Laser radar

Abstract

The invention discloses a laser radar, and the laser radar comprises a laser ranging unit which comprises a first transmitter, a collimating lens, a receiving lens, and a light receiver; light emitted by the first emitter is emitted to a target object after passing through the collimating lens, light reflected by the target object is emitted into the receiving lens, light converged by the receiving lens is emitted into the light receiver, and the light receiver emits an electric signal after receiving the light; the temperature drift detection unit comprises a second emitter and a reflecting surface; the light emitted by the second emitter is reflected by the reflecting surface and then enters the light receiver; the control unit is used for executing a temperature drift detection step and an actual measurement step; the temperature excursion detection step comprises the steps of sending a second driving signal, recording second timing time and calculating a temperature excursion error; the actual measurement step comprises the steps of sending out a first driving signal, recording first timing time and calculating the distance after the temperature drift is eliminated. According to the laser radar, the technical problem that temperature drift affects distance measurement in the prior art is solved, and the laser distance measurement accuracy is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser ranging, and in particular relates to a laser radar. Background Art

[0002] As a new type of distance measurement method, lidar has the advantages of fast measurement speed, high data accuracy and strong real-time performance.

[0003] LiDAR typically uses the direct time-of-flight method for distance measurement. This method calculates the distance to the target by multiplying the total time it takes for a laser to travel from the LiDAR to the target, return from the target, and finally be received by the LiDAR. This method, based on its fundamental principles, requires extremely high precision in time measurement, typically requiring picoseconds to achieve relatively accurate measurements.

[0004] However, in actual operation, the temperature of the LiDAR's internal circuits often fluctuates by tens of degrees Celsius due to environmental influences. This can cause performance drift in the operating circuits, often referred to as temperature drift. Temperature drift is unavoidable in practical LiDAR ranging systems, so eliminating its impact on ranging is a crucial issue for LiDAR. Summary of the Invention

[0005] The present invention provides a laser radar, which solves the technical problem in the prior art that temperature drift affects ranging.

[0006] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0007] A laser radar, comprising:

[0008] A laser ranging unit includes a first transmitter, a collimating lens, a receiving lens, and a light receiver; light emitted by the first transmitter passes through the collimating lens and then reaches a target object; light reflected from the target object enters the receiving lens; light converged by the receiving lens enters the light receiver; and the light receiver emits an electrical signal after receiving the light;

[0009] The temperature drift detection unit includes a second emitter and a reflective surface; the light emitted by the second emitter is reflected by the reflective surface and then enters the light receiver;

[0010] A control unit configured to perform a temperature drift detection step and an actual measurement step;

[0011] The temperature drift detection step includes: sending a second drive signal to the second emitter to drive the second emitter to emit light; recording a second time t from sending the second drive signal to receiving the electrical signal sent by the light receiver; and calculating a temperature drift error γ=c×t-d0, where c is the speed of light in air; and d0 is the sum of the distance from the second emitter to the reflective surface and the distance from the reflective surface to the light receiver.

[0012] The actual measurement steps include: sending a first drive signal to the first emitter to drive the first emitter to emit light; recording a first timing time T from sending the first drive signal to receiving the electrical signal sent by the light receiver; calculating a distance D=c×T / 2; and then the distance D0 after eliminating temperature drift=D-γ.

[0013] In some embodiments of the present application, a temperature drift detection step is performed before each actual measurement step.

[0014] In some embodiments of the present application, the temperature drift detection step is performed once every set time period to update the temperature drift error γ.

[0015] In some embodiments of the present application, the motor of the laser radar drives the laser ranging unit, the temperature drift detection unit, and the control unit to rotate;

[0016] Each time the motor rotates a set number of times, a temperature drift detection step is performed to update the temperature drift error γ.

[0017] In some embodiments of the present application, the optical path between the second emitter and the reflective surface and the optical path between the receiving lens and the optical receiver are perpendicular to each other.

[0018] In some embodiments of the present application, the laser radar further includes a structure having a first sleeve and a second sleeve arranged vertically; the first sleeve is located above the second sleeve;

[0019] The first sleeve is arranged horizontally and has a front opening and a rear opening; the collimating lens is installed in the first sleeve and blocks the front opening of the first sleeve; the first emitter is located in the first sleeve and is close to the rear opening of the first sleeve; the first emitter is fixed to a transmitting circuit board and electrically connected to the transmitting circuit board; the transmitting circuit board is electrically connected to a control board, the control unit is arranged on the control board and is electrically connected to the control unit, and the control board is fixed to the structure;

[0020] The second sleeve is arranged horizontally and has a front opening and a rear opening; the receiving lens is installed in the second sleeve and blocks the front opening of the second sleeve; the optical receiver is located in the second sleeve and is close to the rear opening of the second sleeve; the optical receiver is fixed on a receiving circuit board and is electrically connected to the receiving circuit board; the receiving circuit board is electrically connected to the control board;

[0021] The second emitter and the reflecting surface are arranged opposite to each other on the inner side wall of the second sleeve.

[0022] In some embodiments of the present application, the inner diameter of the first sleeve gradually decreases from the front end opening to the rear end opening.

