Working time sequence control method for laser detection module

Abstract

The invention discloses a working time sequence control method for a laser detection module, and mainly solves the problems that data transmission of the laser detection module is easy to cover, clock alignment is difficult, and receiving and sending of a data processing module are asynchronous. According to the invention, time sequence control is carried out on the laser radar system by using the control signal, when the laser radar system starts to work, clock reset of each frame of data can be carried out through the reset signal, and transmission control of each frame of data is carried out through the data transmission enable signal. The laser radar system can complete continuous multi-frame distance measurement operation when detecting a moving object. And meanwhile, the problem of control confusion during cooperative operation among multiple modules is prevented by using an internal triggering mode. According to the method, an existing time sequence control method is favorably optimized, and the problems that high-speed data clocks are difficult to align, multiple modules are difficult to control and the like are solved by adding control signals.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated circuits, and in particular, relates to a working timing control method for a laser detection module. Background Art

[0002] Compared with traditional microwave radar, laser radar has the advantages of high angular resolution, high distance resolution, small divergence angle, strong anti-interference ability, etc. It is widely used in industrial production, aerospace, military strike, etc. Time-related single-photon counting laser radar has higher time resolution accuracy and detection sensitivity, and is one of the main development directions of contemporary laser radar. Laser radar is a type of optoelectronic radar system that uses laser as an information carrier and time-of-flight method as the ranging principle. The existing laser radar system consists of a laser emission module, a laser detection module, a data processing module, and a measurement and control display module (such as Figure 1 As shown), the three-dimensional image of the area array laser is realized by a single fast flash and frame statistics.

[0003] In the above system, the laser emission module emits a laser signal to the detected target and sends a laser synchronization pulse to the data processing module at the same time. After receiving the laser synchronization pulse, the data processing module sends a control signal to start timing the laser detection module. When the laser flying in the air encounters the detected object, a reflection echo will be generated. When the laser detection module receives the reflected laser echo pulse, it will stop timing and generate the corresponding laser photon flight time data. The laser detection module transmits the photon flight time data to the data processing module, and the data is restored to generate the image data of the detected target.

[0004] To ensure the correctness of the image data of the detection module, the photon flight time data generated in the laser detection module is transmitted bit by bit to the data processing module for image processing, and the data is redefined in the data processing module, including but not limited to data sorting, serial-to-parallel conversion and other data operations that require timing coordination. It can be seen that the timing control of the laser detection module plays a key role in the laser radar system.

[0005] like Figure 2 The figure shows a schematic diagram of the port connection between the laser detection module and the data processing module under the existing timing control logic method. Figure 2 It can be seen that there are three main ports between the data processing module and the laser detection module. The data processing module sends the start working signal and the distance gating signal to the laser detection module through two output ports. After the laser detection module generates the photon flight time count value, it transmits the image data to the data processing module through the port.

[0006] like Figure 3The figure shows the control timing of the laser detection module of the existing Gm-APD mode laser radar. After the detector component is powered on, the laser emission module emits a laser pulse and sends a laser synchronization signal to the data processing module at the same time. After receiving the laser synchronization signal, the data processing module generates a start-of-work signal to control the laser detection module to start working. After detecting the start-of-work signal, the data processing module generates a gated enable signal to the laser detection module after a fixed delay time, enabling the high-frequency clock counter of each pixel in the laser detection module to count the photon flight time. During the period when the gated enable signal is pulled high, when the laser pulse echo signal reaches the photosensitive target surface of the laser detection module, the pixel is photosensitive to generate a Geiger avalanche signal. The readout circuit in the laser detection module detects the avalanche signal and generates a count stop signal. The count stop signal will stop the counting operation of the high-frequency clock counter in each pixel. Finally, after detecting that the gated enable signal is pulled low, the laser detection module serially outputs the count value in the high-frequency clock counter of each pixel to the data processing module, and displays the detected target image in the measurement and control display module, thereby realizing imaging detection.

