A method for detecting and controlling the steering angle of a steering gear without an absolute position sensor

Abstract

The present invention relates to a method for detecting and controlling the steering angle of a servo without an absolute position sensor, including: Step 100: Obtain the initial position a of the steering angle of the servo; Step 200: Obtain the steering angle command value b and determine whether it is a setting command or a rotation command. If it is a rotation command, continue to the next step; Step 300: Read the current value of the non-absolute position sensor and calculate the angle increment of the motor rotation after power-on; Step 400: Calculate the actual position of the current steering angle of the servo; Step 500: Control the servo motor; Step 600: If the control chip does not detect power-off, no interrupt will be executed, and the program jumps to Step 200; if power-off is detected, an interrupt is triggered; Step 700: The interrupt is triggered; Step 800: The control chip stops the rotation of the servo motor and stores the current steering angle position in the internal storage space of the chip. The present invention can achieve absolute steering angle detection and control without relying on an additional absolute position sensor, and the system is simpler.

Description

Technical Field

[0001] The present invention relates to the field of electric steering gears, and more specifically, to a method for detecting and controlling the steering angle of a steering gear without an absolute position sensor. Background Art

[0002] A rudder is a common control device. Autonomous underwater vehicles often use rudders to achieve motion control. In the prior art, various steering gear structures have been developed according to the characteristics of different application scenarios, including: a link mechanism steering gear driven by a hydraulic cylinder, a link mechanism steering gear driven by a linear motor, a steering gear in which a motor drives a steering shaft through a speed reducer, etc. For a link mechanism steering gear driven by a hydraulic cylinder or a linear motor, its steering angle position is usually obtained by measuring the displacement of the hydraulic cylinder or the linear motor and through geometric solution of the link mechanism. For a steering gear in which a motor drives a steering shaft through a speed reducer, its steering angle is measured and calculated by various position sensors.

[0003] With the development of autonomous underwater vehicles towards deeper and faster directions, higher requirements are also put forward for technical parameters such as the size, weight, and torque of the steering gear. Using a Hall position sensor with a small motor can meet the above requirements of underwater vehicles for steering gears. At the same time, using a Hall position sensor in the control algorithm is simpler than other position sensors. However, the Hall position sensor is a non-absolute position sensor. To ensure that the steering angle information is not lost when the power is off, an additional absolute position sensor that does not participate in motor control needs to be added, which will increase the number of system components, and thus increase the complexity of the circuit and the instability of the system. If the control can be improved to eliminate the additional absolute position sensor, not only can the space size of the steering gear be reduced, but also the number of components can be reduced and the circuit connection relationship can be simplified, which is of great significance for optimizing the design of autonomous underwater vehicles and improving system reliability. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for detecting and controlling the steering angle of a steering gear without an absolute position sensor, which is applicable to a steering gear structure that uses a non-absolute position sensor to control a motor. It can achieve absolute steering angle detection and control without relying on an additional absolute position sensor, the system is simpler and the circuit connection is less, and it is particularly applicable to application scenarios with strict requirements for installation space such as autonomous underwater vehicles.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] A method for detecting and controlling the steering angle of a steering gear without an absolute position sensor includes the following steps:

[0007] Step 100: After the control chip is powered on, obtain the initial position a of the steering angle of the steering gear;

[0008] Step 200: The control chip receives a control command and reads the rudder angle command value b. It determines whether it is a setting command or a rotation command. If it is a setting command, b is stored in the internal storage space of the control chip, and then it jumps to Step 100 and reads and assigns it to the initial rudder angle position a, that is, a = b; if it is a rotation command, it continues to the next step;

[0009] Step 300: Read the current value N of the non-absolute position sensor on the steering gear motor, and calculate the angle increment d of the motor rotation after power-on as d = s×N×60 / P, where P is the number of pole pairs of the motor and s is the motor rotation direction;