[0023] In some embodiments of the present application, the second sleeve is sequentially provided with a first diameter-reducing section and a second diameter-reducing section from the front opening to the rear opening;

[0024] The inner diameter of the first diameter-changing section gradually decreases from the front opening to the rear opening;

[0025] The inner diameter of the second diameter-varying section gradually increases from the front opening to the rear opening;

[0026] The receiving lens is located in the first diameter-changing section, and the light receiver is located in the second diameter-changing section; the second emitter and the reflecting surface are arranged opposite to each other on the inner side wall of the second diameter-changing section.

[0027] In some embodiments of the present application, the housing of the laser radar includes an optical cover and a lower housing, wherein the optical cover is located above the lower housing and is detachably connected to the lower housing;

[0028] The structure is located in the optical housing;

[0029] The motor of the laser radar is located in the lower shell, and the stator of the motor is fixed to the lower shell, and the rotor of the motor is fixed to the structure, driving the structure to rotate.

[0030] In some embodiments of the present application, the laser radar further includes an optical communication module, and the optical communication module includes an optical communication transmitting end and an optical communication receiving end;

[0031] The optical communication transmitting end and the optical communication receiving end are arranged vertically in the hollow shaft of the motor; the optical communication receiving end transmits optical signals with the optical communication transmitting end;

[0032] The optical communication transmitting end is electrically connected to the control unit; the optical communication receiving end is electrically connected to the main control unit of the laser radar.

[0033] Compared with the prior art, the advantages and positive effects of the present invention are as follows: the laser radar of the present invention, by designing a temperature drift detection unit, a laser ranging unit, and a control unit, uses the control unit to perform a temperature drift detection step to calculate the temperature drift error γ, uses the control unit to perform an actual measurement step to calculate the distance D, and calculates the distance D0 = D-γ after eliminating the temperature drift, so as to eliminate the influence of the temperature drift on the laser ranging, thereby solving the technical problem of the temperature drift affecting the ranging in the prior art and improving the accuracy of the laser ranging.

[0034] Other features and advantages of the present invention will become more apparent after reading the detailed description of the embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0036] Figure 1 is a cross-sectional view of an embodiment of the laser radar proposed by the present invention;

[0037] Figure 2 is an exploded view of an embodiment of the laser radar proposed by the present invention;

[0038] Figure 3 yes Figure 1 A schematic structural diagram of an embodiment of a laser ranging unit;

[0039] Figure 4 1 is a schematic structural diagram of an embodiment of a temperature drift detection unit;

[0040] Figure 5 1 is a schematic diagram of the circuit structure of an embodiment of a control unit;

[0041] Figure 6 1 is a circuit diagram of another embodiment of a control unit;

[0042] Figure 7 is a flow chart of one embodiment of steps performed by a control unit.

[0043] Reference numerals:

[0044] 10. Laser ranging unit; 11. First transmitter; 12. Collimating lens; 13. Receiving lens; 14. Optical receiver; 15. Transmitting circuit board; 16. Receiving circuit board;

[0045] 20. Temperature drift detection unit; 21. Second emitter; 22. Reflecting surface;

[0046] 30. Structural body; 31. First sleeve; 32. Second sleeve; 32-1. First diameter-reducing section; 32-2. Second diameter-reducing section;

[0047] 40. Motor; 41. Rotor; 42. Stator;

[0048] 51. Optical cover; 52. Lower housing;

[0049] 61. Angle code disk; 62. Photoelectric encoder;

[0050] 71. Optical communication transmitting end; 72. Optical communication receiving end;

[0051] 81. Wireless power receiving module; 82. Wireless power transmitting module;

[0052] 91. Control panel;

[0053] 100. Target object. DETAILED DESCRIPTION

[0054] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0055] In the description of this application, it should be understood that the terms "center", "up", "down", "front", "back", "top", "bottom", "inside", "outside", etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they should not be understood as limitations on this application.

[0056] In the description of this application, it should be understood that the terms "first" and "second" are used for descriptive purposes only and should not be understood to indicate or imply relative importance or implicitly specify the number of the technical features indicated. Therefore, a feature specified as "first" or "second" may explicitly or implicitly include one or more of the features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0057] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal connections between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0058] The laser radar of this embodiment includes a laser ranging unit 10, a temperature drift detection unit 20, a control unit, etc.

[0059] The laser ranging unit 10 (also known as the first optical path structure) includes a first emitter 11, a collimating lens 12, a receiving lens 13, and a light receiver 14. The light emitted by the first emitter 11 is collimated by the collimating lens 12 and then emitted to the target 100. The light reflected by the target 100 enters the receiving lens 13. The light converged by the receiving lens 13 enters the light receiver 14. The light receiver 14 sends an electrical signal after receiving the light. Figures 1 to 4 shown.

[0060] The temperature drift detection unit 20 (also called the second light path structure) includes a second emitter 21 and a reflective surface 22. The light emitted by the second emitter 21 is reflected by the reflective surface 22 and then enters the light receiver 14. Figures 1 to 4 shown.

[0061] The first transmitter 11 is driven by the control unit to emit laser light for realizing the ranging function.

[0062] The collimating lens 12 is mainly used to collimate the laser emitted by the first emitter 11 to achieve a smaller divergence angle, so as to detect targets at a farther distance.

[0063] The receiving lens 13 is mainly used to receive the laser light reflected by the target object and focus the laser light onto the light receiver 14 .

[0064] The optical receiver 14 is mainly used to receive the return light signal, give feedback to the light signal that meets the trigger condition, and trigger the control unit to complete the time measurement.

