia, resulting in a movement distance that does not match the expected range. Summary of the Invention

[0005] The technical problem to be solved by the present invention is: in order to solve the problem of low motion accuracy of existing stepper motors, the present invention provides a stepper motor and its motion control method, which can control the stepper motor according to its motion state, thereby improving the accuracy of the stepper motor's motion stroke.

[0006] The technical solution adopted by this invention to solve its technical problem is: a motion control method for a stepper motor, comprising the following steps:

[0007] S1. Set the target position of the stepper motor;

[0008] S2. Determine the current motion state of the stepper motor;

[0009] S3. Determine the control strategy for the motor motion based on the current motion state of the stepper motor;

[0010] S4. According to the control strategy, control the stepper motor to move to reach the target position.

[0011] This can mitigate the effects of motor inertia and significantly improve the positioning accuracy of the stepper motor.

[0012] Furthermore, the motion states include: stationary state, acceleration state, uniform speed state, and deceleration state.

[0013] Furthermore, when the stepper motor is stationary, if the stepper motor receives a command to set a target position, the control strategy is as follows:

[0014] Determine the distance L0 between the current position of the stepper motor and the target position;

[0015] Calculate the pulse signal corresponding to the stepper motor acceleration a based on the distance L0;

[0016] Set the operating current of the stepper motor, and send the pulse signal to the stepper motor after a 50ms delay.

[0017] Furthermore, when the stepper motor is stationary, if the stepper motor receives a command to set a target position, the control strategy is as follows:

[0018] Determine the distance L1 between the current position of the stepper motor and the target position;

[0019] The stepper motor acceleration a and the pulse signal corresponding to constant speed are calculated based on the distance L1.

[0020] Set the operating current of the stepper motor, and send the pulse signal to the stepper motor after a 50ms delay.

[0021] Furthermore, when the stepper motor is in acceleration or deceleration mode, if the stepper motor receives a command to set the target position, it will issue a setting failure signal.

[0022] Furthermore, when the stepper motor is in a constant speed state, if the stepper motor receives an instruction to set a new target position, the new target position is compared with the current position of the stepper motor to obtain a comparison result; and then a control strategy is output based on the comparison result.

[0023] Furthermore, the comparison results include: the new target position is greater than the current position of the stepper motor, and the new target position is less than the current position of the stepper motor.

[0024] Furthermore, when the new target position is greater than the current position of the stepper motor,

[0025] Calculate the step difference A between the new target position and the current position of the stepper motor;

[0026] If the step difference A is greater than the deceleration step B of the stepper motor, then calculate the number of constant speed steps AB that the stepper motor needs to reach the new target position;

[0027] Control the stepper motor to continue moving at a constant speed for AB pulse signals, then decelerate for B pulse signals to reach the new target position;

[0028] If the step difference A is less than the stepper motor's deceleration step B, then the stepper motor is first controlled to decelerate by B pulse signals, and then the direction of the stepper motor's movement is changed to recalculate the number of steps to reach the new target position.

[0029] Furthermore, when the new target position is smaller than the current position of the stepper motor,

[0030] First, control the stepper motor to decelerate by B pulse signals, then change the direction of the stepper motor's movement;

[0031] Recalculate the distance L2 between the stepper motor and the new target position;

[0032] Calculate the pulse signal corresponding to the stepper motor acceleration a based on the distance L2; or, calculate the pulse signals corresponding to the stepper motor acceleration a and constant speed based on the distance L2.

[0033] Set the operating current of the stepper motor, and send the pulse signal to the stepper motor after a 50ms delay.

[0034] The present invention also provides a stepper motor, which is controlled by the aforementioned motion control method.

[0035] The beneficial effects of the present invention are that the stepper motor and its motion control method of the present invention propose different control strategies for different motor operating conditions, making the control strategies more targeted, significantly improving the positioning accuracy of the stepper motor, reducing the influence of motor inertia, and further improving the stability and reliability of the adaptive high and low beam lighting system. Attached Figure Description

[0036] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0037] Figure 1 This is a flowchart of the motion control method of the present invention.

[0038] Figure 2 This is another flowchart of the motion control method of the present invention.

[0039] Figure 3 This is a schematic diagram of controlling a stepper motor in a stationary state according to the present invention.

