Ranging precision adjusting device applied to laser radar and laser radar

Abstract

The utility model discloses a ranging precision adjusting device applied to a laser radar and the laser radar, and the device comprises a photoelectric conversion module which receives a plurality of echo optical signals, converts the echo optical signals into current signals in sequence, and carries out the gain amplification according to bias voltage signals; the signal processing module is connected with the photoelectric conversion module, receives the current signal and converts the current signal into a voltage signal; the FPGA processing module is connected with the signal processing module, and the FPGA processing module determines the adjustment amount Yn of the bias voltage of the photoelectric conversion module according to the light intensity information of the echo light signal in the nth unit time; the bias voltage Xn = bias voltage Xn-1 + the adjustment amount Yn; and the bias voltage circuit is connected with the FPGA processing module and the photoelectric conversion module and is used for setting the bias voltage signal of the nth unit time according to the bias voltage Xn. According to the utility model, the bias voltage of the photoelectric detector can be adaptively adjusted according to the light intensity level in the environment, so that the ranging precision of the laser radar is higher.

Description

Technical Field

[0001] The utility model relates to the technical field of laser radar based on photoelectric detection, in particular to a distance measurement accuracy adjustment device applied to laser radar and the laser radar. Background Art

[0002] LiDAR (LiDAR) has been widely used in various fields due to its high-precision and high-resolution measurement advantages. In particular, in the field of autonomous vehicles, LiDAR is an essential core sensor for calibration, testing, and real-world applications.

[0003] The photoelectric detector of the lidar can be used under different ambient light intensity conditions. If a unified photoelectric detector parameter setting is used, the measurement capability of the lidar cannot be effectively exerted.

[0004] In fact, the intensity of stray light varies when the ambient light intensity is different. On a clear day, there is more stray light in the environment, which produces sunlight noise, and the noise affects the performance of the point cloud.

[0005] Therefore, for those skilled in the art, how to dynamically adjust the photodetector parameter settings to maximize the measurement capabilities of the lidar under different ambient light intensity conditions will be a technical problem that needs to be solved urgently. Summary of the Invention

[0006] The technical problem solved by the utility model is to provide a ranging accuracy adjustment device applied to a laser radar, so as to adjust the setting parameters of the photoelectric detector at any time according to the light intensity information measured in the current environment, so as to improve the ranging accuracy of the laser radar.

[0007] The utility model discloses a distance measurement accuracy adjustment device applied to a laser radar, the distance measurement accuracy adjustment device comprising:

[0008] The photoelectric conversion module receives multiple echo optical signals and converts the echo optical signals into current signals in sequence and performs gain amplification according to the bias signal;

[0009] A signal processing module is connected to the photoelectric conversion module and receives the current signal and converts it into a voltage signal;

[0010] FPGA processing module, connected to the signal processing module, the FPGA processing module determines the adjustment amount Y of the bias voltage of the photoelectric conversion module according to the light intensity information of the echo light signal in the nth unit time n ;

[0011] Bias voltage X n =Bias voltage X n-1 +Adjustment Amount Y n ;

[0012] The bias voltage circuit is connected to the FPGA processing module and the photoelectric conversion module, and is configured to generate a bias voltage X according to the bias voltage X. n Set the bias signal for the nth unit time.

[0013] The photoelectric conversion module includes a first resistor, a second resistor, a first capacitor and a photodetector;

[0014] The second end of the first resistor is connected to the first end of the photodetector, the first end of the first resistor is grounded, the second end of the photodetector is connected to the first end of the second resistor, the second end of the second resistor is connected to the first end of the first capacitor, the second end of the second resistor is used to input the bias signal, and the second end of the first capacitor is grounded.

[0015] The photodetector is a SPAD, an APD or a SIPM.

[0016] The signal processing module includes a signal amplifying circuit and a differential amplifying circuit.

