Disclosure of Invention
The invention provides an external collision risk early warning system of a ship towing system under a mutual-seeing condition, which can automatically detect whether collision risk exists between other ships and any ship in the towing system, and can issue collision risk early warnings in different levels when collision risk exists, so as to remind towing operators to take reasonable avoidance measures to ensure towing safety of the towing system.
In order to achieve the above purpose, the invention provides an external collision risk early warning system of a ship towing system under a mutual-seeing condition, which is characterized in that: the system comprises an information collection module, an external collision risk detection module and a collision risk early warning quantification module;
the information collection module is used for collecting the towed ship navigation track, the towed ship basic information, the front towed ship basic information, the rear towed ship basic information, and other ship basic information and navigation information around the towing system in the towing system under the environment interference;
the external collision risk detection module is used for judging whether collision risks exist between the towing system and other ships or not according to the ship field theoretical module and the nonlinear velocity barrier algorithm module;
the ship field theoretical module is used for judging whether collision risks exist or not according to whether the ship field of the other ship covers the ship field of the towed ship, the front towed ship or the rear towed ship within a certain observation time, and if the ship field of the other ship does not intersect with the ship field of the towed ship, the front towed ship or the rear towed ship, the other ship does not have collision risks with the towing system; if the ship field of the other ship is intersected with the ship field of the towed ship, or the ship field of the front towed ship or the ship field of the rear towed ship, the other ship and the towing system have collision risks, and then a collision risk early warning quantification module is started;
the nonlinear velocity obstacle algorithm module is used for acquiring a velocity vector set of collision between the other ship and the towing system according to the position of the other ship and the navigation track of each ship in the towing system; if the actual speed of the ship is out of the speed vector set, collision risks do not exist between the ship and the towed ship, or between the ship and a front towed ship, or between the ship and a rear towed ship; if the actual speed of the other ship is in the speed vector set, collision risks exist between the other ship and a towed ship, or between a front towed ship or a rear towed ship, and a collision risk early warning quantification module is started;
the collision risk early warning quantification module comprises a ship avoidance obligation identification module, an other ship intention estimation module, an other ship motion quality evaluation module, a collision avoidance rule examination module, an other ship collision risk elimination capacity quantification module and an early warning grade quantification module;
the ship avoidance obligation identification module is used for determining whether the ship is a way-giving ship or not according to the international maritime collision avoidance rule, and starting the ship intention estimation module if the ship is the way-giving ship; if the ship is not the way-giving ship, collision risk exists, and an early warning level quantification module is started;
the other ship intention estimation module is used for checking whether the other ship takes evasive action to avoid collision or not, and starting the other ship movement quality evaluation module if the other ship takes evasive action; if the other ship does not take evasive action, starting a collision risk eliminating capability quantification module of the other ship;
the method for checking whether other ships take evasive action by the other ship intention estimation module is that if the other ship intention index is 1, the other ships take evasive action; if the intention index of the other ship is 0, the other ship is indicated to not take evasive action; the other boat intention index is expressed as:
wherein,
Int(t 0 ) Is t 0 At the moment, the index of the intention of other ships,
V Intr (t 0 ) Is t 0 At the moment of time the speed of the other vessel,
S NL_VO (t 0 ) Is t 0 The speed at which the other vessel collides with the tug, or the forward tug, or the aft tug (b-2),
the empty set is represented by the number of empty sets,
and n represents the intersection of the two points,
ΔC Intr (t 0 ) Represents t 0 The route change of the other ship at the moment;
the other ship motion quality evaluation module is used for judging whether the avoiding action of the other ship can effectively eliminate the collision risk or not, and if the avoiding action of the other ship can effectively eliminate the collision risk, the collision avoidance rule examination module is started; if the evasive action of other ships can not effectively eliminate the collision risk, starting an early warning level quantification module; the method for judging whether the avoiding action of the other ship can effectively eliminate the collision risk by the other ship action quality evaluation module is that if the avoiding action index of the other ship is 1, the avoiding action of the other ship can effectively eliminate the collision risk; if the evasive action index of the other ship is 0, the evasive action index indicates that the evasive action of the other ship cannot effectively eliminate the collision risk; the avoidance behavior index is expressed as:
