CN110543187A

CN110543187A - positioning and obstacle avoidance unmanned aerial vehicle device and method based on laser radar

Info

Publication number: CN110543187A
Application number: CN201910778910.5A
Authority: CN
Inventors: 钱恭斌; 王春琦; 冯大权; 何春龙; 丁晓欢; 王凯源
Original assignee: Shenzhen University
Current assignee: Shenzhen University
Priority date: 2019-08-22
Filing date: 2019-08-22
Publication date: 2019-12-06

Abstract

The invention provides a positioning and obstacle avoidance unmanned aerial vehicle device and method based on a laser radar, which can provide a structure with a plurality of central positions so that parts such as positioning parts, control assemblies and the like of an unmanned aerial vehicle can be placed at optimal positions, and provides an obstacle avoidance method of the unmanned aerial vehicle so as to jointly solve the problem of insufficient environment perception autonomous flight capability of the unmanned aerial vehicle caused by the fact that the parts of the unmanned aerial vehicle cannot be placed at the optimal positions and the obstacle avoidance method of the unmanned aerial vehicle is insufficient.

Description

positioning and obstacle avoidance unmanned aerial vehicle device and method based on laser radar

Technical Field

The invention relates to the technical field of unmanned aerial vehicles, in particular to a positioning and obstacle avoidance unmanned aerial vehicle device and method based on a laser radar.

Background

With the rapid development of unmanned aerial vehicle technology, unmanned aerial vehicles have gradually come into people's lives and works. Traditional unmanned aerial vehicle still relies on professional's manipulation, and unmanned aerial vehicle technique has the environmental perception ability, the autonomous flight ability scheduling problem inadequately. However, current unmanned aerial vehicle's overall structure is comparatively single, adopts the die sinking design more, and its degree of difficulty is great, and the cost is higher, and the structure is comparatively complicated, can not place each part in the most suitable position, is difficult to use multisensor. In order to realize that the unmanned aerial vehicle can completely and autonomously position and navigate in an unknown environment, an unmanned aerial vehicle positioning system in the prior art mostly depends on a GPS (global positioning system), but the unmanned aerial vehicle cannot position under the environment with weak GPS signals or without GPS signals, so that the wide application and the rapid development of the unmanned aerial vehicle are limited, and the personnel and property in the relative environment have safety risks.

disclosure of Invention

The technical problem to be solved by the invention is as follows: the utility model provides an unmanned aerial vehicle's bearing structure, unmanned aerial vehicle based on laser radar location, can provide the structure that a plurality of central points put, so that unmanned aerial vehicle's positioning element, parts such as control subassembly are arranged in the optimal position, and provide unmanned aerial vehicle keep away the barrier strategy with the problem that unmanned aerial vehicle environment perception autonomous flight ability is not enough that solve jointly because of unmanned aerial vehicle's part can't arrange optimal position, unmanned aerial vehicle keeps away the barrier method and leads to inadequately.

The invention provides a supporting structure of an unmanned aerial vehicle, which comprises a frame plate and a foot rest, wherein a first bearing plate, a second bearing plate, a third bearing plate, a first supporting and fixing component, a second supporting and fixing component and a third supporting and fixing component are arranged on the frame plate;

The reverse side of the first bearing plate is arranged on the front side of the frame plate through a first supporting and fixing component;

the front surface of the second bearing plate is arranged on the back surface of the frame plate through a second supporting and fixing component;

the front surface of the third bearing plate is arranged on the back surface of the second bearing plate through a third supporting and fixing component.

further, the support fixture assembly includes at least one support column.

Furthermore, one end of the foot rest is fixed on the reverse side of the frame plate, and the other end of the foot rest extends out of the plane of the third bearing plate.

furthermore, the other end of the foot rest is provided with a damping and buffering mechanism.

The invention provides an unmanned aerial vehicle in a second aspect, which comprises a laser sensor, an ultrasonic sensor, an onboard processor and a support structure of the unmanned aerial vehicle;

the laser sensor is fixed on the front surface of the first bearing plate;

the ultrasonic sensor is fixed on the reverse side of the third bearing plate; the onboard processor is fixed on the front surface of the third bearing plate and is electrically connected with the laser sensor and the ultrasonic sensor respectively.

further, unmanned aerial vehicle still includes GPS, and GPS fixes openly at the frame.

Further, the laser sensor is a lidar.