[0017] The signal amplifying circuit is connected to the photoelectric conversion module and the differential amplifying circuit;

[0018] The signal amplification circuit includes:

[0019] A first operational amplifier, a third resistor, a transimpedance amplifier resistor and a second capacitor, the first end of the third resistor is connected to the inverting input end of the first operational amplifier to form a signal input end of the signal amplification circuit, the first end of the second capacitor is connected to the non-inverting input end of the first operational amplifier, the second end of the second capacitor is grounded, the output end of the first operational amplifier, the second end of the third resistor are connected to the first end of the transimpedance amplifier resistor, and the second end of the transimpedance amplifier resistor forms a signal output end of the signal amplification circuit.

[0020] The differential amplifier circuit includes:

[0021] a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor, a fourth capacitor, and a second operational amplifier;

[0022] The first end of the fourth resistor constitutes a signal input end of the differential amplifier circuit, the second end of the fourth resistor, the first end of the sixth resistor, and the first end of the third capacitor are connected to the inverting input end of the second operational amplifier, the first end of the fifth resistor is grounded, the second end of the fifth resistor, the first end of the seventh resistor, and the first end of the fourth capacitor are connected to the non-inverting input end of the second operational amplifier, the second end of the sixth resistor and the second end of the third capacitor are connected to the first output end of the second operational amplifier, the second end of the seventh resistor and the second end of the fourth capacitor are connected to the second output end of the second operational amplifier, and the first and second output ends of the second operational amplifier constitute a differential signal output end of the differential amplifier circuit.

[0023] The bias voltage circuit includes a field effect tube, a voltage stabilizing diode, an eighth resistor, a fifth capacitor, a first inductor and a voltage control chip;

[0024] The EXT terminal of the voltage control chip is connected to the first terminal of the field effect tube, the second terminal of the field effect tube is connected to the positive electrode of the voltage stabilizing diode, and the third terminal of the field effect tube is grounded; the negative electrode of the voltage stabilizing diode is connected to the photodetector;

[0025] The FB terminal of the voltage control chip is connected to the first terminal of the eighth resistor, and the second terminal of the eighth resistor is connected to the FPGA processing module;

[0026] The VDD terminal of the voltage control chip, the first terminal of the fifth capacitor, and the negative terminal of the first inductor are connected together, the second terminal of the fifth capacitor is grounded, and the positive terminal of the first inductor is connected to the external power supply;

[0027] The CE terminal of the voltage control chip is connected to the FPGA processing module;

[0028] The GND terminal of the voltage control chip is grounded.

[0029] The FPGA processing module includes a comparator unit and a signal recognition unit;

[0030] The comparator unit compares the multiple voltage signals within a unit time with the first threshold voltage and the second threshold voltage respectively;

[0031] The signal recognition unit recognizes a proportion of a noise signal in the plurality of voltage signals, wherein the amplitude of the noise signal only exceeds the first threshold voltage, and determines light intensity information according to the proportion of the noise signal.

[0032] When the proportion of the noise signal per unit time is less than the first threshold, the adjustment amount Y n Increase;

[0033] When the proportion of the noise signal per unit time is greater than the second threshold, the adjustment amount Y n reduce;

[0034] When the proportion of the noise signal per unit time is less than or equal to the second threshold and greater than or equal to the first threshold, the adjustment amount Y n remain unchanged;

[0035] The first threshold is smaller than the second threshold.

[0036] The utility model discloses a laser radar, comprising: the distance measurement accuracy adjustment device applied to the laser radar.

[0037] Through the above-mentioned method, the utility model can realize adaptive adjustment of the bias voltage of the photodetector according to the light intensity level in the environment, and at the same time utilize the reasonable configuration of the circuit to eliminate signal noise, so that the ranging accuracy of the laser radar is higher and the ranging capability is stronger. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 Shown is a structural schematic diagram of the distance measurement accuracy adjustment device applied to laser radar of the present invention.

[0039] Figure 2 Shown is a structural diagram of the FPGA processing module of the present invention.

