Angle measurement method and device, scanning device and laser radar

Abstract

This disclosure provides an angle measurement method and apparatus, a scanning device, and a lidar. The angle measurement method includes: a first angle sensor outputting a first signal, the first signal changing periodically within an angle measurement range; a second angle sensor outputting a second signal, the second signal changing monotonically within the angle measurement range; and determining the rotation angle of a rotator based on the values ​​of the first and second signals.

Description

Technical Field

[0001] This disclosure relates to the field of angle measurement technology, and more particularly to angle measurement methods and apparatus, scanning devices, and lidar. Background Technology

[0002] Rotators include unidirectional rotary rotaryers and reciprocating rotaryers. Reciprocating rotaryers can perform non-full-circle, non-uniform reciprocating motion. The reciprocating motion of a reciprocating rotaryer typically has a speed-changing zone (e.g., before and after a change in the direction of oscillation). In order to obtain the rotational position of a reciprocating rotaryer or accurately control its motion, the angle sensor of the reciprocating rotaryer needs to provide absolute rotational angle information.

[0003] Depending on their measurement principles, angle sensors include different types such as optical encoders, magnetic encoders, inductive angle sensors, and eddy current angle sensors. However, none of these types of angle sensors can independently meet the angle measurement requirements of reciprocating rotary actuators. Summary of the Invention

[0004] This disclosure provides an angle measurement method and apparatus, a scanning device and a lidar, which meet the angle measurement requirements of a rotator and can provide angle measurement results with high accuracy and high reliability.

[0005] This disclosure provides a method for measuring angles, including:

[0006] The first angle sensor outputs a first signal, which changes periodically within the angle measurement range;

[0007] The second angle sensor outputs a second signal, which changes monotonically within the angle measurement range;

[0008] The rotation angle of the rotator is determined based on the values ​​of the first and second signals.

[0009] Optionally, the rotation angle of the rotator is determined based on the values ​​of the first signal and the second signal, including:

[0010] The first angle is determined based on the value of the first signal;

[0011] The second angle is determined at least based on the value of the second signal;

[0012] The rotation angle is determined based on the first angle and the second angle.

[0013] Optionally, the first angle is the angle corresponding to the value of the first signal within one period;

[0014] The second angle is determined at least based on the value of the second signal, including:

[0015] The first period of the first signal is determined based on the values ​​of the second signal and the first signal;

[0016] The second angle is determined based on the first cycle.

[0017] Optionally, determining the first angle based on the value of the first signal includes:

[0018] The ratio of the first angle signal and the second angle signal is taken, wherein the first signal includes the first angle signal and the second angle signal, and the first angle signal and the second angle signal have a phase difference;

[0019] The first angle is determined based on the ratio.

[0020] Optionally, the phase difference is

[0021] Optionally, the offset angle corresponding to the maximum offset error of the second signal is less than the angle value corresponding to half a cycle of the first signal.

[0022] This disclosure provides an angle measurement apparatus, comprising:

[0023] A first angle sensor is configured to output a first signal, which changes periodically within the angle measurement range;

[0024] A second angle sensor is configured to output a second signal that changes monotonically within the angle measurement range;

[0025] The processor is configured to determine the rotation angle of the rotator based on the values ​​of the first signal and the second signal.

[0026] Optionally, the first signal includes a first angle signal and a second angle signal, and the first angle sensor includes:

[0027] Code disk;

[0028] The first code reader is configured to output a first angle signal;

[0029] The second code reader is configured to output a second angle signal;

[0030] The interval between the first and second code readers is a non-integer multiple of the width of the code track on the code disk.

[0031] Optionally, the interval between the first reader and the second reader is an integer multiple of half the width of the code channel.

[0032] Optionally, the first angle sensor includes at least one of the following:

[0033] Analog optical angle sensor; or,

[0034] Analog magnetic angle sensor;

[0035] The second angle sensor includes:

[0036] Eddy current angle sensor.

[0037] Optionally, the analog optical angle sensor includes:

[0038] Code disk;

[0039] A light emitter is configured to emit light, the size of which forms an illumination area on the code disk that is greater than or equal to the width of the code track on the code disk.

[0040] Optionally, the offset angle corresponding to the maximum offset error of the second signal is less than the angle value corresponding to half a cycle of the first signal.

[0041] This disclosure provides a scanning device, including:

[0042] The rotator is configured to move in response to a motion control signal;

[0043] The angle measuring device in any of the foregoing embodiments is configured to determine the rotation angle of the rotator;

[0044] The scanner is mounted on the rotator and moves with the rotator.

[0045] Optionally, the rotator is configured to reciprocate in response to a motion control signal.

[0046] Optionally, the scanner includes at least one of the following: a mirror, a lens, or a prism.

[0047] This disclosure provides a lidar, including:

[0048] The laser is configured to emit a detection signal;

[0049] The detector is configured to receive the echo signal that returns after the detection signal is reflected by the object;

[0050] The scanning device in any of the foregoing embodiments is disposed on the outgoing optical path of the detection signal, or on the incoming optical path of the echo signal, or on both the outgoing optical path of the detection signal and the incoming optical path of the echo signal.

[0051] The angle measurement scheme in this embodiment determines the rotation angle of the rotator based on the value of the first signal output by the first angle sensor and the value of the second signal output by the second angle sensor. By combining the signal values ​​output by both angle sensors (first and second), the accuracy and reliability of angle measurement for reciprocating rotators or non-uniformly rotating rotators can be improved, thus meeting the angle measurement requirements for reciprocating rotators. Attached Figure Description

[0052] To more clearly illustrate the technical solutions of the embodiments of this disclosure, the drawings used in the description of the embodiments of this disclosure or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this specification. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 A flowchart illustrating an angle measurement method consistent with embodiments of this disclosure is shown.

[0054] Figure 2 An example structural block diagram of an eddy current angle sensor consistent with embodiments of this disclosure is shown.

[0055] Figure 3 A schematic diagram showing the correspondence between a rotation angle and a first signal and a second signal, consistent with an embodiment of this disclosure, is provided.

[0056] Figure 4 A flowchart illustrating a method for determining a first angle based on the value of a first signal, consistent with embodiments of this disclosure, is shown.

[0057] Figure 5 An example frame structure diagram of an angle measurement device consistent with embodiments of this disclosure is shown.

