RU2816411C1 - Method for automatically forming path and speed of movement of robotic wheeled moving object - Google Patents

Abstract

FIELD: control of robotic moving objects.

SUBSTANCE: in the method of automatically forming the path and speed of movement of a robotic wheeled mobile object (RWMO) for transporting goods between an aircraft at its parking site and the airport terminal at each reference point, data from the navigation unit is entered into the computer, determining the positioning and speed of the RWMO, as well as data received from radio beacons installed on static and dynamic obstacles; data on the weight and dimensional characteristics of the RWMO cargo; data on wind speed and direction. The specified data is processed in the computer. Based on the selected path and speed, the movement of the RWMO along the formed path is controlled. In a situation where there is likely oncoming movement of the RWMO and a dynamic obstacle, the speed of the RWMO is reduced to a level at which the speed of the RWMO relative to the dynamic obstacle does not exceed the permitted maximum value. In a situation where the RWMO is likely to follow a dynamic obstacle along one lane, the speed of the RWMO is reduced to the speed of the dynamic obstacle.

EFFECT: improved traffic safety at the airport.

1 cl, 1 dwg

Description

The invention relates to the field of technology for controlling robotic moving objects in terms of forming the path and speed of their movement along the route between its starting and ending points, in particular in the automatic formation of the path and speed of movement of a robotic wheeled moving object (RKPO) intended for transporting goods between aircraft in its parking lot and airport terminal.

There is a known method for constructing the path of an RTS - a robotic vehicle (application KR 20150086065 A, published on July 27, 2015, the first analogue). The method includes representing the global path of the RV on the road as a sequence of reference points, tracking the current position of the RV at these points, forming an additional RV path when an obstacle is detected by generating a set of possible alternative paths equidistant to the global path within the width of the road, and selecting from them optimal path around the obstacle, in the form of an additional sequence of control points, continuing movement along this generated path.

The disadvantage of this method is that it involves, in order to avoid collisions between RTS and obstacles on the road, the formation of an additional route to bypass them, which is often impossible to implement at the airfield due to the safety conditions within the framework of the airfield topography in the presence of not only static, but also moving along different lanes and directions of dynamic obstacles. At the airfield, it is necessary to choose an alternative route of movement that corresponds to the surface markings with established routes for the movement of equipment, as well as the positioning and speeds of traffic participants. In addition, this method does not contain specific recommendations for choosing the optimal speed of movement of the RTS along the formed path.

There is also a known method for automatically generating smooth trajectories of movement of a mobile robot in an unknown environment (patent RU 2661964 C2, published on July 23, 2018. Bulletin No. 21, second analogue). The method includes determining the location of the robot, processing information from on-board rangefinders to determine the distance to possible obstacles and forming a trajectory of the robot's movement taking into account the detected obstacles, wherein the trajectory of the robot's movement is formed in the form of a smooth curve passing along a predetermined sequence of target points, ensuring its location from detected obstacles at a distance no less than permissible. In this case, the trajectory is continuously corrected taking into account the position of additional target points, the coordinates of which are determined on the basis of data on newly detected obstacles, which are obtained from on-board rangefinders.

The disadvantage of this method in relation to its use for automatically forming a robot’s movement path within the airfield topography is the inability to construct and use smooth trajectories for the robot to avoid obstacles when moving only along regulated paths. In addition, the use of on-board rangefinders to determine the location of obstacles at a sufficiently distant distance from the robot in conditions of branching regulated paths is ineffective. The method under consideration also lacks specific recommendations for choosing the speed of the robot.