[0040] Figure 4 This is another schematic diagram of the present invention controlling a stepper motor in a stationary state.

[0041] Figure 5 This is a schematic diagram of the pulse signal of the present invention.

[0042] Figure 6 This is a schematic diagram of the present invention issuing control commands in acceleration / deceleration states.

[0043] Figure 7 This is the first schematic diagram of the present invention for controlling the speed in a uniform state.

[0044] Figure 8 This is a second schematic diagram of the present invention for controlling the speed in a uniform state.

[0045] Figure 9 This is the third schematic diagram of the present invention for controlling the speed in a uniform state.

[0046] Figure 10 This is the fourth schematic diagram of the present invention in the uniform speed control state.

[0047] Figure 11 This is a schematic diagram of the commutation signal of the present invention. Detailed Implementation

[0048] The present invention will now be described in further detail with reference to the accompanying drawings. These drawings are simplified schematic diagrams, illustrating only the basic structure of the invention, and therefore only show the components relevant to the invention.

[0049] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., indicating orientation or positional relationships, are based on the orientation or positional relationships shown in the accompanying drawings and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, features defined with "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0050] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0051] like Figures 1 to 2 As shown, the motion control method for a stepper motor of the present invention includes the following steps:

[0052] S1, Set the target position of the stepper motor.

[0053] S2. Determine the current motion state of the stepper motor.

[0054] S3. Determine the control strategy for the motor motion based on the current motion state of the stepper motor.

[0055] S4. According to the control strategy, control the stepper motor to move to reach the target position.

[0056] A stepper motor is an electric motor that converts electrical pulse signals into corresponding angular or linear displacement. For each input pulse signal, the rotor rotates by an angle or moves forward one step. The output angular or linear displacement is proportional to the number of input pulses, and the rotational speed is proportional to the pulse frequency. The motion states of a stepper motor include: stationary, accelerating, constant speed, and decelerating. Due to the characteristics of stepper motors, the higher the rotational speed, the lower the torque. This necessitates acceleration and deceleration during operation to change the torque from high to low or vice versa. Therefore, different control strategies are required for stepper motors in different states.

[0057] (a) Static state

[0058] When the stepper motor is stationary, if it receives a command to set the target position, there are two control strategies.

[0059] The first method involves determining the distance L0 between the current position of the stepper motor and the target position, calculating the pulse corresponding to the acceleration a of the stepper motor based on the distance L0, setting the operating current of the stepper motor, and sending the pulse to the stepper motor after a 50ms delay.

[0060] like Figure 3As shown, the horizontal axis represents time, and the vertical axis represents velocity. When the distance L0 is small, the stepper motor can reach the target position during acceleration and deceleration. In this case, it is only necessary to calculate the pulse signal corresponding to the stepper motor's acceleration 'a' (the acceleration is the same during acceleration and deceleration). This pulse signal includes the pulse width and the number of pulses.

[0061] The second method involves determining the distance L1 between the current position of the stepper motor and the target position, calculating the stepper motor acceleration a and the pulse signal corresponding to the constant speed based on the distance L1, setting the operating current of the stepper motor, and sending the pulse signal to the stepper motor after a 50ms delay.

[0062] like Figure 4 As shown, the horizontal axis represents time, and the vertical axis represents velocity. At this point, distance L1 is greater than distance LO; therefore, the stepper motor's motion includes a period of uniform motion. At this time, it is necessary to calculate the stepper motor's acceleration 'a' and the corresponding pulse signal for the uniform velocity. This pulse signal includes the pulse width and the number of pulses.

[0063] Figure 5 The curves of the operating current and the pulse signal are shown. When the operating current is first output, there is a buffering process. At this time, the operating current is not yet stable. Therefore, it is necessary to delay for 50ms before sending the pulse signal to the stepper motor. The stepper motor starts to run according to the pulse signal.

[0064] When the stepper motor is stationary, a target position command can be set at any time, and the stepper motor will respond accordingly.

[0065] (II) Acceleration and Deceleration

[0066] like Figure 6 As shown, when the stepper motor receives a command to set a target position while it is accelerating or decelerating, the stepper motor will send a feedback signal indicating that the setting was unsuccessful and will need to wait (pending). That is, a new target position cannot be set during the acceleration and deceleration process of the stepper motor.