[0058] Figure 6 An example frame structure diagram of a scanning device consistent with embodiments of this disclosure is shown.

[0059] Figure 7 An example diagram of a lidar frame structure consistent with embodiments of this disclosure is shown. Detailed Implementation

[0060] In some applications (such as angle measurement in lidar scanning devices), high demands are placed on the angle measurement performance of the devices. For example, some lidar systems use a reciprocating rotator (e.g., a reciprocating motor) to drive a scanner (e.g., a tilting mirror) for field-of-view scanning. The reciprocating rotator typically performs non-full-circle, non-uniform reciprocating motion, often with speed-changing zones (e.g., before and after changes in the direction of oscillation). To obtain the rotational position of the reciprocating rotator or accurately control its motion, the angle sensor of the reciprocating rotator needs to provide absolute rotational angle information.

[0061] To accurately obtain the scanning angle of a lidar system and improve the accuracy of lidar detection data, the angle measurement device needs to possess characteristics such as high accuracy and high environmental stability. However, for angle measurement of reciprocating or non-uniformly rotating actuators, traditional angle measurement devices, such as optical encoders, magnetic encoders, inductive angle sensors, and eddy current angle sensors, are insufficient to meet these angle measurement requirements.

[0062] This disclosure provides methods and apparatus for angle measurement, scanning devices, and lidar, which can meet the angle measurement requirements of rotators and provide angle measurement results with high accuracy and reliability.

[0063] Figure 1 A flowchart illustrating an angle measurement method consistent with embodiments of this disclosure is shown. In some embodiments, reference is made to... Figure 1 The method for measuring the angle may include steps 102, 104 and 106.

[0064] Step 102: The first angle sensor outputs a first signal, which changes periodically within the angle measurement range.

[0065] In some embodiments, the first angle sensor includes an analog optically encoded angle sensor. The analog optically encoded angle sensor converts the rotation angle of the rotating part of the rotator (e.g., a rotor) into an electrical signal via photoelectric conversion. The electrical signal characterizes the rotation angle of the rotating part of the rotator. The electrical signal changes periodically within the angle measurement range and can be output as a first signal. The first signal provides absolute angle information within one cycle. For example, the first signal output by the analog optically encoded angle sensor is a periodically changing quasi-sine wave signal; within one cycle, the angle can be determined based on the value of the first signal.

[0066] In some embodiments, the first angle sensor includes an analog magnetic angle sensor. An analog magnetic angle sensor is a sensor that uses changes in a magnetic field to detect the rotation angle of a rotator and convert it into an electrical signal output.

[0067] The type of first angle sensor in the above examples is merely illustrative. This disclosure does not limit the specific type of the first angle sensor. In practical implementation, the first signal output by the selected first angle sensor simply needs to change periodically within the angle measurement range.

[0068] Step 104: The second angle sensor outputs a second signal, which changes monotonically within the angle measurement range.

[0069] The second angle sensor can be selected from angle sensors capable of providing absolute angle information. The second signal output by the second angle sensor changes monotonically within the angle measurement range.

[0070] In some embodiments, the second angle sensor includes an eddy current angle sensor. An eddy current angle sensor is a sensor that measures angle or distance using the eddy current effect. Eddy current angle sensors have advantages such as low cost, small space requirements, and the ability to provide high-precision absolute angle information.

[0071] Figure 2 An example structural block diagram of an eddy current angle sensor consistent with embodiments of this disclosure is shown. In some embodiments, reference is made to... Figure 2 The eddy current angle sensor 200 includes a metal target 202, an inductor coil 204, a resonant circuit 206, and a measurement circuit 208. The metal target 202 can interact with a rotator (the rotator is located in...). Figure 2 A rotating part (not shown) is connected. An inductor coil 204 can be positioned opposite the metal target 202 and fixed relative to the fixing part of the rotator. A resonant circuit 206 can be electrically connected to the inductor coil 204 to generate a resonant signal. A measuring circuit 208 can be connected to the resonant circuit 206 and outputs a second signal based on the resonant signal.

[0072] The second signal output by the eddy current angle sensor can vary with the distance or overlap area between the inductor coil and the metal target. In some embodiments, the second signal may include a square wave signal based on a resonant signal, and the frequency of the second signal is the same as the frequency of the resonant signal. The relative position (e.g., relative distance or relative angle) between the inductor coil and the metal target can be determined based on the magnitude of the second signal frequency. In some embodiments, the second signal may include the frequency of the resonant signal, and the relative position (e.g., relative distance or relative angle) between the inductor coil and the metal target can be determined based on the magnitude of the second signal.

[0073] It should be noted that the above is merely an illustrative example. This disclosure does not limit the type of the second angle sensor. The second angle sensor can output a second signal that monotonically changes within the angle measurement range.

[0074] Step 106: Determine the rotation angle of the rotator based on the values ​​of the first signal and the second signal.

[0075] In some embodiments, a first angle can be determined based on the value of a first signal. A second angle is determined based at least on the value of a second signal. The rotation angle of the rotator can be determined based on the first angle and the second angle.

[0076] The first signal changes periodically within the angle measurement range, therefore the angle within one cycle can be determined based on the value of the first signal. The second signal changes monotonically within the angle measurement range, therefore the cycle of the first signal can be determined based on the second angle signal. Thus, the rotation angle of the rotator can be determined relatively accurately based on the values ​​of the first and second signals. Figure 1 The angle measurement method provided in the consistent embodiments can improve the accuracy of angle measurement and meet the angle measurement requirements of the rotator in practical applications, especially suitable for reciprocating rotators or rotators with non-uniform rotation speed.

[0077] This disclosure provides some embodiments for determining the rotation angle of a rotator based on the values ​​of a first signal and a second signal.

[0078] The first signal changes periodically within the angle measurement range, and can provide absolute angle information within one cycle. Therefore, the angle corresponding to a non-complete cycle of the first signal output by the first angle sensor can be determined by the value of the first signal, referred to here as the first angle. The second signal changes monotonically within the angle measurement range, so the angle value corresponding to all complete cycles of the first signal output by the first angle sensor can be determined by at least the value of the second signal, referred to here as the second angle. Based on the first angle and the second angle, the rotation angle of the rotator can be determined. In some embodiments, in step 106, the second angle can be determined based on the value of the second signal. The correspondence between the value of the second signal and the value of the second angle can be preset. For example, the first cycle of the first signal can be directly determined based on the value of the second signal, and the second angle can be determined based on the first cycle.

