Automatic berthing control method for inland ship
By combining model predictive control and PID control algorithms, precise berthing of inland waterway vessels in low-speed, shallow water, and windy conditions has been achieved, solving the problems of maneuvering complexity and safety during the berthing process and improving the level of automation.
Patent Information
- Application Number
- CN202510951330.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-10
- Publication Date
- 2025-12-02
AI Technical Summary
Inland waterway vessels face challenges such as low speed, shallow water, and increased wind and current disturbances during berthing. Traditional control strategies are not applicable, leading to increased maneuvering complexity, low safety and efficiency, and reliance on manual operation, which is prone to fatigue and misoperation.
By employing a model predictive control-based trajectory control algorithm and a PID control algorithm, and through coordinated control in three stages—approaching the berth, stabilizing outside the berth, and lateral berthing—combined with the joint control of the propulsion system, bow thruster, and rudder, the ship achieves precise berthing at the berth.
It has improved the safety and efficiency of berthing for inland waterway vessels, reduced the labor intensity of crew members, promoted the automation development of inland waterway transportation, and met the requirements for high-precision and safe automatic berthing.
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Figure CN121050418A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of inland waterway vessel control, and in particular to an automatic berthing control method for inland waterway vessels under conditions of low speed, shallow water, and relatively enhanced wind and current disturbances in waters with restricted berths. Background Technology
[0002] With the rapid development of the Yangtze River Economic Belt, inland waterway transportation, as a key component of the transportation system, plays an increasingly important role in cargo transport and regional exchange. Especially in densely populated inland waterway areas like the Yangtze River Economic Belt, inland waterway transportation, with its advantages of large capacity, low cost, and low energy consumption, has become a vital support for economic development. The berthing of inland vessels is a crucial link in inland waterway transportation. Traditional manual operation methods heavily rely on crew experience, and physiological and psychological stress can easily lead to crew fatigue and operational errors. Automated berthing of inland vessels can reduce labor intensity and minimize the physical and mental exertion of crew members during berthing operations. This allows crew members to concentrate more on other aspects of vessel navigation, reducing the risk of collisions with docks and other vessels due to crew fatigue or misjudgment during berthing. It also helps alleviate the shortage of inland waterway crew members.
[0003] On the other hand, during berthing, the ship's speed is low, rudder efficiency is poor, and environmental disturbances such as wind and current are relatively enhanced, requiring multi-control surface joint control via bow thrusters to achieve bow turning and lateral movement, increasing the complexity of maneuvering. Simultaneously, at low speeds, the ship is affected by shallow water and bank effects, resulting in strong nonlinear hydrodynamics. Factors such as wharf topography and channel depth further complicate the design of berthing decision-making control algorithms. Research on automatic berthing control technology for inland waterways can effectively improve the efficiency of inland waterway transportation, promote intelligent development, and accurately plan berthing paths. Through the design of control algorithms, high-precision berthing control can be achieved, reducing berthing time, increasing ship turnaround rate, and increasing port throughput. Automatic berthing and unberthing are important components of intelligent inland waterway transportation, providing crucial technical support for achieving autonomous ship navigation and intelligent port construction, and powerfully promoting the intelligent and automated development of inland waterway transportation. Therefore, research on automatic berthing control technology for inland waterway vessels is of great significance.
[0004] In response to the various challenges faced by inland waterway vessels during berthing, such as narrow channels, low speeds, shallow waters, and environmental disturbances, and the inapplicability of traditional mature control strategies and methods used on seagoing vessels, it is necessary to design an automatic berthing control method for inland waterway vessels to improve the safety and efficiency of berthing. Summary of the Invention
[0005] The above-mentioned objective of this invention is achieved through the following technical solution:
[0006] An automatic berthing control method for inland waterway vessels includes three sequentially set stages: the first stage is the approach to berth stage; the second stage is the stabilization stage outside the berth stage; and the third stage is the lateral berthing stage.
[0007] During the approach to the berth phase, the ship sails at a constant speed to the transition point. When the ship reaches a certain distance from the transition point, it enters the subsequent berth stabilization phase.