[0067] (III) Uniform speed state

[0068] When the stepper motor is moving at a constant speed, if it receives a command to set a new target position, the new target position is compared with the current position of the stepper motor to obtain a comparison result. The control strategy is then output based on this comparison result. The comparison result includes: the new target position is greater than the current position of the stepper motor, and the new target position is less than the current position of the stepper motor.

[0069] It should be noted that when a stepper motor receives a command to set a new target position, the stepper motor is in the process of moving towards the original target position. In other words, the stepper motor receives the command to change the target position while executing the original target position. Therefore, when a stepper motor receives a command to set a target position while moving at a constant speed, it also needs to be discussed on a case-by-case basis.

[0070] The first method involves calculating the step difference A between the new target position and the current stepper motor position when the new target position is greater than the current stepper motor position. If the step difference A is greater than the stepper motor's deceleration step B, then the number of constant speed steps AB required for the stepper motor to reach the new target position is calculated. The stepper motor is then controlled to continue moving at a constant speed for AB pulse signals, and then decelerated for B pulse signals to reach the new target position.

[0071] For example, suppose the original target position needs to be moved 5mm, and a new instruction is received midway, requiring it to move to 10mm. When the new instruction is received, the stepper motor has not yet reached the 5mm mark. If the step difference A at this point is greater than the stepper motor's deceleration step number B, it indicates that the stepper motor has not yet entered the deceleration state. The number of constant-speed steps AB required to reach the 10mm position can be directly calculated. After the stepper motor moves at a constant speed of AB, it then decelerates for B pulse signals (the pulse signal corresponds to the step number). Figure 7 As shown, the solid line represents the actual speed change of the stepper motor, and the dashed line represents the speed change when reaching the original target position.

[0072] For example, suppose the original target position needs to be moved 8mm, and a new instruction is received midway, requiring only a movement of 6mm. When the new instruction is received, the stepper motor has not yet reached the 6mm mark. If the step difference A is greater than the stepper motor's deceleration step B, it indicates that the stepper motor has not yet entered deceleration mode. The number of constant-speed steps AB required to reach the current position of 10mm can be directly calculated. After the stepper motor moves at a constant speed of AB, it decelerates for B pulse signals (the pulse signals correspond to the step count). Figure 7 As shown, the solid line represents the actual speed change of the stepper motor, and the dashed line represents the speed change to reach the original target position. Figure 8 As shown, the solid line represents the actual speed change of the stepper motor, and the dashed line represents the speed change when reaching the original target position.

[0073] The second scenario is when the new target position is greater than the current position of the stepper motor, but the step difference A is less than the stepper motor's deceleration step B, indicating that the stepper motor's movement stroke cannot be directly changed. In this case, the stepper motor is first controlled to decelerate by B pulse signals, and then the stepper motor's movement direction is changed to recalculate the number of steps to reach the new target position.

[0074] The third method involves controlling the stepper motor to decelerate by B pulse signals when the new target position is smaller than the current position of the stepper motor. Then, the direction of the stepper motor's movement is changed. The distance L2 between the current position of the stepper motor and the new target position is recalculated, and the pulse signal corresponding to the stepper motor's acceleration a is calculated based on the distance L2. The operating current of the stepper motor is set, and the pulse signal is sent to the stepper motor after a 50ms delay.

[0075] like Figure 9 As shown, the dashed line represents the speed change towards the original target position. When the stepper motor receives a new position setting command, if the new target position is smaller than the current position of the stepper motor, it indicates that the stepper motor has exceeded the new target position, and the direction of the new target position is opposite to that of the original target position. Therefore, the stepper motor needs to be decelerated to zero before reversing direction. For example, suppose the original target position was to move 10mm, and a new command was received midway to move 5mm. At this point, the current position of the stepper motor has exceeded 5mm (for example, at 6mm), so the stepper motor needs to be decelerated and stopped before changing the direction of movement. At this time, the distance L2 from the current position of the stepper motor to 5mm is recalculated. The pulse signal corresponding to the stepper motor acceleration 'a' is calculated based on the distance L2, the operating current of the stepper motor is set, and the pulse signal is sent to the stepper motor after a 50ms delay, and the stepper motor starts moving.