The third aspect of the invention provides an unmanned aerial vehicle obstacle avoidance method for an unmanned aerial vehicle, which comprises the following steps:

s100: obtaining the distance of the nearest barrier;

S200: comparing the distance of the nearest barrier with the warning safety radius, if the distance of the nearest barrier is greater than the warning safety radius, not inhibiting the moving speed, and entering S400;

if the distance of the nearest barrier is smaller than the warning safety radius, the step S300 is entered;

S300: suppressing the moving speed of the unmanned aerial vehicle;

S400: starting barrier speed amplitude limiting, and carrying out amplitude limiting on the total speed;

s500: and issuing instructions to the position control to control the downward movement of the machine body.

Further, S300 includes the steps of:

S310: compare the distance of the nearest obstacle to the dangerous safety radius:

If the distance between the nearest obstacles is greater than the dangerous safety radius, performing first-stage inhibition on the moving speed;

And if the distance between the nearest obstacles is less than the dangerous safety radius, performing second-stage inhibition on the moving speed.

further, after S500, the method includes the following steps:

S600: calculating the current position and the expected landing position distance of the unmanned aerial vehicle;

If the distance between the current position of the unmanned aerial vehicle and the expected landing position is less than 0.3m, controlling the unmanned aerial vehicle to land;

and if the distance between the current position of the unmanned aerial vehicle and the expected landing position is greater than or equal to 0.3m and the information indicating landing is acquired, controlling the unmanned aerial vehicle to land.

drawings

the detailed structure of the invention is described in detail below with reference to the accompanying drawings

fig. 1 is a basic front view of an unmanned aerial vehicle apparatus according to a first embodiment of the present invention;

FIG. 2 is a right side view of the drone assembly of the first embodiment of the present invention;

FIG. 3 is a basic constitution diagram of a second embodiment of the present invention;

fig. 4 is a SLAM system framework of a third embodiment of the invention;

FIG. 5 is a Cartographer algorithm architecture according to a third embodiment of the present invention;

FIG. 6 is a data processing flow of a third embodiment of the present invention;

FIG. 7 is a software implementation flow of the third embodiment of the present invention;

fig. 8 is a basic flowchart of an obstacle avoidance method according to a third embodiment of the present invention;

Fig. 9 is a flowchart of an obstacle avoidance method according to a third embodiment of the present invention.

each reference numeral indicates:

101. A support pillar;

110. A first bearing plate; 111. a laser sensor;

120. a frame; 121. a foot rest; 122. a GPS; 124. a flight control unit; 125. a foam sponge;

130. A second carrier plate; 131. a data transmission radio station;

140. a third bearing plate; 141. an ultrasonic sensor; 142. an onboard processor.

Detailed Description

In order to explain technical contents, structural features, and objects and effects of the present invention in detail, the following detailed description is given with reference to the accompanying drawings in conjunction with the embodiments.

referring to fig. 1, fig. 1 is a basic front view of an unmanned aerial vehicle device according to a first embodiment of the present invention, and provides a support structure of an unmanned aerial vehicle, which includes a frame 120, a foot rest 120, a first bearing plate 110, a second bearing plate 130, a third bearing plate 140, a first supporting and fixing component, a second supporting and fixing component, and a third supporting and fixing component;

The reverse side of the first bearing plate 110 is mounted on the front side of the frame 120 plate through a first supporting and fixing component;

The front surface of the second bearing plate 130 is mounted on the back surface of the frame 120 plate through a second supporting and fixing component;

the front surface of the third carrier plate 140 is mounted on the back surface of the second carrier plate 130 through a third supporting and fixing assembly.

according to the invention, a multilayer space structure is formed by supporting and fixing the components, each bearing plate forms two central positions, and six central positions are provided, so that the most suitable devices arranged at the central part of the unmanned aerial vehicle, such as the cloud deck, the laser radar and the flight control unit 124, can be conveniently placed, and the scanning effect of the laser radar with 360 degrees and the sensitivity of the flight control unit 124 are ensured while the sensitivity of the cloud deck in use is improved.

And each floor space provides the mounted position of a large amount of unmanned aerial vehicle devices, can fix different devices, and the equipment and the maintenance of being convenient for also make things convenient for masses to reform transform unmanned aerial vehicle once more, assemble into the unmanned aerial vehicle of oneself.

in addition, because the existence of supporting fixed subassembly, the shell that need not unmanned aerial vehicle still can fly, conveniently observes unmanned aerial vehicle's inherent structure, and the learner of being convenient for observes the operation conditions of each part of unmanned aerial vehicle among the different flight states, conveniently measures each part condition of generating heat.

in the above, the supporting and fixing assembly includes four metal supporting columns 101 and screws for fixing the supporting columns 101.