[0007] The existing timing control system has the following drawbacks: 1) There is no constraint on the transmission timing of the received image, that is, the start bit of each frame is not distinguished, which easily causes the latter data to cover the previous data, resulting in data string code, and then produces erroneous image data. 2) There is no enable signal for image data transmission, and there is no constraint on the data output clock, which makes it very difficult for the lower computer data processing module to receive data. If the clock is not aligned, it is difficult to receive the correct image data. 3) There is only one way to trigger the external laser, and the system operation depends on the synchronization signal emitted by the external laser. When there are multiple laser emission modules or multiple data processing modules, control confusion is prone to occur. Summary of the invention

[0008] The purpose of the present invention is to provide a working timing control method for a laser detection module, which mainly solves the problems of easy coverage of data transmission of the laser detection module, difficulty in clock alignment, and asynchronous reception and transmission of the data processing module.

[0009] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0010] A method for controlling the working timing of a laser detection module comprises the following steps:

[0011] S1, after the laser detection module is powered on, the data processing module in the laser detection module generates a frame RST reset signal to reset a frame of data, and restart the generation and reception of a frame of data;

[0012] S2, after the reset is completed, determine the trigger type of the data processing module;

[0013] S3, if it is an external trigger mode, the data processing module enters step S4 after detecting the external trigger laser synchronization signal, if it is an internal trigger mode, the data processing module enters step S4 after sending the self-generated laser synchronization signal;

[0014] S4, after the data processing module detects the external trigger laser synchronization signal or the self-generated laser synchronization signal, it pulls up the GATE signal after a set fixed time interval, and controls the light receiving time of the laser radar detection component through the GATE signal;

[0015] S5, after the GATE signal is pulled high, the detector starts to receive light, and the data processing module generates a START signal after a set fixed time interval;

[0016] S6, the high-frequency clock counter in each pixel of the laser detection module starts counting. When the system light receiving time set by the laser radar is met, the GATE signal is pulled low, and a READ signal is generated after a set fixed time interval. The READ signal is the time information output enable, which controls the laser detection module to transmit the time count value to the data processing module;

[0017] S7, when the transmission time of one frame of data is met, if there is no power-off operation, a frame RST signal is generated again after a set fixed time interval, and the next frame of data is detected and received, and this cycle repeats; if there is a power-off operation, the laser receiving component is powered off and waits for the next power-on.

[0018] Furthermore, in step S2, the trigger type is set by an external host computer.

[0019] Furthermore, in step S3, in the external trigger mode, the data processing module continuously performs timeout detection. When the external laser synchronization signal is not detected for a long time, the data processing module determines that the detection has timed out, automatically powers off the detector, and shuts down the detection system.

[0020] Furthermore, the fixed time intervals in step S4 and step S6 are set by an external host computer.

[0021] Furthermore, in the present invention, the data processing module has four output ports and one input port. The output ports are respectively a frame reset signal, a light-connected enable signal, a timing start signal and a data readout signal, which are output to the laser detection module; the input port is used to send image data from the laser detection module to the data processing module.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] Based on the existing Gm-APD laser detection module timing control logic, the present invention adds a reset signal, a light control signal, and a data transmission enable signal, effectively solving the problems of easy coverage of laser detection module data transmission, difficulty in clock alignment, and asynchronous reception and transmission of the data processing module. At the same time, the laser synchronization signal reception mode is divided into two types, internal triggering and external triggering, which effectively solves the problem of multi-module control confusion. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 A laser radar system according to the prior art.

[0025] Figure 2 The present invention is a schematic diagram of the port connection of the timing logic control method of the existing laser radar system.

[0026] Figure 3 The figure is a timing control logic flow chart of an existing lidar system.

[0027] Figure 4 Schematic diagram of port connection of a data processing module in an embodiment of the present invention.

[0028] Figure 5 It is a timing control logic flow chart of the present invention.

[0029] Figure 6 A single-frame timing diagram of a timing control method for an existing lidar system.

[0030] Figure 7 This is a timing control waveform diagram of the control method of the present invention in the external trigger mode.

[0031] Figure 8 This is a timing control waveform diagram of the control method of the present invention in the internal trigger mode.