[0008] During the stabilization phase outside the berth, the vessel begins to adjust its bow to be parallel to the berth, and the longitudinal displacement of the vessel is controlled according to the berth position. When the longitudinal position of the vessel reaches the desired longitudinal position, the subsequent transverse berthing phase begins.
[0009] During the transverse berthing control phase, the vessel smoothly approaches the berth in a direction parallel to it until it precisely arrives at the predetermined position on the berth.
[0010] Furthermore, during the approach phase to the berth, the berthing route is planned based on the relative position and speed of the vessel to the berth, and a trajectory control algorithm based on model predictive control is adopted. The trajectory control algorithm is designed as follows:
[0011] The ship's responsiveness model was obtained through parameter identification using the Z-type maneuvering test.
[0012]
[0013] in, The 'r' represents the heading angle, and 'r' represents the heading angular velocity, i.e., the turning rate. δ represents the forward acceleration, δ represents the rudder angle, K represents the yaw rate index, and T represents the rudder response index.
[0014] The model (1) is expressed in the form of a general state-space equation:
[0015]
[0016] In the formula,
[0017]
[0018] Discretizing the state-space model using first-order Euler discretization yields:
[0019]
[0020] To ensure zero steady-state error in control, a new state-space equation is constructed as follows:
[0021] Δx m (k+1)=A m Δx m (k)+B m Δu(k) (4)
[0022] in,
[0023] Δx m (k+1)=x m (k+1)-x m (k)
[0024] Δu(k)=u(k)-u(k-1)
[0025] The new state variable is constructed as follows:
[0026] x(k)=[Δx m (k) T y(k)] T (5)
[0027] According to equation (3):
[0028]
[0029] Combining equations (3) and (6), we can obtain:
[0030]
[0031] Based on equations (5) and (7), a new state-space equation can be constructed as follows:
[0032]
[0033] Set at sampling time k i System state variable x(k) i It can be measured that, using model (8) as the prediction model, the following prediction state is obtained through iteration.
[0034]
[0035] Where: N p To predict step size, N c To predict the step size; based on the state predictor variables, the output predictor variables are represented as follows:
[0036]
[0037] Define a vector:
[0038]
[0039] Combining equations (9) and (11), we can obtain
[0040] Y = Fx(k) i )+ΦΔU (12)
[0041] In the formula:
[0042]
[0043]
[0044] Define the cost function as
[0045]
[0046] Where R is the commanded heading sequence, These are the weighting coefficients;
[0047] Find the first derivative of equation (15)
[0048]
[0049] Setting equation (16) to zero yields...
[0050]
[0051] Apply the first quantity in equation (17) to the controlled object to complete the heading control.
[0052] Moreover, during the stabilization phase outside the berth, a PID control algorithm is used to maintain the ship's stable position and attitude outside the berth through the combined control of the propulsion device, bow thruster, and rudder.
[0053] Moreover, during the lateral berthing phase, based on the relative distance between the ship and the berth, and using a three-degree-of-freedom decoupled control system and a PID control algorithm, the propulsion device and bow thruster are coordinated to control the real-time position deviation between the ship and the berth, enabling the ship to smoothly approach the berth in a direction parallel to it, until it precisely reaches the predetermined position at the berth.
[0054] Moreover, during the lateral berthing phase, the PID control algorithms employed include longitudinal displacement control, lateral velocity control, and heading control algorithms.
[0055] Set the ship's longitudinal position control command x according to the berth location. d The ship's two propellers are controlled synchronously. The longitudinal displacement control algorithm is designed as follows:
[0056] n = Kp x ·(x d -x)-Kd x ·u (18)
[0057] In the formula, n is the propeller speed, x is the longitudinal position feedback of the ship, and u is the longitudinal velocity component of the ship.