In this embodiment, the metal supporting pillar 101 is not limited to be made of metal, and other materials may be applied to the supporting pillar 101. The screws can fix both ends of the supporting column 101, and can also be used for reinforcing the column shaft of the supporting column 101. The number of support posts 101 includes, but is not limited to, 4. In this embodiment, one end of each of the four foot rests 120 is fixed to the opposite side of the frame 120, and the other end of each of the four foot rests 120 extends out of the plane of the third supporting plate 140 and exceeds the laser sensor 111 on the opposite side of the third supporting plate 140.

Therefore, the frame 120 ensures that the unmanned aerial vehicle cannot be damaged when landing, and each device in the unmanned aerial vehicle is protected.

further, the other end of the foot stand 120 is provided with a shock absorbing and buffering mechanism.

the damping and buffering mechanism of the present embodiment may be a foam sponge 125, or may be a rubber material.

The buffer structure can also be a buffer air bag which can be stored by a storage box fixed on the machine body, an air inlet and outlet pipeline is arranged between the storage box and the machine body, one end of the air inlet and outlet pipeline is connected with an air inlet fan fixedly arranged on the machine body, and the other end of the air inlet and outlet pipeline extends into the storage box and is hermetically connected with an air bag stacked in the storage box; the air bag is an inflatable bag body made of non-elastic, flexible and airtight materials.

Referring to fig. 2 and 3 of the drawings,

fig. 3 is a basic configuration diagram of a second embodiment of the present invention.

The unmanned aerial vehicle provided by the invention comprises a laser sensor 111, an ultrasonic sensor 141 and a supporting structure of the unmanned aerial vehicle;

the laser sensor 111 is fixed on the front surface of the first bearing plate 110;

the ultrasonic sensor 141 is fixed at a central region of the opposite surface of the third loading plate 140;

an on-board processor 142, the on-board processor 142 being secured to the front side of the third carrier plate 140.

The laser sensor 111 is located on a laser radar, and the radar in this embodiment is a 360-degree rotating radar, which is convenient for calculating four minimum distances in the front, rear, left and right directions.

preferably, the present drone can enhance the effect of the laser sensor 111 by installing and setting the GPS 122.

Therefore, the method comprises the steps of firstly detecting a region in an effective detection range by using the laser radar to obtain the relative coordinates of the surrounding obstacles from a detection point of the unmanned aerial vehicle, then constructing an environment map which takes the detection point as the center and takes the radar scanning radius as the maximum region, and finally continuously detecting the unmanned aerial vehicle by using the laser radar in the advancing process to obtain environment information which takes the current position as the center, and determining the position of the unmanned aerial vehicle in the map after comparing the environment information with the feature points in the map, so that the purposes of completely autonomous positioning and intelligent planning obstacle avoidance are achieved.

the ultrasonic sensor transmitter transmits the sound wave back and arrives the receiver through reflection object reflection, calculates unmanned aerial vehicle apart from ground relative height through the flight time of measuring the sound wave, and measurement accuracy is high, the module is with low costs, predicts fast and keeps away the barrier condition, in addition, still guarantees that unmanned aerial vehicle possesses the height function of deciding.

Under the better condition of GPS122 signal, through fusing laser radar data, can further improve positioning accuracy, the highest positioning accuracy of system can reach centimetre level.

the onboard processor of the present embodiment may be any of the nvidia Jetson TX2 models, or may be similar.

further, the present invention is provided with a data transmission station 131, and the data transmission station 131 is disposed on the front surface of the second carrier plate 130. The data transfer radio 131 can receive ground information to assist the operation of the unmanned aerial vehicle.

the onboard processor is arranged at the center part of the front face of the third bearing plate 140, and when the unmanned aerial vehicle is large in size, the onboard processor can transmit height information with ultrasonic waves at the fastest speed, so that the obstacle avoidance method is quickened.

Referring to fig. 4, fig. 4 is a SLAM system framework according to a third embodiment of the invention.

The onboard processor performs data modeling by using a local SLAM algorithm and a global SLAM algorithm.

