Summary of the invention
For use multi-line laser radar to carry out terrain construction in the prior art and caused by the low problem of cost performance, this hair
It is bright to provide before a kind of vehicle based on single line laser radar to landform construction method, it uses with the list for having angle with horizontal plane
Line laser radar carries out the scanning that swings, and without scanning up and down, data volume is few, and hardware configuration is of less demanding, improves
The cost performance of laser radar building map device.
To landform construction method before the vehicle based on single line laser radar, its technical solution is that: it is being loaded with list
When the vehicle of line laser radar moves in the X-axis direction, the X-axis opposite direction of barrier relative vehicle is moved, by the movement of barrier
Directional Decomposition is movement to laser radar X, Z-direction, in conjunction with the scanning of laser radar itself Y-direction, complete to barrier or
The 3D of landform is scanned;There are certain angle thetas with horizontal plane for single line laser radar1。
The safe distance for needing to identify is determined according to vehicle speed, by safe distance, laser radar height and vehicle landform
Handling capacity determines the tilt angle theta of laser radar1,Wherein, l represents what vehicle needed to identify
The shortest distance, h1Represent laser radar height, h2Represent obstacle height when vehicle needs avoidance.
By the X-axis opposite direction Kinematic Decomposition of barrier relative vehicle, the correspondence object height or depth of Z-directionWherein, t is time of the laser pulse from barrier bottom scan to top;V is Vehicle Speed;
Then the length of the X-direction of barrier is v*t2;Wherein, V is Vehicle Speed, t2To measure automobile when height is h
The time that the time of traveling, i.e. scanning are same object;
Single line laser radar feathering angle θ 2 is then known the width in the direction y of barrier by cosine formula are as follows:Wherein, L1、L2To barrier when signal emits twice respectively before and after single line laser radar
Distance.
The beneficial effects of the present invention are: when the present invention is moved in X direction by vehicle, the X-direction of barrier relative vehicle
Movement, be decomposed into inclination installation laser radar X, Z-direction movement, obtained by the geometrical relationship on laser radar and ground
Obtain the height of barrier profile or the width of depth and barrier.The cost performance that the present invention has is high, data volume is few, weight
The advantages that light.
Specific embodiment
The present invention is further detailed with reference to the accompanying drawing.
Present invention is mainly applied to car speed it is not high in the case where, in terms of agricultural automation.Based on single line laser thunder
It can be from laser radar position by single line laser radar loaded on tractor vehicle top to landform construction method before the vehicle reached
Measurement starts terrain detection, and laser beam, which is tilted in, to be incident upon in landform, includes the following steps when in use;
Step 1: the shortest safe distance that needs identify can be determined by vehicle speed according to light propagation formula, by
Safe distance, laser radar height and vehicle landform handling capacity determine the tilt angle of laser radar.
Wherein, above-mentioned safe distance refers to when vehicle needs avoidance, since vehicle has certain travel speed,
When carrying out turning operation, a certain distance is needed to carry out avoidance, this avoidance is safe distance with shortest distance.This distance
Increase with the increase of speed.Vehicle landform handling capacity refer to the height by method acquired disturbance object m described herein,
After wide and thickness information, by program judge vehicle whether can by ability.If vehicle handling capacity itself is high
30cm is spent, it is then more than the handling capacity of vehicle that the height of barrier m, which is 35cm, and vehicle stops.If if vehicle itself passes through
Ability is height 30cm, and the height of barrier m is 25cm, then is no more than the handling capacity of vehicle, vehicle passes through.
Cause to scatter Step 2: the laser pulse that laser is launched is incident on body surface, a portion light wave meeting
By reflection back into the receiver of laser radar, it converts light signals into electric signal and records, meanwhile, by being matched
The same laser pulse signal of standby timer record is by being emitted to the time interval being received.Since the light velocity is known, biography
The measurement adjusted the distance can be converted by broadcasting time interval.