[0065] The second emitter 21 is driven by the control unit to emit laser light for measuring temperature drift error.

[0066] The reflective surface 22 is used to redirect the laser light emitted by the second emitter 21 so that the laser light can be irradiated onto the light receiver 14 .

[0067] A control unit is used to perform the temperature drift detection step and the actual measurement step.

[0068] The temperature drift detection step includes: a control unit sending a second drive signal to the second emitter to drive the second emitter to emit light; recording a second timing time t from the issuance of the second drive signal to the receipt of the electrical signal from the light receiver; and calculating a temperature drift error γ = c × t - d0, where c is the speed of light in air and d0 is the sum of the distance from the second emitter to the reflecting surface and the distance from the reflecting surface to the light receiver.

[0069] The actual measurement steps include: a control unit sends a first drive signal to a first emitter to drive the first emitter to emit light; recording a first timing time T from sending the first drive signal to receiving the electrical signal sent by the light receiver; calculating a distance D = c × T / 2; and then the distance D0 after eliminating temperature drift = D-γ.

[0070] The distance between the second emitter 21 and the reflecting surface 22 is fixed, the distance between the reflecting surface 22 and the light receiver 14 is fixed, and the sum d0 of these two distances is also fixed.

[0071] Generally speaking, the speed of light in air, c, is constant, and the dimensional error of the lidar structure caused by temperature changes is basically negligible. Therefore, the temperature drift error mainly comes from the change in the timing of the circuit part, that is, the temperature drift of the control unit.

[0072] When recording the second timing time t and calculating d, the temperature drift difference due to temperature changes is the same as when recording the first timing time T and calculating D. Therefore, the calculated distance D to the target object can be compensated using the temperature drift error (γ = d - d0), resulting in a distance D0 = D - γ after temperature drift elimination.

[0073] When calculating the temperature drift error and the distance to the target object, a shared optical receiver and control unit work in time-sharing mode, which can eliminate the error caused by temperature drift.

[0074] The laser radar of this embodiment is designed with a temperature drift detection unit, a laser ranging unit, and a control unit. The control unit performs a temperature drift detection step to calculate the temperature drift error γ, and the control unit performs an actual measurement step to calculate the distance D. The distance D0 after temperature drift elimination is calculated as D0 = D-γ, thereby eliminating the influence of temperature drift on laser ranging. This solves the technical problem of temperature drift affecting ranging in the prior art and improves the accuracy of laser ranging.

[0075] The laser radar of this embodiment eliminates the influence of temperature drift and realizes the basic function of ranging.

[0076] In some embodiments of the present application, in order to further improve the accuracy of laser ranging, a temperature drift detection step is performed before each actual measurement step.

[0077] A temperature drift detection step is performed first to calculate the latest temperature drift error γ, and then the actual measurement step is performed to improve the ranging accuracy.

[0078] In some other embodiments of the present application, in order to improve both the accuracy and speed of laser ranging, a temperature drift detection step is performed every set time period to update the temperature drift error γ.

[0079] In some other embodiments of the present application, the motor of the laser radar drives the laser ranging unit, the temperature drift detection unit, and the control unit to rotate; each time the motor rotates a set number of times, the temperature drift detection step is performed to update the temperature drift error γ, thereby improving both the accuracy and speed of the laser ranging.

[0080] The change in ambient temperature during normal use is slow and continuous. Therefore, in order to improve the calculation speed, γ is stored in the storage medium of the lidar (such as a register). The lidar measures and updates γ every time it scans one or more circles, or at a set time interval, instead of measuring and calculating γ before each ranging.

[0081] The control unit can realize temperature drift detection and actual distance calculation through software or by building a circuit.

[0082] For example, the control unit includes a driving circuit, a timer, a calculation circuit, and the like.

[0083] The driver circuit has a first driver output connected to the first emitter 11 and sends a first drive signal to the first emitter 11 to drive the first emitter 11 to emit light. The driver circuit has a second driver output connected to the second emitter 21 and sends a second drive signal to the second emitter 21 to drive the second emitter 21 to emit light. The first emitter 11 and the second emitter 21 do not emit light at the same time, that is, the driver circuit drives the first emitter 11 and the second emitter 21 to operate at staggered times.

[0084] A timer is used to measure a second timing time t from the second drive output end sending the second drive signal to the receipt of the electrical signal sent by the optical receiver; the timer is also used to measure a first timing time T from the first drive output end sending the first drive signal to the receipt of the electrical signal sent by the optical receiver.

[0085] The calculation circuit generates a temperature drift error according to the second timing time; calculates the distance to the target object according to the first timing time, and subtracts the temperature drift error to obtain the distance after the temperature drift is eliminated.

[0086] The distance between the second emitter 21 and the reflective surface 22 is fixed, as is the distance between the reflective surface 22 and the light receiver 14. The sum of these two distances, d0, is also fixed. The speed of light in air, c, is also fixed. c and d0 are pre-stored in a register. Therefore, the optical path distance d0 of the light emitted by the second emitter 21, after being reflected by the reflective surface 22 and entering the light receiver 14, is fixed.

[0087] When the second driving output terminal of the driving circuit sends out the second driving signal, the timer starts timing; when the timer receives the electrical signal sent by the optical receiver, the timer stops timing.