[0040] Figure 3 Shown is a structural diagram of the signal processing module of the present invention.

[0041] Figure 4 Shown is a circuit structure diagram of the distance measurement accuracy adjustment device of the present utility model.

[0042] Figure 5 Shown is a circuit structure diagram of the bias voltage circuit of the present utility model. DETAILED DESCRIPTION

[0043] The following describes the implementation process of the technical solution of the present invention in conjunction with specific embodiments, which are not intended to limit the present invention.

[0044] The utility model provides a distance measurement accuracy adjustment device applied to a laser radar, which can adjust the setting parameters of the photoelectric detector at any time according to the light intensity information measured in the current environment to improve the distance measurement accuracy of the laser radar.

[0045] like Figure 1 The figure shows a schematic diagram of the structure of the distance measurement accuracy adjustment device for laser radar of the present invention. The distance measurement accuracy adjustment device for laser radar of the present invention is applied to laser radar equipment.

[0046] The distance measurement accuracy adjustment device includes: a photoelectric conversion module 10 , a signal processing module 20 , an FPGA processing module 30 and a bias voltage circuit 40 .

[0047] The photoelectric conversion module 10 is arranged on the receiving focal plane of the receiving lens assembly and is used to sequentially receive multiple echo light signals corresponding to the multiple laser signals projected by the laser radar. The photoelectric conversion module 10 includes a photodetector, which sequentially converts the echo light signals into current signals and performs gain amplification according to the bias signal. The photodetector is a SPAD, APD, or SIPM. Avalanche photodiodes (APDs) have advantages such as large current gain, high sensitivity, and fast frequency response. They are commonly used laser echo receiving photodetection devices in pulsed laser radars. In order to improve the ranging capability of the laser radar, the current gain of the APD should be adjusted in real time according to the ranging environment. The current gain of the APD is directly related to its operating bias voltage. When the bias voltage is too low, the current gain is also low, and the APD cannot achieve optimal performance. When the bias voltage is too high, the noise increases, and the echo signal will be annihilated by the noise, affecting signal extraction. The same is true for other types of photodetectors.

[0048] The signal processing module 20 is connected to the photoelectric conversion module 10 . The signal processing module 20 is configured to receive the current signal generated by the photoelectric conversion module 10 and convert the current signal into a voltage signal.

[0049] The FPGA processing module 30 is connected to the signal processing module 20 . The FPGA processing module calculates the adjustment amount of the bias voltage of the photoelectric conversion module 10 based on the recognition of the light intensity information in the echo light signal.

[0050] The FPGA processing module determines the adjustment amount Y of the bias voltage of the photoelectric conversion module according to the light intensity information of the echo light signal in the nth unit time. n ; Bias voltage X n =Bias voltage X n-1 +Adjustment Amount Y n The system is pre-set with an initial bias voltage X0 and an initial adjustment value Y0.

[0051] The bias voltage circuit 40 is connected to the FPGA processing module 30 and the photoelectric conversion module 10. The bias voltage circuit 40 is connected to the FPGA processing module 30 and the photoelectric conversion module 10. n The bias signal is set for the photoelectric conversion module 10 to form a feedback closed loop.

[0052] The FPGA processing module 30 processes a plurality of voltage signals received sequentially within a unit time, which may be 1 second, but is not limited thereto.

[0053] like Figure 2 As shown, the FPGA processing module includes a comparator unit 31 and a signal recognition unit 32 .

[0054] Comparator unit 31 is equipped with a threshold voltage group, which includes multiple threshold voltages, such as a first threshold voltage and a second threshold voltage. The number of threshold voltage groups is determined by actual needs and is not limited thereto. The multiple threshold voltages are arranged in order, with the first threshold voltage being the minimum. The first threshold voltage corresponds to the voltage amplitude of the return light signal from the most distant target under normal circumstances and is also considered to be the typical level of the noise signal.