[0079] For example, the second angle sensor includes an eddy current angle sensor. The second signal includes the resonant frequency f of the resonant signal. The resonant frequency f changes monotonically within the angle measurement range. The third angle corresponding to the second signal output by the eddy current angle sensor has a first relationship with the resonant frequency. For example, the first relationship between the value of the third angle θ3 and the resonant frequency f can be expressed as formula (1).

[0080] θ3=k(fb)(1)

[0081] For example, before a radar incorporating an eddy current angle sensor leaves the factory, the constants k and b in this linear relationship can be determined through measurement. Based on the value of the second signal and the first relationship, the value of the third angle θ3 can be determined. Since the angle measurement ranges of the first and second signals are consistent, the first cycle of the first signal can be determined based on the value of the second signal (e.g., the resonant frequency f or the third angle θ3). Because the angle value corresponding to each cycle of the first signal is fixed, the second angle can be determined based on the first cycle of the first signal.

[0082] Figure 3 A schematic diagram showing the correspondence between a rotation angle and a first signal and a second signal, consistent with an embodiment of this disclosure, is provided. Figure 3 Two coordinate systems are shown. The first coordinate system has the horizontal axis representing the rotation angle θ and the vertical axis representing the amplitude A of the first signal, used to characterize the correspondence between the value of the first signal and the rotation angle θ. For example, the first signal 302 is a sinusoidal signal, and its value is assumed to change periodically within the range [-1, 1]. The second coordinate system has the horizontal axis representing the rotation angle θ and the vertical axis representing the value of the second signal, for example. The value of the second signal can be a current value or a voltage value. The second signal 304 is a linearly changing signal.

[0083] In some embodiments, reference Figure 3 Assume that when the value of the second signal 304 is between 0 and 5, it corresponds to the first cycle of the first signal 302 of the first angle sensor, i.e., the first cycle T = 1. When the value of the second signal is between 5 and 10, it corresponds to the second cycle of the first signal, i.e., the first cycle T = 2. And so on, each cycle of the first signal 302 corresponds to a range of values ​​for the second signal. Assuming that one complete cycle of the first signal corresponds to 0.2°, the number of complete cycles that the first signal has passed can be determined based on the value of the second signal, and thus the second angle can be determined. For example, when the value of the second signal is 6, it can be determined that the cycle of the first signal is the second cycle, and the number of complete cycles it has passed is 1, so the value of the second angle is 0.2°. If the value of the first angle is determined to be 0.1° based on the value of the first signal, the rotation angle θ of the rotator can be determined to be the sum of the value of the first angle θ1 and the value of the second angle θ2, i.e., θ = θ1 + θ2 = 0.1° + 0.2° = 0.3°.

[0084] In some embodiments, a second angle can be determined based on the values ​​of a first signal and a second signal. The first angle is the angle corresponding to the value of the first signal within one cycle. In step 106, the first cycle in which the first signal is located can be determined based on the values ​​of the second signal and the first signal. The second angle can be determined based on the first cycle.

[0085] When both the first and second angle sensors are error-free, the rotation angles of the rotator corresponding to the first and second signals are consistent. However, due to temperature drift or device aging effects, the value of the second signal output by the second angle sensor (e.g., an eddy current angle sensor) may have an offset error. In this case, the correspondence between the values ​​of the first and second signals may not be consistent. Therefore, the second angle can be determined based on the values ​​of the first and second signals. The following example illustrates this with a specific application scenario.

[0086] Continue to refer to Figure 3 For example, the first signal 302 is a sinusoidal signal. Assume the value of the first signal 302 changes periodically within the range [-1, 1]. Without temperature drift, the value of the second signal 304 between 0 and 5 corresponds to the first period T1 = 1 of the first signal, and the value of the second signal 304 between 5 and 10 determines the first period T1 = 2 of the first signal 302. Assume the second angle sensor experiences temperature drift or aging, and the relationship between the value of the second signal and the rotation angle changes, becoming as follows: Figure 3 The second signal 306 is shown. When the value of the second signal 306 is between -2 and 3, the first period T1 of the first signal 302 is determined to be 1. When the value of the second signal 306 is between 3 and 8, the first period T1 of the first signal 302 is determined to be 2. Assume that at a certain moment, the value of the first signal 302 is 0.9 and the value of the second signal is 4. (Reference) Figure 3 Based on the value of the first signal 302 being 0.9, it can be determined that the current rotation angle is in the positive half-cycle of a certain period of the first signal 302. Based on the value of the second signal 304 being 4, it can be determined that the current rotation angle is in the negative half-cycle of the first period of the first signal. The periods of the current rotation angle determined by the first signal 302 and the second signal 304 are different. This inconsistency indicates that the second signal 304 may have deviated due to temperature drift. Based on this, the first period of the first signal 302 can be determined based on the values ​​of the first signal 302 and the second signal 304. Compared with the second angle sensor, the first angle sensor has higher environmental stability. In some embodiments, when the periods of the current rotation angle determined by the first signal 302 and the second signal 304 are different, the period determined by the first signal 302 shall be used. For example, continue to refer to Figure 3 When the value of the first signal 302 is 0.9 and the value of the second signal is 4, the periods of the current rotation angle determined by the first signal 302 and the second signal 304 are different. This indicates that the second angle sensor is experiencing temperature drift. Based on the value of the second signal 304, the period of the first signal 302 is determined to be T0 = 1. Combining this with the value of the first signal 302, the first period of the first signal 302 is determined to be T1 = T0 + 1 = 2. Thus, the number of complete periods for the first signal 302 can be determined to be 1, corresponding to a second angle of 0.2°. Furthermore, based on the value of the first signal 302 being 0.9, let's assume the first angle θ1 is determined to be 0.04°. Therefore, the rotation angle θ of the rotator can be determined to be the sum of the values ​​of the first angle θ1 and the second angle θ2, i.e., θ = θ1 + θ2 = 0.04° + 0.2° = 0.24°.

[0087] In some embodiments, the offset angle corresponding to the maximum offset error of the second signal is less than the angle value corresponding to half a cycle of the first signal.