[0088] The timer records the time from when the second drive output terminal of the drive circuit sends the second drive signal to when the timer receives the electrical signal sent by the optical receiver. This time is recorded as the second timing time t. The calculation circuit calculates d = c × t. The difference γ between d and d0 is the temperature drift error, γ = d - d0 = c × t - d0.

[0089] When the first driving output terminal of the driving circuit sends out the first driving signal, the timer starts timing; when the timer receives the electrical signal sent by the optical receiver, the timer stops timing.

[0090] The timer records the time from when the first driving output terminal of the driving circuit sends the first driving signal to when the timer receives the electrical signal sent by the optical receiver. This period of time is recorded as the first timing time T.

[0091] According to the principle of laser ranging, laser light is emitted from first transmitter 11 to a target, reflected by the target, and received by optical receiver 14. The transmission distance of the laser light during this process is twice the distance to the target. Therefore, by using a timer to measure the first time interval T from the issuance of the first drive signal to the receipt of the electrical signal from optical receiver 14, the calculation circuit can calculate the distance to the target D = c × T / 2.

[0092] The calculated distance D is compensated by using the temperature drift error γ, that is, the temperature drift error is subtracted to obtain the distance D0=D-γ after the temperature drift is eliminated.

[0093] The driving circuit drives the first emitter 11 and the second emitter 21 to work in a time-sharing manner, emitting light in a time-sharing manner. When a temperature drift error needs to be generated, the second driving output terminal of the driving circuit drives the second emitter 21 to emit light, a timer records the second time, and a calculation circuit calculates the temperature drift error γ. When the distance to a target object needs to be measured, the first driving output terminal of the driving circuit drives the first emitter 11 to emit light, a timer records the first time, and a calculation circuit calculates the distance D to the target object and subtracts the temperature drift error γ from it to obtain the distance D0 after temperature drift is eliminated.

[0094] In some embodiments of the present application, the calculation circuit includes a first register, a second register, a third register, a fourth register, a first multiplier, a second multiplier, a first subtractor, a second subtractor, etc. Figure 5 shown.

[0095] A timer, wherein a first input end thereof is connected to a first trigger output end of a driving circuit, a second input end thereof is connected to a second trigger output end of a driving circuit, a third input end thereof is connected to an output end of an optical receiver, a first output end thereof is connected to an input end of a first multiplier, and a second output end thereof is connected to an input end of a second multiplier.

[0096] When the second driving output terminal of the driving circuit sends a second driving signal, the second trigger output terminal of the driving circuit outputs a start signal to the second input terminal of the timer, and the timer starts timing, which is recorded as the second starting time; when the third input terminal of the timer receives the electrical signal sent by the optical receiver, the timer stops timing, which is recorded as the second ending time. The second starting time is subtracted from the second ending time to obtain the second timing time t, and the second output terminal of the timer outputs the second timing time t to the input terminal of the second multiplier.

[0097] When the first driving output terminal of the driving circuit sends a first driving signal, the first trigger output terminal of the driving circuit outputs a start signal to the first input terminal of the timer, and the timer starts timing, which is recorded as the first starting time; when the third input terminal of the timer receives the electrical signal sent by the optical receiver, the timer stops timing, which is recorded as the first ending time. The first starting time is subtracted from the first ending time to obtain the first timing time T, and the first output terminal of the timer outputs the first timing time T to the input terminal of the first multiplier.

[0098] The first register is used to store the speed c of light in air.

[0099] The second register is used to store the sum d0 of the distance from the second emitter to the reflecting surface and the distance from the reflecting surface to the light receiver. That is, d0 is equal to the distance between the second emitter 21 and the reflecting surface 22 plus the distance between the reflecting surface 22 and the light receiver 14.

[0100] The fourth register is used to store a multiplier of 0.5.

[0101] The second multiplier is used to multiply the speed c in the first register by the second timing time t output from the second output terminal of the timer, and the product is d=c×t.

[0102] The second subtractor is used to subtract the sum of the distances d0 in the second register from the product d output by the second multiplier to obtain a temperature drift error γ=d-d0.

[0103] The third register is used to store the temperature drift error γ output by the second subtractor.

[0104] The first multiplier is used to multiply the speed c in the first register, the first timing time T output by the first output terminal of the timer, and the multiplier 0.5 stored in the fourth register, and the product is D=c×T×0.5.

[0105] The first subtractor is used to subtract the temperature drift error γ in the third register from the product D output by the first multiplier to obtain a distance D0=D-γ after eliminating the temperature drift.

[0106] By designing the above-mentioned calculation circuit, the temperature drift error can be calculated using components, and finally the distance after the temperature drift is eliminated can be obtained, thereby eliminating the influence of the temperature drift. The circuit is simple to build, low in cost, and easy to implement.

[0107] When the second transmitter is required to operate, the second drive output terminal of the driver circuit sends a second drive signal to the second transmitter, and the timer measures a second time t from the time the second drive output terminal sends the second drive signal to the time the timer receives the electrical signal from the optical receiver. A second multiplier multiplies the speed c in the first register by the second time t output by the second output terminal of the timer, resulting in a product d = c × t. A second subtractor subtracts the distance d0 in the second register from the product d output by the second multiplier to obtain a temperature drift error γ = d - d0.