[0055] For multiple voltage signals received sequentially within a unit time, the comparator unit 31 compares each voltage signal with the multiple threshold voltages, and records the time when the rising edge and falling edge of each voltage signal reach each threshold voltage.

[0056] The amplitude of noise signals, especially sunlight noise, is usually much lower than that of the target signal. Therefore, the noise signal can reach the first threshold voltage but cannot reach the higher second threshold voltage. The voltage signal corresponding to the normal echo light signal can reach the higher second threshold voltage.

[0057] The signal identification unit 32 records the situation where multiple voltage signals reach the corresponding threshold voltage, and identifies the voltage signal whose amplitude only exceeds the first threshold voltage as a noise signal, calculates the proportion of the noise signal in the multiple voltage signals per unit time, and determines the light intensity information based on the proportion of the noise signal.

[0058] When the proportion of the noise signal per unit time is less than the first threshold, it is considered that the sunlight noise is small and the light intensity level is low. At this time, the bias voltage can be increased to increase the gain, that is, the adjustment amount Y n to increase, as by one unit;

[0059] When the proportion of the noise signal per unit time is greater than the second threshold, it is considered that there are more sunlight noise points and the light intensity level is high. At this time, the bias voltage needs to be reduced to reduce the gain, that is, the adjustment amount Y n Reduce, for example, by one unit to avoid excessive sunlight noise affecting the ranging of the lidar;

[0060] When the proportion of the noise signal per unit time is less than or equal to the second threshold and greater than or equal to the first threshold, the adjustment amount Y n remain unchanged;

[0061] The first threshold is smaller than the second threshold.

[0062] Through the above method, the bias voltage of the photodetector can be adaptively adjusted according to the light intensity level in the environment, so that the ranging accuracy of the laser radar is higher and the ranging capability is stronger.

[0063] like Figure 3 The structure diagram of the signal processing module 20 of the present invention is shown in FIG. Figure 4 Shown is a circuit structure diagram of the distance measurement accuracy adjustment device of the present utility model.

[0064] The photoelectric conversion module 10 includes a first resistor R1, a second resistor R2, a first capacitor C1 and a photodetector APD;

[0065] The first end of the first resistor is grounded, the second end of the first resistor is connected to the first end of the photodetector, the second end of the photodetector is connected to the first end of the second resistor, the second end of the second resistor is connected to the first end of the first capacitor, the second end of the second resistor is used to input the bias signal, and the second end of the first capacitor is grounded. The second end of the first resistor is the signal output end of the photoelectric conversion module 10, which is connected to the signal processing module 20.

[0066] The signal processing module 20 includes a signal amplifying circuit 21 and a differential amplifying circuit 22. The signal amplifying circuit 21 is connected to the photoelectric conversion module 10 and the differential amplifying circuit 22;

[0067] The signal amplifying circuit 21 includes:

[0068] The first operational amplifier D1, the third resistor R3 and the second capacitor C2, the first end of the third resistor R3 and the inverting input terminal of the first operational amplifier D1 are connected to form the signal input terminal of the signal amplification circuit, the first end of the second capacitor C2 is connected to the non-inverting input terminal of the first operational amplifier D1, the second end of the second capacitor C2 is grounded, the output terminal of the first operational amplifier D1, the second end of the third resistor R3 and the first end of the transimpedance amplifier resistor R3' are connected, and the second end of the transimpedance amplifier resistor R3' constitutes the signal output terminal of the signal amplification circuit 21. The current signal is converted to voltage and amplified by the signal amplification circuit 21. The above structure allows the voltage signal to be accurately amplified, which facilitates subsequent calculations and improves the ranging accuracy.