[0088] As mentioned earlier, when the periods of the current rotation angle determined by the first signal 302 and the second signal 304 are different, it can be assumed that the second signal 304 has deviated due to temperature drift. By setting the period length of the first signal, the offset angle corresponding to the maximum offset error of the second signal is made smaller than the angle value corresponding to half a period of the first signal. In this way, the first period of the first signal can be obtained with a relatively certainty based on the value of the second signal. That is, based on the value of the first signal, it can be determined whether the second signal has deviated from the current period, and whether the second signal has deviated to the previous period or the next period of the first signal. In this way, an accurate rotation angle can be obtained. This can reduce the impact of temperature drift or aging problems of the second angle sensor on the measurement accuracy of the rotation angle of the rotator.

[0089] For example, the first angle sensor includes an analog optical coding angle sensor, and the rotation angle corresponding to the width of the code track (e.g., clear code track or dark code track) of the analog optical coding angle sensor can be set to be greater than the offset angle corresponding to the maximum offset error of the second signal. As another example, the first angle sensor includes an analog magnetic coding angle sensor, and the rotation angle corresponding to the width of the code track (e.g., N-pole or S-pole) of the analog magnetic coding angle sensor can be set to be greater than the offset angle corresponding to the maximum offset error of the second signal.

[0090] This disclosure also provides some embodiments for determining a first angle based on the value of a first signal to solve the problem of inaccurate measurement of the first angle sensor due to temperature drift, and to improve the measurement accuracy of the first angle.

[0091] The example of a first angle sensor including an analog optically encoded angle sensor is illustrated. The first signal output by the analog optically encoded angle sensor is subject to temperature drift. When the temperature changes, the amplitude of the first signal may change. In this case, the first angle determined based on the value of the first signal may be inaccurate.

[0092] To address the impact of temperature drift on the first signal of the first angle sensor, the first angle sensor can acquire two angle signals and determine the first angle based on these two angle signals.

[0093] Figure 4 A flowchart illustrating a method for determining a first angle based on the value of a first signal, consistent with embodiments of this disclosure, is shown. In some embodiments, reference is made to... Figure 4 This may include steps 402 and 404.

[0094] Step 402: Compare the first angle signal and the second angle signal.

[0095] In some embodiments, the first signal may include a first angle signal and a second angle signal, wherein the first angle signal and the second angle signal have a phase difference. For example, the phase difference between the first angle signal and the second angle signal is greater than 0 and less than 2. π .

[0096] Step 404: Determine the first angle based on the ratio.

[0097] The ratio of the first angle signal and the second angle signal has a displacement relationship with the value of the first angle within one cycle. Therefore, the value of the first angle can be determined based on this ratio.

[0098] For ease of understanding, the phase difference between the first angle signal and the second angle signal is taken as... Example. In some embodiments, the amplitude A of the first angle signal and the second angle signal are equal.

[0099] For example, if the first angle signal is a sinusoidal signal, then the relationship between the first angle signal and the first angle θ1 can be expressed as: x1 = Asinθ1. The relationship between the second angle signal and the first angle θ1 can be expressed as: In step 402, the ratio of the first angle signal x1 to the second angle signal x2 can be calculated, i.e. The relationship between the ratio of the first angle signal and the second angle signal and the first angle θ1 is as follows: Therefore, it can be determined that...

[0100] For example, still taking the phase difference between the first angle signal and the second angle signal as... Example. Assuming the first angle signal is a cosine signal, the relationship between the first angle signal and the first angle θ1 can be expressed as: x3 = Acosθ1. The relationship between the second angle signal and the first angle θ1 can be expressed as x4 = Asinθ1. In step 402, the ratio of the first angle signal x3 to the second angle signal x4 can be taken, i.e. Therefore, it can be determined that...

[0101] It should be noted that the above is only an example. The phase difference between the first angle signal and the second angle signal can also be... Other values ​​besides the first angle signal. The first angle signal can be any other type of sinusoidal signal with an initial phase that is not zero. For example, the first angle signal and Not zero.

[0102] This disclosure also provides some angle measurement devices to meet the angle measurement requirements of the rotator.

[0103] Figure 5An example frame structure diagram of an angle measurement device consistent with embodiments of the present disclosure is shown. In some embodiments, reference is made to... Figure 5 The angle measuring device 500 may include a first angle sensor 502, a second angle sensor 504, and a processor 506.

[0104] The first angle sensor 502 outputs a first signal. This first signal changes periodically within the angle measurement range. The second angle sensor 504 outputs a second signal. This second signal changes monotonically within the angle measurement range. The processor 506 can determine the position of the rotator (the rotator is within the range of...) based on the values ​​of the first and second signals. Figure 5 The rotation angle (not shown in the figure).

[0105] In the angle measuring device 500, the processor 506 determines the rotation angle of the rotator based on the values ​​of the first signal and the second signal, which can improve the accuracy and reliability of angle measurement and meet the angle measurement requirements of the rotator's rotation angle.

[0106] Processor 506 is a circuit with signal processing capabilities. In some embodiments, processor 506 may be a circuit with instruction read and execute capabilities. For example, processor 506 may be a central processing unit (CPU), a microcontroller unit (MCU), a graphics processing unit (GPU), or a digital signal processor (DSP). In other embodiments, processor 506 can implement certain functions through the logical relationships of hardware circuits, which may be fixed or reconfigurable. For example, processor 506 may be a hardware circuit implemented using an application-specific integrated circuit (ASIC) or a programmable logic device (PLD). For example, processor 506 may be a field-programmable gate array (FPGA). In reconfigurable hardware circuits, processor 506 loads configuration documents to implement the hardware circuit configuration process. Furthermore, processor 506 may also be a hardware circuit designed for artificial intelligence, which is essentially an ASIC. For example, processor 506 may include at least one of a neural network processing unit (NPU), a tensor processing unit (TPU), or a deep learning processing unit (DPU).

[0107] The functions of processor 506 can be implemented entirely through program calls. Alternatively, the functions of processor 506 can be implemented entirely through hardware circuitry. Or, the functions of processor 506 can be partially implemented through program calls, with the remaining functions implemented through hardware circuitry.

[0108] This disclosure also provides embodiments of a first angle sensor and a second angle sensor.

