阅读说明：本技术 一种多线激光雷达扫描时序控制方法 (Multi-line laser radar scanning time sequence control method ) 是由 王锴磊 刘柯 郭天茂 王晓光 朱浩 鲍晨兴 于 2020-11-27 设计创作，主要内容包括：本发明提出一种多线激光雷达扫描时序控制方法,多线激光雷达以FPGA作为主控模块,主控模块内部包含电机控制单元、时序控制单元、触发控制单元和采集控制单元；其中电机控制单元与电机驱动单元、电机以及增量编码器组成电机的旋转控制模块；触发控制单元、采集控制单元和多通道激光驱动探测单元组成多通道激光测距模块；增量编码器将输出的脉冲信号发送给FPGA,FPGA依据设定的采样频率对脉冲信号进行分频或倍频得到与采样频率一致的有效控制信号；然后将有效控制信号变换后形成触发信号,用于控制多通道激光驱动探测单元进行激光测距；FPGA在控制多通道激光驱动探测单元进行激光测距的同时,增量编码器记录当前的方位角,由此确保测角、测距的同步性。(The invention provides a multi-line laser radar scanning time sequence control method, wherein a multi-line laser radar takes an FPGA (field programmable gate array) as a main control module, and the main control module internally comprises a motor control unit, a time sequence control unit, a trigger control unit and an acquisition control unit; the motor control unit, the motor driving unit, the motor and the incremental encoder form a rotation control module of the motor; the trigger control unit, the acquisition control unit and the multi-channel laser driving detection unit form a multi-channel laser ranging module; the incremental encoder sends the output pulse signal to the FPGA, and the FPGA carries out frequency division or frequency multiplication on the pulse signal according to the set sampling frequency to obtain an effective control signal consistent with the sampling frequency; then converting the effective control signal to form a trigger signal for controlling the multi-channel laser driving detection unit to carry out laser ranging; the FPGA controls the multi-channel laser driving detection unit to carry out laser ranging, and the incremental encoder records the current azimuth angle, so that the synchronism of angle measurement and ranging is ensured.)

1. A scanning time sequence control method for a multi-line laser radar is characterized in that the multi-line laser radar takes an FPGA (field programmable gate array) as a main control module, and the main control module internally comprises a motor control unit, a time sequence control unit, a trigger control unit and an acquisition control unit; the motor control unit, the motor driving unit, the motor and the incremental encoder form a rotation control module of the motor; the trigger control unit, the acquisition control unit and the multi-channel laser driving detection unit form a multi-channel laser ranging module; the method is characterized in that:

the incremental encoder sends the output pulse signal to an FPGA (field programmable gate array), and the FPGA carries out frequency division or frequency multiplication on the pulse signal according to a set sampling frequency to obtain an effective control signal consistent with the sampling frequency; then the FPGA converts the effective control signal to form a trigger signal for controlling the multichannel laser driving detection unit to carry out laser ranging; and the FPGA controls the multichannel laser driving detection unit to carry out laser ranging, and the incremental encoder records the current azimuth angle.

2. The multiline lidar scanning timing control method of claim 1 wherein: the FPGA takes each rising edge of the effective control signal as a trigger point to form the rising edge of the trigger signal; and then controlling the multichannel laser driving detection unit to perform ranging at each rising edge of the trigger signal.

3. The multiline lidar scanning timing control method of claim 1 wherein: each channel of the multichannel laser driving detection unit corresponds to a pitch angle, and the FPGA forms effective three-dimensional measurement data by combining the current azimuth angle recorded by the incremental encoder and the pitch angle corresponding to the channel while controlling the multichannel laser driving detection unit to carry out laser ranging.