The local SLAM algorithm and the global SLAM algorithm in the embodiment are based on the Cartograer SLAM algorithm of Google to realize accurate local position estimation and complete the functions of autonomous positioning and obstacle avoidance.

local SLAM, whose work is to create a series of subgraphs, which drift over time.

Global SLAM, which runs in a background thread, mainly works to find the loop closure constraints, implement subgraphs by scanning matching scans (collected in nodes), and also combine other sensor data to obtain higher level views and determine the most consistent view global solution.

because of the observation noise problem, to solve the observation noise problem, a band pass filter is first applied. To reduce the computational weight of point processing, a sub-sampled point cloud is typically required. In order to solve the density problem, a fixed-size voxel filter is used, and after passing through the fixed-size voxel filter, an adaptive voxel filter is used.

the inertial measurement unit can be a useful source of information for SLAM because it provides an accurate direction of gravity. Once scan assembled and filtered from multiple range data, the local SLAM algorithm can be prepared. Local SLAM inserts a new scan into its current sub-graph construct through scan matching using an initial guess from the gesture extrapolator. The gesture extrapolator uses sensor data of other sensors than the rangefinder to predict where the next scan should be inserted into the sub-graph. To avoid inserting too many scans per sub-graph, it will happen to pass through the motion filter as soon as the scan match finds motion between two scans. If the motion that caused it is not important enough, the scan would be deleted. One will insert a scan into the current sub-picture only if the motion of the scan is above a certain distance, angle or time threshold.

When a local SLAM has received a given amount of range data, the child map is considered complete. Over time, the local SLAM drifts, and the global SLAM is used to address this drift problem. The subgraphs must be small enough to have their internal drift lower than the resolution so that they are modified locally. On the other hand, they should be large enough to allow the loop closure to work properly.

please refer to fig. 5, fig. 6 and fig. 7:

The Cartogrier algorithm comprises an input module, an algorithm module and an output module.

The input module comprises laser radar point cloud data, the current position of the unmanned aerial vehicle, the expected position of the unmanned aerial vehicle, the minimum angle and the maximum angle of the detection range of the laser radar and the like.

The algorithm module comprises a warning level safety radius, a danger level safety radius, a large circle proportion parameter, a small circle proportion parameter, a nearest barrier distance and angle, a barrier avoiding part speed amplitude limit, a tracking part position ring, a tracking part speed amplitude limit, a landing zone bit and the like.

The output module comprises a flag bit for entering the obstacle avoidance mode, the total speed amplitude limit, issued control commands and the like.

The specific process of the Cartogrrapher software implementation flow design is as follows: the method comprises the steps of firstly setting frequency, subscribing radar data, subscribing the current position of the unmanned aerial vehicle under an NED coordinate system, issuing a command sent to position control, reading parameters in a parameter list, printing real inspection parameters, initializing, updating radar point cloud data, calculating the minimum distance in four directions (front, back, left and right), judging whether an obstacle avoidance method is started or not according to the minimum distance, calculating tracking speed, limiting the tracking speed, initializing the speed of an obstacle avoidance part, starting the obstacle avoidance method, and issuing the command to the position control.

initialization in the software implementation process of the Cartogrier mainly comprises tracking part speed initialization, obstacle avoidance part speed initialization, total speed initialization, landing flag bit initialization, output instruction initialization and the like. And calculating the minimum four-way distance, eliminating the situation that the laser radar data is infinite, taking the distance value of the previous angle as the current distance value when the radar data is infinite, and keeping the current radar data distance value if the radar data is infinite.

please refer to fig. 8 and fig. 9:

fig. 9 is a flowchart of an obstacle avoidance method according to a third embodiment of the present invention;

Step S100: obtaining the distance of the nearest barrier;

Step S200: comparing the distance of the nearest obstacle with a warning safety radius, if the distance of the nearest obstacle is greater than the warning safety radius, not inhibiting the moving speed, and entering the step S400;

if the distance of the nearest barrier is smaller than the warning safety radius, the step S300 is executed;

step S300: suppressing the moving speed of the unmanned aerial vehicle;

Step S400: starting barrier speed amplitude limiting, and carrying out amplitude limiting on the total speed;

step S500: and issuing an instruction to position control, and enabling the machine body to move downwards.