[0069] The differential amplifier circuit 22 includes:

[0070] a fourth resistor R4, a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a third capacitor C3, a fourth capacitor C4, and a second operational amplifier D2;

[0071] The first end of the fourth resistor constitutes the signal input terminal of the differential amplifier circuit 22. The second end of the fourth resistor, the first end of the sixth resistor, and the first end of the third capacitor are connected to the inverting input terminal of the second operational amplifier. The first end of the fifth resistor is grounded. The second end of the fifth resistor, the first end of the seventh resistor, and the first end of the fourth capacitor are connected to the non-inverting input terminal of the second operational amplifier. The second end of the sixth resistor and the second end of the third capacitor are connected to the first output terminal of the second operational amplifier. The second end of the seventh resistor and the second end of the fourth capacitor are connected to the second output terminal of the second operational amplifier. The first and second output terminals of the second operational amplifier constitute the differential signal output terminals of the differential amplifier circuit. Through the above structure, the voltage signal is further differentially amplified, signal noise is eliminated, and ranging accuracy is improved.

[0072] like Figure 5 Shown is a circuit structure diagram of the bias voltage circuit of the present utility model.

[0073] The bias voltage circuit 40 includes a field effect transistor U1, a voltage stabilizing diode D3, an eighth resistor R8, a fifth capacitor C5, a first inductor L1 and a voltage control chip A1;

[0074] The EXT terminal of the voltage control chip is connected to the first terminal of the field effect tube, the second terminal of the field effect tube is connected to the positive electrode of the voltage stabilizing diode, and the third terminal of the field effect tube is grounded; the negative electrode of the voltage stabilizing diode is connected to the photodetector;

[0075] The FB terminal of the voltage control chip is connected to the first terminal of the eighth resistor, and the second terminal of the eighth resistor is connected to the FPGA processing module 30;

[0076] The VDD terminal of the voltage control chip, the first terminal of the fifth capacitor, and the negative terminal of the first inductor are connected together, the second terminal of the fifth capacitor is grounded, and the positive terminal of the first inductor is connected to the external power supply;

[0077] The CE terminal of the voltage control chip is connected to the FPGA processing module;

[0078] The GND terminal of the voltage control chip is grounded.

[0079] The voltage control chip may be a high-current voltage control chip ME209.

[0080] Through the above-mentioned method, the utility model can realize adaptive adjustment of the bias voltage of the photodetector according to the light intensity level in the environment, and at the same time utilize the reasonable configuration of the circuit to eliminate signal noise, so that the ranging accuracy of the laser radar is higher and the ranging capability is stronger.

[0081] The above embodiments are only used to describe the technical solutions of the present invention and are not to be regarded as limiting the present invention.

Claims

1. A ranging accuracy adjustment device for laser radar, characterized in that: The distance measurement accuracy adjustment device comprises: The photoelectric conversion module receives multiple echo optical signals and converts the echo optical signals into current signals in sequence and performs gain amplification according to the bias signal; A signal processing module is connected to the photoelectric conversion module and receives the current signal and converts it into a voltage signal; FPGA processing module, connected to the signal processing module, the FPGA processing module determines the adjustment amount Y of the bias voltage of the photoelectric conversion module according to the light intensity information of the echo light signal in the nth unit time n ; Bias voltage X n =Bias voltage X n-1 +Adjustment Amount Y n ; The bias voltage circuit is connected to the FPGA processing module and the photoelectric conversion module, and is configured to generate a bias voltage X according to the bias voltage X. n Set the bias signal for the nth unit time.

2. The ranging accuracy adjustment device for laser radar according to claim 1, characterized in that: The photoelectric conversion module includes a first resistor, a second resistor, a first capacitor and a photodetector; The second end of the first resistor is connected to the first end of the photodetector, the first end of the first resistor is grounded, the second end of the photodetector is connected to the first end of the second resistor, the second end of the second resistor is connected to the first end of the first capacitor, the second end of the second resistor is used to input the bias signal, and the second end of the first capacitor is grounded.

3. The ranging accuracy adjustment device for laser radar according to claim 2, characterized in that: The photodetector is a SPAD, an APD or a SIPM.

