Parallel platform and control method of parallel platform

Abstract

The application discloses a parallel platform and a control method thereof, and relates to the technical field of ship and ocean engineering. The control method comprises the following steps: predicting a pose error of a floating platform caused by sea state disturbance at a next moment as a sea state disturbance error by using a pre-set sea state disturbance error prediction model according to historical monitoring results of sea state disturbance parameters; obtaining an error of a current pose of the floating platform relative to a target pose of the floating platform as a current tracking error; and controlling a parallel motion branch to adjust the floating platform according to the target pose, the predicted sea state disturbance error at the next moment and the current tracking error, so that the pose of the floating platform at the next moment is maintained in a neighborhood of the target pose. The application can improve the stability of the aircraft in the sea state of the marine environment.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of marine and ocean engineering, in particular to a parallel platform and a control method of the parallel platform. BACKGROUND

[0002] With the continuous advancement of deep-sea oil and gas development, marine scientific research and ocean-going operations, aircraft such as helicopters or drones serve as important transportation and rescue tools for offshore operations and play a crucial role in scenarios such as deep-sea platforms, research vessels, and ocean-going vessels. However, the oscillation motion (roll, yaw, pitch, sway, surge, and heave) of offshore installations caused by sea state disturbances can significantly affect the six-degree-of-freedom motion of offshore installations, making it extremely difficult and risky for aircraft to take off and land in a marine environment.

[0003] To enable aircraft to take off and land normally on offshore installations, a landing auxiliary platform is often installed on the offshore installation to suppress the pose error caused by sea state disturbances and assist the aircraft in stable takeoff and landing.

[0004] Existing landing auxiliary platforms generally use a damping device plus a floating platform to suppress the pose error caused by sea state disturbances, but the stabilizing effect is limited, and the aircraft may still deviate, jump, or even lose stability during takeoff and landing.

[0005] Therefore, how to assist aircraft in taking off and landing in a sea state of a marine environment to improve the stability of aircraft taking off and landing in a sea state of a marine environment is still a technical problem that needs to be solved by those skilled in the art. SUMMARY

[0006] Therefore, to solve the above technical problems, the present application provides a parallel platform and a control method of the parallel platform.

[0007] To solve the above technical problems, one technical solution adopted by the present application is to provide a control method of a parallel platform, the parallel platform comprising a parallel kinematic chain and a floating platform, the floating platform being arranged on the parallel kinematic chain; the control method comprising:

[0008] predicting the pose error of the floating platform at the next time caused by the sea state disturbance as the sea state disturbance error according to the historical monitoring results of the sea state disturbance parameters using a pre-set sea state disturbance error prediction model;

[0009] obtaining the error of the current pose of the floating platform relative to the target pose of the floating platform as the current tracking error;

[0010] According to the target pose, the predicted sea state disturbance error of the next moment and the current tracking error, the parallel motion branch adjusts the floating platform so that the pose of the floating platform at the next moment is maintained in the neighborhood of the target pose.

[0011] To solve the above technical problems, another technical solution adopted by the present application is to provide a parallel platform, which comprises:

[0012] A fixed base;

[0013] A parallel motion branch arranged on the fixed base;

[0014] A floating platform arranged on the parallel motion branch;

[0015] A sea state monitoring unit for scanning the marine environment to obtain sea state disturbance parameters according to the scanning results;

[0016] A pose monitoring unit for monitoring the pose of the floating platform to obtain the pose of the floating platform;

[0017] And a controller in communication with the sea state monitoring unit, the pose monitoring unit and the parallel motion branch to control the parallel platform control method described above.

[0018] Beneficial effects: Different from the prior art, in the present application, the feedforward control that can be achieved based on the predicted sea state disturbance error of the next moment is combined with the feedback control that can be achieved based on the current tracking error, to form a composite control strategy including feedforward control and feedback control, so that the pose of the floating platform at the next moment is maintained in the neighborhood of the target pose. Therefore, the control method of the parallel platform of the present application can make the floating platform more stably maintained in the neighborhood of the target pose, to assist the aircraft to take off and land more stably in the sea state of the marine environment. That is, the present application can improve the stability of the aircraft taking off and landing in the marine environment. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 is a structural schematic diagram of the parallel platform of the present application;

[0020] Figure 2 is a module schematic block diagram of the parallel platform of the present application;

[0021] Figure 3 is a mechanism diagram of the parallel platform of the present application, Figure 3 viewed from the oblique upper direction of the parallel platform;

[0022] Figure 4 is a mechanism diagram of a single motion branch of the parallel platform of the present application;

[0023] Figure 5is a flowchart of the control method of the parallel platform of the present application;

[0024] Figure 6 is a mechanism diagram of the parallel platform of the present application, Figure 6 obtained from the top of the parallel platform and looking down, Figure 6 the static coordinate system is indicated in the middle;

[0025] Figure 7 is a mechanism diagram of the parallel platform of the present application, Figure 7 obtained from the top of the parallel platform and looking down, Figure 7 the dynamic coordinate system is indicated in the middle;

[0026] Figure 8 is a comparison diagram of the target pose of the floating platform of the parallel platform and the current pose of the floating platform, Figure 8 the dashed line shows the target pose of the floating platform, Figure 8 the solid line shows the current pose of the floating platform;

[0027] Figure 9 is a diagram of the pose of the dynamic coordinate system of the current time in the static coordinate system.

[0028] Explanation of reference signs:

[0029] parallel platform 100; fixed base 110; parallel kinematic chain 120; kinematic chain 121; moving pair P; spherical hinge S; universal joint U; 1st kinematic chain 121-1; 2nd kinematic chain 121-2; 3rd kinematic chain 121-3; 4th kinematic chain 121-4; 5th kinematic chain 121-5; 6th kinematic chain 121-6; floating platform 130; sea state monitoring unit 140; pose monitoring unit 150; controller 160; 1st circle O a ; 2nd circle O b ;

[0030] 1st moving pair P1; 2nd moving pair P2; 3rd moving pair P3; 4th moving pair P4; 5th moving pair P5; 6th moving pair P6; 1st spherical hinge S1; 2nd spherical hinge S2; 3rd spherical hinge S3; 4th spherical hinge S4; 5th spherical hinge S5; 6th spherical hinge S6; 1st universal joint U1; 2nd universal joint U2; 3rd universal joint U3; 4th universal joint U4; 5th universal joint U5; 6th universal joint U6. DETAILED DESCRIPTION

[0031] In order to make the technical personnel in the art better understand the technical solutions of the present application, the present application will be described in further detail below in conjunction with the drawings and specific embodiments. Obviously, the described embodiments are only part of the embodiments of the present application, not all. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0032] Please refer to Figures 1-4 The parallel platform 100 of the present application comprises a fixed base 110, a parallel kinematic chain 120, a floating platform 130, a sea state monitoring unit 140, a pose monitoring unit 150 and a controller 160. The parallel kinematic chain 120 is arranged on the fixed base 110. The floating platform 130 is arranged on the parallel kinematic chain 120 and can be used to carry an aircraft. The aircraft can be a helicopter or a drone. The sea state monitoring unit 140 is used to scan the marine environment to obtain sea state disturbance parameters according to the scanning results. The pose monitoring unit 150 is used to monitor the pose of the floating platform 130 to obtain the pose of the floating platform 130. The controller 160 is communicatively connected to the sea state monitoring unit 140, the pose monitoring unit 150 and the parallel kinematic chain 120.

[0033] Optionally, as Figures 1-4 shown, the parallel kinematic chain 120 comprises a plurality of kinematic chains 121, which are arranged uniformly along the circumference of the floating platform 130. Optionally, as Figures 1-4 shown, the controller 160 can control the parallel kinematic chain 120 according to the sea state disturbance parameters monitored by the sea state monitoring unit 140 and the pose of the floating platform monitored by the pose monitoring unit 150 to adjust the floating platform.

[0034] Optionally, the parallel platform 100 can be arranged separately on the sea, for example, arranged separately to float or support on the sea. The parallel platform 100 floating on the sea can be limited by a limiting structure (not marked in the figure) extending to the sea surface. The limiting structure can be a combination of a chain and a ship anchor, but is not limited thereto. The sea state monitoring unit 140 can be arranged at a position fixed relative to the fixed base 110, and the pose monitoring unit 150 can be arranged at a position fixed relative to the pose of the floating platform 130, but is not limited thereto. For example, when the parallel platform 100 is floating separately on the sea, the sea state monitoring unit 140 can be arranged on the fixed base 110, and the pose monitoring unit 150 can be arranged on the floating platform 130.

[0035] Optionally, the parallel platform 100 can be installed as a functional module on a marine device such as a deep-sea platform, a scientific research vessel or an ocean-going ship.

[0036] The parallel platform 100 of the present application can be used to implement the control method of the parallel platform 100 in embodiments one to eight.

[0037] Embodiment one

[0038] The parallel platform of the present embodiment can be installed in a marine device such as a deep-sea platform, a research vessel or an ocean-going vessel, and the control method of the parallel platform can include steps S100 to S300.

[0039] Step S100: predicting the pose error of the floating platform at the next time caused by the sea state disturbance as the sea state disturbance error according to the historical monitoring results of the sea state disturbance parameters using the pre-set sea state disturbance error prediction model.

[0040] By way of example but not limitation, the sea state disturbance parameters can be monitored by a sea state monitoring unit to obtain the historical monitoring results of the sea state disturbance parameters. The controller can load the sea state disturbance error prediction model to predict the pose error of the floating platform at the next time caused by the sea state disturbance as the sea state disturbance error according to the historical monitoring results of the sea state disturbance parameters.

[0041] In this way, in step S210, the pose error of the floating platform at the next time caused by the sea state disturbance is actively predicted as the sea state disturbance error, which is beneficial to the subsequent step of using the predicted sea state disturbance error at the next time to control the parallel kinematic chain at the next time to adjust the floating platform, thereby realizing feedforward control.

[0042] Step S220: obtaining the error of the pose of the floating platform at the current time relative to the target pose of the floating platform as the current tracking error.

[0043] By way of example but not limitation, the target pose of the floating platform can be pre-input by a user to the controller. The pose of the floating platform at the current time can be monitored by a pose monitoring unit to obtain the pose of the floating platform at the current time. The controller can obtain the error of the pose of the floating platform at the current time relative to the target pose of the floating platform as the current tracking error.

[0044] In step S220, the current tracking error is obtained, which is beneficial to the subsequent step of using the current tracking error to control the parallel kinematic chain at the next time to adjust the floating platform, thereby realizing feedback control.

[0045] Step S230: controlling the parallel kinematic chain to adjust the floating platform according to the target pose, the predicted sea state disturbance error at the next time and the current tracking error, so that the pose of the floating platform at the next time is maintained within the neighborhood of the target pose.

[0046] Through the steps S210 to S230, the feedforward control based on the predicted sea state disturbance error of the next time instant is combined with the feedback control based on the current tracking error to form a compound control strategy including the feedforward control and the feedback control, so as to maintain the pose of the floating platform in the next time instant within the neighborhood of the target pose. Thus, the control method of the parallel platform can make the floating platform more stably maintained in the neighborhood of the target pose, so as to assist the aircraft to more stably take off and land in the sea state of the marine environment. That is, the application can improve the stability of the aircraft taking off and landing in the marine environment.

[0047] Optionally, the target pose of the floating platform can be a horizontal pose, which is that the floating platform is parallel to the horizontal plane, but is not limited thereto. In this way, the floating platform can be dynamically maintained in the horizontal pose to assist the stability of the aircraft taking off and landing in the marine environment.

[0048] It should be understood that in an alternative example, the target pose of the floating platform can be a pose inclined relative to the horizontal pose, but is not limited thereto.

[0049] It should be noted that the current time instant and the next time instant can be separated by 0.5s to 2s. For example, the current time instant and the next time instant can be separated by 0.5s, 1s or 2s, but are not limited thereto.

[0050] Embodiment Two

[0051] Embodiment Two is further limited based on Embodiment One, and the same parts of Embodiment Two and Embodiment One will not be repeated. Embodiment Two is further limited relative to Embodiment One as follows.

[0052] The sea state disturbance error prediction model includes a sea state prediction model and an error prediction model.

[0053] The sea state prediction model is configured to predict the sea state disturbance parameter of the next time instant as an output according to the historical detection results of the sea state disturbance parameter.

[0054] By way of example and not limitation, the sea state disturbance parameter can include a sea wave height, a sea wind speed and a sea wind direction angle.

[0055] The marine environment can be scanned by different monitoring methods to obtain the sea wave height, the sea wind speed and the sea wind direction angle according to the scanning results.

[0056] For example, the sea state monitoring unit can include a wave radar and an anemometer, but is not limited thereto. The wave radar can monitor the sea wave height, and the anemometer can monitor the sea wind speed and the sea wind direction angle, but is not limited thereto.

[0057] Optionally, the sea state prediction model can be a wave propagation model, which can be described by a wave propagation function (1) as follows:

[0058] (1)

[0059] wherein, , , and are positive integers; t is the next time; is the time before the time ; is the th sea state parameter in the predicted sea state disturbance parameters at the time ; is the th auto-regressive coefficient for the th sea state parameter in the predicted sea state disturbance parameters; is the th sea state parameter in the monitored sea state disturbance parameters at the time ; the 1st sea state parameter can be the wave height, the 2nd sea state parameter can be the sea wind speed, and the 3rd sea state parameter can be the sea wind direction angle. Preferably, s1≥2.

[0060] The error prediction model is configured to predict the pose error of the floating platform at the next time due to the sea state disturbance as the sea state disturbance error according to the output of the sea state prediction model.

[0061] By way of example and not limitation, the error prediction model can be described by a hull motion response function (2) as follows:

[0062] (2)

[0063] wherein, is a positive integer; t is the next time; is the predicted sea state disturbance error at the time ; is the wave propagation and hull motion response function; is the predicted wave height at the time ; is the predicted sea wind speed at the time ; is the predicted sea wind direction angle at the time .

[0064] Embodiment Three

[0065] Embodiment Three is further limited based on Embodiment One or Embodiment Two. The same parts of Embodiment Three as Embodiment One or Embodiment Two are not repeated here. Embodiment Three is further limited relative to Embodiment One or Embodiment Two as follows.

[0066] Step S120 can further include steps S121-S123.

[0067] Step S121: obtaining multiple pose monitoring results of the current time of the floating platform by monitoring the pose of the floating platform at the current time through different monitoring manners.

[0068] By way of example but not limitation, the pose monitoring unit can include an inertial monitoring unit, an inclinometer, and a three-axis gyroscope, and the multiple pose monitoring results of the floating platform at the current time can be obtained by monitoring the pose of the floating platform at the current time through the inertial monitoring unit (IMU), the inclinometer, and the three-axis gyroscope, respectively.

[0069] Step S122: fusing the multiple pose monitoring results according to Kalman filtering to obtain the fused pose of the floating platform at the current time.

[0070] Optionally, the fused pose of the floating platform at the current time can be obtained according to Kalman filtering fusion formula (3), which can be:

[0071] (3)

[0072] wherein, is a positive integer; is the current time; is the fused pose of the floating platform at the current time; is a Kalman filtering function; is the multiple pose monitoring results of the floating platform at the current time monitored by different monitoring manners.

[0073] In step S121, since the fused pose of the floating platform at the current time is obtained according to Kalman filtering fusion of the pose monitoring results of the floating platform at the current time by the inertial monitoring unit, the inclinometer, and the three-axis gyroscope, respectively, the noise of a single monitoring manner can be effectively filtered out, the measurement error can be corrected, and the fused pose of the floating platform at the current time can more accurately represent the actual pose of the floating platform at the current time. That is, the monitoring accuracy and robustness of the actual pose of the floating platform at the current time are improved.

[0074] Step S123: obtaining the error of the fused pose of the floating platform at the current time relative to the target pose of the floating platform as the current tracking error.

[0075] ​Optionally, the current tracking error can be obtained according to a current tracking error obtaining formula (4), which can be:

[0076] (4)

[0077] wherein, is a positive integer; the current time is a current time; is the current tracking error; is a fused pose of the floating platform at the current time; is a target pose of the floating platform.

[0078] The measurement accuracy of the current tracking error can be significantly improved through the steps S121 to S123.

[0079] Embodiment Four

[0080] Embodiment Four is further limited based on Embodiment One, Embodiment Two or Embodiment Three. The same parts of Embodiment Four as Embodiment One, Embodiment Two or Embodiment Three will not be repeated. The further limitation of Embodiment Four relative to Embodiment One, Embodiment Two or Embodiment Three is as follows.

[0081] Step S130 can further include steps S131 to S135.

[0082] Step S131: generating a feedforward compensation pose according to the predicted sea state disturbance error at the next time, the feedforward compensation pose being used to offset the predicted sea state disturbance error at the next time.

[0083] Optionally, the predicted sea state disturbance error at the next time and the feedforward compensation pose can satisfy a feedforward compensation pose obtaining formula (5), which can be:

[0084] (5)

[0085] wherein, is a positive integer; the current time is a current time; is the current tracking error; is a fused pose of the floating platform at the current time;

[0086] Step S132: generating a feedback compensation pose according to the current tracking error, the feedback compensation pose being used to offset the error caused by the current tracking error at the next time.

[0087] Optionally, the current tracking error and the feedback compensation pose can satisfy a feedback compensation pose obtaining formula (6), which can be:

[0088] (6)

[0089] wherein, is a positive integer; is a current time; is a feedback compensation pose; is a current tracking error.

[0090] Step S133: compensating the target pose according to the feedforward compensation pose and the feedback compensation pose to obtain an anti-interference pose at the next time.

[0091] Optionally, the feedforward compensation pose, the feedback compensation pose, the target pose and the anti-interference pose at the next time satisfy an anti-interference pose acquisition formula (7), the anti-interference pose acquisition formula (7) is:

[0092] (7)

[0093] wherein, is the anti-interference pose at the next time; is the target pose of the floating platform; is the feedforward compensation pose; is the feedback compensation pose.

[0094] Step S134: obtaining, by using an inverse kinematics model of the parallel platform, the driving displacement of each kinematic chain in the parallel kinematic chain as a target driving displacement when the pose of the floating platform is the anti-interference pose at the next time.

[0095] In step S134, that is, by using the inverse kinematics model of the parallel platform, the driving displacement of each kinematic chain in the parallel kinematic chain is obtained as the target driving displacement of each kinematic chain when the pose of the floating platform is the anti-interference pose at the next time without considering the predicted sea state disturbance error at the next time, without considering the current tracking error.

[0096] Step S135: controlling each kinematic chain of the parallel kinematic chain to adjust the floating platform according to the target driving displacement of each kinematic chain, so that the pose of the floating platform at the next time is maintained within the neighborhood of the target pose.

[0097] Through the above steps S131 to S135, the anti-interference pose under the influence of the predicted sea state disturbance error at the next time and the current tracking error makes the pose of the floating platform at the next time maintained within the neighborhood of the target pose.

[0098] Embodiment five

[0099] Embodiment Five is further limited based on Embodiment Four, and the same parts of Embodiment Five as Embodiment Four are not repeated. Embodiment Five is further limited relative to Embodiment Four as follows.

[0100] Optionally, as shown in Figures 1-4 and Figure 6 Parallel kinematic chain 120 can include six kinematic chains 121, which are sequentially arranged along the circumference of floating platform as first kinematic chain 121-1 to sixth kinematic chain 121-6. The six kinematic chains can each be a PSU kinematic chain.

[0101] By way of example, but not limitation, in conjunction with 1- Figure 3 , referring to Figure 4 , the PSU kinematic chain can include a moving pair P, a spherical hinge S, a connecting rod L, and a universal joint U. The moving pair P can be arranged on the fixed base 110, and the moving pair P is connected to the connecting rod L through the spherical hinge S. The connecting rod L can be connected to the floating platform 130 through the universal joint U. Thus, the parallel kinematic chain 120 can be a 6-PSU parallel mechanism. In this way, the moving pair P can drive the spherical hinge S to move up and down, and then drive the floating platform 130 through the connecting rod L and the universal joint U.

[0102] Optionally, in conjunction with 1- Figure 3 , referring to Figure 4 , the moving pair P can be a motor telescopic drive device (not labeled in the figure). The output stroke of the motor telescopic drive device can range from 1.2m to 1.8m. For example, the output stroke of the motor telescopic drive device can be 1.2m, 1.5m, or 1.8m, but is not limited thereto. The rated thrust of the motor telescopic drive device can be not less than 50kN.

[0103] Optionally, the motor telescopic drive device can include a driving motor and a ball screw mechanism. The driving motor and the ball screw mechanism are arranged on the fixed base, and the ball screw mechanism is connected to the corresponding connecting rod L through the corresponding spherical hinge S. The driving motor is used to drive the ball screw mechanism to drive the spherical hinge S to move, so that the moving pair P outputs the driving displacement.

[0104] Optionally, the controller 160 can control the driving motor according to the target driving displacement of the kinematic chain 121 corresponding to the driving motor, so that the driving displacement output by the moving pair P is the target driving displacement. For example, the controller 160 can generate a corresponding PID control signal according to the target driving displacement of the kinematic chain 121 corresponding to the driving motor, to control the driving motor, so that the driving displacement output by the moving pair P is the target driving displacement.

[0105] It should be noted that in other alternative examples, the positions of the ball joint S and the universal joint U can be interchanged, that is, the floating joint P is connected to the link L through the universal joint U, and the link L is connected to the floating platform 130 through the ball joint S, but it is not limited to this.

[0106] Optionally, combined Figures 1-4 See Figures 6-9 As shown, the static coordinate system O0-X0Y0Z0 can be defined as a coordinate system that is stationary relative to the ground and whose origin O0 is located on the floating platform 130 when the floating platform 130 is in the target pose. The dynamic coordinate system O1-X1Y1Z1 can be defined as a coordinate system that moves with the floating platform 130 and whose origin O1 coincides with the origin O0 of the static coordinate system O0-X0Y0Z0 when the floating platform 130 is in the target pose. The pose of the floating platform 130 may include, but is not limited to, the coordinates of the origin O1 of the dynamic coordinate system O1-X1Y1Z1 in the static coordinate system O0-X0Y0Z0 and the attitude angles of the dynamic coordinate system O1-X1Y1Z1 in the static coordinate system O0-X0Y0Z0.

[0107] It should be noted that when the parallel motion chain in the parallel platform is a 6-PSU parallel mechanism, the inverse kinematic model of the parallel platform is the inverse kinematic model of the 6-PSU parallel mechanism. In this case, the inverse kinematic model of the parallel platform can be described by the state-space expression (8), which can be:

[0108] (8)

[0109] in, Let be the driving displacement of the kth moving branch in the static coordinate system; Let be the unit direction vector of the kth k-th kinematic branch in the static coordinate system; Let be the initial length of the k-th k-th kinematic branch; Let be the position vector of the center of the spherical hinge of the k-th moving branch in the static coordinate system; The coordinates of the origin of the moving coordinate system in the static coordinate system; The attitude angle of the moving coordinate system on the static coordinate system; Let be the rotation transformation matrix of the moving coordinate system relative to the static coordinate system; Let be the position vector of the center of the gimbal of the k-th k-th kinematic branch in the moving coordinate system; is the anti-interference pose at the next moment; k is a positive integer.

[0110] It should be understood that when the parallel motion branch of the parallel platform is a 6-PSU parallel mechanism, step S134 can be the inverse kinematics solution step of the 6-PSU parallel mechanism. In this case, step S134 can refer to the existing inverse kinematics solution steps of the 6-PSU parallel mechanism, and will not be described in detail here.

[0111] Optionally, optionally, in combination with Figures 1-4 , refer to Figure 6 It is shown that the centers of the universal joints U of the first to sixth motion branches 121-1 to 121-6 can be sequentially divided into three groups uniformly distributed on the outer periphery of the floating platform 130, but not limited to this. The centers of the spherical hinges S of the first to sixth motion branches 121-1 to 121-6 can be sequentially divided into three groups uniformly distributed on the outer periphery of the fixed base 110, but not limited to this.

[0112] Optionally, in combination with Figures 1-4 , refer to Figures 6-9 It is shown that, it should be noted that the roll can be rotation around the X0 axis, the pitch can be rotation around the Y0 axis, the yaw can be rotation around the Z0 axis, the surge can be forward and backward movement along the X0 axis, the sway can be left and right movement along the Y0 axis, and the heave can be up and down movement along the Z0 axis.

[0113] In the above manner, through actual experiments, it is found that the parallel platform 100 can achieve the following effects one to two under the sea conditions that the wave height does not exceed 3 meters and the sea wind speed does not exceed 12 m / s, so that the fixed base 110 has a roll of-16° to +16°, the fixed base has a pitch of-18° to +18°, and the fixed base 110 has a heave of-1.4 m to +1.4 m. Effect one: keep the error between the attitude angle of the next moment of the pose of the floating platform 130 in the static coordinate system O0-X0Y0Z0 and the attitude angle of the target pose of the floating platform 130 within the range of-4° to +4°. Effect two: keep the error between the coordinate on the Z0 axis of the next moment of the pose of the floating platform 130 and the coordinate on the Z0 axis of the target pose of the floating platform 130 within the range of-0.3 m to +0.3 m.

[0114] Embodiment six

[0115] Embodiment six is further limited based on embodiment five, and the same parts of embodiment six and embodiment five will not be repeated. The further limitation of embodiment six relative to embodiment five is as follows.

[0116] By way of example, but not limitation, in combination with Figures 1-4 , refer to Figures 6-9 It is shown that the moving pair P of the kth motion branch is counted as the kth moving pair Pk, the spherical hinge S of the kth motion branch is counted as the kth spherical hinge Sk, the universal joint U of the kth motion branch is counted as the kth universal joint Uk, and the static coordinate system O0-X0Y0Z0 and the dynamic coordinate system O1-X1Y1Z1 can be defined as follows, but not limited to this.

[0117] The coordinate origin O0 of the static coordinate system O0-X0Y0Z0 can be the center of the first circle O of the centers of the first to sixth universal joints U1-U6 when the floating platform 130 is located at the target pose. a The positive direction of the X0 axis of the static coordinate system O0-X0Y0Z0 can be from the coordinate origin O0 to the first midpoint, which is the midpoint between the center of the first universal joint U1 and the center of the sixth universal joint U6, when the floating platform 130 is located at the target pose. The positive direction of the Z0 axis of the static coordinate system O0-X0Y0Z0 can be vertically upward with respect to the floating platform 130 when the floating platform 130 is located at the target pose. The positive direction of the Y0 axis of the static coordinate system O0-X0Y0Z0 can be from the coordinate origin O0 to the side close to the second universal joint U2 when the floating platform 130 is located at the target pose.

[0118] The coordinate origin O1 of the moving coordinate system O1-X1Y1Z1 can be the center of the first circle O of the centers of the first to sixth universal joints U1-U6. a The positive direction of the X1 axis of the moving coordinate system O1-X1Y1Z1 can be from the coordinate origin O1 to the first midpoint, which is the midpoint between the center of the first universal joint U1 and the center of the sixth universal joint U6. The positive direction of the Z1 axis of the moving coordinate system O1-X1Y1Z1 can be vertically upward with respect to the floating platform 130 when the floating platform 130 is located at the target pose. The positive direction of the Y1 axis of the moving coordinate system O1-X1Y1Z1 can be from the coordinate origin O0 to the side close to the second universal joint U2 when the floating platform 130 is located at the target pose.

[0119] Optionally, the angle between the position vector of the center of the first universal joint U1 on the moving coordinate system O1-X1Y1Z1 and the positive direction of the X1 axis is The radius of the circle on which the centers of the first to sixth universal joints U1-U6 are located is At this time, the position vectors of the center of the first universal joint U1 to the center of the sixth universal joint U6 on the moving coordinate system O1-X1Y1Z1 can be represented in sequence as .

[0120] wherein is:

[0121] ;

[0122] wherein is:

[0123] ;

[0124] wherein is:​

[0125] ;

[0126] wherein,

[0127] ;

[0128] wherein,

[0129] ;

[0130] wherein,

[0131] .

[0132] When the floating platform 130 is located at the target pose and the lengths of the first motion branch 121-1 to the sixth motion branch 121-6 are all initial lengths, the angle between the position vector of the center of the first universal joint U1 on the moving coordinate system O1-X1Y1Z1 and the positive direction of the X1 axis is The radius of the circle on which the centers of the six universal joints U of the first universal joint U1 to the sixth universal joint U6 are located is The distance between the center of the first circle O a on which the centers of the six spherical hinges S of the first spherical hinge S1 to the sixth spherical hinge S6 are located and the center of the second circle O b is The position vectors of the center of the first spherical hinge S1 to the center of the sixth spherical hinge S6 on the static coordinate system O0-X0Y0Z0 can be represented in sequence as .

[0133] wherein,

[0134] ;

[0135] wherein,

[0136] ;

[0137] wherein,

[0138] ;

[0139] wherein,

[0140] ​​​​​​​​ ;

[0141] in, for:

[0142] ;

[0143] in, for:

[0144] .

[0145] Example 7

[0146] Example 7 is derived from Example 6 with further limitations. The parts that are the same in Example 7 and Example 6 will not be repeated. The further limitations of Example 7 compared to Example 6 are as follows.

[0147] Optionally, with The time is the current time, with The moment is the next moment, with equal , equal ,by Time to Total time The moment is Time to Distributed at equal intervals between time points At any given time, n is a positive integer. Step S135 may further include step S135a.

[0148] Step S135a: Obtain the driving speed according to formula (9) The driving velocity of the k-th moving branch in the static coordinate system at time k is such that the floating platform... The pose at any given time is maintained within the neighborhood of the target pose, and the driving speed acquisition formula (9) can be used.

[0149] (9)

[0150] in, It is an integer; for The driving velocity of the k-th moving branch in the static coordinate system at time k; This is the energy consumption weight matrix; It is a smoothing factor; for The inverse Jacobian matrix of a time-parallel platform; For response coefficients; for The driving velocity of the k-th moving branch in the static coordinate system at time k; for The positive Jacobian matrix of the parallel platform at the moment.

[0151] In this way, the instantaneous impact of each kinematic chain can be reduced, and the energy consumption of each kinematic chain can be optimized, so that the instantaneous impact of each kinematic chain is minimized.

[0152] The positive Jacobian matrix of the parallel platform may be expressed as: The inverse Jacobian matrix of the parallel platform may be expressed as:

[0153]

[0154] wherein, is a rotation transformation matrix of the moving coordinate system relative to the static coordinate system, and satisfies the rotation transformation matrix acquisition formula (10), and the rotation transformation matrix acquisition formula (10) is:

[0155] (10)

[0156] wherein, is the attitude angle of the moving coordinate system at the moment in the static coordinate system. The attitude angle described in the present application can be a Tait-Bryan angle.

[0157] Embodiment eight

[0158] Embodiment eight is further limited based on embodiment one, and the same parts of embodiment eight and embodiment one will not be described again. The further limitation of embodiment eight relative to embodiment one is as follows.

[0159] Optionally, as Figures 1-4 shown, the parallel platform 100 itself can also be used as a marine device, for example, the parallel platform 100 can float or be supported on the sea surface. Optionally, the parallel platform 100 floating on the sea surface can be limited by extending to a limiting structure (not marked in the figure) under the sea surface. The limiting structure can be a combination of a chain and an anchor, but is not limited thereto.

[0160] Optionally, the fixed base 110 includes a steel structure floating body (not marked in the figure), and a ballast tank (not shown) and a ballast system (not shown) can be arranged in the steel structure floating body. The ballast system is connected with the ballast tank, and is used to control the content of water contained in the ballast tank to adjust the buoyancy of the fixed base 110.

[0161] It should be noted that the content related to the ballast tank and the ballast system can be referred to the related description in the prior art, and will not be repeated here. Optionally, the outer periphery of the fixed base 110 can be provided with a guide stabilizing fin (not shown in the figure) for reducing the disturbance error of the sea state. The content related to the guide stabilizing fin can be referred to the related description in the prior art, and will not be repeated here.

[0162] Optionally, the aircraft can be a helicopter, and the floating platform 130 can be provided with a helicopter landing deck (not shown in the figure), and the surface of the helicopter landing deck can be sequentially provided with a buffer layer and a non-slip layer. In this way, the helicopter landing deck can assist the helicopter in taking off and landing, which can improve the stability of the helicopter parked on the floating platform 130 and can reduce the impact force of the helicopter on the floating platform by using the buffer layer to buffer during the process of the helicopter descending to the helicopter landing deck. Optionally, the helicopter landing deck can also be provided with an identification layer. For example, but not limited to, the identification layer can be used to assist the helicopter pilot in judging the distance between the helicopter and the helicopter landing deck. It should be noted that the helicopter landing deck can refer to the related description of the helicopter landing deck in the prior art, and will not be repeated here.

[0163] The above is only an embodiment of the present application, and does not limit the patent scope of the present application, and any equivalent structure or equivalent process transformation using the content of the specification and drawings of the present application, or directly or indirectly applied to other related technical fields, are also included in the patent protection scope of the present application.

Claims

1. A control method for a parallel platform, characterized in that, The parallel platform includes a parallel motion chain and a floating platform, wherein the floating platform is disposed on the parallel motion chain; the control method includes: Based on the historical monitoring results of sea state disturbance parameters, the pose error of the floating platform caused by sea state disturbance at the next moment is predicted by a pre-set sea state disturbance error prediction model and used as the sea state disturbance error. The error between the current pose of the floating platform and the target pose of the floating platform is obtained as the current tracking error; The parallel motion chain is controlled to adjust the floating platform according to the target pose, the predicted sea state disturbance error at the next moment, and the current tracking error, so that the pose of the floating platform at the next moment is maintained within the neighborhood of the target pose. The sea state disturbance error prediction model includes a sea state prediction model and an error prediction model; the sea state prediction model is a wave propagation model; the error prediction model is described by the ship motion response function. The sea state prediction model is used to predict the sea state disturbance parameters at the next moment based on the historical detection results of the sea state disturbance parameters, and outputs them as such. The error prediction model is used to predict the pose error of the floating platform caused by sea state disturbance at the next moment based on the output of the sea state prediction model, as the sea state disturbance error. The sea state disturbance parameters include wave height, wind speed, and wind direction angle; the ship motion response function is: in, It is a positive integer; The time is the next time; the stated For the prediction The sea state disturbance error at the specified time; The wave propagation and hull motion response function; For the prediction The wave height at the specified time; For the prediction The sea breeze speed at the specified time; For the prediction The wind direction angle of the sea breeze at that moment.

2. The control method for a parallel platform according to claim 1, characterized in that, The control method includes: The marine environment is scanned using different monitoring methods to obtain the wave height, wind speed, and wind direction angle based on the scan results.

3. The control method for a parallel platform according to claim 1, characterized in that, The step of obtaining the error between the current pose of the floating platform and the target pose of the floating platform as the current tracking error includes: Multiple pose monitoring results were obtained by monitoring the pose of the floating platform at the current moment using different monitoring methods; The current pose of the floating platform is obtained by fusing multiple pose monitoring results using Kalman filtering. The error between the fused pose of the floating platform at the current moment and the target pose of the floating platform is obtained as the current tracking error.

4. The control method for a parallel platform according to claim 1, characterized in that, The step of controlling the parallel motion chain to adjust the floating platform according to the target pose, the predicted sea state disturbance error at the next moment, and the current tracking error, so as to maintain the pose of the floating platform at the next moment within the neighborhood of the target pose, includes: A feedforward compensation pose is generated based on the predicted sea state disturbance error at the next moment, and the feedforward compensation pose is used to offset the predicted sea state disturbance error at the next moment. A feedback compensation pose is generated based on the current tracking error, and the feedback compensation pose is used to offset the error caused by the current tracking error in the next moment. The target pose is compensated based on the feedforward compensated pose and the feedback compensated pose to obtain the anti-interference pose at the next moment. When the pose of the floating platform is obtained using the inverse kinematics model of the parallel platform as the anti-interference pose at the next moment, the driving displacement of each kinematic branch in the parallel kinematic chain is used as the target driving displacement of each kinematic branch. The floating platform is adjusted by controlling each of the parallel motion branches according to the target driven displacement of each of the motion branches, so that the pose of the floating platform at the next moment is maintained within the neighborhood of the target pose.

5. The control method for a parallel platform according to claim 4, characterized in that, The parallel motion chain includes 6 motion chains, which are sequentially numbered 1 to 6 along the circumference of the floating platform. A static coordinate system is defined as a coordinate system that is stationary relative to the ground and whose origin is located on the floating platform when the floating platform is in the target pose. A dynamic coordinate system is defined as a coordinate system that moves with the floating platform and whose origin coincides with the origin of the static coordinate system when the floating platform is in the target pose. The pose of the floating platform includes the coordinates of the origin of the dynamic coordinate system in the static coordinate system and the attitude angle of the dynamic coordinate system in the static coordinate system. The inverse kinematics model of the parallel platform is described by the following state-space expression: Among them, the The driving displacement of the k-th moving branch in the static coordinate system; Let k be the unit direction vector of the k-th kinematic branch in the static coordinate system; Let be the initial length of the k-th kinematic branch; Let be the position vector of the center of the spherical hinge of the k-th k-th kinematic branch in the static coordinate system; The coordinates of the origin of the moving coordinate system on the static coordinate system; The attitude angle of the moving coordinate system on the static coordinate system; Let be the rotation transformation matrix of the moving coordinate system relative to the static coordinate system; Let be the position vector of the center of the gimbal of the k-th kinematic branch in the moving coordinate system; The anti-interference pose is the position at the next moment; k is a positive integer.

6. A parallel platform, characterized in that, The parallel platform includes: Fixed base; Parallel motion chains are provided on the fixed base; A floating platform is provided on the parallel motion chain; The sea state monitoring unit is used to scan the marine environment in order to obtain sea state disturbance parameters based on the scanning results; The pose monitoring unit is used to monitor the pose of the floating platform in order to obtain the pose of the floating platform. The controller is communicatively connected to the sea state monitoring unit, the pose monitoring unit, and the parallel motion chain to control and implement the control method of the parallel platform according to any one of claims 1-5.

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