[0109] The first angle sensor can output a first signal that changes periodically within the angle measurement range. In some embodiments, the first angle sensor may include a code disk and a code reader. One of the code disk and the code reader may be disposed on the rotor of the rotating device, and the other may be disposed on the stator of the rotating device. The code disk has code tracks. As the rotor of the rotating device rotates, the code reader can detect the position change of the code tracks on the code disk and convert the detected signal into an electrical signal as the first signal. One code track corresponds to half a cycle of the first signal output by the first angle sensor.

[0110] To avoid the influence of temperature drift on the measurement of the first angle sensor, in some embodiments, the first signal may include a first angle signal and a second angle signal. The first angle sensor may include a first barcode reader and a second barcode reader. The first barcode reader can output the first angle signal, and the second barcode reader can output the second angle signal. The interval between the first barcode reader and the second barcode reader is a non-integer multiple of the width of the code track on the code disk. In some embodiments, the interval between the first barcode reader and the second barcode reader can be an integer multiple of half the width of the code track. For example, the relationship between the angular interval between the first barcode reader and the second barcode reader and the rotation angle corresponding to the width of the code track can be expressed by formula (2).

[0111] G=(n+0.5)*α (2)

[0112] Where G represents the angular interval between the first and second code readers, n is an integer greater than or equal to 0, and α is the rotation angle corresponding to one code track.

[0113] In some embodiments, the first angle sensor includes an analog optical coding angle sensor. In the analog optical coding angle sensor, the code disk has alternating light and dark code tracks. A code track can refer to a light code track or a dark code track. The code track width refers to the width of a code track, specifically the width of a light code track or the width of a dark code track.

[0114] In some embodiments, the first angle sensor includes an analog magnetically encoded angle sensor. The code track of the magnetically encoded angle sensor is a magnetic code track. The code disk of the magnetically encoded angle sensor has a sinusoidally varying magnetic field. One magnetic code track corresponds to half a cycle of the sinusoidal variation.

[0115] The first angle sensor incorporates a first code reader and a second code reader, with the interval between them set to an integer multiple of half a code track width. This results in a phase difference between the first angle signal and the second angle signal. Since temperature drift has the same effect on the amplitude of the first angle signal and the amplitude of the second angle signal, by calculating the ratio of the first angle signal and the second angle signal and determining the first angle based on the ratio, the influence of temperature drift in determining the value of the first angle can be eliminated, thus improving the measurement accuracy and environmental stability.

[0116] It is understandable that the phase difference between the first angle signal and the second angle signal can also be... Other than the values ​​specified in this disclosure. As long as there is a phase difference between the first angle signal and the second angle signal, the specific value of the phase difference is not limited.

[0117] This disclosure provides some embodiments of analog optical angle sensors.

[0118] In some embodiments, the analog optical angle sensor may include a code disk and an optical transceiver. The optical transceiver may include an optical emitter and an optical receiver. The optical emitter may include a light-emitting element. The optical receiver may include a photosensitive element. The code disk may include multiple code tracks, including clear code tracks and dark code tracks. The clear code tracks and dark code tracks are arranged alternately. The code disk may be made of metal, resin, or glass, etc. In some embodiments, the code disk may be fixedly connected to a rotating part (e.g., a rotor) of a rotator. The optical transceiver may be fixedly connected to a fixed part (e.g., a stator) of the rotator. In some embodiments, the code disk may be fixedly connected to a fixed part (e.g., a stator) of a rotator. The optical transceiver may be fixedly connected to a rotating part (e.g., a rotor) of a rotator.

[0119] Analog optical encoder angle sensors can be divided into two types: transmissive and reflective. In a transmissive analog optical encoder angle sensor, the light receiver and light emitter are located on opposite sides of the code disk. The light receiver detects whether the light emitted by the light emitter passes through the code track of the code disk. In a reflective analog optical encoder angle sensor, the light receiver and light emitter can be located on the same side of the code disk. The light receiver detects whether the light emitted by the light emitter is reflected by the code disk.

[0120] In some embodiments, the code disk can be disposed on the rotating part of the rotator, and the optical transceiver can be disposed on the fixed part of the rotator. For example, the code disk can be fixedly disposed relative to the rotor of the rotator. The optical transceiver can be fixedly disposed relative to the stator of the rotator. It is understood that the optical transceiver can also be disposed on other fixed components. For example, the optical transceiver can be disposed on a circuit board or a mechanical component of a device (e.g., a lidar). For example, the optical transceiver can be disposed on the inner wall of the housing of a device (e.g., a lidar). As the rotating part of the rotator rotates, the light emitted by the optical transmitter is transmitted or reflected by the code disk and received by the optical receiver and converted into an electrical signal, which can be output as a first signal.

[0121] In some embodiments, the analog optical angle sensor may include a code disk, a first optical transceiver, and a second optical transceiver. The first and second optical transceivers may each function as a reader. For example, the first optical transceiver may function as a first reader, outputting a first angle signal; the second optical transceiver may function as a second reader, outputting a second angle signal.

[0122] The interval between the first and second optical transceivers is a non-integer multiple of the code track width of the code disk. For example, the angular interval between the first and second optical transceivers is an integer multiple of the rotation angle corresponding to half the code track width. In some embodiments, the relationship between the angular interval between the first and second optical transceivers and the rotation angle corresponding to the code track width can be expressed by formula (2). For example, the interval between the first and second optical transceivers can be 0.5 times, 1.5 times, 2.5 times, or 3.5 times the rotation angle corresponding to the code track width, etc.

[0123] In some embodiments, the analog optical encoder angle sensor can be a dual-channel optical encoder angle sensor. The analog optical encoder angle sensor may include a code disk, an optical transmitter, a first optical receiver, and a second optical receiver. The first and second optical receivers can each function as a reader. For example, the first optical receiver can function as a first reader, outputting a first angle signal; the second optical receiver can function as a second reader, outputting a second angle signal.

[0124] The interval between the first optical receiver and the second optical receiver is a non-integer multiple of the code track width of the code disk. In some embodiments, the angular interval between the first optical receiver and the second optical receiver is an integer multiple of the rotation angle corresponding to half the code track width. For example, the relationship between the interval between the first optical receiver and the second optical receiver and the code track width can be expressed by formula (2). For example, the angular interval between the first optical transceiver and the second optical transceiver is 0.5 times, 1.5 times, 2.5 times, or 3.5 times the rotation angle corresponding to the code track width, etc.