4. The ranging accuracy adjustment device for laser radar according to claim 1, characterized in that: The signal processing module includes a signal amplifying circuit and a differential amplifying circuit.

5. The ranging accuracy adjustment device for laser radar according to claim 4, characterized in that: The signal amplifying circuit is connected to the photoelectric conversion module and the differential amplifying circuit; The signal amplification circuit includes: A first operational amplifier, a third resistor, a transimpedance amplifier resistor and a second capacitor, the first end of the third resistor is connected to the inverting input end of the first operational amplifier to form a signal input end of the signal amplification circuit, the first end of the second capacitor is connected to the non-inverting input end of the first operational amplifier, the second end of the second capacitor is grounded, the output end of the first operational amplifier, the second end of the third resistor are connected to the first end of the transimpedance amplifier resistor, and the second end of the transimpedance amplifier resistor forms a signal output end of the signal amplification circuit.

6. The ranging accuracy adjustment device for laser radar according to claim 4, characterized in that: The differential amplifier circuit includes: a fourth resistor, a fifth resistor, a sixth resistor, a seventh resistor, a third capacitor, a fourth capacitor, and a second operational amplifier; The first end of the fourth resistor constitutes a signal input end of the differential amplifier circuit, the second end of the fourth resistor, the first end of the sixth resistor, and the first end of the third capacitor are connected to the inverting input end of the second operational amplifier, the first end of the fifth resistor is grounded, the second end of the fifth resistor, the first end of the seventh resistor, and the first end of the fourth capacitor are connected to the non-inverting input end of the second operational amplifier, the second end of the sixth resistor and the second end of the third capacitor are connected to the first output end of the second operational amplifier, the second end of the seventh resistor and the second end of the fourth capacitor are connected to the second output end of the second operational amplifier, and the first and second output ends of the second operational amplifier constitute a differential signal output end of the differential amplifier circuit.

7. The distance measurement accuracy adjustment device for laser radar according to claim 2, characterized in that: The bias voltage circuit includes a field effect tube, a voltage stabilizing diode, an eighth resistor, a fifth capacitor, a first inductor and a voltage control chip; The EXT terminal of the voltage control chip is connected to the first terminal of the field effect tube, the second terminal of the field effect tube is connected to the positive electrode of the voltage stabilizing diode, and the third terminal of the field effect tube is grounded; the negative electrode of the voltage stabilizing diode is connected to the photodetector; The FB terminal of the voltage control chip is connected to the first terminal of the eighth resistor, and the second terminal of the eighth resistor is connected to the FPGA processing module; The VDD terminal of the voltage control chip, the first terminal of the fifth capacitor, and the negative terminal of the first inductor are connected together, the second terminal of the fifth capacitor is grounded, and the positive terminal of the first inductor is connected to the external power supply; The CE terminal of the voltage control chip is connected to the FPGA processing module; The GND terminal of the voltage control chip is grounded.

8. The distance measurement accuracy adjustment device for laser radar according to claim 1, characterized in that: The FPGA processing module includes a comparator unit and a signal recognition unit; The comparator unit compares the multiple voltage signals within a unit time with the first threshold voltage and the second threshold voltage respectively; The signal recognition unit recognizes a proportion of a noise signal in the plurality of voltage signals, wherein the amplitude of the noise signal only exceeds the first threshold voltage, and determines light intensity information according to the proportion of the noise signal.

9. The ranging accuracy adjustment device for laser radar according to claim 8, characterized in that: When the proportion of the noise signal per unit time is less than the first threshold, the adjustment amount Y n Increase; When the proportion of the noise signal per unit time is greater than the second threshold, the adjustment amount Y n reduce; When the proportion of the noise signal per unit time is less than or equal to the second threshold and greater than or equal to the first threshold, the adjustment amount Y n remain unchanged; The first threshold is smaller than the second threshold.

10. A laser radar, characterized in that: include: A ranging accuracy adjustment device for a laser radar as described in any one of claims 1 to 9.

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