[0010] Step 400: Calculate the actual position e of the current steering gear rudder angle as e = a + d / n, where n is the total reduction ratio of the steering gear reduction mechanism;

[0011] Step 500: Control the steering gear motor according to the actual position e of the steering gear rudder angle and the rudder angle command value b, where the control increment for the steering gear rudder angle is f = (b - e)×n;

[0012] Step 600: If the control chip does not detect a power-off, it will not execute an interruption, and the program jumps to Step 200; if it detects a power-off, it triggers an interruption and executes the next step;

[0013] Step 700: Interruption triggered;

[0014] Step 800: After entering the interruption, the control chip first stops the rotation of the steering gear motor and stores the current rudder angle position in the internal storage space of the chip. After that, after a delay, it waits for the control chip to completely power off and ends the operation.

[0015] The control chip is connected to an energy storage circuit. The energy storage circuit is provided with a capacitor C. In Step 800, after entering the interruption, the control chip completes the storage operation of the current rudder angle position information by releasing energy through the capacitor C.

[0016] The capacitor C of the energy storage circuit is C = 2×p×t / (U1 2 -U2 2 ), where U1 is the interruption trigger voltage, U2 is the minimum operating voltage of the control chip, t is the time length for the voltage to drop from U1 to U2, the time required to execute the rudder angle information storage after triggering the interruption is t1, and t ≥ t1, and p is the power of the control chip.

[0017] The control chip is provided with pins VDD_x and VSS_x connected to the energy storage circuit, and the pins VDD_x and VSS_x are also voltage interruption trigger signal input pins.

[0018] In Step 300, s is the motor rotation direction. When the motor rotates forward according to the control requirements, the value is 1, and when it rotates backward, the value is -1.

[0019] The non-absolute position sensor is a Hall sensor.

[0020] The advantages and positive effects of the present invention are as follows:

[0021] 1. The present invention is applicable to a servo structure that uses a non-absolute position sensor to control a motor. The power-off storage function of the steering angle can be realized without adding an additional absolute position sensor to the output shaft of the servo, and further, the control of the absolute position of the steering angle after repeated power-on can be realized. The present invention has the characteristics of a simple system, being convenient for improving the system integration, reducing the size and weight.

[0022] 2. The present invention uses a Hall position sensor to control the rotation angle of the motor. The change amount of the steering angle can be calculated through the reduction ratio of the reduction gear. Due to the large reduction ratio, the detection accuracy of the change amount of the steering angle is high.

[0023] 3. The present invention utilizes the interrupt trigger function of the control chip and the slow discharge function of the energy storage circuit to automatically store the current steering angle position when power is off. When power is on again, the previously stored steering angle position can be read, and the absolute position at any time can be obtained without an absolute position sensor. Description of the Drawings

[0024] Figure 1 is a flow chart of the present invention,

[0025] Figure 2 is a schematic diagram of the control chip adopted by the controller of the present invention,

[0026] Figure 3 is for Figure 2 a schematic diagram of the energy storage circuit connected to the control chip in

[0027] Figure 4 is a schematic diagram of a servo structure adopting the method of the present invention,

[0028] Figure 5 is for Figure 4 the A-A view in Detailed Embodiment

[0029] The present invention will be described in further detail below with reference to the drawings.

[0030] As shown in Figures 4 - 5The figure shows a steering gear structure applied in the present invention, which includes a steering gear base 301, a steering gear motor 302, a worm 303, a worm wheel 304 and an output shaft 305, wherein the steering gear motor 30 is provided with a reducer and a Hall sensor, the worm 303 and the worm wheel 304 are meshed to form a reduction mechanism, and the worm 303 and the worm wheel 304 are self-locking meshing, the worm 303 is driven to rotate by the steering gear motor 302, the worm wheel 304 is coaxially arranged with the output shaft 305 and drives the output shaft 305 to rotate, and the steering propeller is installed on the output shaft 305.