[0125] When the first angle sensor includes an analog optical coding angle sensor, if the size of the illumination area (also called a light spot) formed on the code disk by the light emitted by the optical transmitter is too small, the first signal output by the analog optical coding angle sensor will not be a sinusoidal signal, but rather a trapezoidal signal. The first angle cannot be determined from the value of the first signal at the plateau portion of the trapezoid. To address this problem, in some embodiments, the size of the illumination area formed on the code disk by the light emitted by the optical transmitter can be configured to be greater than or equal to the width of the code track on the code disk. In this way, the value of the first angle within one cycle can be determined based on the value of the first signal output by the analog optical coding angle sensor.

[0126] Furthermore, if the size of the illumination area formed on the code disk by the light emitted by the optical transmitter is too large, the amplitude of the analog electrical signal converted by the optical coding analog angle sensor may be small, and the analog signal acquisition circuit in the analog optical coding angle sensor may have difficulty distinguishing the values ​​of the first signal corresponding to two similar angles. This situation affects the resolution of the analog optical coding angle sensor. In some embodiments, the size of the illumination area formed on the code disk by the light emitted by the optical transmitter can be configured to be less than or equal to twice the code track width. This improves the angle measurement resolution of the measuring device.

[0127] For example, the size of the illumination area formed on the code disk by the light emitted by the optical transmitter can be greater than or equal to the width of one code track, and less than or equal to the width of two code tracks. Assuming that the shape of the illumination area formed on the code disk by the light emitted by the optical transmitter is circular, the relationship between the diameter D of the illumination area and the width d of the code track can be expressed as: d ≤ D ≤ 2d.

[0128] This disclosure provides some embodiments of analog magnetic angle sensors.

[0129] In some embodiments, the magnetically encoded angle sensor may include a magnetic code disk and a magnetic sensor (e.g., a Hall element). The magnetic code disk generates a stable magnetic field. The magnetic sensor detects changes in the direction of the magnetic field.

[0130] The magnetic code disk can be made of permanent magnets. In some embodiments, the magnetic code disk can be in the shape of a disk or an arc, and magnetized in the radial or axial direction of the disk or arc structure. In some embodiments, the magnetic code disk can include multiple magnetic tracks. These magnetic tracks are composed of multiple magnetic poles arranged alternately. These alternating magnetic poles form a periodic magnetic field, and a magnetic sensor can detect changes in the direction of the magnetic field.

[0131] For example, a magnetic code disk can be mounted at the end of the rotating part (e.g., rotor) of a rotator. A magnetic sensor can be mounted on a fixed component within the magnetic field range of the magnetic code disk. This fixed component can be the fixed part of the rotator (e.g., stator), or it can be the inner wall of a circuit board, the housing of a device (e.g., a lidar), or other types of fixed components. When the magnetic code disk rotates with the rotating part of the rotator, the magnetic sensor can detect changes in the direction of the magnetic field. This change can be converted into an electrical signal (e.g., a voltage signal or a current signal) that is sinusoidally or cosinely related to the angle of the magnetic field, serving as a first signal.

[0132] For example, a magnetic code disk can be mounted on the fixed part (e.g., stator) of a rotator, and a magnetic sensor can be mounted on the end of the rotating part (e.g., rotor) of the rotator, within the magnetic field range of the magnetic code disk. As the rotating part of the rotator rotates, the magnetic sensor can also detect changes in the direction of the magnetic field and convert them into electrical signals (e.g., voltage or current signals) as the first signal.

[0133] In some embodiments, to avoid the impact of temperature drift on the measurement results of the analog magnetic encoder angle sensor, the analog magnetic encoder angle sensor, as the first angle sensor, may include a magnetic code disk, magnetic poles alternately arranged around the disk, and two magnetic sensors. The magnetic sensors can detect the change in magnetic field when the magnetic code disk rotates and convert the change in magnetic field into an angle signal in the form of a sine wave or a cosine wave.

[0134] In some embodiments, the analog magnetic encoder angle sensor may include a first magnetic sensor and a second magnetic sensor. The first magnetic sensor acts as a first reader, outputting a first angle signal; the second magnetic sensor acts as a second reader, outputting a second angle signal. The interval between the first and second magnetic sensors is a non-integer multiple of the width of the magnetic code track. For the analog magnetic encoder angle sensor, one magnetic code track corresponds to half a cycle of the sinusoidal change in the first or second angle signal from the first or second magnetic sensor.

[0135] This disclosure also provides some embodiments of second angle sensors.

[0136] In some embodiments, the second angle sensor includes an eddy current angle sensor. An eddy current sensor is a sensor that measures angle or distance using the eddy current effect. Eddy current angle sensors have advantages such as low cost, small space requirements, and the ability to provide high-precision absolute angle information. However, the performance of eddy current angle sensors is susceptible to temperature drift and aging effects, resulting in low environmental stability.

[0137] In some embodiments, continue to refer to Figure 2 The eddy current angle sensor 200 may include a metal target 202, an inductor coil 204, a resonant circuit 206, and a measurement circuit 208. The metal target 202 may be coupled to a rotator (the rotator is located in...). Figure 2 A rotating part (not shown) is connected. The inductor coil 204 can be positioned opposite the metal target 202 and fixed relative to the fixed part of the rotator. The resonant circuit 206 can be electrically connected to the inductor coil 204 to generate a resonant signal. The measuring circuit 208 can be connected to the resonant circuit 206 and outputs a second signal based on the resonant signal.

[0138] The first signal output by the eddy current angle sensor 200 can vary with the distance or overlap area between the inductor coil 204 and the metal target 202. In some embodiments, the second signal may include a square wave signal based on a resonant signal, and the frequency of the second signal is the same as the frequency of the resonant signal. The relative position (e.g., relative distance or relative angle) between the inductor coil and the metal target can be determined based on the magnitude of the second signal frequency. In some embodiments, the second signal may include the resonant frequency of the resonant signal. The relative position (e.g., relative distance or relative angle) between the inductor coil and the metal target can be determined based on the magnitude of the second signal.