4. The multiline lidar scanning timing control method of claim 1, 2 or 3 wherein: the multi-line laser radar adopts a 4000-line incremental encoder, and 4000 pulses are output in each circle; setting single line sampling frequency as 20 KHz;

when the rotating speed of the multi-line laser radar is 5 revolutions per second, the frequency of a pulse signal output by the incremental encoder is 20KHz, and the FPGA carries out 0 frequency division on the pulse signal to obtain an effective control signal of 20 KHz;

when the set rotating speed of the multi-line laser radar is 10 revolutions per second, the frequency of a pulse signal output by the incremental encoder is 40KHz, and the FPGA carries out frequency division on the pulse signal by 2 to obtain an effective control signal of 20 KHz;

when the set rotating speed of the multi-line laser radar is 20 revolutions per second, the frequency of the pulse signal output by the incremental encoder is 80KHz, the FPGA carries out frequency division on the pulse signal by 4, and an effective control signal of 20KHz is obtained.

5. The multiline lidar scanning timing control method of claim 3 wherein: and in the process of rotating the multi-line laser radar by 360 degrees, the FPGA records the three-dimensional measurement data of each measurement point and the measurement time to form a multi-line laser radar measurement data packet.

Technical Field

The invention relates to a time sequence control method, in particular to a multiline laser radar scanning time sequence control method.

Background

The multi-line laser radar is an active rotary full-circle sensitive navigation obstacle avoidance device, and the basic working principle of the multi-line laser radar is that under the control of a certain time sequence, distance testing is carried out once when the multi-line laser radar rotates by a fixed angle (a set angle value), and therefore the multi-line laser radar is uniformly measured at a certain angle interval when the multi-line laser radar rotates by the full circle.

At present, the multi-line laser radar on the market mainly comprises 16 lines and 32 lines, rotates at a constant speed under a master control time sequence at a certain speed, measures at fixed time intervals at a certain fixed time interval, and uniformly realizes 360-degree full-circle measurement. The master control timing sequence is generally generated by adopting the following technology:

the FPGA actively generates a time sequence, namely the time sequence is completely generated by the FPGA, and the generated time sequence is subjected to frequency division or frequency multiplication and then provides control time sequence, measurement trigger, position traction and rotation control for the multi-line laser radar. The method is simple to use, is completely output by the FPGA, and can work normally without excessive intervention; however, in actual operation, although the time sequence is generated by active control, the time sequence needs to be consistent with the angle measurement element of the multi-line laser radar, because the sampling rate of the angle measurement element is low, complete synchronization is difficult to realize, so that the azimuth angle error of the measurement point position is easy to generate, and uniform test in a 360-degree circumference cannot be realized.

Disclosure of Invention

In view of this, the present invention provides a method for controlling a scanning timing sequence of a multi-line lidar, which is based on position pulse information output by an angle measurement element (i.e., an encoder) as a master control timing sequence, so as to implement scanning timing sequence control of the multi-line lidar, and effectively ensure consistency among a rotation position, a measurement position and a measurement time, i.e., ensure synchronization of angle measurement and distance measurement.

The multi-line laser radar takes the FPGA as a main control module, and the main control module internally comprises a motor control unit, a time sequence control unit, a trigger control unit and an acquisition control unit; the motor control unit, the motor driving unit, the motor and the incremental encoder form a rotation control module of the motor; the trigger control unit, the acquisition control unit and the multi-channel laser driving detection unit form a multi-channel laser ranging module; the scanning time sequence control method of the multi-line laser radar comprises the following steps:

the incremental encoder sends the output pulse signal to an FPGA (field programmable gate array), and the FPGA carries out frequency division or frequency multiplication on the pulse signal according to a set sampling frequency to obtain an effective control signal consistent with the sampling frequency; then the FPGA converts the effective control signal to form a trigger signal for controlling the multichannel laser driving detection unit to carry out laser ranging; and the FPGA controls the multichannel laser driving detection unit to carry out laser ranging, and the incremental encoder records the current azimuth angle.

As a preferred embodiment of the present invention: the FPGA takes each rising edge of the effective control signal as a trigger point to form the rising edge of the trigger signal; and then controlling the multichannel laser driving detection unit to perform ranging at each rising edge of the trigger signal.

As a preferred embodiment of the present invention: each channel of the multichannel laser driving detection unit corresponds to a pitch angle, and the FPGA forms effective three-dimensional measurement data by combining the current azimuth angle recorded by the incremental encoder and the pitch angle corresponding to the channel while controlling the multichannel laser driving detection unit to carry out laser ranging.