wherein,
AQ(t 0 ) Is t 0 The evasive action index of other ships at the moment,
P TS (x,y,t 0 ) Is t 0 Position of trailing, or leading, or trailing, vessel at the moment, P Intr (x,y,t 0 ) Is t 0 At the moment in time the position of the other vessel,
Dis(P TS (x,y,t 0 ),P Intr (x,y,t 0 ) Is t) 0 The distance between the other ship and the towed ship, or the front towed ship, or the rear towed ship at the moment,
minDisTS represents the minimum distance at which collision risk can be eliminated by adopting evasive action;
the collision avoidance rule examination module is used for examining whether the avoiding action of other ships violates the relevant avoiding action clause of the international maritime collision avoidance rule, and starting the early warning level quantification module no matter whether the avoiding action of other ships violates the relevant avoiding action clause of the international maritime collision avoidance rule;
the method for the collision avoidance rule examination module to examine whether the avoiding action of other ships violates the international maritime collision avoidance rule is that if the examination result index is 1, the other ships do not violate the international maritime collision avoidance rule; if the examination result index is 0, the ship violates the international maritime collision avoidance rule; the examination result index is expressed as:
wherein,
col is the examination result index of the International rules for avoiding collision at sea,
CPA means the closest point of approach to ensure arrival of the tow vessel or forward or aft tug with other vessels,
RB CPA indicating the relative orientation of his ship when it arrives at the CPA;
the other ship collision risk eliminating capacity quantifying module is used for determining the capacity of the other ship for eliminating collision risks according to the operation performance of the other ship and starting the early warning level quantifying module according to the level of the capacity of the other ship for eliminating collision risks;
the risk elimination capability in the other ship collision risk elimination capability quantification module is expressed as follows:
wherein,
L AMM for the risk elimination capability that the ship has,
the AMM is the operational margin that other vessels have,
AMM 1 is the upper threshold limit that other vessels have,
AMM 2 a lower threshold for other vessels;
the early warning level quantification module is used for carrying out level quantification on the external collision risk and issuing risk early warning;
the early warning level quantification module quantifies 'caution, warning and warning' three levels of external collision risks, and the specific quantification standard is,
if the ship is not the way-giving ship, collision risk exists, and the collision risk level is 'alarm';
if the other ship is a concession ship and takes evasive action, but the evasive action of the other ship cannot effectively eliminate the collision risk, the collision risk level is 'alarm';
if the ship is a way-giving ship and takes evasive action, and the evasive action of the ship can effectively eliminate the collision risk, but the evasive action of the ship violates action terms of the international maritime collision avoidance rule, the collision risk level is 'warning';
if the ship is a way-giving ship and takes evasive action, the evasive action of the ship can effectively eliminate the collision risk, and the evasive action of the ship complies with action terms of International rules for avoiding collision at sea, the collision risk level is 'careful';
if the other ship is a way-letting ship and does not take evasive action, determining a collision risk level matched with the collision risk elimination capability of the other ship according to a collision risk elimination capability quantification module of the other ship, wherein the specific method comprises the following steps: the collision risk level is "caution" if his ship collision risk elimination capability is high, "warning" if his ship collision risk elimination capability is moderate, and "alarm" if his ship collision risk elimination capability is low.
The invention has the advantages that:
1. according to the method, a ship field theoretical module and a nonlinear speed obstacle algorithm module are combined, the dynamic property of the avoidance behavior is considered, and on one hand, whether collision risks exist is judged according to whether the ship field of other ships is covered with the ship field of a towed ship, a front towed ship or a rear towed ship within a certain observation time; on the other hand, whether collision risks exist is judged according to whether the actual speed of the other ship is in the speed vector set, so that whether collision risks exist between the other ship and any ship in the towing system is automatically detected;
2. when determining that a collision risk exists between the other ship and any ship in the towing system, the method and the system issue corresponding collision risk early warnings in three levels of caution, warning and alarming respectively according to the judgment of whether the other ship is a way-giving ship, whether the other ship takes evasion action, whether the evasion action of the other ship can effectively eliminate the collision risk, whether the evasion action of the other ship violates the related evasion action terms of the international maritime collision avoidance rule and the capability of the other ship for eliminating the collision risk, and remind a towing operator to take reasonable avoidance measures to ensure the towing safety of the towing system.