[0139] In some embodiments, the metal target 202 and the inductor coil 204 may be arranged opposite each other along a direction parallel to the rotation axis of the rotator. When the rotator rotates, the overlapping area of ​​the projections of the metal target 202 and the inductor coil 204 along the rotation axis of the rotator changes, thereby changing the frequency of the resonant signal. In some embodiments, the metal target 202 and the inductor coil 204 may be arranged opposite each other along a direction perpendicular to the rotation axis of the rotator. When the rotator rotates, the distance between the metal target 202 and the inductor coil 204 changes, thereby changing the frequency of the resonant signal.

[0140] In some embodiments, the offset angle corresponding to the maximum offset error of the second signal output by the second angle sensor is less than the angle value corresponding to half a cycle of the first signal output by the first angle sensor. This allows for a more accurate determination of the first cycle of the first signal output by the first angle sensor based on the value of the second signal, reducing the impact of temperature drift or aging issues of the second angle sensor on the accuracy of angle measurement, and improving the accuracy and environmental stability of angle measurement. For example, the first angle sensor includes an analog optical coding angle sensor, and the second angle sensor includes an eddy current angle sensor. The maximum angular offset error of the second signal output by the eddy current angle sensor is less than the rotation angle corresponding to the width of the code track on the code disk. As another example, the first angle sensor includes an analog magnetic coding angle sensor, and the second angle sensor includes an eddy current angle sensor. The maximum angular offset error of the second signal output by the eddy current angle sensor is less than the rotation angle corresponding to the width of the magnetic code track.

[0141] In this embodiment of the present disclosure, the rotator includes a rotating part and a fixed part.

[0142] In some embodiments, the fixing part of the rotator may be disposed on a circuit board. In other embodiments, the fixing part of the rotator may be fixed to the inner wall of the housing of a device (e.g., a lidar).

[0143] In some embodiments, the rotary device may include a reciprocating rotary device. A reciprocating rotary device can perform reciprocating motion.

[0144] In some embodiments, the rotating part of the rotator can be the rotor of an electric motor. The fixed part of the rotator can be the stator of an electric motor.

[0145] It should be noted that the above is merely an illustrative example of a rotator. The angle measurement method or apparatus in this disclosure is also applicable to unidirectional rotators. This disclosure does not limit the structure or movement of the rotator in any way.

[0146] This disclosure also provides embodiments of scanning devices, which may include means for measuring angles.

[0147] Figure 6 An example frame structure diagram of a scanning device consistent with embodiments of this disclosure is shown. (Refer to...) Figure 6 In some embodiments, the scanning device 600 may include a rotator 602, an angle measuring device 604, and a scanner 606.

[0148] The rotator 602 can move in response to a motion control signal. The angle measuring device 604 can determine the rotation angle of the rotator 602. The scanner 606 is disposed on the rotator 602 and moves with the rotator 602.

[0149] The specific implementation of the angle measuring device 604 can be referenced in... Figure 5 An embodiment consistent with the angle measuring device shown is described herein. Further details are omitted here.

[0150] In some embodiments, the rotator 602 may reciprocate in response to a motion control signal.

[0151] In some embodiments, scanner 606 may include a reflector. In some embodiments, scanner 606 may include a lens or prism.

[0152] It should be noted that the embodiments disclosed herein do not limit the type of scanner. For example, scanner 606 may also be other components that can change the laser emission direction.

[0153] The scanning device 600 can be installed in a lidar. Specifically, the scanning device 600 can be installed on the output optical path of the detection signal, or on the incident optical path of the echo signal, or on both the output optical path of the detection signal and the incident optical path of the echo signal.

[0154] based on Figure 6 The scanning device 600 shown can achieve high accuracy and high environmental stability in measuring the angle of the scanning mirror, thus meeting the angle measurement requirements of the lidar.

[0155] In some embodiments, the scanning device 600 may further include a driver (the driver is in...) Figure 6 (Not shown). The driver can output motion control signals to the rotator to control the rotation of the rotator's rotating part, enabling the lidar to scan one or all of the vertical or horizontal field of view. For example, the laser detection signal is emitted through the scanner, and the rotation of the scanner can change the emission path of the detection signal. Similarly, the echo signal can be incident on the scanner, guided by the scanner to the light receiving path, and received by the detector.

[0156] This disclosure also provides some lidars that can provide detection data with high accuracy and high environmental stability.

[0157] Figure 7 An example diagram of a lidar frame structure consistent with embodiments of this disclosure is shown. In some embodiments, reference is made to... Figure 7 The lidar 700 may include a laser 702, a detector 704, and a scanning device 706.

[0158] The laser 702 can emit a detection signal. The laser 702 in the lidar 700 can emit light based on set emission control parameters to form a detection signal.

[0159] In some embodiments, laser 702 may include a semiconductor laser, a fiber laser, or other types of lasers. For example, a semiconductor laser may include a laser emitting circuit, a vertical cavity surface emitting laser (VCSEL), an edge emitting laser (EEL), a distributed feedback laser (DFB), or similar devices or circuits. The types of lasers described above are merely illustrative examples, and this disclosure does not limit the types of lasers used.

[0160] Detector 704 can receive the echo signal returned after the detection signal is reflected by an object. Detector 704 can convert the optical signal into an electrical signal using the photoelectric effect. In some embodiments, detector 704 may include: a photodetector circuit, a pin photodiode (PINPD), an avalanche photodiode (APD), a single photon avalanche diode (SPAD), a silicon photomultiplier (SiPM), or similar devices or circuits. The above types of detectors are merely illustrative examples, and the embodiments disclosed herein do not limit the type of detector.

[0161] In some embodiments, there may be multiple lasers 702. There may also be multiple detectors 704. The lidar 700 may include multiple detection channels. Different detection channels can detect objects at different angles. A detection channel may include one or more lasers and one or more detectors. The correspondence between detection channels and lasers or detectors can be physically configured or configured by an algorithm. For example, one or more lasers included in a detection channel may have a preset correspondence with one or more detectors. When one or more lasers in a detection channel emit light, the corresponding one or more detectors receive the echo. As another example, the lidar 700 may include a detector array. One or more detectors at different positions on the detector array constitute pixels of a detection channel. Detectors within a pixel can receive echoes and output electrical signals. Pixels in different detection channels may include the same detectors. Pixels in different detection channels may also not include the same detectors.