[0032] Fig. 9 This is a timing diagram of data transmission control during multi-frame measurement of the timing control method of the existing laser radar system.

[0033] Fig.10 This is a data transmission control timing diagram of the control method of the present invention when performing multi-frame measurement in an external trigger mode.

[0034] Fig.11 Schematic diagram of laser synchronization signal transmission in an existing lidar system.

[0035] Fig.12 Schematic diagram of synchronization signal transmission in the internal trigger mode of the present invention. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with the accompanying drawings and embodiments. The embodiments of the present invention include but are not limited to the following embodiments.

[0037] Example

[0038] This embodiment discloses a method for controlling the working timing of a laser detection module. Figure 4 FIG. 1 is a schematic diagram showing the port connection between the laser detection module and the data processing module under the timing control logic method of this embodiment. Figure 4 It can be seen that in this embodiment, there are four output ports and one input port for the data processing module. The output ports are respectively a frame reset signal, a light-connected enable signal, a timing start signal and a data readout signal, which are output to the laser detection module. The input port is where the laser detection module sends image data to the data processing module.

[0039] Figure 5 The figure shows the timing flow chart in the data processing module, which is used to further explain the flow chart of the timing control logic of the method.

[0040] When the laser detection module is powered on, the data processing module will generate a frame RST reset signal to reset a frame of data and restart the generation and reception of a frame of data.

[0041] When the reset is completed, the trigger type is determined. The trigger type is set by the external host computer and is divided into external trigger and internal trigger. In the internal trigger mode, the synchronization between the modules is dominated by the data processing module. In the external trigger mode, the synchronization between the modules is dominated by the laser emission module. The dominant mode is that the dominant module sends the laser synchronization signal to other modules.

[0042] In the external trigger mode, timeout detection is continuously performed. When the external laser synchronization signal is not detected for a long time, the data processing module will determine that the detection has timed out, automatically power off the detector, and shut down the detection system.

[0043] When the data processing module detects the laser synchronization signal sent by the external laser emission module or the self-generated laser synchronization signal, it will pull up the GATE signal after a set fixed time interval, and control the light-receiving time of the laser radar detection component through the GATE signal. After the GATE signal is pulled high, the detector starts to receive light.

[0044] When the data processing module pulls up the GATE signal for a set fixed time interval, a START signal will be generated. START is the timing start signal of the laser detection module. After the START signal is generated, the high-frequency clock counter in each pixel of the laser detection module starts counting.

[0045] When the system light receiving time set by the laser radar is met, the GATE signal is pulled low, and a READ signal is generated after a set fixed time interval. The READ signal is the time information output enable, which controls the laser detection module to transmit the time count value to the data processing module.

[0046] When a frame of data transmission time is met, if there is no power-off operation, a frame RST signal will be generated again after a set fixed time interval to detect and receive the next frame of data, and this cycle will repeat. If there is a power-off operation, the laser receiving component will be powered off and wait for the next power-on.

[0047] In this method, the time interval between each control signal and the pulse width of the signal are set by an external host computer.

[0048] This method has no restrictions on the laser detection mode of the laser radar and is not limited to the Gm-APD mode.

[0049] The following is an application of this timing control method in a practical example.

[0050] Figure 6 It is the laser receiving timing control logic in the existing Gm-APD mode. After the laser detection module is powered on, the laser emission module sends a synchronization signal to the data processing module. After receiving the synchronization signal, the data processing module immediately generates a start-up signal to the laser detection module to control the laser detection module to start working. The start-up signal pulls up the gate enable signal after a fixed time interval. The gate enable signal controls the laser detection module to start clock timing. The gate enable signal is pulled low after passing through the gate width set by the host computer. During the gate enable period, the echo pulse generates a stop signal. When the stop signal is generated, the clock counter on the laser detection module is stopped immediately. After the laser detection module detects the falling edge of the gate enable signal, the data of the clock counter in each pixel is transmitted to the data processing module according to a certain rule.