[0058] Lateral velocity planning is performed based on the distance between the ship and the berth, so that the ship's speed converges to 0 when it arrives at the berth, thus achieving lateral berthing. The lateral velocity planning algorithm is shown in the following formula:
[0059]
[0060] Where, d lim To obtain the maximum lateral speed V of the ship through maneuvering tests max During navigation, the distance that can be traveled by relying on resistance to slow down, where d is the distance between the ship and the berth, and V is the distance that can be traveled. cmd This refers to the commanded lateral berthing speed;
[0061] The lateral velocity control algorithm based on PD control is as follows:
[0062]
[0063] In the formula, p is the lateral thrust rotation speed, e v For lateral velocity error, The derivative of the lateral velocity error;
[0064] Using the commanded rudder angle calculated in formula (17), bow control is performed. When the rudder angle is saturated, the remaining required bow control force is supplemented by propeller differential control. Combining the main engine speed command calculated by the longitudinal displacement control algorithm, the ship's left and right propeller control commands are calculated as follows:
[0065]
[0066]
[0067] In the formula, The heading control error is given by r, where r is the turning rate and n is the turning speed. L ,n R The rotational speeds of the left and right propellers.
[0068] The advantages and positive effects of this invention are as follows:
[0069] This invention addresses the challenges faced by inland waterway vessels during berthing, including low-speed, shallow-water navigation, increased wind and current disturbances, and the need for high-precision control in narrow channels. Through coordinated control of three stages—approaching the berth, stabilizing outside the berth, and lateral berthing—it achieves fully automated control of the entire berthing process. This invention not only improves the safety and efficiency of inland waterway vessel berthing and reduces the workload of crew members, but also provides crucial technical support for the automation development of inland waterway shipping, demonstrating broad application prospects and significant economic benefits. Attached Figure Description
[0070] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0071] Figure 1 This is a flowchart of the automatic berthing process for inland waterway vessels;
[0072] Figure 2 It is a curve showing the change in the ship's position during the automatic berthing process;
[0073] Figure 3 It is a curve showing the change in the longitudinal position of the ship during the automatic berthing process;
[0074] Figure 4 It is a curve showing the change in the ship's lateral position during the automatic berthing process;
[0075] Figure 5 It is the control curve for the bow thruster;
[0076] Figure 6 It is the control curve of the left propulsion device;
[0077] Figure 7 It is the control curve for the right propulsion device;
[0078] Figure 8 It is the rudder angle control curve;
[0079] Figure 9 It is a longitudinal velocity curve;
[0080] Figure 10 It is a transverse velocity curve. Detailed Implementation
[0081] The structure of the present invention will be further described below with reference to the accompanying drawings and embodiments. It should be noted that these embodiments are descriptive and not limiting.
[0082] For an automatic berthing control method for inland waterway vessels, please refer to [link / reference]. Figure 1 Its invention features three stages: the first stage is approaching the berth; the second stage is stabilizing outside the berth; and the third stage is lateral berthing.
[0083] During the approach to the berth phase, the ship sails at a constant speed to the transition point. When the ship reaches a certain distance from the transition point, it enters the subsequent berth stabilization phase.
[0084] During the stabilization phase outside the berth, the vessel begins to adjust its bow to be parallel to the berth, and its longitudinal displacement is controlled according to the berth position. When the vessel's longitudinal position reaches the commanded longitudinal position, the subsequent lateral berthing phase begins.
[0085] During the transverse berthing control phase, the vessel smoothly approaches the berth in a direction parallel to it until it precisely arrives at the predetermined position on the berth.
[0086] During the aforementioned approach-to-berth phase, berthing route planning is performed based on the ship's relative position and speed to the berth. A model predictive control-based trajectory control algorithm is employed. The trajectory control algorithm for the approach-to-berth phase is designed as follows:
[0087] The ship's responsiveness model was obtained through parameter identification using the Z-type maneuvering test.
[0088]
[0089] in, The 'r' represents the heading angle, and 'r' represents the heading angular velocity, i.e., the turning rate. δ represents the forward acceleration, δ represents the rudder angle, K represents the yaw rate index, and T represents the rudder response index.