[0162] The scanning device 706 can be placed on the outgoing optical path of the detection signal, or on the incoming optical path of the echo signal, or on both the outgoing optical path of the detection signal and the incoming optical path of the echo signal.

[0163] In some embodiments, the scanning device 706 may include a rotator, an angle measuring device, and a scanner. Embodiments of the scanning device 706 may employ... Figure 6 An embodiment identical to the scanning device 600 shown is not described in detail here.

[0164] In some embodiments, the scanning device 706 may further include a driver (the driver is in...) Figure 7 (Not shown in the image). The implementation method can be referred to the aforementioned embodiments, and will not be repeated here.

[0165] In some embodiments, the lidar 700 may further include a control and processing system (the control and processing system is in...) Figure 7 (Not shown in the image). When the lidar 700 includes a scanning device 706, the control and processing system can also control the movement of the scanning device 706.

[0166] The above embodiments illustrate some methods and apparatuses for angle measurement, scanning devices, and lidar. It should be noted that any method may include more or fewer steps, and the order of the steps may be the same or different. Embodiments of different methods or apparatuses can be referenced interchangeably, and embodiments of different methods or apparatuses can be combined for implementation.

[0167] In this disclosure, the term "or" describes the relationship between related objects and indicates a non-exclusive inclusion. For example, "A or B" can include: the presence of only "A", the presence of only "B", and the presence of both "A" and "B", where "A" and "B" can be singular or plural. As another example, "A, B, or C" can include: the presence of only "A", the presence of only "B", the presence of only "C", the presence of both "A" and "B", the presence of both "A" and "C", the presence of both "B" and "C", and the presence of both "A", "B", and "C", where "A", "B", and "C" can be singular or plural. In this disclosure, the term "at least one A or B" has the same meaning as "A or B" as described above. The term "at least one A, B, or C" has the same meaning as "A, B, or C" as described above.

[0168] It is understood that the devices in different embodiments of this disclosure that use the same markings or the same names are only used to characterize their relative positions and functions in the apparatus or device, and do not limit their specific models or parameters. The required device models or parameters can be used according to actual needs, and are not intended to limit the relationship between the various embodiments.

[0169] In this disclosure, unless otherwise expressly specified and limited, ordinal numbers, such as “first,” “second,” etc., are used only to distinguish and describe related objects, and should not be construed as indicating or implying the relative importance or order between related objects. Furthermore, ordinal numbers do not represent the quantity of related objects. For example, “multiple” includes two or more, and other quantifiers are similar.

[0170] While the embodiments disclosed herein are as described above, this disclosure is not limited thereto. Any person skilled in the art can make various alterations and modifications without departing from the spirit and scope of this disclosure; therefore, the scope of protection of this disclosure should be determined by the scope defined in the claims.

Claims

1. A method for measuring an angle, comprising: The first angle sensor outputs a first signal, which changes periodically within the angle measurement range; The second angle sensor outputs a second signal, which changes monotonically within the angle measurement range; The rotation angle of the rotator is determined based on the values ​​of the first signal and the second signal.

2. The method according to claim 1, characterized in that, Determining the rotation angle of the rotator based on the values ​​of the first signal and the second signal includes: The first angle is determined based on the value of the first signal; The second angle is determined at least based on the value of the second signal; The rotation angle is determined based on the first angle and the second angle.

3. The method of claim 2, wherein, The first angle is the angle corresponding to the value of the first signal within one cycle; Determining the second angle based at least on the value of the second signal includes: The first period of the first signal is determined based on the value of the second signal and the value of the first signal; The second angle is determined based on the first period.

4. The method according to claim 2 or 3, characterized in that, Determining the first angle based on the value of the first signal includes: The ratio of the first angle signal and the second angle signal is taken, wherein the first signal includes the first angle signal and the second angle signal, and the first angle signal and the second angle signal have a phase difference; The first angle is determined based on the ratio.

5. The method of claim 4, wherein, The phase difference is 6. The method according to any one of claims 1 to 5, characterized in that, The offset angle corresponding to the maximum offset error of the second signal is less than the angle value corresponding to half a cycle of the first signal.

7. An angle measuring device, comprising: A first angle sensor is configured to output a first signal, which varies periodically within the angle measurement range; A second angle sensor is configured to output a second signal that varies monotonically within the angle measurement range; The processor is configured to determine the rotation angle of the rotator based on the values ​​of the first signal and the second signal.

8. The apparatus of claim 7, wherein, The first signal includes a first angle signal and a second angle signal, and the first angle sensor includes: Code disk; The first code reader is configured to output the first angle signal; The second code reader is configured to output the second angle signal; Wherein, the interval between the first barcode reader and the second barcode reader is a non-integer multiple of the width of the code track of the code disk.

9. The apparatus of claim 8, wherein, The interval between the first reader and the second reader is an integer multiple of half the width of the code channel.

10. The apparatus according to any one of claims 7-9, characterized in that, The first angle sensor includes at least one of the following: Analog optical angle sensor; or, Analog magnetic angle sensor; The second angle sensor includes: Eddy current angle sensor.

11. The apparatus of claim 10, wherein, The analog optical encoder angle sensor includes: Code disk; A light emitter is configured to emit light, wherein the size of the illumination area formed on the code disk by the light is greater than or equal to the width of the code track of the code disk.

12. The device of any one of claims 7-9, wherein, The offset angle corresponding to the maximum offset error of the second signal is less than the angle value corresponding to half a cycle of the first signal.

13. A scanning device, comprising: The rotator is configured to move in response to a motion control signal; The apparatus according to any one of claims 7-12 is configured to determine the rotation angle of the rotator; The scanner is mounted on the rotator and moves with the rotator.

14. The scanning device of claim 13, wherein, The rotator is configured to reciprocate in response to the motion control signal.

15. The scanning device of claim 13, wherein, The scanner comprises at least one of: a mirror, a lens or a prism.

16. A lidar, comprising: a laser configured to emit a probe signal; a detector configured to receive a return signal returned after the probe signal is reflected by an object; The scanning device of any one of claims 13-15 is disposed on an outgoing light path of the probe signal, or on an incoming light path of the return signal, or on both the outgoing light path of the probe signal and the incoming light path of the return signal.

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