[0108] When the first transmitter is required to operate, the first drive output terminal of the driver circuit sends a first drive signal to the first transmitter. A timer measures a first time interval T from the time the first drive output terminal sends the first drive signal to the time the timer receives the electrical signal from the optical receiver. A first multiplier multiplies the speed c stored in the first register, the first time interval T output by the first output terminal of the timer, and the multiplier 0.5 stored in the fourth register to obtain a product D = c × T × 0.5. A first subtractor subtracts the temperature drift error γ stored in the third register from the product D output by the first multiplier to obtain a distance D0 = D - γ after temperature drift elimination.

[0109] In some embodiments of the present application, since the first transmitter and the second transmitter do not work at the same time, only one timing unit may be designed inside the timer.

[0110] In some other embodiments of the present application, two timing units can also be designed inside the timer: a first timing unit and a second timing unit. Figure 6 shown.

[0111] The second timing unit measures a second timing time t from when the second driving output terminal of the driving circuit sends out the second driving signal to when the second timing unit receives the electrical signal sent by the optical receiver.

[0112] The first timing unit measures a first timing time T from when the first driving output terminal of the driving circuit sends out the first driving signal to when the first timing unit receives the electrical signal sent by the optical receiver.

[0113] When the second driving output terminal of the driving circuit sends a second driving signal, the second trigger output terminal of the driving circuit outputs a start signal to the second timing unit, and the second timing unit starts timing; when the second timing unit receives the electrical signal sent by the optical receiver, the second timing unit stops timing, and the second timing unit outputs the second timing time t to the input terminal of the second multiplier.

[0114] When the first driving output terminal of the driving circuit sends a first driving signal, the first trigger output terminal of the driving circuit outputs a start signal to the first timing unit, and the first timing unit starts timing; when the first timing unit receives the electrical signal sent by the optical receiver, the first timing unit stops timing, and the first timing unit outputs the first timing time T to the input terminal of the first multiplier.

[0115] In the laser radar of this embodiment, a reflecting surface (diffuse reflecting plane) with a fixed angle is provided at the opposite position of the second emitter. The second optical path completely overlaps with the first optical path at the position of the optical receiver. The driving circuit drives the second emitter to emit a short pulse of light. The timer records the second starting time. The light emitted by the second emitter is reflected by the reflecting surface and irradiates the optical receiver. After receiving the light signal, the optical receiver generates a driving electrical signal and sends it to the timer, so that the timer obtains the second end time. The second start time is subtracted from the second end time to obtain the second timing time t. The temperature drift error γ = c × t-d0.

[0116] The first emitter is located behind the collimating lens. The driver circuit drives the first emitter to emit a short pulse of light. A timer records the first start time. The light emitted by the first emitter is collimated by the collimating lens and then flies toward the target. The light receiver is located behind the receiving lens. The light returning from the target is focused by the receiving lens and illuminates the light receiver. After receiving the light signal, the light receiver generates a driving electrical signal, which is sent to the timer, causing the timer to obtain the first end time. The first start time is subtracted from the first end time to obtain the first timed time T. The distance after temperature drift elimination is D0 = c × T × 0.5 - γ.

[0117] The control unit is a set of precision measurement circuits that primarily time and calculate the start and end times. It couples with the corresponding drive circuits to drive the transmitter and receive the drive signals from the optical receiver. It is the core circuit of the lidar and the primary source of temperature drift. For example, under certain temperature conditions, the time from when the timer starts counting the start time to when the first transmitter emits a pulse of light becomes longer. Or under other temperature conditions, the optical receiver responds slowly, lengthening the time from when the optical signal is received to when it is converted into the drive electrical signal captured by the timer. This adds an unexpected delay between the start and end times, causing the calculated measured distance to become longer, thus affecting ranging accuracy.

[0118] The distance d0 that the light beam travels from the second emitter through the reflecting surface to the optical receiver is physically a constant value and can be called the reference scale. When the lidar is affected by temperature and produces the aforementioned temperature drift, the same temperature drift will also occur in the second optical path. That is, if the driving time of the second emitter to emit pulsed light becomes longer or the time it takes for the optical receiver to drive the timer to obtain the end time becomes longer, then the reference scale measurement value d obtained through the second optical path will deviate from the actual value d0 of the reference scale by γ (i.e., temperature drift error). This deviation γ is the relative impact of temperature drift on the lidar, γ = d - d0.

[0119] By subtracting the corresponding temperature drift deviation γ from the distance measurement value D obtained by the first optical path, the accurate distance measurement value D0 = D-γ can be obtained. Figure 7 That is, the influence of temperature drift on the distance measurement in the first optical path can be eliminated by the difference γ between the measured value d and the actual value d0 of the reference ruler.

[0120] The laser radar of this embodiment measures the reference scale by adding a relatively independent second optical path, and then uses the difference γ to completely eliminate the influence of temperature drift in the ranging system in a calculable manner. Compared with other methods of eliminating temperature drift by measuring temperature and performing table lookup compensation at different temperatures, the laser radar of this embodiment does not require a large amount of preliminary testing to obtain a compensation value database, and is simple to use and has better accuracy.

[0121] In some embodiments of the present application, the optical path between the second emitter 21 and the reflective surface 22 and the optical path between the receiving lens 13 and the optical receiver 14 are perpendicular to each other. Figure 4 As shown, this can reduce the overlap between the two light paths and reduce the chance of mutual influence.

[0122] In some embodiments of the present application, the laser radar further includes a structure 30 , which includes a first sleeve 31 and a second sleeve 32 arranged up and down; the first sleeve 31 is located above the second sleeve 32 .

[0123] The first sleeve 31 is arranged horizontally and has a front end opening and a rear end opening; the collimating lens 12 is installed in the first sleeve 31 and blocks the front end opening of the first sleeve 31; the first emitter 11 is located in the first sleeve 31 and is close to the rear end opening of the first sleeve 31; the first emitter 11 is fixed on the transmitting circuit board 15 and is electrically connected to the transmitting circuit board 15; the transmitting circuit board 15 is electrically connected to the control board 91, and the control unit is arranged on the control board 91 and is electrically connected to the control unit, and the control board 91 is fixed on the structure 30.

[0124] The second sleeve 32 is arranged horizontally and has a front end opening and a rear end opening; the receiving lens 13 is installed in the second sleeve 32 and blocks the front end opening of the second sleeve 32; the optical receiver 14 is located in the second sleeve 32 and is close to the rear end opening of the second sleeve 32; the optical receiver 14 is fixed on the receiving circuit board 16 and is electrically connected to the receiving circuit board 16, and the receiving circuit board 16 is electrically connected to the control board 91.

[0125] The second emitter 21 and the reflective surface 22 are disposed opposite to each other on the inner wall of the second sleeve 32. The second emitter 21 is electrically connected to the control board 91.

[0126] By designing the structure 30 as a first sleeve 31 and a second sleeve 32 arranged up and down, not only is the spatial layout reasonable, but it is also convenient to fix the first transmitter 11, the collimating lens 12, the receiving lens 13, the light receiver 14, the second transmitter 21, and the reflecting surface 22.

[0127] The first transmitter 11 is fixed on the transmitting circuit board 15, the optical receiver 14 is fixed on the receiving circuit board 16, and the control unit is fixed on the control board 91. This not only facilitates the fixation of the first transmitter 11, the optical receiver 14, and the control unit, but also facilitates the communication between the first transmitter 11, the optical receiver 14 and the control unit.

[0128] The transmission process of the first driving signal is: control unit→control board 91→transmitting circuit board 15→first transmitter 11.

[0129] The transmission process of the second driving signal is: control unit→control board 91→second transmitter 21.

[0130] The transmission process of the electrical signal between the optical receiver 14 and the control unit is: optical receiver 14 →receiving circuit board 16 →control board 91 →control unit.

[0131] In some embodiments of the present application, the inner diameter of the first sleeve 31 gradually decreases from the front opening to the rear opening.

[0132] The collimating lens 12 is large in size and occupies a large space, so the inner diameter of the first sleeve 31 near the front end opening can be designed to be larger; the first emitter 11 is small in size and occupies a small space, so the inner diameter of the first sleeve 31 near the rear end opening can be designed to be smaller to reduce the internal space size of the first sleeve 31 and increase the structural strength of the structure 30.

[0133] In some embodiments of the present application, the second sleeve 32 is sequentially provided with a first diameter-reducing section 32-1 and a second diameter-reducing section 32-2 from the front opening to the rear opening. Figure 4 shown.

[0134] The inner diameter of the first diameter-reducing section 32-1 gradually decreases from the front opening to the rear opening;

[0135] The inner diameter of the second diameter-changing section 32-2 gradually increases from the front opening to the rear opening;

[0136] The receiving lens 13 is located in the first diameter-reducing section 32 - 1 and is close to the front end opening of the second sleeve 32 ;

[0137] The optical receiver 14 is located in the second diameter-reducing section 32 - 2 and is close to the rear end opening of the second sleeve 32 ;

[0138] The second emitter 21 and the reflecting surface 22 are arranged opposite to each other on the inner side wall of the second diameter-reducing section 32 - 2 .

[0139] The receiving lens 13 is large in size and occupies a large space, so the inner diameter of the first variable diameter section 32-1 near the front end opening can be designed to be larger; since the second variable diameter section 32-2 is provided with the light receiver 14, the second transmitter 21, and the reflecting surface 22, the inner diameter of the second variable diameter section 32-2 near the rear end opening needs to be designed to be larger.

[0140] By designing the inner diameter of the second sleeve 32 to first become smaller and then larger from the front opening to the rear opening, it is convenient to install the receiving lens 13, the second transmitter 21, and the reflecting surface 22, and the internal space size of the second sleeve 32 is minimized to increase the structural strength of the structure 30.

[0141] In some embodiments of the present application, the reflective surface 22 is a portion of the inner side wall of the second diameter-reducing section 32 - 2 of the second sleeve 32 .

[0142] In some embodiments of the present application, the housing of the laser radar includes an optical housing 51 and a lower housing 52. The optical housing 51 is located above the lower housing 52. The optical housing 51 and the lower housing 52 are detachably connected, making assembly and disassembly easy. For example, the bottom surface of the optical housing 51 contacts the top surface of the lower housing 52, and the two are connected together by screws.

[0143] The structure 30 is located in the optical cover 51. The optical cover 51 is generally made of optical plastic material, which can normally transmit the laser used for ranging and is mainly used to protect the ranging optical part.

[0144] The main function of the structure 30 is to provide structural support for each functional component and to physically isolate the transmitting optical path from the receiving optical path.

[0145] The motor 40 of the laser radar is located in the lower shell 52, and the stator 42 of the motor is fixed to the lower shell 52, and the rotor 41 of the motor is fixed to the structure 30. The rotor 41 drives the structure 30 to rotate around the motor's axis, thereby driving the laser ranging unit and the temperature drift detection unit to complete the circular scan.

[0146] The laser distance measuring unit and the temperature drift detection unit rotate along with the structure 30 to detect the distance of the target object in the circumferential direction.

[0147] The lower shell 52 is a metal shell and is the structural foundation of the laser radar. It is used to fix various functional components and provide structural support and external protection.

[0148] In some embodiments of the present application, in order to facilitate the acquisition of the rotation angle of the motor rotor, the laser radar includes an angle code disk 61 and a photoelectric encoder 62.

[0149] The angle code disk 61 is an annular structure, which is sleeved on the outside of the rotor 41 of the motor, arranged coaxially with the rotor 41, and fixedly connected to the rotor 41; the top of the angle code disk 61 has a tooth groove that cooperates with the photoelectric encoder 62.

[0150] The photoelectric encoder 62 is fixedly connected to the lower housing 52 to detect the rotation angle of the rotor 41 and send the detected angle signal to the main control unit of the laser radar.

[0151] The angle code disc 61 rotates along with the rotor 41. During the rotation, the tooth slots switch the light transmission and light blocking of the photoelectric encoder 62. The photoelectric encoder 62 obtains the rotation angle of the rotor according to the distribution of the tooth slots.

[0152] The real-time angular position of the rotor is obtained by reading the tooth groove features on the angle code disk 61 through the photoelectric encoder 62.

[0153] The main control unit is located in the lower housing 52 . The main control unit can obtain the angle of the rotor 41 based on the signal sent by the photoelectric encoder 62 , and further accurately obtain the orientation angle of the laser ranging unit.

[0154] In some embodiments of the present application, the laser radar further includes an optical communication module, which includes an optical communication transmitting end 71 and an optical communication receiving end 72. Figure 1 shown.

[0155] The motor is a hollow shaft rotary motor, that is, the motor's rotating shaft is a hollow shaft that passes through from top to bottom. The optical communication transmitting end 71 and the optical communication receiving end 72 are arranged vertically inside the hollow shaft of the motor. The optical communication receiving end 72 transmits optical signals with the optical communication transmitting end 71. The optical communication transmitting end 71 is located above the optical communication receiving end 72.

[0156] The optical communication transmitting end 71 is electrically connected to the control unit; the optical communication receiving end 72 is electrically connected to the main control unit of the laser radar.

[0157] By arranging the optical communication transmitting end 71 and the optical communication receiving end 72 up and down in the hollow shaft of the motor, the hollow shaft is used to transmit optical signals for real-time information transmission, which not only rationally utilizes space but also ensures smooth transmission of optical signals.

[0158] The signal transmission process is: control unit → control board 91 → optical communication transmitting end 71 → optical communication receiving end 72 → main control unit.

[0159] In some embodiments of the present application, in order to facilitate power supply for the laser ranging unit and the temperature drift detection unit, the laser radar also includes a wireless power receiving module 81 and a wireless power transmitting module 82.

[0160] The wireless power receiving module 81 is sleeved on the outside of the rotor 41 of the motor and is fixedly connected to the rotor 41 .

[0161] The wireless power transmission module 82 is located below the wireless power reception module 81 and is fixedly connected to the lower housing 52 .

[0162] The wireless power transmission module 82 and the wireless power receiving module 81 are arranged in an upper and lower spaced relationship. The wireless power transmission module 82 generates an alternating magnetic field. The wireless power receiving module 81 undergoes electromagnetic induction in the alternating magnetic field, generating an induced current to power the first transmitter 11, the second transmitter 21, the optical receiver 14, the control unit, etc.

[0163] The wireless power transmitting module 82 and the wireless power receiving module 81 are arranged vertically and spaced apart from each other, for example, the gap between the two is 2 mm to 3 mm.

[0164] The wireless power transmission module 82 includes a wireless power transmission circuit board and a wireless power transmission coil; the wireless power reception module 81 includes a wireless power reception circuit board and a wireless power reception coil.

[0165] The wireless power transmission circuit board drives the wireless power transmission coil to generate an alternating magnetic field, and the wireless power receiving coil generates an induced current and sends the generated induced current to the wireless power receiving circuit board. The wireless power receiving circuit board processes the received induced current and supplies power to the first transmitter 11, the second transmitter 21, the optical receiver 14, and the control unit.

[0166] When the laser radar is powered on, the wireless power transmission module 82 transmits the power supply in the lower shell 52 to the wireless power receiving module 81 through electromagnetic induction. After obtaining the electrical energy, the wireless power receiving module 81 transmits it to the laser ranging unit, temperature drift detection unit, control unit, etc. to start ranging.

[0167] The laser radar of this embodiment uses a control unit to drive two transmitters to work in a time-sharing manner, obtains distance information on the same optical receiver, and uses an internal fixed optical path to eliminate the temperature drift generated by the control unit, thus simply and efficiently completing the elimination and compensation of the temperature drift effect.