The external collision risk early warning system of the ship towing system under the mutual condition can automatically detect whether collision risk exists between other ships and any ship in the towing system; when collision danger exists, collision risk early warning of different levels can be issued, towing operation personnel are reminded to take reasonable avoidance measures to guarantee towing safety of the towing system, passing limitation on ships around the towing system is not needed, and the utilization rate of a channel cannot be reduced.
Detailed Description
The invention is described in further detail below with reference to the figures and specific embodiments.
In the description of the present invention, it should be noted that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc. indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed in a specific orientation, and be operated, and thus, should not be construed as limiting the invention.
The external collision risk early warning system of the ship towing system under the mutual-seeing condition comprises an information collecting module 1, an external collision risk detecting module 2 and a collision risk early warning quantifying module 3.
The information collection module 1 is used for collecting the sailing track of the towed ship a, the basic ship information of the front towed ship b-1, the basic ship information of the rear towed ship b-2, and the basic ship information and the sailing information of other ships c around the towing system in the towing system under the environment interference through the AIS data.
The sailing track of the ship in the towing system under the environmental interference is obtained through modeling, and specific ship model parameters are shown in table 1. In the towing system simulation, basic information of the towed ship a, the front towed ship b-1, the rear towed ship b-2, and the other ships c is shown in Table 1.
TABLE 1 basic information of fore, aft, towed and other vessels
Other vessel c-1, other vessel c-2, forward tug b-1, aft tug b-2, and tug a in Table 1 were modeled based on "TitoNeri"260, and "CyberShip II," respectively; the length of the towing cable is 1m, the maximum value of the thruster is 10N, the change rate of the towing angle between the front towing vessel b-1 and the towed vessel a is not more than 5 degrees/s, and the towing angle alpha between the rear towing vessel b-2 and the towed vessel a 2 (t) the rate of change does not exceed 5 °/s; the maximum drag force of the front tug b-1 is 3N, the maximum drag force of the rear tug b-2 is 3N, and the traction force change rate is less than 1N/s.
Using scaled models of the fore tug b-1, aft tug b-2, and tug a in Table 1, a towing operation plan is given, as shown in Table 2.
TABLE 2 design of steering point towing operation under environmental disturbance
Table 2 shows the initial state including the starting positions and the heading of the forward tug b-1, the backward tug b-2 and the tug a, and the two turning points and one ending point are designed during the course of the voyage.
In the case where the wind is assumed to be constant, the relative wind speed is maintained at 1 m/s and the wind direction is 255 °. Furthermore, the towing work is performed under good visibility conditions.
The external collision risk detection module 2 is used for judging whether collision risks exist between the towing system and other ships c according to the ship field theoretical module 2-1 and the nonlinear velocity barrier algorithm module 2-2;
the ship field theoretical module 2-1 is used for judging whether collision risks exist or not according to whether the ship field of the other ship c is covered with the ship field of the towed ship a, the front towed ship b-1 or the rear towed ship b-2 within a certain observation time, and if the ship field of the other ship c is not intersected with the ship field of the towed ship a, the front towed ship b-1 or the rear towed ship b-2, the other ship c does not have collision risks with a towing system; if the ship field of the other ship c is intersected with the ship field of the towed ship a, the front towed ship b-1 or the rear towed ship b-2, the other ship c and the towing system have collision risks, and then the collision risk early warning quantification module 3 is started.
The nonlinear velocity barrier algorithm module 2-2 is used for obtaining a velocity vector set of collision between the other ship c and the towing system according to the position of the other ship c and the navigation track of each ship in the towing system; if the actual speed of the ship c is out of the speed vector set, no collision risk exists between the ship c and the towed ship a, or the front towed ship b-1, or the rear towed ship b-2; if the actual speed of the ship c is in the speed vector set, collision risks exist between the ship c and the towed ship a, the front towed ship b-1 or the rear towed ship b-2, and then the collision risk early warning quantification module 3 is started.
According to the method, a ship field theoretical module 2-1 and a nonlinear velocity barrier algorithm module 2-2 are combined, the dynamics of avoidance behaviors are considered, and on one hand, whether collision risks exist is judged according to whether the ship field of other ships is covered with the ship field of a towed ship, a front towed ship or a rear towed ship within a certain observation time; on the other hand, whether collision risks exist is judged according to whether the actual speed of the ship is in the speed vector set, so that whether collision risks exist between the ship and any ship in the towing system is automatically detected.