As a preferred embodiment of the present invention: the multi-line laser radar adopts a 4000-line incremental encoder, and 4000 pulses are output in each circle; setting single line sampling frequency as 20 KHz;

when the rotating speed of the multi-line laser radar is 5 revolutions per second, the frequency of a pulse signal output by the incremental encoder is 20KHz, and the FPGA carries out 0 frequency division on the pulse signal to obtain an effective control signal of 20 KHz;

when the set rotating speed of the multi-line laser radar is 10 revolutions per second, the frequency of a pulse signal output by the incremental encoder is 40KHz, and the FPGA carries out frequency division on the pulse signal by 2 to obtain an effective control signal of 20 KHz;

when the set rotating speed of the multi-line laser radar is 20 revolutions per second, the frequency of the pulse signal output by the incremental encoder is 80KHz, the FPGA carries out frequency division on the pulse signal by 4, and an effective control signal of 20KHz is obtained.

As a preferred embodiment of the present invention: and in the process of rotating the multi-line laser radar by 360 degrees, the FPGA records the three-dimensional measurement data of each measurement point and the measurement time to form a multi-line laser radar measurement data packet.

Has the advantages that:

(1) based on the control principle of encoder angle measurement, the invention uses the position pulse output by the encoder in the rotary scanning as the control time sequence to realize the logic control of the multi-line laser radar; meanwhile, the measurement is started at the rising edge of the control time sequence, so that high-precision measurement can be realized through a low-resolution encoder, the aim of emitting laser on a carving line of the encoder for target detection is fundamentally realized, and the synchronism of angle measurement and distance measurement is ensured.

(2) The method fundamentally solves the problem of angle measurement of the whole step of the low-resolution encoder, not only can realize the stable control of the time sequence of the multi-line laser radar and the synchronization of angle measurement and distance measurement, but also realizes the accurate angle output at the moment of laser distance measurement.

(3) The method can ensure that the control of the same scanning point number in a single circle can be realized in the scanning at different rotating speeds.

Drawings

Fig. 1 is a basic block diagram of a multiline lidar.

FIG. 2 is a schematic of encoder signal output;

FIG. 3 is a timing diagram of control signals.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples.

The embodiment provides a scanning time sequence control method of a multi-line laser radar, which adopts the output pulse of an angle measuring element encoder of the multi-line laser radar as a master control clock, and the master control clock is used for working time sequence control, measurement triggering, position traction and rotation control of the multi-line laser radar after frequency division and frequency multiplication of an FPGA (field programmable gate array); due to the high sampling frequency of the FPGA, the FPGA can be completely synchronous with the output pulse signal of the encoder, so that higher measurement precision is achieved, and uniform test in the whole circumference is realized; meanwhile, the measuring points are all positioned on the output points of the angle measuring pulses, namely on the integer code channels of the angle measuring elements, so that the azimuth angle precision of the laser measuring points can be greatly improved.

The basic working principle of the multi-line laser radar is shown in fig. 1, the basic control mode of the multi-line laser radar is that an FPGA serves as a main control module, and the interior of the multi-line laser radar comprises a motor control unit, a time sequence control unit, a trigger control unit and an acquisition control unit; the motor control unit, the motor driving unit, the torque motor and the incremental encoder form a rotation control module of the motor, and the rotation control module is used for ensuring that the multi-line laser radar rotates at a constant speed according to a set rotating speed; the trigger control unit, the acquisition control unit and the 32-channel laser driving detection unit form a 32-channel laser ranging module, which is used for ensuring that a target is uniformly detected in a 360-degree circumference, and effective three-dimensional measurement data is formed according to current azimuth information (namely an azimuth angle) acquired by the incremental encoder and a pitch angle corresponding to the channel.

The multiline laser radar time sequence control method provided by the embodiment is based on the basic working principle of the multiline laser radar shown in fig. 1, and the rotation, triggering and test data synchronization of the multiline laser radar is realized by combining the output signal of the incremental encoder and the FPGA.

FIG. 2 illustrates explicitly the relationship between the incremental encoder code track and its output signal; in this example, the multiline laser radar adopts a 4000-line incremental encoder, that is, 4000 pulses are output per circle; when the multiline lidar starts to make a rotation measurement, the incremental encoder outputs a signal as shown in fig. 2. Wherein Vs5/CTR is a pulse signal output by the encoder when the multiline laser radar rotates at 5 revolutions per second, and the frequency of the pulse signal is 20 KHz; vs10 is a pulse signal output by the encoder at 10 revolutions per second, and the frequency of the pulse signal is 40 KHz; vs20 is a pulse signal output by the encoder at 20 revolutions per second, and the frequency of the pulse signal is 80 KHz; TR is a laser ranging trigger control signal that triggers laser ranging at the rising edge of the signal.

The FPGA in the multi-line laser radar automatically carries out different subdivision on the pulse signals output by the incremental encoder according to the set different speeds of the multi-line laser radar and the set adopted frequency, and finally obtains effective control signals; the effective control signal enters the FPGA to be used as a basic time sequence for controlling the multi-line laser radar, and all measurement operations are synchronous with the basic time sequence by taking the basic time sequence as a reference. Meanwhile, the effective control signal is converted to form a trigger signal TR (namely, each rising edge of the effective control signal is used as a trigger point to form the rising edge of the trigger signal TR) for controlling the 32-channel laser ranging module to carry out laser ranging; and simultaneously, the incremental encoder records the current azimuth angle and combines the known pitch angle to form effective three-dimensional measurement information uploading.

Specifically, if the rotation speed of the multi-line laser radar is designed to be 20 revolutions per second, 10 revolutions per second and 5 revolutions per second respectively, the sampling frequency of a single line is 20KHz, namely the rate of effective control signals of the multi-line laser radar is 20 KHz; in this setting, the scan timing control method is as follows:

when the set rotating speed of the multi-line laser radar is 5 revolutions per second, the frequency of the pulse signal output by the incremental encoder is 20KHz, and the signal is also an effective control signal of the multi-line laser radar, so that the FPGA carries out 0 frequency division on the signal after receiving the pulse signal output by the incremental encoder, and the effective control signal of 20KHz is directly obtained.

When the set rotating speed of the multi-line laser radar is 10 revolutions per second, the frequency of the pulse signal output by the incremental encoder is 40KHz, and at the moment, the FPGA carries out frequency division on the received pulse signal output by the incremental encoder by 2 so as to obtain an effective control signal of 20 KHz;

when the set rotating speed of the multi-line laser radar is 20 revolutions per second, the frequency of the pulse signal output by the incremental encoder is 80KHz, and at the moment, the FPGA carries out 4 frequency division on the received pulse signal output by the incremental encoder so as to obtain an effective control signal of 20 KHz.

Finally, the FPGA converts the acquired 20KHz effective control signal to form a trigger signal TR, and the multi-line laser radar is controlled through the trigger signal TR, namely the multi-line laser radar is controlled to carry out distance test on the rising edge of each pulse of the trigger signal TR; at the moment, the encoder records the current azimuth angle, the pitch angle is determined according to the ID number of the laser ranging channel, and the pitch value of each laser ranging channel is constant.

Therefore, pulse signals output by the incremental encoder are sent to the FPGA, the FPGA carries out corresponding conversion and synchronous control on the FPGA, and complete synchronization of position information, angle measurement information and distance measurement control is guaranteed, so that distance measurement of 20K point locations is completed synchronously, the measurement azimuth angle, the pitch angle, the measurement time and the like of each point location are recorded simultaneously, and uploading of a multiline laser radar measurement data packet is formed.

The multi-line laser radar scanning time sequence control method not only realizes time sequence control and scanning point control, but also realizes accurate control of scanning angles.

Although the invention has been described in detail above with reference to a general description and specific examples, it will be apparent to one skilled in the art that modifications or improvements may be made thereto based on the invention. Accordingly, such modifications and improvements are intended to be within the scope of the invention as claimed.