[0051] Figure 7 This is the laser receiving timing control logic in the Gm-APD mode of this embodiment. Since the traditional timing control method can be understood as the external trigger mode of this embodiment, the process of the timing control method of this embodiment is first analyzed in the external trigger mode.

[0052] After the Gm-APD laser detection module is powered on, it first pulls up the frame reset signal with a pulse width of 100ns. Since it is in external trigger mode, it waits for the synchronization pulse signal sent by the external laser emission module.

[0053] If no synchronization pulse signal is detected within one frame of working sequence (200us), the system will be powered off and wait for the system to be powered on again.

[0054] When the rising edge of the synchronization pulse signal is detected, the delay time t0 is used to pull up the light-connection enable signal. t0 is the delayed light-connection time. The subsequent light-connection timing is adjusted by controlling the delayed light-connection time. The default value of t0 is 200ns.

[0055] After t0 time, pull up the light-enabling signal with a pulse width of 20us. At this time, the laser detection module starts to receive laser echoes, and different lengths of light-enabling time can detect objects of different speeds.

[0056] When the rising edge of the light-enable signal is detected 30ns later, the counting start signal is pulled high with a pulse width of 50ns. At this time, the high-frequency counting clock in the laser detection module starts counting.

[0057] When the falling edge of the light-enable signal is detected 100ns later, the data readout signal is pulled high with a pulse width of 100us. At this time, the laser detection module transmits the data to the data processing module.

[0058] When the falling edge of the data readout signal is detected 500ns later, the reset signal is pulled high again to wait for the next frame of laser synchronization signal to trigger a new control timing.

[0059] Secondly, Figure 8 It is a timing control waveform diagram in the trigger mode in this embodiment.

[0060] In the internal trigger mode, the laser synchronization signal that triggers the control sequence is generated by the data processing module. After detecting the falling edge of the reset signal for 100ns, the laser synchronization signal is pulled high. After the control sequence of one frame is completed, the reset signal and laser synchronization signal are generated again to count and transmit the next frame. Except for the trigger mode, the generation methods of other signals are the same as those in the external trigger mode.

[0061] In this embodiment, all durations and units can be controlled by the host computer, including the time delay before all signals are generated (such as the delay t0 before generating the light-on signal) and the pulse width duration of all signals (such as the pulse width of the reset signal is 100ns).

[0062] The above example illustrates:

[0063] 1. The existing timing control method is only suitable for single-frame data transmission, and has good application performance for distance measurement of stationary objects. However, the application field of LiDAR has gradually shifted to the distance measurement of movable and unfixed objects, such as cars, airplanes, tanks, etc., which require real-time multi-frame measurement. At this time, the use of the existing timing control method will result in data overlay, causing the data processing module to receive erroneous data, and the accuracy of the image data cannot be guaranteed, which has certain disadvantages. Fig. 9As shown, the transmission of data is controlled by the gate enable signal. When the amount of data is too large, if the first frame of data has not been transmitted yet, the gate enable signal of the second frame reaches the set fixed gate width and then pulls down, then the data of the second frame will start to be transmitted, and data overlap will occur.

[0064] In this embodiment, the frame reset control signal can accurately control the transmission of each frame timing data of the laser detection module, and the light receiving control signal can perform the counting clock control of each pixel. For the data processing module, the data transmission enable signal can control the data clock alignment of the sender and receiver.

[0065] At the same time, compared with the traditional timing control method, the stop signal is removed and the time interval of each frame is strictly controlled, which is conducive to the data processing module to receive and process data.

[0066] like Fig.10 As shown, when the data is too long, the data frame reset signal and data enable signal in this embodiment control the laser detection module not to transmit the next frame of data when the previous frame has not been transmitted. This can better control the interval between the two frames and leave enough data processing time for the next-level data processing module.

[0067] 2. The existing method only uses the synchronization signal transmitted by the external laser emission module for timing synchronization, which is suitable for the "single laser emission module single data processing module" transceiver mode. In actual situations, there may be a situation where the laser emission module is far away from the control module, and there is a delay in the transmission of electrical signals. The use of the internal trigger mode can ensure the timing priority triggering of the data processing module. At the same time, in actual applications, there may be many situations such as "multiple laser emission modules and a single data processing module", "single laser emission module and multiple data processing modules", and "multiple laser emission modules and multiple data processing modules".