Specifically, the nonlinear velocity barrier algorithm module 2-2 obtains a velocity vector set of the collision between the ship c and the towing system through the following nonlinear velocity barrier algorithm formula,
wherein,
S NL_VO (t 0 ) Is t 0 The speed at which the other vessel c collides with the tug a, or the forward tug b-1, or the aft tug b-2,
ConfP (O, R) is all possible locations where other vessel c collides with the tug a, or the forward tug b-1, or the aft tug b-2,
P TS (x, y, t) is the motion track of the tug a, the front tug b-1 or the rear tug b-2 at the time t,
P Intr (x,y,t 0 ) Is t 0 At the moment in time the position of the other ship c,
r represents the size of the ship domain.
≧ represents a bridgefski addition operation.
Specifically, for the external collision risk detection module 2, if there is a collision risk between the other ship c and the towed ship a, or the forward towing ship b-1, or the backward towing ship b-2, that is, the collision risk index is 1; if no collision risk exists between the other ship c and the towed ship a, or the front towed ship b-1 or the rear towed ship b-2, the collision risk index is 0; the collision risk indicator is expressed as:
wherein,
IC(t 0 ) Is t 0 Time of day collisionThe risk indicator is a measure of the risk of,
V Intr (t 0 ) Is t 0 At the moment in time the speed of his ship c,
S NL_VO (t 0 ) Is t 0 The speed at which the other vessel c collides with the towed vessel a, or the front towed vessel b-1, or the rear towed vessel b-2,
the empty set is represented by the number of empty sets,
and n represents crossing.
The collision risk early warning quantification module 3 comprises a ship avoidance obligation identification module 3-1, an other ship intention estimation module 3-2, an other ship motion quality evaluation module 3-3, a collision avoidance rule examination module 3-4, an other ship collision risk elimination capacity quantification module 3-5 and an early warning level quantification module 3-6.
The ship avoidance obligation identification module 3-1 is used for determining whether the ship c is a way-giving ship or not according to the international maritime collision avoidance rule, and starting the ship intention estimation module 3-2 if the ship c is the way-giving ship; if the ship c is not the way-giving ship, collision risk exists, and the early warning level quantification module 3-6 is started.
The other ship intention estimation module 3-2 is used for checking whether the other ship c takes evasive action to avoid collision, and starting the other ship movement quality evaluation module 3-3 if the other ship c takes evasive action; and if the ship c does not take the avoiding action, starting a collision risk eliminating capacity quantifying module 3-5 of the ship c.
The other ship motion quality evaluation module 3-3 is used for judging whether the avoiding action of the other ship c can effectively eliminate the collision risk, and if the avoiding action of the other ship c can effectively eliminate the collision risk, the collision avoidance rule examination module 3-4 is started; and if the avoiding action of the ship c cannot effectively eliminate the collision risk, starting an early warning level quantification module 3-6.
The collision avoidance rule examination module 3-4 is used for examining whether the avoidance action of the ship c violates the relevant avoidance action clause of the international maritime collision avoidance rule, and starting the early warning level quantification module 3-6 regardless of whether the avoidance action of the ship c violates the relevant avoidance action clause of the international maritime collision avoidance rule.
The other-ship collision risk eliminating capacity quantifying module 3-5 is used for determining the capacity of the other ship c for eliminating the collision risk according to the operation performance of the other ship c and starting the early warning level quantifying module 3-6 according to the level of the capacity of the other ship c for eliminating the collision risk.
The early warning level quantification module 3-6 is used for carrying out level quantification on external collision risks and issuing risk early warning.
Specifically, the method for the other-ship intention estimation module 3-2 to check whether the other ship c takes the avoidance action is that if the other-ship intention index is 1, the other ship c takes the avoidance action; if the intention index of the ship is 0, the ship c does not take evasive action; the other boat intention index is expressed as:
wherein,
Int(t 0 ) Is t 0 At all times, other ship intention indicators;
V Intr (t 0 ) Is t 0 At the moment in time the speed of the other vessel c,
S NL_VO (t 0 ) Is t 0 The speed at which the other vessel c collides with the towed vessel a, or the front towed vessel b-1, or the rear towed vessel b-2,
the empty set is represented by a representation of,
and n represents the intersection of the two points,
ΔC Intr (t 0 ) Represents t 0 The route of the other ship c changes at that moment.
Specifically, the method for the other-ship behavior quality evaluation module 3-3 to determine whether the evasive action of the other ship c can effectively eliminate the collision risk includes that if the evasive action index of the other ship c is 1, the other ship c is indicated that the evasive action can effectively eliminate the collision risk; if the avoidance action index of the other ship c is 0, the avoidance action of the other ship c is represented to be incapable of effectively eliminating the collision risk; the avoidance behavior index is expressed as:
wherein,
AQ(t 0 ) Is t 0 The evasive action index of the other ship c at the moment;
P TS (x,y,t 0 ) Is t 0 The position of the towed ship a, or the front towed ship b-1, or the rear towed ship b-2 at the moment;
P Intr (x,y,t 0 ) Is t 0 The location of other vessel c at time;
Dis(P TS (x,y,t 0 ),P Intr (x,y,t 0 ) Is t) 0 The distance between the other ship c and the towed ship a, or the front towed ship b-1, or the rear towed ship b-2 at the moment;
minDisTS represents the minimum distance at which collision risk can be eliminated with evasive action.
Specifically, the collision avoidance rule review module 3-4 reviews whether the avoidance behavior of the other ship c violates the international maritime collision avoidance rule, and if the review result index is 1, the other ship c does not violate the international maritime collision avoidance rule; if the examination result index is 0, the ship c violates the international maritime collision avoidance rule; the examination result index is expressed as:
wherein,
col is the examination result index of the international maritime collision avoidance rule,
CPA means the closest point of approach to ensure the tug a, or the forward tug b-1, or the aft tug b-2, reaches the other vessel c,
RB CPA indicating the relative orientation of his ship c as it arrives at the CPA.
Specifically, the risk elimination capability in the other-ship collision risk elimination capability quantification module 3-5 is expressed as:
wherein,
L AMM for the risk elimination capability that his ship c has,
AMM is the operational margin that other vessel c has,
AMM 1 for the upper threshold limit that other vessel c has,
AMM 2 the lower threshold that other ship c has.
If other vessel c is a small cargo ship, then AMM 1 Is 0.9 of AMM 2 Is 0.4.
Specifically, the early warning level quantification module 3-6 quantifies the external collision risk in three levels of "caution, warning, and warning", wherein the "caution" indicates that the collision risk has occurred, and the towing system as a straight ship does not allow any avoidance action to be taken, but needs to pay attention to the change situation of the current collision situation. "warning" means that the towing system as a straight vessel allows avoidance actions to be taken to eliminate conflicts, as a situation of urgency arises if no action is taken. An "alert" indicates that a reasonable evasive action should be taken to avoid a collision when the towing system is acting as either a way-giving vessel or a straight vessel.
The specific quantization standard is as follows,
if the ship c is not the way-giving ship, collision risk exists, and the collision risk level is 'alarm';
if his ship c is a yielding ship and takes evasive action (Int (t) 0 ) = 1), but the evasive action of his ship c is not effective in eliminating the collision risk (AQ = 0), the collision risk level is "alarm";
if the ship is a concessional ship and takes evasive action (Int (t) 0 ) = 1), while the avoidance behavior of the other ship c can effectively eliminate the collision risk (AQ = 1), but the avoidance behavior of the other ship c violates the action clause of international maritime collision avoidance rule (Col = 0), the collision risk level is "warning";
if he ship is a way-giving ship and takes evasive action (Int (t) 0 ) = 1), while the avoidance behavior of the other ship c can effectively eliminate the collision risk (AQ = 1), and in addition, the avoidance behavior of the other ship c complies with the action clause of international maritime collision avoidance rule (Col = 1), the collision risk level is "caution";
if the ship is a passing ship and no evasive action is taken (Int (t) 0 ) = 0), determining the collision risk level matched with the collision risk elimination capability of the other ship c according to the collision risk elimination capability quantification module 3-5 of the other ship, wherein the specific method is as follows: high capability of eliminating collision risk if other ship c is in collision (L) AMM = H), the collision risk level is "caution", if his ship c has moderate collision risk elimination capability (L) AMM = M), the collision risk level is "warning", if the collision risk elimination capability of the other ship c is low (L) AMM = L), the collision risk level is "alarm".
The flow chart of the present invention for quantifying the external collision risk level is shown in fig. 8.
Case analysis was performed as follows.
Case 1, see fig. 2 a-2 f, where fig. 2 a-2 f show the location, heading, and warning level information for six samples of the towed system as it encounters his ship c-1.
Fig. 2a shows a meeting scenario when t =1s, where IC =1 indicates a collision risk, but Int =0 indicates that the ship c-1 is not taking evasive action, and then L is equal to L according to the fifth risk level quantification criterion AMM When = H, i.e. his ship c-1 has a high collision risk elimination capability, the collision risk level is "caution", see fig. 4. In the next 100s, his ship c-1 is still sailing straight at a constant speed and is constantly approaching the towing system, see fig. 3.
Fig. 2b is a meeting scene when t =100s, IC =1 indicates a collision risk, int =0 indicates that the ship c-1 does not take evasive action, and L =0 indicates that the ship is not in a collision state AMM If M, i.e., if the collision risk elimination capability of the ship c-1 is moderate, the collision risk level is "warning" according to the fifth risk level quantification criterion, as shown in fig. 4. At this point, the towing system is allowed to take evasive action to ensure safe passage.
Fig. 2c is a meeting scene when t =120s, IC =1 indicates that there is a collision risk, int =1 indicates that the ship c-1 takes evasive action, whereas AQ =0 indicates that the evasive maneuver adopted by the ship c-1 is poor, i.e., the evasive action of the ship c-1 cannot effectively eliminate the collision risk, and then the collision risk level is "alarm" according to the second risk level quantification criterion, as shown in fig. 4.
Fig. 2d shows a meeting scenario when t =150s, IC =1 indicates a collision risk, int =1 indicates that the ship c-1 takes evasive action, whereas AQ =0 indicates that the evasive action of the ship c cannot effectively eliminate the collision risk, and then the collision risk level is "alarm" according to the second risk level quantification criterion, as shown in fig. 4.
Fig. 2e shows a meeting scenario when t =240s, IC =1 indicates a collision risk, but Int =0 indicates that the ship c-1 does not take evasive action, and then L is equal to L according to the fifth risk level quantification criterion AMM When = L, i.e., his ship c-1 has low collision risk elimination capability, the collision risk level is "alarm", see fig. 4. At this time, the distance between the other ship c-1 and the towed ship a, or the front towed ship b-1, or the rear towed ship b-2 is reduced to a minimum value, and as shown in FIG. 3, the ship domain of the other ship c-1 overlaps with the ship domain of the towed ship a, or the front towed ship b-1, or the rear towed ship b-2.
Fig. 2f shows a meeting scenario when t =300s, where IC =1 indicates a collision risk, but Int =0 indicates that the ship c-1 is not taking evasive action, and then L is equal to L according to the fifth risk level quantification criterion AMM And L, i.e. the collision risk elimination capability of his ship c-1 is low, the collision risk level is "alarm", see fig. 4.
As can be seen from fig. 2a to 2f, when the ship in the towing system meets the other ship c-1, the collision risk exists in the whole meeting process, and a dangerous close meeting occurs between the towing system and the other ship c-1 due to the poor maneuvering efficiency of the other ship c-1.
The change of the detection and early warning parameters of the towing system with time in case 1 is shown in table 3.