Specifically, step S100, the distance of the nearest obstacle is acquired,

from the above description, the beneficial effects of the present invention are: the method has the advantages of less obstacle avoidance steps, less calculated amount, high calculation efficiency, fast obstacle avoidance response and strong obstacle avoidance effect.

further, S300 further includes the steps of:

S310: comparing the distance of the nearest obstacle to the dangerous safety radius:

if the distance between the nearest obstacles is greater than the dangerous safety radius, the first-level inhibition is carried out on the moving speed;

and if the distance between the nearest obstacles is less than the dangerous safety radius, the moving speed is restrained for the second level.

The first-stage inhibition of the moving speed is the inhibition with small amplitude; the second stage of suppression of the moving speed is large amplitude suppression.

Therefore, the speed of the unmanned aerial vehicle is restrained in two situations, the algorithm for restraining the moving speed is simplified, and the situation of operation disorder is avoided. A dangerous safe radius; the moving speed is restrained in a small amplitude; the relationship of the speed of movement is greatly suppressed.

further, after S500, the method further includes the following steps:

After S500, the method comprises the following steps:

specifically, the landing flag is usually set to 1, and when the landing flag is 1, the unmanned aerial vehicle lands; the unmanned aerial vehicle can also depend on other information for indicating landing to control the unmanned aerial vehicle to land.

therefore, the landing can be safely carried out, and the surrounding people and the environment are not greatly influenced.

further, the first-stage speed limit is smaller than the second-stage speed limit.

Specifically, the distance of the nearest obstacle detected by the laser radar can be assumed to be d, the default warning safety radius set by the system is R, the dangerous safety radius is R, the large circle proportion parameter p _ R and the small circle proportion parameter p _ R are set by the system, the normal movement speed of the unmanned aerial vehicle is V, and the speed of the unmanned aerial vehicle after the obstacle avoidance strategy is started is V.

when d is greater than R, no speed limit is made;

when R < d < R, the first stage rate limiting is performed, i.e., V-p _ R (R-d);

when d < R, the second stage rate limiting, i.e., V-p _ R (R-R) -p _ R (R-d), is performed.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all modifications of equivalent structures and equivalent processes performed by the present specification and drawings, or directly or indirectly applied to other related technical fields, are included in the scope of the present invention.

Claims

1. the utility model provides an unmanned aerial vehicle's bearing structure, includes frame board and foot rest, its characterized in that: the bearing plate comprises a first bearing plate, a second bearing plate, a third bearing plate, a first supporting and fixing component, a second supporting and fixing component and a third supporting and fixing component;

the reverse side of the first bearing plate is arranged on the front side of the frame plate through a first supporting and fixing assembly;

2. an unmanned aerial vehicle structure as claimed in claim 1, wherein: the support fixture assembly includes at least one support column.

3. An unmanned aerial vehicle structure as claimed in claim 2, wherein: one end of the foot rest is fixed on the reverse side of the frame plate, and the other end of the foot rest extends out of the plane where the third bearing plate is located.

4. A drone structure according to claim 3, characterised in that: and the other end of the foot rest is provided with a damping and buffering mechanism.

5. an unmanned aerial vehicle, its characterized in that: the unmanned aerial vehicle comprises a laser sensor, an ultrasonic sensor, an onboard processor and a support structure of the unmanned aerial vehicle, wherein the support structure of the unmanned aerial vehicle is the support structure of the unmanned aerial vehicle according to any one of claims 1-4;

The laser sensor is fixed on the front surface of the first bearing plate;

The ultrasonic sensor is fixed on the reverse side of the third bearing plate;

The onboard processor is fixed on the front face of the third bearing plate and is electrically connected with the laser sensor and the ultrasonic sensor respectively.

6. A drone according to claim 6, characterised in that: the GPS is fixed on the front surface of the frame.

7. a drone according to claim 6, characterised in that: the laser sensor is a laser radar.

8. An unmanned aerial vehicle obstacle avoidance method of an unmanned aerial vehicle is characterized by comprising the following steps:

S100: obtaining the distance of the nearest barrier;

s200: comparing the distance of the nearest obstacle with a warning safety radius, if the distance of the nearest obstacle is greater than the warning safety radius, not inhibiting the moving speed, and entering S400;

If the distance of the nearest barrier is smaller than the warning safety radius, entering S300;

S300: suppressing the moving speed of the unmanned aerial vehicle;

9. The unmanned aerial vehicle obstacle avoidance method of an unmanned aerial vehicle of claim 8, wherein the S300 further comprises the steps of:

10. An unmanned aerial vehicle obstacle avoidance method for an unmanned aerial vehicle as claimed in claim 9, wherein after S500, the method comprises the following steps: