CN102774481B - For supporting the Parallel mechanism platform of bow chaser - Google Patents

Abstract

A kind of Parallel mechanism platform for supporting bow chaser of disclosure, parallel institution is applied on the support platform of bow chaser, obtain the Parallel mechanism platform for supporting bow chaser that a kind of rigidity is big, bearing capacity is strong, precision is high, error is little, can quickly respond external impacts, thus keeping stability and accuracy that bow chaser launches. The parallel institution being applied to is made up of upper and lower two platforms and six roots of sensation bar, and six roots of sensation bar is connected with dynamic and static platform by ball pivot. Wherein upper mounting plate is silent flatform, the accuracy that stably can be greatly improved bow chaser transmitting of upper mounting plate; Lower platform is moving platform, is connected with naval vessel body, under the impact of the load such as stormy waves, no matter moving platform wave again violent, by the adjustment of six roots of sensation bar and control, it is possible to remain the steady of silent flatform.

Description

Parallel mechanism platform device for supporting bow gun

Technical Field

The invention relates to a support platform device of a warship bow gun, in particular to a support platform device of a warship bow gun with a parallel mechanism.

Background

The bow gun is a core part of the warship, the launching accuracy of the bow gun is related to the safety of the national sea area, and the bow gun has higher requirements on a support platform of the bow gun in order to improve the launching stability and accuracy of the bow gun.

At present, most of the designs of the primary cannon stabilizing platform adopt a two-degree-of-freedom platform capable of compensating the pitching and rolling of a ship, adopt a hydraulic driving system, and use a plurality of methods such as a sensor device, a servo control unit, a dynamic positioning system and the like to compensate pose errors caused by external unstable factors, so that the transverse and longitudinal oscillation of the ship is controlled to a certain extent.

The gyro stable platform is a most typical design scheme, and is applied to some weaponry due to the characteristics of simple structure, high precision, low cost and the like. In addition, the stable tracking platform based on the micro inertial sensor is widely applied to advanced weapons such as main warfare tanks and missile marine launching platforms. However, when a ship sails on the sea, the ship shakes due to the influence of various severe environmental factors such as wind, wave, tide and the like, the equipment bow cannon arranged on the ship can follow the swing of the ship, so that obvious rolling, pitching and hammering motions exist, and the large-amplitude swing of the ship under a high sea condition is difficult to compensate. Many naval vessels stabilized platform systems do not have wave motion compensation function now, make it reduce greatly to sway and heave under adverse conditions, let alone can keep relative quiescent condition all the time. Therefore, the launching precision of the bow gun can be influenced to a great extent, so that the high-precision striking performance of the bow gun is restricted, and the requirement of current development cannot be met.

Therefore, a new technical solution is needed to solve the above problems.

Disclosure of Invention

Aiming at the problems and the defects in the prior art, the invention aims to provide a parallel mechanism platform device for supporting a bow gun, which improves the stability of the bow gun.

In order to achieve the purpose, the parallel mechanism platform device for supporting the bow gun can adopt the following technical scheme:

a parallel mechanism platform device for supporting a bow gun is arranged on a ship body and used for bearing the bow gun.

Compared with the prior art, the invention has the advantages that: the parallel mechanism is applied to the support platform of the bow gun, so that the parallel mechanism platform device for supporting the bow gun is high in rigidity, strong in bearing capacity, high in precision and small in error, and can quickly respond to external force impact, and therefore stability and accuracy of launching of the bow gun are maintained. The applied parallel mechanism consists of an upper platform, a lower platform and six rods, wherein the six rods are connected with the movable platform and the static platform through spherical hinges. The upper platform is a static platform, and the stability of the upper platform can greatly improve the accuracy of the launching of the bow gun; the lower platform is a movable platform and is connected with the ship body, and under the impact of loads such as storms and the like, no matter the swinging of the movable platform is severe again, the stability of the static platform can be always kept through the adjustment and the control of the six rods.

Drawings

Fig. 1 is a schematic structural diagram of a parallel mechanism platform device for supporting a bow gun.

Fig. 2 is a control scheme schematic diagram of a parallel mechanism platform device for supporting a bow gun.

Figure 3 is a schematic diagram of a control system for a parallel mechanism platform assembly for supporting a bow gun.

Detailed Description

The present invention is further illustrated by the following detailed description in conjunction with the accompanying drawings, it being understood that the following detailed description is illustrative of the invention only and is not intended to limit the scope of the invention, which is to be given the full breadth of the appended claims and any and all equivalent modifications thereof which will occur to those skilled in the art upon reading the present specification.

As shown in fig. 1, the parallel mechanism platform device for supporting a bow gun of the present invention includes a static platform 1 (six-degree-of-freedom static platform) for bearing a bow gun 4, a movable platform 2 (six-degree-of-freedom movable platform) connected to a ship body (not shown), and six rods 3 connecting the static platform 1 and the movable platform 2, wherein the six rods 3 are connected to the movable platform 2 and the static platform 1 through spherical hinges (not numbered), the 6 spherical hinges of the movable platform and the static platform are respectively located in two planes, and each moving branch chain is composed of two spherical hinge pairs and one moving pair. The middle of the rod is driven by hydraulic pressure. The movable platform 2 generates pitching, rolling and hammering motion along with the ship impacted by the outside, and finally the relative stability of the launcher base (namely the parallel mechanism static platform) of the bow gun can be realized through all links of the control system schematic diagram of fig. 2, so that the launching precision of the bow gun is improved, and the design requirement is met.

At present, the analysis method of the parallel mechanism is more perfect, and the stability of the parallel mechanism can be completely achieved by applying the parallel mechanism to a support platform of a bow gun. Three sets of methods for parallel mechanism kinematics analysis forming system are as follows.

Vector analysis method: the inverse kinematics solution becomes easy and intuitive by the vector analysis method, but the relationship between the expected pose and the active joint and the passive joint is difficult to obtain.

Transformation matrix method: the transformation matrix method establishes the motion analysis of a mechanism based on D-H parameters, provides good conditions for the dynamics analysis, but is difficult and not intuitive in inverse kinematics solution.

Lie algebra: the motion spiral and the force spiral are used as basic quantities, the exponential mapping and the reciprocal operation are used as basic calculation, the exponential mapping is a state transition matrix in state space analysis, a modern control theory can be introduced into the control of a parallel mechanism, and the reciprocal operation (bearing brackets) is the popularization of a three-dimensional vector outer product.

The exponential mapping of the kinematics positive solution is established according to the lie algebra method, and the problem of the kinematics inverse solution is solved by adopting the analytical method. The high nonlinear problem of the kinematic positive solution of the parallel mechanism is converted into the Paden-kaha subproblem of joint space through exponential mapping, and the problem of the kinematic positive solution of the parallel mechanism is basically solved. And the jacobian matrix of each branch is used for judging whether the applied drive can not control some movements, namely the singular problem of the jacobian matrix. The accuracy and effectiveness of the methods are proved through experiments and analysis of actual parallel mechanisms.

For clarity of description, each branch and each kinematic pair is numbered. The kinematic pairs are numbered in the following manner_i,j(i 1.. 6, j 1.. 6). Wherein i represents the ith branched chain, and j represents the jth kinematic pair from the fixed platform. Theta_i,jThe joint variables representing the ith branched chain and the jth kinematic pair may be linear displacement or angular displacement. And numbering the rod pieces from the fixed platform, wherein the jth kinematic pair is connected with the j-1 member and the j member. The component 0 is a fixed platform, the component 6 is a movable platform, and the milling cutter and the movable platform can be regarded as fixedly connected. The joint space of the cross-bar type parallel machine tool consists of 36 variables, and the configuration space of the cross-bar type parallel machine tool consists of 6 independent variables, so that only 6 of the 36 joint variables are independent and 30 constraint conditions are required. For revolute pair joint variables of rotation angle, θ_i,j∈ [0,2 π), all joint angles are measured in the right-hand system, and the joint variables are displaced by lines θ for the mobile joint_i,j∈R¹To indicate.

The j motion pair direction vector of the ith chain is as shown in formula (1), wherein P_i,j、P_i,j+1The position vector of the ith motion pair axis of the ith chain is shown as a formula (2), wherein h is spiral pitch, the motion spiral coordinate of the jth motion pair of the ith chain is shown as a formula (3), the motion spiral of the jth motion pair of the ith chain (which belongs to a se (3) group) is shown as a formula (4), the exponential mapping of the jth motion pair of the ith chain is shown as a formula (5), the absolute coordinate system of the ith chain is shown as an exponential mapping formula (6), and the Jacobian matrix of the absolute coordinate system of the ith chain is shown as a matrix of 6 × 6 (7), a formula (8) and a formula (8)The velocity map of the i chain joint space and the working space is shown in formula (9). The mapping between the i-th chain joint force and the force acting on the cutter is shown in equation (10).

${\mathrm{\ω}}_{i,j}=\frac{\left(p_{i,j+1}-p_{i,j}\right)}{|p_{i,j+1}-p_{i,j}|}---\left(1\right)$

v_i,j＝-ω_i,j×p_i,j+h·ω_i,j(2)

ξ_i,j'＝[v_i,j ^T,ω_i,j ^T]^T(3)

${\widehat{{\mathrm{\ξ}}_{i,j}}}^{\′}=\left[\begin{array}{cccc}0& -{\mathrm{\ω}}_{i,j}\[3\]& {\mathrm{\ω}}_{i,j}\[2\]& v_{i,j}\[1\]\\ {\mathrm{\ω}}_{i,j}\[3\]& 0& -{\mathrm{\ω}}_{i,j}\[1\]& v_{i,j}\[2\]\\ -{\mathrm{\ω}}_{i,j}\[2\]& {\mathrm{\ω}}_{i,j}\[1\]& 0& v_{i,j}\[3\]\\ 0& 0& 0& 0\end{array}\right]---\left(4\right)$

gst(θ_i,1,θ_i,2,θ_i,3,θ_i,4,θ_i,5,θ_i,6)＝(6)

sd_i,1·sd_i,2·sd_i,3·sd_i,4·sd_i,5·sd_i,6·gst0

${{\mathrm{\ξ}}_{i,j}}^{\′}=\left({\mathrm{Ad}}_{\left({\mathrm{sd}}_{i,1}\·{\mathrm{sd}}_{i,2}\·\mathrm{..}\·{\mathrm{sd}}_{i,j-1}\right)}\right)\·{\mathrm{\ξ}}_{i,j}---\left(7\right)$

J_i＝[ξ_i,1',ξ_i,2',ξ_i,3',ξ_i,4',ξ_i,5',ξ_i,6'](8)

[v_x,v_y,v_z,w_x,w_y,w_z]^T＝(9)

[ξ_i,1',ξ_i,2',ξ_i,3',ξ_i,4',ξ_i,5',ξ_i,6']·[θ_i,1,θ_i,2,θ_i,3,θ_i,4,θ_i,5,θ_i,6]^T

τ＝[ξ_i,1',ξ_i,2',ξ_i,3',ξ_i,4',ξ_i,5',ξ_i,6']^T·[f_i,1,f_i,2,f_i,3,f_i,4,f_i,5,f_i,6]^T(10)

Formula (III) ξ_i,j' is the instantaneous motion helix of the ith chain and jth kinematic pair, which is a matrix of 4 × 4, and is an element of lie group.Is an exponential mapping of the ith chain, the jth kinematic pair, which is a matrix of 4 × 4.Is the adjoint transformation matrix of 6 × 6, the coordinates for the motion spiral represent the transformation from one coordinate system to another.

The main idea of the Paden-Kahan subproblem of parallel machine tool kinematic forward solution is to decompose a complex mechanism kinematic inverse solution into a plurality of inverse solution subproblems with definite geometric meaning, and then solve the problems step by step, i.e. a complex motion is decomposed into a plurality of continuous simple motions, and each simple motion can be represented by an exponential product of motion momentum. There are mainly 4 main problems of the Paden-kahan subproblem.

(1) A point is rotated about a fixed axis xi by an angle theta.

(2) A point rotates in turn about two intersecting axes in order.

(3) A point moves a distance along the fixed axis.

(4) One point orderly rotates to a position with a certain distance from the point around three intersecting axes in sequence, an angle constraint is added to change the positive problem of the kinematics into an inverse problem, and the solution is intuitive and simple in operation.

Six spherical hinges of the movable platform are fixed relative to the movable platform, and three line segments with fixed positions on the object are needed for determining the motion of the space object, the length of the three line segments is determined by the Fangwu problem, but the directions of the three line segments are not reflected, so the subproblem 4 is not determined, and the directions of the three line segments are determined by three included angles between the three line segments. The positive solution of the parallel mechanism can be solved by adding three constraints by three inner products.

When the parallel machine tool is processed, because only 6 rod lengths are active variables, the inverse solution algorithm is quick and visual, other passive joint variables can know the change condition through inverse solution, and further a path with small acceleration can be selected, and the path planning has optimized indexes, so that the inverse solution algorithm has many advantages and has superiority compared with a vector analysis method and a transformation matrix method.

The technical scheme adopted by the design for solving the technical problem is as follows: the ship 6 freedom degree stable platform is composed of an upper platform and a lower platform, the upper platform is a static platform for installing a bow gun, the lower platform is a movable platform fixed on the ship, and a static coordinate system and a movable coordinate system are respectively established on the upper platform and the lower platform. The static platform and the movable platform are connected through 6 telescopic rods, the position and the posture of the platform correspond to the length of a group of rods one to one, and the driving of the rods is realized by adopting a hydraulic servo system consisting of a sensor, a hydraulic cylinder, a hydraulic valve and a control system. When a ship sails on the sea or is in battle exercise, the ship is impacted by factors such as external wind and waves and can shake, at the moment, a movable platform fixed on a deck of the ship moves correspondingly along with the ship, corresponding kinematics and dynamics data of the movable platform in a movable coordinate system of the movable platform can be obtained through equipment such as a displacement sensor, an acceleration sensor and a monitoring device, the data in the coordinate system are converted through a rotating matrix, and corresponding pole length data can be obtained through computer processing under the condition that the upper platform is guaranteed to be kept relatively static. Therefore, the relative still of the pose of the static platform can be adjusted by controlling the corresponding rod length of the ship in real time when the pose is at a certain moment. The method is characterized in that the calculation of the rod length by the pose of the moving platform is an inversion process of the parallel mechanism, the input of a group of rod lengths to calculate the pose corresponding to the platform is the forward solution problem of the parallel mechanism, and in fact, the parallel mechanism platform device for supporting the bow gun is designed by firstly calculating and feeding back the inverse solution and then controlling the forward solution input, wherein the lengths of 6 rods corresponding to the pose of the given group of moving platform are calculated under the condition that the upper platform can be kept relatively static, and the change of the lengths of the 6 rods is controlled to meet the stability of the upper platform.

The center of a spherical hinge on the platform is taken as the origin of coordinates, the connecting line from the center of the spherical hinge to the center of the static platform is taken as the X axis, the vector of the static platform pointing to the dynamic platform is taken as the Z axis, and the Y axis is determined by the right-hand rule, so that the whole mechanism coordinate system is established.

The moving coordinate system O-XYZ is established on the moving platform, and the static coordinate system O '-X' Y 'Z' is fixed on the static platform. Any vector R' in the moving coordinate system can be transformed into the static coordinate system through a coordinate transformation method. Coordinate transformation formula

R＝[T]R'+P

Wherein: t is a direction cosine matrix of the attitude of the static platform, and P is a coordinate of the origin of the moving coordinate system in the fixed coordinate system.

Thus, 6 driver rod length vectors l_iCan be represented as in the static coordinate system

Thereby obtaining a position solution calculation equation of the mechanism

$l_i=\sqrt{{l_{ix}}^2+{l_{iy}}^2+{l_{iz}}^2},(i=1,2,3,4,5,6)$

The above formula is 6 independent explicit equations, and when the basic size of the mechanism and the position and the posture of the movable platform are known, the above formula can be used for solving the displacement of 6 drivers under the condition of the requirement of keeping the static platform relatively static, so as to determine the motion rule which each rod should meet. The main idea is that the coordinates of each hinge point in the moving coordinate system are transformed into coordinate representation in the static coordinate system through a coordinate transformation method, the length that each rod should meet can be calculated, so that the static platform can keep a relatively stable pose, and then the goal can be realized by controlling the rod length change in real time.

Fig. 2 is a schematic diagram of a system control scheme for implementing the desired functionality of the parallel mechanism of fig. 1. When a ship sails, shock excitation factors such as external wind, waves and the like impact a ship body to enable the ship body to swing, the movable platform is fixed on a deck of the ship, so that the movable platform loses stability like the ship to generate swing and shake to change the posture, generate changes such as displacement, speed, acceleration and the like, the data are transmitted to the control system by the sensor, the control system combines the data of the movable platform with the data of the posture, the displacement, the acceleration of the speedometer and the like of the static platform to obtain corresponding conclusion and judgment, sends corresponding commands to the servo motor controller, drives the rod length of 6 connecting rods to change by the servo valve controller, adjusts the pose of the static platform indirectly by adjusting the length of 6 rods, ensures that the static platform is relatively stable by coordinating the whole process through a certain feedback mechanism, and further ensures that the nose cannon can be interfered by external sea conditions and even is not interfered, the target striking accuracy required by the device is exerted to the maximum extent.

Fig. 3 is a parallel mechanism control system, which essentially takes the displacement and speed of a plurality of executing components (each motion axis) of the mechanism as control objects, and makes the static platform of the parallel mechanism always keep static, so as to provide a very stable launching environment for the naval head cannon, and is a computer control system equipped with a special self-adaptive system. The device consists of input and output equipment, a numerical control device, a driving device and a transposition device. The parallel mechanism platform mainly works by receiving various data information of the movable platform through various input modes, decoding the data information through a CNC device, processing and calculating the data information through a computer, converting the data information into the motion amount of each rod, sending the motion amount to a driving circuit of each rod, and driving a servo motor to drive each rod to move through conversion and amplification. And real-time position feedback control is carried out, so that the fixed platform is relatively stable, and a good condition is created for launching the carrier-based gun.

The function of a CNC device refers to methods and means to meet user operation and machine control requirements. The method comprises the following steps: a basic function and a selection function. The function of the CNC is mainly reflected on the preparation function G instruction code and the auxiliary function M instruction code. The preparation functions include basic movement, program pause, plane selection, coordinate setting, tool compensation, datum point return, fixed cycle, metric-to-english conversion, and the like. The auxiliary functions comprise starting and stopping of the spindle, steering of the spindle, switching of cutting fluid or starting and stopping of a tool magazine and the like. In addition, the system also comprises a feeding function, an interpolation function, a compensation function, a programming function, a character and graph display function, an input/output and communication function, a self-diagnosis function for automatically realizing fault prediction and fault positioning and the like.

The servo drive system is an automatic control system, also called a servo system or a drag system, which controls the position and speed of a moving member of a parallel mechanism. The servo system receives the feeding pulse from the interpolation device or interpolation software, converts the feeding pulse into the movement of 6 rods relative to a reference system through certain signal conversion, voltage amplification and power amplification, and is mainly realized through controlling feeding driving elements such as a stepping motor, a servo motor and the like. The parallel mechanism is a connection link between a numerical control system and a parallel mechanism transmission part, is an important component of the parallel mechanism of the carrier-based gun launching platform, accurately converts a position instruction generated by interpolation operation of the numerical control system into the motion of a carrier-based gun launching platform motion part, and directly reflects a parallel mechanism tracking motion instruction and actual positioning performance. The performance of the servo system determines the efficiency and precision of the numerical control machine tool to a great extent, and the servo system comprises mechanical transmission, electric driving, detection, automatic control and the like. The servo system of the parallel mechanism of the shipborne cannon launching platform meets the requirements of quick response characteristic, large speed regulation range, high precision, good system reliability and the like.

The D/A conversion circuit of the position control output component of the parallel mechanism platform consists of a buffer register, a binary counter, a numerical value detector, a direction control circuit and a comparison amplifier. The sensor receives the impact load and converts the impact load into a digital signal, and the digital signal outputs an analog voltage in a pulse width modulation mode. The buffer register stores a 16-bit (in the form of an inverse code) binary signal representing the following error. Each sampling period, a sampling pulse is sent out, and data and symbols on the data bus are read into the buffer register. The binary counter is an addition counter, the following error of the buffer register is delayed and then sent to the binary counter, the highest bit of the counter is a sign bit and is used for controlling the direction, the addition counting is started after the data is put in, and when the counter overflows, the number of pulses counted by the counter is equal to the absolute value of the following error. The pulse width is proportional to the following error. After the value is changed into pulse width, it is output by two NAND gates controlled by sign bit signal to distinguish direction. The sign bit is 0, and the rectangular wave signal is output by a positive terminal; otherwise, the output is from the negative terminal. The signal then enters a comparison amplifier which outputs a dc command voltage signal whose amplitude is indicative of the magnitude of the following error.

After the parallel mechanism platform is processed by the chip, the parallel mechanism platform is subjected to D/A conversion and then the servo motor is controlled to move by the position control unit. The photoelectric pulse encoder arranged on the motor generates sequential pulses along with the rotation of the motor. The pulse is fed back to the chip via the receiver and then split into two paths. One path is used as the feedback of the position quantity, and the other path is subjected to frequency voltage conversion and is sent to the speed control unit as a feedback signal of the speed quantity. If the chip is used for controlling the linear servo motor, only corresponding angle quantity is required to be converted into linear quantity.

In addition, the launching system of the warhead gun basically comprises a bullet launching gun barrel, a continuous bullet gun barrel and a gun body, and the swinging and rotation of the two gun barrels can realize zero collision through the kinematic and dynamic analysis of the gun barrels, so that the larger impact of the motion of the gun barrels on a platform is reduced.

Claims (1)

1. The utility model provides a parallel mechanism platform device for supporting first big gun of warship which characterized in that: the parallel mechanism platform device is arranged on the ship body and is used for bearing the bow gun; the device comprises a static platform for bearing a bow gun, a movable platform connected with a ship body and six rods for connecting the static platform and the movable platform, wherein the six rods are connected with the movable platform and the static platform through spherical hinges; the driving of the rod is realized by adopting a hydraulic servo system consisting of a sensor, a hydraulic cylinder, a hydraulic valve and a control system;

setting a moving coordinate system O-XYZ on a moving platform, and fixing a static coordinate system O '-X' Y 'Z' on a static platform; any vector R' in the moving coordinate system can be transformed into a static coordinate system by a coordinate transformation method; coordinate transformation formula

R＝[T]R'+P

Wherein: t is a direction cosine matrix of the attitude of the static platform, and P is a coordinate of the origin of the moving coordinate system in the fixed coordinate system;

vector quantityThe position coordinates of the end point of the driving rod on the static platform in the static coordinate system; vector quantityThe position coordinates of the end point of the driving rod on the movable platform in the static coordinate system; and is provided with a vectorRepresenting the coordinates of the end points on the movable platform in a movable coordinate system;

wherein ${\stackrel{\→}{a}}_i=\left[\begin{array}{c}{a}_{ix}\\ a_{iy}\\ 0\end{array}\right];{\stackrel{\→}{b}}_i^{\′}=\left[\begin{array}{c}{b}_{ix}\\ b_{iy}\\ 0\end{array}\right];$

The position coordinate of the origin of the moving coordinate system in the static coordinate system is $P=\left[\begin{array}{c}{X}_P\\ Y_P\\ Z_P\end{array}\right],$ Transformation matrix $T=\left[\begin{array}{ccc}{l}_x& m_x& o_x\\ l_y& m_y& o_y\\ l_z& m_z& o_z\end{array}\right],$ Each parameter respectively represents the direction cosine of the coordinate axis of the moving coordinate system relative to the coordinate axis of the static coordinate system; therefore, the coordinates of the end point of the driving rod on the movable platform in the static coordinate systemIs shown as

${\stackrel{\→}{b}}_i=\left[\begin{array}{c}{l}_x{b}_{ix}+m_x{b}_{iy}+X_P\\ l_y{b}_{ix}+m_y{b}_{iy}+Y_P\\ l_z{b}_{ix}+m_z{b}_{iy}+Z_P\end{array}\right];$

Thus, 6 driver rod length vectorsCan be represented as in the static coordinate system

Wherein i is 1,2,3,4,5,6

Thereby obtaining a position solution calculation equation of the mechanism

Wherein i is 1,2,3,4,5, 6;

wherein,andrespectively representing two endpoint coordinate vectors of the support rod;

the dynamic platform loses stability like a ship and generates swing and shake to change the posture, displacement, speed and acceleration changes are generated, a sensor is arranged to transmit displacement, speed and acceleration data to a control system, the control system combines the dynamic platform data with the posture, displacement and speedometer acceleration data of the static platform to obtain corresponding conclusion and judgment, a corresponding command is sent to a servo motor controller, the servo valve controller drives the rod length of 6 connecting rods to change, and the posture of the static platform is indirectly adjusted by adjusting the length of the 6 rods, so that the static platform is relatively stable.