[0090] The model (1) is expressed in the form of a general state-space equation:
[0091]
[0092] In the formula,
[0093]
[0094] Discretizing the state-space model using first-order Euler discretization yields:
[0095]
[0096] To ensure zero steady-state error in control, a new state-space equation is constructed as follows:
[0097] Δx m (k+1)=A m Δx m (k)+B m Δu(k) (4)
[0098] in,
[0099] Δx m (k+1)=x m (k+1)-x m (k)
[0100] Δu(k)=u(k)-u(k-1)
[0101] The new state variable is constructed as follows:
[0102] x(k)=[Δx m (k) T y(k)] T (5)
[0103] According to equation (3):
[0104]
[0105] Combining equations (3) and (6), we can obtain:
[0106]
[0107] Based on equations (5) and (7), a new state-space equation can be constructed as follows:
[0108]
[0109] Set at sampling time k i System state variable x(k) i It can be measured that, using model (8) as the prediction model, the following prediction state is obtained through iteration:
[0110]
[0111] Where: N p To predict step size, N c To predict the step size. Based on the state predictor variables, the output predictor variables are represented as:
[0112]
[0113] Define a vector:
[0114]
[0115] Combining equations (9) and (11), we can obtain
[0116] Y = Fx(k) i )+ΦΔU (12)
[0117] In the formula:
[0118]
[0119]
[0120] The cost function is defined as follows:
[0121]
[0122] Where R is the commanded heading sequence, These are the weighting coefficients.
[0123] Find the first derivative of equation (15)
[0124]
[0125] Setting equation (16) to zero yields...
[0126] U=(Φ T Φ+R) -1 Φ T [Y d -Fx(k)] (17)
[0127] Apply the first quantity in equation (17) to the controlled object to complete the heading control.
[0128] During the stabilization phase outside the berth, a PID control algorithm is used to maintain the vessel in a stable position and attitude outside the berth through the combined control of the propulsion device, bow thruster, and rudder, providing a foundation for subsequent lateral berthing.
[0129] After the initial stabilization phase outside the berth, the vessel is parallel to the berth. To ensure safe berthing, it is necessary to control the vessel to move slowly laterally. During this lateral berthing phase, based on three-degree-of-freedom decoupled control and a PID control algorithm, the relative distance between the vessel and the berth is monitored. This real-time positional deviation between the vessel and the berth is then used to coordinate the control of the propulsion system and bow thruster, enabling the vessel to smoothly approach the berth parallel to its position until it precisely reaches the predetermined position at the berth.
[0130] Design longitudinal displacement control algorithm, lateral velocity control algorithm and heading control algorithm based on PID control algorithm:
[0131] 1. Longitudinal displacement control algorithm: Set the ship's longitudinal position control command x according to the berth position. d The ship's two propulsion systems are controlled synchronously. The longitudinal displacement control algorithm is designed as follows:
[0132] n = Kp x ·(x d -x)-Kd x ·u (18)
[0133] In the formula, n is the propeller speed, x is the longitudinal position feedback of the ship, and u is the longitudinal velocity component of the ship.
[0134] 2. Lateral Speed Control Algorithm: The objective of lateral berthing control is to achieve zero longitudinal displacement of the vessel. Lateral speed planning is performed based on the distance between the vessel and the berth, ensuring that the vessel's speed converges to 0 upon arrival at the berth, thus achieving lateral berthing. The lateral speed planning algorithm is shown in the following formula:
[0135]
[0136] Where, d lim To obtain the maximum lateral speed V of the ship through maneuvering tests max During navigation, the distance that can be traveled by relying on resistance to slow down, where d is the distance between the ship and the berth, and V is the distance that can be traveled. cmd This refers to the commanded lateral berthing speed;
[0137] Based on PD control, the following lateral velocity control algorithm can be designed:
[0138]
[0139] In the formula, p is the lateral thrust rotation speed, e v For lateral velocity error, This is the derivative of the lateral velocity error.
[0140] 3. Bowing Control Algorithm: During lateral berthing control, the bow thrust and environmental disturbances cause the vessel to generate a turning force, making it unable to maintain parallel alignment with the berth. The vessel's rudder effectiveness is poor at low speeds during lateral berthing. By designing the vessel to berth in head-on current conditions, a certain level of rudder effectiveness is achieved, and this is combined with propeller differential control to realize bowing control under low-speed lateral berthing conditions. Specifically:
[0141] Using the command rudder angle calculated in formula (17), bow control is performed. When the rudder angle is saturated, the remaining required bow control force is supplemented by propeller differential speed control. Combining the main engine speed command calculated by the longitudinal displacement control algorithm, the ship's left and right propeller control commands can be calculated as shown in the following formula;
[0142]
[0143]
[0144] In the formula, The heading control error is given by r, where r is the turning rate and n is the turning speed. L ,n R The rotational speeds of the left and right propellers.
[0145] The automatic berthing control method for inland waterway vessels of this invention was simulated and verified, specifically:
[0146] Based on the MATLAB simulation platform, a simulation model of an inland waterway vessel, a trajectory control module for the berthing stage, and a berthing and lateral movement module were built to complete the berthing control of the inland waterway vessel. This verified the rationality of the automatic control strategy for inland waterway vessels designed in this invention and the effectiveness of the automatic berthing control algorithm.
[0147] Example:
[0148] This study focuses on a 10,000-ton bulk carrier on the Yangtze River. The ship is 130m long, 16.2m wide, and has a draft of 5.2m. It is equipped with twin propellers, twin rudders, and a bow thruster, giving it good maneuverability. The simulation sets the ship's initial position to (0,0), the transition point to (600,600), the berth position to (700,800), and the berth orientation to 0°.
[0149] Figure 2 The figure shows the ship's position change curve during automatic berthing. The ship first performs track tracking control to move to the transition point, and then moves laterally to berth at the berthing point. Figure 3 and Figure 4 These are the longitudinal and lateral displacements of the ship, from Figure 3 It can be seen that the ship's longitudinal position converges to 700m, which coincides with the longitudinal position of the berth. From Figure 4 It can be seen that the ship's lateral position is 794m, which is 6m away from the lateral position of the berth. This is less than half the ship's beam, thus meeting the requirements for ship berthing. Figures 5 to 8 The control curves for the actuators are shown, specifically for the side thruster, port propulsion unit, starboard propulsion unit, and rudder angle. These curves demonstrate that the actuator control actions are smooth, consistent with human captain's experience in maneuvering. From... Figure 9 It can be seen that during the lateral berthing phase, the longitudinal velocity is 0, thus achieving lateral berthing control. From Figure 10 It can be seen that the lateral speed of the vessel upon arrival at the berth is 0.04 m / s, which meets the berthing safety requirements. The statistical data on the automatic berthing control indicators for inland waterway vessels upon arrival at the berth are shown in Table 1. Table 1 shows that the longitudinal position deviation of the vessel from the berth at the end of berthing is 0, the lateral position deviation is 6 m, and the bow angle with the berth is 0.6°, all meeting the berthing requirements.
[0150] Table 1:
[0151]
[0152]
[0153] In summary, this invention provides an automatic berthing control method for inland waterway vessels. Through an innovative control strategy, it addresses the challenges faced by inland waterway vessels during berthing, such as low-speed shallow water navigation and relatively enhanced wind and current disturbances. By designing an automatic berthing control strategy and algorithm, it achieves safe, reliable, and high-precision automatic berthing control.
[0154] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for automatic berthing control of inland waterway vessels, characterized in that: The process consists of three phases: the first phase is the approach to the berth; the second phase is the stabilization phase outside the berth; and the third phase is the lateral berthing phase. During the approach to the berth phase, the ship sails at a constant speed to the transition point. When the ship reaches a certain distance from the transition point, it enters the subsequent berth stabilization phase. During the stabilization phase outside the berth, the vessel begins to adjust its bow to be parallel to the berth, and the longitudinal displacement of the vessel is controlled according to the berth position. When the longitudinal position of the vessel reaches the desired longitudinal position, the subsequent transverse berthing phase begins. During the transverse berthing control phase, the vessel smoothly approaches the berth in a direction parallel to it until it precisely arrives at the predetermined position on the berth.
2. The automatic berthing control method for inland waterway vessels according to claim 1, characterized in that: During the approach phase to the berth, the berthing route is planned based on the relative position and speed of the vessel to the berth. A trajectory control algorithm based on model predictive control is adopted, and the trajectory control algorithm is designed as follows: The ship's responsiveness model was obtained through parameter identification using the Z-type maneuvering test. in, The 'r' represents the heading angle, and 'r' represents the heading angular velocity, i.e., the turning rate. δ represents the forward acceleration, δ represents the rudder angle, K represents the yaw rate index, and T represents the rudder response index. The model (1) is expressed in the form of a general state-space equation: In the formula, Discretizing the state-space model using first-order Euler discretization yields: The new state-space equations are constructed as follows: Δx m (k+1)=A m Δx m (k)+B m Δu(k) (4) in, Δx m (k+1)=x m (k+1)-x m (k) Δu(k)=u(k)-u(k-1) The new state variables are constructed as follows: x(k)=[Δx m (k) T y(k)] T (5) According to equation (3): Combining equations (3) and (6), we can obtain: Based on equations (5) and (7), a new state-space equation can be constructed as follows: Set at sampling time k i System state variable x(k) i It can be measured that, using model (8) as the prediction model, the following prediction state is obtained through iteration: Where: N p To predict step size, N c To predict the step size; based on the state predictor variables, the output predictor variables are represented as follows: Define a vector: Combining equations (9) and (11), we can obtain Y=Fx(k i )+FDU (12) In the formula: The cost function is defined as follows: Where R is the commanded heading sequence, These are the weighting coefficients; Find the first derivative of equation (15) Setting equation (16) to zero, we get: U=(Φ T (Φ+R) -1 Φ T [Y d -Fx(k)] (17) Apply the first quantity in equation (17) to the controlled object to complete the course control command solution.
3. The automatic berthing control method for inland waterway vessels according to claim 1, characterized in that: During the stabilization phase outside the berth, a PID control algorithm is used to maintain the ship's stable position and attitude outside the berth through the combined control of the propulsion device, bow thruster, and rudder.
4. The automatic berthing control method for inland waterway vessels according to claim 1, characterized in that: During the lateral berthing phase, based on the relative distance between the ship and the berth, and using a three-degree-of-freedom decoupled control system and a PID control algorithm, the propulsion system and bow thruster are coordinated to control the ship smoothly approaching the berth in a direction parallel to it, until the ship accurately reaches the predetermined position at the berth.
5. The automatic berthing control method for inland waterway vessels according to claim 4, characterized in that: During the lateral berthing phase, the PID control algorithms employed include longitudinal displacement control, lateral velocity control, and heading control. Set the ship's longitudinal position control command x according to the berth location. d The ship's two propellers are controlled synchronously. The longitudinal displacement control algorithm is designed as follows: n=Kp x ·(x d -x)-Kd x ·u (18) In the formula, n is the propeller speed, x is the longitudinal position feedback of the ship, and u is the longitudinal velocity component of the ship; Lateral velocity planning is performed based on the distance between the ship and the berth, so that the ship's speed converges to 0 when it arrives at the berth, thus achieving lateral berthing. The lateral velocity planning algorithm is shown in the following formula: Where, d lim To obtain the maximum lateral speed V of the ship through maneuvering tests max During navigation, the distance that can be traveled by relying on resistance to slow down; d is the distance between the ship and the berth, V cmd This refers to the commanded lateral berthing speed; The lateral velocity control algorithm based on PD control is as follows: In the formula, p is the lateral thrust rotation speed, e v For lateral velocity error, The derivative of the lateral velocity error; Using the commanded rudder angle calculated in formula (17) for bow control, when the rudder angle is saturated, the remaining required bow control force is supplemented by propeller differential speed control; combined with the main engine speed command calculated by the longitudinal displacement control algorithm, the ship's left and right propeller control commands can be calculated as follows: In the formula, The heading control error is given by r, where r is the turning rate and n is the turning speed. L ,n R The rotational speeds of the left and right propellers.