Step 3: when being moved in X direction by vehicle, the movement of the X-direction of barrier m relative vehicle is decomposed such as Fig. 1
For the movement of laser radar X, Z-direction to inclination installation, barrier m can be found out by the geometrical relationship on laser radar and ground
The height or depth and width of profile.
Step 4: there is the blind area of a distance before vehicle driving, need that one ultrasonic wave thunder is installed in front of the car
It reaches.
Step 5: microprocessor carries out terrain construction, control system determines whether vehicle has handling capacity to this landform.
The step 1 includes following procedure: inclination angle theta of the pulsed light beam that laser radar issues relative to vertical direction1's
Expression formula are as follows:
Wherein, l represents vehicle and needs to be set to 5m, h at the beginning of the shortest distance identified1It represents laser radar height and is just set to 3m, h2
Vehicle is represented to need barrier m height when avoidance just θ can be obtained by being set to 0.2m1It is 61 °.
Barrier m linear distance measurement in step 2 laser radar road includes following procedure: laser radar road barrier m
Linear distance L expression formula are as follows:Wherein, L is laser emitter to the geometric distance between reflection point, and c is the light velocity, t
A laser can only be obtained by being emitted to the time interval being received, an echo-signal of beam of laser pulse for laser pulse
The range information of reflection point obtains the range information with a series of laser reflection points of certain bandwidth to be continuous, need to be by one
Fixed mechanical device makes laser emitter carry out operation by way of scanning.Because laser pulse is connect with light velocity propagation
It receives device and always receives the previous pulse being reflected back toward before next pulse sending.
Such as Fig. 2, the step 3 barrier m height or depth and width measurement include following procedure: passing through trigonometric function
Transformation, utilizes the mounting height of laser radar, the inclination angle of laser light number, laser radar swing angle and laser radar to obstacle
Object m distance can calculate barrier m profile elevations h and width, and calculation formula is as follows:
The height of barrier m or the expression formula of depth h are as follows:Wherein, t is laser pulse from barrier m
Time of the bottom scan to top;V is Vehicle Speed;
As the expression formula of Fig. 3, the width d of barrier m areIn formula, L1、L2Respectively
To the distance of barrier m, θ when signal emits twice before and after radar2For radar swing angle.
Such as Fig. 4, the length of the X-direction thickness of barrier m is v*t2;Wherein, V is Vehicle Speed, t2For measurement height
The time of running car, that is, scan time-consuming when same object when for h.
In use, microprocessor can be set, the radar scanning line buffering in a distance is established in the microprocessor
Area (FIFO) constructs complete landform or barrier m using iteration closest approach algorithm.The microprocessor is according to measuring landform or obstacle
Whether the judgement of object m profile has handling capacity to this landform, if it is possible to then be continued on by obstacle, otherwise control system will
It issues command signal and takes appropriate avoidance measure to execution system.
Because method of the present invention needs vehicle to advance after a distance and could form map structuring, in order to
Guarantee safety, several ultrasonic radars can be installed in vehicle front and detect whether that there are object, ultrasonic radar and micro processs
Device communication, if the data that ultrasonic radar is sent back to indicate existence body, and object can positioned at this method at a distance from vehicle
Between the near distance spot and vehicle of detection, microprocessor controls vehicle avoiding obstacles m.
Specifically, the rotation of single line laser radar can be realized by rotary frame, the rotary frame include base,
With the stepper motor being arranged below base;Single line laser radar is set on base, and base angle with horizontal plane is θ1;The folder
Angle θ1It can be default by above-mentioned mode.The angle of light and horizontal plane that single line laser radar projects is also angle theta1;Base
It is fixedly connected, is rotated with the output shaft of stepper motor and rotates with the output shaft of stepper motor.Stepper motor and microprocessor
Electrical connection, microprocessor can acquire the active angle of stepper motor.Simultaneously by presetting, the maximum of stepper motor can be determined
Corner.
The foregoing is merely the preferred embodiment of invention, oneself, is not intended to limit the invention, all in spirit of the invention
With any modifications, equivalent replacements, and improvements made within principle etc., should all be included in the protection scope of the present invention.