[0031] like Figure 2 The figure shows a schematic diagram of the control chip used in the controller of the present invention, wherein VDD_x and VSS_x are the power supply pins of the chip, and VDD_x and VSS_x are also the voltage interruption trigger signal input pins. The steering gear rudder angle information when the power is off is stored in the storage space of the chip. In addition, the power supply pins VDDx and VSSx of the control chip are connected to the Figure 3 The energy storage circuit shown is connected, and the energy storage circuit is arranged in the power output section. When the controller is powered off and triggers an interrupt, the capacitor C in the energy storage circuit will release energy to ensure that there is enough time for the control chip to complete the storage operation of the current rudder angle position information after the power is off.

[0032] like Figure 1 As shown, the method of the present invention comprises the following steps:

[0033] Step 100: After the control chip is powered on, the initial position a of the steering gear rudder angle stored in the memory is first read;

[0034] Step 200: The control chip receives the control command and reads the rudder angle command value b in the command to determine whether it is a setting command or a rotation command. If it is a setting command, b is stored in the storage space inside the control chip, and then jumps to step 100 and reads the value assigned to the initial position a of the rudder angle of the servo, that is, a=b; if it is a rotation command, continue to the next step;

[0035] Step 300: The control chip reads the current value N of the Hall position sensor and calculates the angle increment d=s×N×60 / P of the motor after power-on, where P is the number of motor pole pairs and s is the direction of motor rotation. According to the control requirements, the value of the motor is 1 when it is rotating forward and -1 when it is rotating reversely.

[0036] Step 400: Calculate the current actual position of the steering gear rudder angle e=a+d / n according to the initial steering gear rudder angle position a read in step 100, the angle increment d obtained in step 300 and the total reduction ratio of the reduction mechanism (the reduction mechanism in this embodiment includes the worm 303 and the worm wheel 304), where n is the total reduction ratio of the reduction mechanism;

[0037] Step 500: Control the motor based on the actual rudder angle position e calculated in Step 400 and the target rudder angle value given by the rotation command, that is, the rudder angle command value b. At this time, the increment required for controlling the rudder angle of the steering gear is f = (b - e) × n;

[0038] Step 600: The control chip always monitors whether there is a power outage. If no power outage is detected, no interrupt will be executed and the program will jump to Step 200; if a power outage is detected, an interrupt will be triggered to execute the next step;

[0039] Step 700: Interrupt trigger;

[0040] Step 800: After entering the interrupt, the control chip first stops the rotation of the steering gear motor and stores the current rudder angle position in the internal storage space of the chip. Then, after a set delay time, it waits for the control chip to completely power off and ends the operation.

[0041] As Figure 3 shown, the energy storage circuit is provided at the power output section, which has the function of slowing down the discharge process to ensure that in Step 800 above, there is enough time for the control chip to complete the storage operation of the rudder angle position information after power off. The energy storage circuit is designed as a large capacitor and can also provide control of the slope of the power-off voltage curve. Its specific design process is as follows:

[0042] Assume that the supply voltage of the control chip is U, the interrupt trigger voltage is U1, the minimum operating voltage of the control chip is U2, the time required to execute the storage of rudder angle information after the interrupt is triggered is t1, and the power of the control chip is p. At this time, if the storage work of the power-off rudder angle information is to be completed, the time length t for the voltage at the power output section to drop from U1 to U2 must satisfy t ≥ t1. The energy W1 required for this time period is W1 = p × t. According to the formula for the energy stored in a capacitor W = C × U 2 / 2, it can be known that during the power-off process, the energy released by the capacitor of the energy storage circuit is W2 = C × (U1 2 - U2 2 ) / 2, where C is the capacitance value of the capacitor. So, p × t = C × (U1 2 - U2 2 ) / 2. Therefore, the capacitance value C required for the energy storage circuit at the power output section can be calculated as C = 2 × p × t / (U1 2 - U2 2 ).