[0076] like Figure 10 As shown, the dashed line represents the speed change towards the original target position. For example, suppose the original target position is moved 10mm, and a new instruction is received midway to move 5mm. At this point, the stepper motor's current position has already exceeded 5mm (for example, at 8mm), so the stepper motor needs to be decelerated and stopped before changing its direction of movement. Then, the distance L2 from the current stepper motor position to 5mm is recalculated. Based on distance L2, the stepper motor acceleration 'a' and the corresponding pulse signal for constant speed are calculated. The stepper motor's operating current is set, and after a 50ms delay, this pulse signal is sent to the stepper motor, which then begins to move.

[0077] Figure 11 The changes in current and pulse signals are shown, where curve C represents the commutation signal of the stepper motor, which commutates during the execution of the stepper motor.

[0078] The present invention also provides a stepper motor, which is controlled by the above-described motion control method.

[0079] In summary, the stepper motor and its motion control method of the present invention propose different control strategies for different motor operating conditions, making the control strategies more targeted, significantly improving the positioning accuracy of the stepper motor, mitigating the influence of motor inertia, and further enhancing the stability and reliability of the adaptive high and low beam lighting system.

[0080] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined by the scope of the claims.

Claims

1. A motion control method for a stepper motor, characterized in that, Includes the following steps: S1. Set the target position of the stepper motor; S2. Determine the current motion state of the stepper motor; S3. Determine the control strategy for the motor motion based on the current motion state of the stepper motor; S4. According to the control strategy, control the stepper motor to move to reach the target position; The motion states include: stationary state, accelerating state, constant speed state, and decelerating state; When the stepper motor is in a constant speed state, if the stepper motor receives a command to set a new target position, the new target position is compared with the current position of the stepper motor to obtain the comparison result; and then the control strategy is output according to the comparison result. The comparison results include: the new target position is greater than the current position of the stepper motor, and the new target position is less than the current position of the stepper motor; When the new target position is greater than the current position of the stepper motor Calculate the step difference A between the new target position and the current position of the stepper motor; If the step difference A is greater than the deceleration step B of the stepper motor, then calculate the number of constant speed steps AB that the stepper motor needs to reach the new target position; Control the stepper motor to continue moving at a constant speed for AB pulse signals, then decelerate for B pulse signals to reach the new target position; If the step difference A is less than the stepper motor's deceleration step B, then first control the stepper motor to decelerate by B pulse signals, then change the stepper motor's direction of movement, and recalculate the number of steps to reach the new target position. When the new target position is smaller than the current position of the stepper motor First, control the stepper motor to decelerate by B pulse signals, then change the direction of the stepper motor's movement; Recalculate the distance L2 between the stepper motor and the new target position; Calculate the pulse signal corresponding to the stepper motor acceleration a based on the distance L2; or, calculate the pulse signals corresponding to the stepper motor acceleration a and constant speed based on the distance L2. Set the operating current of the stepper motor, and send the pulse signal to the stepper motor after a 50ms delay.

2. The motion control method for a stepper motor as described in claim 1, characterized in that, When the stepper motor is stationary, if the stepper motor receives a command to set a target position, the control strategy is as follows: Determine the distance L0 between the current position of the stepper motor and the target position; Calculate the pulse signal corresponding to the stepper motor acceleration a based on the distance L0; Set the operating current of the stepper motor, and send the pulse signal to the stepper motor after a 50ms delay.

3. The motion control method for a stepper motor as described in claim 1, characterized in that, When the stepper motor is stationary, if the stepper motor receives a command to set a target position, the control strategy is as follows: Determine the distance L1 between the current position of the stepper motor and the target position; The stepper motor acceleration a and the pulse signal corresponding to constant speed are calculated based on the distance L1. Set the operating current of the stepper motor, and send the pulse signal to the stepper motor after a 50ms delay.

4. The motion control method for a stepper motor as described in claim 1, characterized in that, When the stepper motor is in acceleration or deceleration mode, if the stepper motor receives a command to set the target position, it will issue a setting failure signal.

5. A stepper motor, characterized in that, The motion control method described in any one of claims 1-4 is used for control.

Images