The closest to the claimed method is a method for creating a track for the autonomous movement of a moving object and a method for implementing the autonomous movement of a moving object along a track for moving (patent RU 2691679 C1, IPC G01C 22/00 G01C 21/00 G05D1/12, publ. 2019, prototype). In terms of forming a path for the autonomous movement of a moving object, in the prototype a path is first laid out (based on the processing of previously obtained information - aerial photometric, cartographic, etc.) in the form of a set of successive path segments, each of which connects a pair of successive reference points, a set of parameters of the object’s movement on the subsequent section of the path (with the necessary correction of this section), for which this point is the starting point, the trajectory control of the object’s movement from the initial to the final point of the path is implemented using the navigation control complex (NCC). The method proposed in the prototype, as indicated in the patent, can be used to form a path for the autonomous movement of various moving objects - land, water, air. However, this method cannot be directly used in relation to the formation of the path and speed of autonomous movement of each of these objects, in particular the automatic formation of the path and speed of movement of RKPO for the transportation of goods in the specific conditions of the airfield infrastructure. This is due to the fact that the paths of movement of a moving object along the airfield are regulated, which limits the possibilities of correcting sections of the path using the prototype method, in particular with avoiding static and dynamic obstacles. In addition, such a detour is extremely undesirable for safety reasons (reducing the risk of collisions between a moving object and obstacles). It is also undesirable for oncoming traffic on the airfield of moving objects and obstacles along equidistant strips of a two-lane track with a high relative speed. The prototype also does not specify an algorithm for selecting the speed of autonomous movement of a moving object along an airfield, which ensures a comprehensive minimization of the time of its movement from the starting point to the final point and the energy consumption for this movement.

Thus, we can conclude that the known methods for automatically forming the path of autonomous movement of moving objects, in particular RKPO, in the specific conditions of the airfield, expressed in regulating possible paths of movement, in strictly minimizing the risk of collision between RKPO and other traffic participants, are either not feasible, or do not ensure compliance with safety requirements. In addition, the known methods do not specifically reflect the solution to the problem of optimizing the speed of the RKPO along the path of its movement from the aircraft parking lot to the airport terminal (and in the opposite direction).

The main technical result of the proposal during its implementation is the possibility of forming a route for the movement of RKPO with cargo, ensuring a high level of safety for this movement along the airfield, where surface markings regulate the routes of movement of equipment. This is achieved by minimizing the risk of collisions between the RKPO and static and dynamic obstacles at the airfield. This risk is especially great when there is oncoming traffic of RKPO and obstacles along equidistant strips of a two-lane road. An additional technical result of the proposal is the optimization of the speed of movement of the RKPO along the chosen path, which comprehensively minimizes the time and energy costs for this movement.

The specified technical results are achieved by the fact that in the method of automatically forming the path and speed of movement of the RKPO for the transportation of goods between an aircraft at its parking and the airport terminal in the presence of dynamic and static obstacles on the marked surface of the airfield with installed two-lane traffic routes, equipped with a navigation system, a block with RKPO navigation parameters sensors, a RKPO motion control unit and a computer, which consists in representing the movement path in the form of a set of sections, each of which connects a pair of consecutive reference points, determining the speed of the subsequent movement of the RKPO at each reference point, implementing the movement of the RKPO from the initial to the final waypoints using the traffic control unit, while information about possible paths and corresponding trajectories of RKPO movement along the airfield is placed in the memory of the NUK RKPO computer, and at each reference point the following is entered into the computer:

- data coming from the navigation unit and determining the positioning and speed of the RKPO, as well as data coming from radio beacons installed on static and dynamic obstacles and transmitting information about the positioning of static obstacles, as well as the positioning and speeds of dynamic obstacles, both RKPO and dynamic obstacles are considered only for participants in right-hand traffic;

- data on the weight and dimensional characteristics of the RKPO cargo, while the RKPO is designed with the ability to weigh the cargo placed on it;

- data on wind speed and direction, as well as on the weather condition of the surface at the airfield, received from the airport dispatch service through receiving devices located on board the RKPO,

process in the NUK computer data on the positioning and speed of the RKPO, on the positioning of static obstacles, on the positioning and speed of dynamic obstacles, on the weight and dimensional characteristics of the RKPO cargo, on the speed and direction of the wind, on the weather condition of the surface at the airfield,

as a result:

paths whose lanes are blocked by static obstacles are identified and excluded from the formation procedure;

determine the coefficients the risk of collision of the RKPO with each of the dynamic obstacles moving along different paths, with the probable oncoming movement of the RKPO and the obstacle along equidistant strips of a two-lane track, where

- number of the possible path option;

- number of dynamic obstacle;

- the probability of a dynamic obstacle moving towards the RKPO;

- the ratio of the current speed of a dynamic obstacle to its maximum value allowed at the airfield;

choose the path of subsequent movement of the RKPO to the end point, which corresponds to the minimum average value of the coefficient from among its values identified for the entire set of j-obstacles on each of the possible ix paths,

determine the optimal speed V of the RKPO movement along the chosen path as the speed that minimizes the objective function Where

- respectively, the time and energy costs of moving along the chosen path;

- weight coefficients,

with limiting the speed of movement of the RKPO to the maximum value permitted at the airfield, as well as the value at which slipping of the drive wheels of the RKPO occurs under the current weather condition of the surface at the airfield,

Based on the selected path and speed, trajectory control of the RKPO movement is implemented along the formed path by supplying control signals from the motion control unit to the wheel drive, while:

- in a situation of probable oncoming traffic of the RKPO and a dynamic obstacle along equidistant lanes in the time interval of passage of the RKPO and the dynamic obstacle relative to each other, the speed of movement of the RKPO is reduced to a level at which the speed of the RKPO relative to the dynamic obstacle does not exceed the permitted maximum value;

- in a situation where the RKPO is likely to follow a dynamic obstacle along one lane, the speed of the RKPO is reduced to the speed of the dynamic obstacle.

The figure shows, in relation to one of the sections of the aerodrome, the possible routes of movement of RKPO 5, designated by numbers 1, 2, 3, 4, from the starting point O to terminal 6 to the end point U. The figure also shows a possible layout of aircraft (AC) ) 7, two dynamic 8, 9 and static 10 obstacles at the initial moment of time with the location of RKPO 5 at the starting point of the path O at the parking lot BC 11. Also indicated here are: the dotted dividing lines between equidistant lanes of tracks 1, 2, 3, 4; reference points 12 partially marked with circles; route forks marked with the letters A, B, C, D, N, P, including branches with turns; turns marked with the letters R, L, Q that are not part of the forks on possible routes for the movement of equipment; designated as AU, AB, NP, CD, PB, RN, OR the lengths of the corresponding sections of the paths. The figure also shows the axes of the geographic coordinate system in the horizontal plane of the airfield surface. (O _G - origin of the coordinate system, axis directed to the East, axis directed to the North). The wind speed vector V _w is also indicated here, making an angle α with the axis , as well as eastern and northern components of the wind speed vector V _w .

The sequence of actions for automatic formation of the path and speed of movement of the RKPO for the transportation of goods between the aircraft and the airport terminal is as follows. Information about the possible paths installed at the airfield and the corresponding trajectories of movement of the RKPO along the airfield are stored in the memory of the NUK RKPO computer. These paths are presented as a set of sections, each of which connects a pair of consecutive reference points, the distance between which is 5-7 meters (this distance corresponds to the path traversed by the RKPO between the reference points during the time interval between two successive signals coming from static and dynamic radio beacons obstacles, as well as from the airport dispatch service - the frequency of receipt of these signals is about 1 Hz). At each reference point, the path (from among the possible ones) and the speed of the subsequent movement of the RKPO are determined. At each section, with the help of the NCC, trajectory control of the movement of the RKPO is implemented, including the determination of the parameters of its movement and the generation of control signals to the wheel drive of the RKPO (The main components of the NCC and its functionality in terms of algorithms for the navigation unit and trajectory control are presented, for example, in the work [Aleshin B. S, Kuris E.D., Petrukhin V.A., Chernomorsky A.I., Lelkov K.S., Khorev T.S., Mikheev V.V. “Ground-based single-axle wheeled modules for transporting and controlling the angular orientation of monitoring equipment environment" // XXVIII St. Petersburg International Conference on Integrated Navigation Systems. Collection of materials. St. Petersburg, 2021.-p.158-165]).

Immediately before the start of the journey, the RKPO is located at one of the aircraft stands (Fig.) and from the sensors of the NUK navigation unit, the computer receives data on the positioning and speed of the RKPO, and through the radio beacons of other traffic participants, the NUK computer also receives information about positioning and speeds through receiving devices movement of dynamic obstacles, positioning of static obstacles. In addition, data on the dimensional and weight characteristics of the cargo are entered into the NUK computer, while the RKPO is configured to weigh the cargo placed on it and determine its dimensional characteristics. The NUK computer also receives data from the dispatch service on wind speed and direction, and on the weather condition of the surface at the airfield through receiving devices located on board the RKPO. In the process of forming a possible RKPO path, unacceptable paths with sections where static obstacles are located are excluded from the formation procedure on board the RKPO (path 3 in Fig.). For each possible path (after excluding unacceptable paths) in relation to each dynamic obstacle - a participant in the movement, coefficients are determined the risk of collision of the RKPO with each of the dynamic obstacles in the event of possible oncoming traffic of the RKPO and the obstacle along equidistant strips of two-lane tracks.

where i is the number of the possible path option; j - number of dynamic obstacle; - the probability of a dynamic obstacle moving towards the RKPO; - the ratio of the current speed of a dynamic obstacle to its maximum value allowed at the airfield. In this case, P _mij on the i-th path of each j-th dynamic obstacle is determined as the product of the probabilities of this dynamic obstacle following the branches in the forks of the route in the direction of the i-th path. In turn, the probability of a dynamic obstacle following the corresponding branch in one fork in the direction of the i-th path is determined as the reciprocal of the number of right-hand branches emanating from this fork. Next, select a path for the subsequent movement of the RKPO to the end point, which corresponds to the minimum average value of the coefficient from among its values identified for the entire set of j-th obstacles on each of the possible ix paths.

Then the optimal speed V of the RKPO movement along the chosen path is determined as the speed that minimizes the objective function Q(V):

Where - respectively, the time and energy costs of moving along the chosen path; - weighting coefficients characterizing the contribution of T and E, respectively, to the objective function Q(V).

Time T is determined by the relation:

where S is the length of the chosen path.

Energy E, spent mainly on overcoming aerodynamic drag and rolling resistance, as well as consumed for servicing the RKPO board, is determined as follows:

Where - number of a continuous segment of the selected path with a constant direction of movement of the RKPO; - length of the p-th segment of the selected path - coefficient that takes into account internal energy costs on board the RKPO; - aerodynamic drag coefficient and air density, respectively; - speed of the RKPO relative to the air on the p-th segment of the selected path - wind speed in the direction of movement of the RKPO on the r-th segment of the selected path); M, N, G - respectively the width, height and weight of the RKPO with load; - rolling resistance coefficient, depending on the type and weather condition of the coating.

Check for traction (no slipping) between the RKPO drive wheels and the airfield pavement; on each section of the chosen path the following inequality must be satisfied:

where ϕ is the coefficient of longitudinal adhesion of the driving wheels, depending mainly on the weather condition of the coating.

The calculated value of the optimal speed is reduced to a level at which it does not exceed the permitted maximum value at the airfield and at which inequality (5) is satisfied.

Based on the selected path and speed of movement of the RKPO, trajectory control of its movement is implemented by supplying control signals from the motion control unit to the wheel drive, reducing, if necessary, the speed of the RKPO to a level at which its speed relative to the obstacle does not exceed the permitted maximum value at the airfield in a situation of probable oncoming traffic RKPO and dynamic obstacles along equidistant lanes of the selected path in the time interval of passage of RKPO and the obstacle relative to each other, and also, if necessary, reducing the speed of movement of the RKPO to the speed of the dynamic obstacle in a situation where the RKPO is likely to follow this obstacle along one lane.

Let's consider an example of application of the proposed method. We will assume that at the initial moment of time RKPO two dynamic and one static obstacles are located in accordance with the diagram in the figure. The parameters used in the example are: speeds dynamic obstacles (DP) - first (8) , second (9) permitted maximum speed at the airport wind speed (in accordance with Fig. at α=30° the eastern component northern component drag coefficient air density The width, height and weight of the RKPO with a load are respectively - M = 1.5 m, H = 2 m, G = 15000 N.

Let's choose the path of right-hand traffic RKPO from the starting point O at the aircraft parking lot to the ending point U (at the terminal). The figure shows four possible paths 1, 2, 3, 4 of the RKPO movement. Path 3 should be excluded because there is a static obstacle in its lane. On paths i = 1, 2, 4 we define for DP1 and DP2 (j = 1, 2) the probabilities movement of each of these obstacles towards the RKPO along equidistant strips of these paths. For DP1 (j = 1), taking into account the number of forks on the corresponding paths and the number of branches on each fork, we obtain: For DP2 (j = 2) we have: Current speed ratios To Then, in accordance with (1), the risk coefficients of collision of the RKPO with each of the two dynamic obstacles on each of the three possible paths are as follows:

Average risk ratios on each of the three possible paths are as follows:

Based on the results obtained, in accordance with the proposed method, at the starting point we select the second path of movement of the RKPO to the terminal; it corresponds to the minimum average value of the risk of collisions between RKPO and obstacles (K _d2 = 0.11).

Let us now determine the optimal speed of movement of the RKPO along the chosen path, minimizing the objective function (2) with respect to speed V. Let us divide the pre-selected path into continuous segments with constant directions of movement of the RKPO: In this case, the entire path S is 1480 m. Weighting coefficients in (2) we select from the condition of equal contribution to Q(V) the time component Г (3) and the component of its energy component E (4), which depends on the RKPO speed, under the conditions of the RKPO moving at the maximum speed allowed at the airfield. In this case, we will neglect the energy component spent on overcoming rolling friction due to the small dependence of the rolling resistance coefficient on the speed of the RKPO. This is true when the speed of movement of the RKPO is V<15 m/s on a dry asphalt concrete pavement that is in satisfactory condition [Tarasik V.P. Theory of car motion. - S. - Petersburg: BHV-Petersburg, 2006]. The equality of the time and energy contributions to Q(V) based on (2), (4) is determined by the relation: Within the framework of the accepted division of the second (selected) path into segments, as well as taking into account the directions of the wind speed components on the segments, this relationship can be rewritten as follows:

From here, taking Taking into account the accepted parameter values, we obtain:

Then, the objective function Q(V), having the form:

reaches a minimum at The optimal speed _VO found in this way satisfies the relation: _VO < V _max .

Condition (5) to ensure adhesion between the driving wheels of the RKPO and the airfield pavement (there is no slipping of the driving wheels) is also satisfied on all segments of the selected path.

where ϕ=0.7...0.8 (dry asphalt concrete pavement), 0.34...0.45 (wet asphalt concrete pavement); ƒ _k = 0.02 (asphalt concrete pavement in satisfactory condition).

We will assume that DP1 and DP2 are in close proximity to forks A and D, respectively. At the speed of RKPO and DGT2 speed RKPO reaches fork B faster than the 1/4 probability of DP2 reaching it, and, therefore, there is no possibility of oncoming movement of RKPO and DP2 on the segment RV, as well as the possibility of RKPO following DP2 on the segment BU = AB + AU. At RKPO speed and speed DP1 DP1 can reach fork B earlier than RKPO and, with a probability of 1/6, head towards RKPO in the right lane towards fork R. On the segment RV at 72.2 s, in this regard, a meeting between DP1 and RKPO moving in equidistant lanes is possible. In the time interval of their passage relative to each other, in accordance with the proposed method, it is necessary to reduce the speed of the RKPO to a level at which this speed relative to DP1 becomes equal to or less than V _max , i.e. the speed of movement of the RKPO must satisfy the condition V < 0.56 m/s on this section of travel.

In the example considered, the results of the formation of the path and the speed of movement of the RKPO were obtained in relation to the position of the RKPO at the initial point O of the path. Based on the selected path and speed, trajectory control of the RKPO movement is implemented through the NUC RKPO and the drive of its wheels. The procedure for subsequent formation of the path and speed of movement of the RKPO must be repeated at each reference point.

Claims (20)

A method for automatically generating the path and speed of movement of a robotic wheeled moving object (RKPO) for transporting goods between an aircraft at its parking and an airport terminal in the presence of dynamic and static obstacles on the marked surface of an airfield with installed two-lane traffic routes, equipped with a navigation control complex (NUK) ), including a navigation unit with sensors of navigation parameters RKPO, a motion control unit RKPO and a computer, which consists in representing the movement path in the form of a set of sections, each of which connects a pair of consecutive reference points, determining the speed of subsequent movement of the RKPO at each reference point, and implementing the movement of the RKPO from the initial to the final point of the path using a traffic control unit, characterized in that information about possible paths and corresponding trajectories of movement of the RKPO along the airfield is placed in the memory of the NUK RKPO computer, and at each reference point the following is entered into the computer: - data coming from the navigation unit and determining the positioning and speed of the RKPO, as well as data coming from radio beacons installed on static and dynamic obstacles and transmitting information about the positioning of static obstacles, as well as the positioning and speeds of dynamic obstacles, both RKPO and dynamic obstacles are considered only for participants in right-hand traffic; - data on the weight and dimensional characteristics of the RKPO cargo, while the RKPO is designed with the ability to weigh the cargo placed on it; - data on wind speed and direction, as well as on the weather condition of the surface at the airfield, received from the airport dispatch service through receiving devices located on board the RKPO, process in the NUK computer data on the positioning and speed of the RKPO, on the positioning of static obstacles, on the positioning and speed of dynamic obstacles, on the weight and dimensional characteristics of the RKPO cargo, on the speed and direction of the wind, on the weather condition of the surface at the airfield, as a result: paths whose lanes are blocked by static obstacles are identified and excluded from the formation procedure; determine the coefficients K _dij =P _mij K _vj of the risk of collision of the RKPO with each of the dynamic obstacles moving along different paths, with the probable oncoming movement of the RKPO and the obstacle along equidistant stripes of a two-lane track, where i - number of possible path option; j - number of dynamic obstacle; P _mij is the probability of a dynamic obstacle moving towards the RKPO; K _vj - the ratio of the current speed of a dynamic obstacle to its maximum value allowed at the airfield; choose the path of subsequent movement of the RKPO to the end point, which corresponds to the minimum average value of the coefficient K _dij from among its values identified for the entire set of j-obstacles on each of the possible ix paths, determine the optimal speed V of the RKPO movement along the chosen path as the speed that minimizes the objective function Q(V)=K _t T+K _e E, where T, E - respectively, time and energy costs for moving along the chosen path; K _t , K _e - weighting coefficients, with limiting the speed of movement of the RKPO to the maximum value permitted at the airfield, as well as the value at which slipping of the drive wheels of the RKPO occurs under the current weather condition of the surface at the airfield, Based on the selected path and speed, trajectory control of the RKPO movement is implemented along the formed path by supplying control signals from the motion control unit to the wheel drive, while: - in a situation of probable oncoming traffic of the RKPO and a dynamic obstacle along equidistant lanes in the time interval of passage of the RKPO and the dynamic obstacle relative to each other, the speed of movement of the RKPO is reduced to a level at which the speed of the RKPO relative to the dynamic obstacle does not exceed the permitted maximum value; - in a situation where the RKPO is likely to follow a dynamic obstacle along one lane, the speed of the RKPO is reduced to the speed of the dynamic obstacle.

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