[0043] The present invention is applicable to a servo structure that controls a motor using a non-absolute position sensor including a Hall sensor. It detects the rotation angle of the motor shaft through the non-absolute position sensor on the motor, calculates the angle of the rudder through the reduction ratio, determines the initial zero position of the rudder angle through initial calibration, triggers the interrupt function of the control chip through the voltage change during power-off, and stores the current rudder angle information to achieve the storage of the rudder angle information at the power-off position. The function of the energy storage circuit on the controller to slow down the discharge process is utilized to ensure that the controller has sufficient time to complete the storage operation of the position information after power-off. When power is restored again, the real-time rudder angle position can be obtained by reading the stored rudder angle position and the change in the rudder angle after this power-on calculated from the non-absolute position sensor data, thereby realizing the control of the rudder angle. The present invention does not rely on an additional absolute position sensor to achieve absolute rudder angle detection and control, the system is simpler, the circuit connection is less, and it is particularly suitable for application scenarios with strict installation space requirements such as autonomous underwater vehicles.

Claims

1. A method for detecting and controlling the steering angle of a steering gear without an absolute position sensor, characterized in that: It includes the following steps: Step 100: After the control chip is powered on, obtain the initial position a of the servo steering angle; Step 200: The control chip receives a control command, reads the steering angle command value b, and determines whether it is a setting command or a rotation command. If it is a setting command, b is stored in the internal storage space of the control chip, and then it jumps to Step 100 and reads and assigns it to the initial position a of the steering angle, that is, a = b; if it is a rotation command, it continues to execute the next step; Step 300: Read the current value N of the non-absolute position sensor on the servo motor, and calculate the angle increment d of the motor rotation after power-on as d = s×N×60 / P, where P is the number of pole pairs of the motor and s is the rotation direction of the motor; Step 400: Calculate the actual position e of the current servo steering angle as e = a + d / n, where n is the total reduction ratio of the servo reduction mechanism; Step 500: Control the servo motor according to the actual position e of the servo steering angle and the steering angle command value b, where the control increment for the servo steering angle is f = (b - e)×n; Step 600: If the control chip does not detect power-off, it will not execute an interruption, and the program jumps to Step 200; if it detects power-off, it triggers an interruption and executes the next step; Step 700: Interruption trigger; Step 800: After entering the interruption, the control chip first stops the rotation of the servo motor and stores the current steering angle position in the internal storage space of the chip. After that, after a delay, it waits for the control chip to be completely powered off and ends the operation.

2. The method for detecting and controlling the rudder angle of a steering gear without an absolute position sensor according to claim 1, characterized in that: The control chip is connected to an energy storage circuit. The energy storage circuit is provided with a capacitor C. In Step 800, after entering the interruption, the control chip stores the current steering angle position information by releasing energy through the capacitor C.

3. The method for detecting and controlling the rudder angle of a steering gear without an absolute position sensor according to claim 2, wherein: The capacitance C of the energy storage circuit is C = 2×p×t / (U1 2 -U2 2 ), where U1 is the interrupt trigger voltage, U2 is the minimum operating voltage of the control chip, t is the time length for the voltage to drop from U1 to U2, the time required to execute the storage of rudder angle information after the interrupt is triggered is t1, and t≥t1, and p is the power of the control chip.

4. The servo rudder angle detection and control method without an absolute position sensor according to claim 2, characterized in that: The control chip is provided with pins VDD_x and VSS_x connected to the energy storage circuit, and the pins VDD_x and VSS_x are also voltage interruption trigger signal input pins.

5. The method for detecting and controlling the rudder angle of a steering gear without an absolute position sensor according to claim 1, wherein: In Step 300, s is the rotation direction of the motor. When the motor rotates forward according to the control requirements, the value is 1, and when it rotates backward, the value is -1.

6. The servo rudder angle detection and control method without an absolute position sensor according to claim 1, characterized in that: The non-absolute position sensor is a Hall sensor.

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