[0168] The temperature drift detection unit and control unit are used to calculate the temperature drift error; the laser ranging unit and control unit are used to calculate the distance to the target object, and then the temperature drift error is subtracted to obtain the ranging result after eliminating the temperature drift. The ranging result is sent to the main control unit (central processing unit) of the laser radar through the optical communication module. The motor rotates at a constant speed according to the set speed, driving the structure 30 and the angle code disk 61 to rotate together. Through the starting mark arranged on the angle code disk 61, the central processing unit of the laser radar can calculate the angle pointed by the angle code disk 61 at the same time. The central processing unit integrates the ranging result obtained by the optical communication module and the angle result at the same time to obtain an orientation information. Similarly, the distance and angle information of the target object within a 360-degree range can be obtained after the motor rotates one circle, completing the basic function of the laser radar.

[0169] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A laser radar, characterized in that: include: The laser distance measuring unit comprises a first transmitter, a collimating lens, a receiving lens, and a light receiver; the light emitted by the first transmitter is emitted to a target object after passing through the collimating lens, the light reflected by the target object is emitted to the receiving lens, the light converged by the receiving lens is emitted to the light receiver, and the light receiver emits an electrical signal after receiving the light; A temperature drift detection unit, comprising a second emitter and a reflective surface; The light emitted by the second emitter is reflected by the reflective surface and then emitted into the light receiver; A control unit, which is used to perform a temperature drift detection step and an actual measurement step; The temperature drift detection step includes: sending a second drive signal to the second emitter to drive the second emitter to emit light; recording a second timing time t from sending the second drive signal to receiving the electrical signal sent by the light receiver; calculating the temperature drift error γ=c×t-d0; wherein c is the speed of light in air; d0 is the sum of the distance from the second emitter to the reflective surface and the distance from the reflective surface to the light receiver; The actual measurement steps include: sending a first drive signal to the first emitter to drive the first emitter to emit light; recording a first timing time T from sending the first drive signal to receiving the electrical signal sent by the light receiver; calculating the distance D=c×T / 2; then the distance D0 after eliminating temperature drift=D-γ.

2. The laser radar according to claim 1, characterized in that: Before each actual measurement step, a temperature drift detection step is performed first.

3. The laser radar according to claim 1, characterized in that: The temperature drift detection step is performed once at a set time interval to update the temperature drift error γ.

4. The laser radar according to claim 1, characterized in that: The motor of the laser radar drives the laser ranging unit, the temperature drift detection unit, and the control unit to rotate; Each time the motor rotates a set number of times, a temperature drift detection step is performed to update the temperature drift error γ.

5. The laser radar according to claim 1, characterized in that: The optical path between the second emitter and the reflecting surface and the optical path between the receiving lens and the optical receiver are perpendicular to each other.

6. The laser radar according to claim 1, characterized in that: The laser radar further includes a structure, wherein the structure has a first sleeve and a second sleeve arranged up and down; the first sleeve is located above the second sleeve; The first sleeve is arranged horizontally, and has a front opening and a rear opening; the collimating lens is installed in the first sleeve and blocks the front opening of the first sleeve; the first transmitter is located in the first sleeve and close to the rear opening of the first sleeve; the first transmitter is fixed on the transmitting circuit board and electrically connected to the transmitting circuit board; the transmitting circuit board is electrically connected to the control board, the control unit is arranged on the control board and electrically connected to the control unit, and the control board is fixed on the structure; The second sleeve is arranged horizontally, and has a front opening and a rear opening; the receiving lens is installed in the second sleeve and blocks the front opening of the second sleeve; the optical receiver is located in the second sleeve and close to the rear opening of the second sleeve; the optical receiver is fixed on the receiving circuit board and is electrically connected to the receiving circuit board; the receiving circuit board is electrically connected to the control board; The second emitter and the reflecting surface are arranged opposite to each other on the inner wall of the second sleeve.

7. The laser radar according to claim 6, characterized in that: The inner diameter of the first sleeve gradually decreases from the front end opening to the rear end opening.

8. The laser radar according to claim 6, characterized in that: The second sleeve is provided with a first diameter-reducing section and a second diameter-reducing section in sequence from the front end opening to the rear end opening; The inner diameter of the first diameter-changing section gradually decreases from the front opening to the rear opening; The inner diameter of the second diameter-changing section gradually increases from the front opening to the rear opening; The receiving lens is located in the first diameter-changing section, and the optical receiver is located in the second diameter-changing section; the second transmitter and the reflecting surface are arranged on the inner side wall of the second diameter-changing section opposite to each other.

9. The laser radar according to claim 6, characterized in that: The housing of the laser radar comprises an optical outer cover and a lower housing, wherein the optical outer cover is located above the lower housing and is detachably connected to the lower housing; The structure is located in the optical housing; The motor of the laser radar is located in the lower shell, and the stator of the motor is fixed to the lower shell, and the rotor of the motor is fixed to the structure, driving the structure to rotate.

10. The laser radar according to claim 9, characterized in that: The laser radar further includes an optical communication module, and the optical communication module includes an optical communication transmitting end and an optical communication receiving end; The optical communication transmitting end and the optical communication receiving end are arranged vertically in the hollow shaft of the motor; the optical communication receiving end transmits optical signals with the optical communication transmitting end; The optical communication transmitting end is electrically connected to the control unit; the optical communication receiving end is electrically connected to the main control unit of the laser radar.

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