TABLE 3 variation of various detection and early warning parameters of the towing system with time
Time:s
|
IC
|
Int
|
AQ
|
Col
|
L AMM |
CAL
|
10
|
1
|
0
|
/
|
/
|
0.9143
|
Care is taken that
|
20
|
1
|
0
|
/
|
/
|
0.9143
|
Care is taken that
|
30
|
1
|
0
|
/
|
/
|
0.9143
|
Care is taken that
|
40
|
1
|
0
|
/
|
/
|
0.9143
|
Care is taken that
|
50
|
1
|
0
|
/
|
/
|
0.9143
|
Care is taken
|
60
|
1
|
0
|
/
|
/
|
0.9143
|
Care is taken
|
70
|
1
|
0
|
/
|
/
|
0.9143
|
Care is taken that
|
80
|
1
|
0
|
/
|
/
|
0.9
|
Warning
|
90
|
1
|
0
|
/
|
/
|
0.8857
|
Warning
|
100
|
1
|
0
|
/
|
/
|
0.7286
|
Warning
|
110
|
1
|
1
|
0
|
/
|
/
|
Alarm device
|
120
|
1
|
1
|
0
|
/
|
/
|
Alarm device
|
130
|
1
|
1
|
0
|
/
|
/
|
Alarm device
|
140
|
1
|
1
|
0
|
/
|
/
|
Alarm device
|
150
|
1
|
1
|
0
|
/
|
/
|
Alarm device
|
160
|
1
|
1
|
0
|
/
|
/
|
Alarm device
|
170
|
1
|
0
|
/
|
/
|
0
|
Alarm device
|
180
|
1
|
0
|
/
|
/
|
0
|
Alarm device
|
190
|
1
|
0
|
/
|
/
|
0
|
Alarm device
|
200
|
1
|
0
|
/
|
/
|
0
|
Alarm device
|
210
|
1
|
0
|
/
|
/
|
0
|
Alarm device
|
220
|
1
|
0
|
/
|
/
|
0
|
Alarm device
|
230
|
1
|
0
|
/
|
/
|
0
|
Alarm device
|
240
|
1
|
0
|
/
|
/
|
0
|
Alarm device
|
250
|
1
|
0
|
/
|
/
|
0
|
Alarm device
|
260
|
1
|
0
|
/
|
/
|
0
|
Alarm device
|
270
|
1
|
0
|
/
|
/
|
0
|
Alarm device
|
280
|
1
|
0
|
/
|
/
|
0
|
Alarm device
|
290
|
1
|
0
|
/
|
/
|
0
|
Alarm device
|
300
|
1
|
0
|
/
|
/
|
0
|
Alarm device |
Case 2 is the intersection of the ship towing system and other ships c-2, with the towing system in a straight-ahead position. The risk of collision arises from the beginning, and the risk of collision between the two is eliminated between 470 seconds due to the effective evasive action taken by his vessel c-2 (fig. 7). FIGS. 5 a-5 f show the position, heading, and warning level information for six samples of the towed system as it encounters the other vessel c-2.
At 300 seconds, the towing system creates a risk of collision with other vessels. Since his ship c-2 takes no collision avoidance action to avoid collision (Int (t) 0 ) = 0), but at this time its risk elimination capacity is high L AMM H, so the warning level is marked as "caution" (see fig. 5 a). Before 380 seconds, his ship c-2 approaches the towing system continuously at a constant speed and heading (see fig. 6). At 340 seconds, the risk of collision still exists, and the risk-elimination capability of his ship c-2 is reduced, but still at a higher level L AMM H, so the warning level is "caution" (see fig. 5 b). At 370 seconds, there is a risk of collision, but the risk-eliminating capacity of his ship c-2 drops to a medium level L AMM = M, the warning level is therefore marked as "warning" (see fig. 5 c). From 390 seconds to 520 seconds, his ship c-2 turns starboard to avoid a collision. Through action quality evaluation and COLREGs examination, the collision avoidance actions adopted by the ship c-2 are judged to be effective and accord with the COLREGs. At 420 seconds, the distance between his ship, c-2, and the tug is reduced to about 19 meters (FIG. 6). The warning level is reduced to "caution" (see fig. 5 d) considering that the collision can be eliminated only by the collision avoidance action taken by his ship c-2. The risk of collision is eliminated at 470 seconds due to the effective collision avoidance action taken by his vessel c-2, see fig. 7. The towing system and other vessel c-2 are close until 590 seconds. At 590 seconds, his vessel c-2 and the tug reach the Closest Point of Approach (CPA), and their distance is reduced to a minimum of 7.38m (FIG. 6), at safe distance. After 590 seconds, the distance between them increases.
The change of the detection and early warning parameters of the towing system with time in the above case 2 is shown in table 4.
TABLE 4 variation of detection and early warning parameters of towing system with time
The external collision risk early warning system of the ship towing system under the mutual condition can automatically detect whether collision risk exists between other ships and any ship in the towing system, can issue collision risk early warnings in different levels when collision risk exists, reminds towing operators to take reasonable avoidance measures to ensure towing safety of the towing system, does not need to take traffic restrictions on ships around the towing system, and does not reduce the utilization rate of a navigation channel.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.