[0068] Down Fig.11 As shown, assuming that there are two laser emission modules, in the absence of mutual constraints, there may be a situation where laser synchronization signals are sent to the data transmission module at the same time. However, due to distance reasons, the time when the two laser synchronization signals arrive at the data transmission module must be different, that is, the time when laser synchronization signal 1 and laser synchronization signal 2 are sent to the data processing module is different and adjacent. At this time, the data transmission module will generate two consecutive start working signals, causing control confusion of the laser detection module.

[0069] In this embodiment, the internal trigger mode (such as Fig.12As shown in the figure, the picture used is wrong), the laser synchronization signal is generated by the data processing module itself and sent to the laser emission module and the laser detection module at the same time. Since the data processing module controls the sending of the laser synchronization signal, when the laser synchronization signal is sent to the laser emission module 2, it will not be sent to the laser emission module 1 at the same time, which can effectively prevent the control confusion problem in this case.

[0070] The above use cases illustrate that the timing control method of the present invention imposes detailed timing constraints on the laser detection module in the lidar system. Compared with the existing timing control methods, it has certain advantages in moving object ranging and multi-module situations, and effectively avoids the data coverage problem under multi-frame detection and the control confusion problem in multi-module situations, and has positive practical significance and use value.

[0071] The above embodiment is only one of the preferred implementation modes of the present invention and should not be used to limit the protection scope of the present invention. Any changes or modifications that are made to the main design concept and spirit of the present invention and have no substantive significance, and the technical problems they solve are still consistent with the present invention, should be included in the protection scope of the present invention.

Claims

1. A working timing control method for a laser detection module, It is characterized in that The following steps are involved: S1, after the laser detection module is powered on, a frame RST reset signal is generated by the data processing module in the laser detection module to reset a frame of data, and restart the generation and reception of a frame of data; S2, after the reset is completed, determine the trigger type of the data processing module; S3, if it is an external trigger mode, the data processing module enters step S4 after detecting the external trigger laser synchronization signal, if it is an internal trigger mode, the data processing module enters step S4 after sending the self-generated laser synchronization signal; S4, after the data processing module detects the external trigger laser synchronization signal or the self-generated laser synchronization signal, it pulls up the GATE signal after a set fixed time interval, and controls the light receiving time of the laser radar detection component through the GATE signal; S5, after the GATE signal is pulled high, the detector starts to receive light, and the data processing module generates a START signal after a set fixed time interval; S6, the high-frequency clock counter in each pixel of the laser detection module starts counting. When the system light receiving time set by the laser radar is met, the GATE signal is pulled low, and a READ signal is generated after a set fixed time interval. The READ signal is the time information output enable, which controls the laser detection module to transmit the time count value to the data processing module; S7, when the transmission time of one frame of data is met, if there is no power-off operation, a frame RST signal is generated again after a set fixed time interval, and the next frame of data is detected and received, and this cycle repeats; if there is a power-off operation, the laser receiving component is powered off and waits for the next power-on.

2. A method for controlling the working timing of a laser detection module according to claim 1 It is characterized in that In step S2, the trigger type is set by an external host computer.

3. A method for controlling the working timing of a laser detection module according to claim 2, It is characterized in that In step S3, in the external trigger mode, the data processing module continues to perform timeout detection. When the external laser synchronization signal is not detected for a long time, the data processing module will determine that the detection has timed out, automatically power off the detector, and shut down the detection system.

4. A method for controlling the working timing of a laser detection module according to claim 3, It is characterized in that The fixed time intervals in step S4 and step S6 are set by an external host computer.

5. A method for controlling the working timing of a laser detection module according to claim 4, It is characterized in that The data processing module has four output ports and one input port, and the output ports are respectively a frame reset signal, a light-connection enable signal, a timing start signal and a data readout signal, which are output to the laser detection module; The input port sends image data from the laser detection module to the data processing module.

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