KR100523445B1 - Real Time Simulation for a Track Vehicle - Google Patents

Abstract

The present invention divides the entire track into unit tracks, and by combining the unit tracks sequentially, six degrees of freedom can be expressed as a single degree of freedom exercise model. Tracked vehicle) method and a computer-readable recording medium recording the same,

According to the present invention, in the real-time simulation method of a tracked vehicle using a computer system, the form of the entire track is inputted by the combination of the unit tracks in a state in which the unit tracks are divided into several unit tracks according to the track type. Receiving a first initial value for the first step; The acceleration, the speed, the position coordinates, the time and the attitude angle of the vehicle in the first unit track section are calculated using the geometric information about the first initial value and the unit track, and the first initial value and the calculated result are included in a table. A second step of storing; Until the calculation for all the unit tracks input by the user is completed, the result value calculated in the previous unit track section is input as the second initial value of the next unit track, and the input second initial value and each unit track A third step of calculating an acceleration, a speed, a position coordinate, a time, and an attitude of the vehicle by using the geometric information and storing the same in a table; A fourth step of calculating an angular change rate by using a posture angle obtained by linearly interpolating a time interval of each unit track module at a predetermined sampling interval when calculation of all unit tracks is completed; And a fifth step of performing a simulation using the acceleration, the speed, the position coordinate, the time, the attitude angle, and the calculated angular change rate of the vehicle stored in the table for each unit track.

Description

Real time simulation method of tracked vehicle and recording medium recording the same {Real Time Simulation for a Track Vehicle}

The present invention relates to a real-time simulation method of a track vehicle and a recording medium recording the same. More particularly, the six tracks are divided into unit tracks and six unit degrees of freedom are combined by sequentially combining the unit tracks. The present invention also relates to a method for realizing a track vehicle (entertainment track vehicle) simulation in real time in a general personal computer and a computer-readable recording medium recording the same.

In general, six degrees of freedom motion has a linear motion in three directions and a rotational motion in three directions. Linear movement in the x-axis is called sway, linear movement in the y-axis is called surge, and linear movement in the z-axis is called heve. The rotational movement on the x-axis is called a pitch, the rotational movement on the y-axis is called a roll, and the rotational movement on the z-axis is called a yaw.

An exercise model is the center of information that conveys information about the subject's movement to other subsystems. Such exercise information is transmitted to the imaging system to represent a visual expression, and also transferred to the exercise system to realize a person's exercise cognitive ability as if in reality. This simulation environment is suitable for building a hardware-in-the-loop simulation (HILS) environment because computer software and mechanical devices form a simulation loop. In order to satisfy the time constraints of the simulation, a real-time scheduler is applied, and real-time simulation can be implemented through this.

However, in real-time simulation, if one module experiences a time delay, there will be a time delay in the other modules that make up the entire system. This time error gradually accumulates, resulting in a significant time delay over the entire simulation time. Real-time simulations require as little computational motion as possible.

Most conventional models of tracked vehicles describe the motion of the target in detail, assuming the vehicle body is a rigid body, while the computational load is high for simulation because of a large amount of computation. In other words, the model of a conventional tracked vehicle is represented by six degrees of freedom (DoF) motion in the representation of a rigid body, which calculates six quadratic differential equations and increases the cumulative error due to integration over time. . Therefore, the hardware performance requirements of the system required for the calculation are increased, which increases the development cost of the entire system.

Accordingly, the present invention is to solve the problems of the prior art as described above, the present invention is to divide the entire track into a unit track, by expressing the six degrees of freedom motion in a one degree of freedom exercise model by combining the unit tracks sequentially Accordingly, an object of the present invention is to provide a simulation method capable of real-time simulation of a training or recreational track vehicle in a general personal computer and a computer-readable recording medium recording the same.

In the present invention for achieving the above object, in the real-time simulation method of a tracked vehicle using a computer system, in the state divided into several unit tracks according to the type of track, the form of the entire track is input by the combination of the unit tracks A first step of receiving a first initial value for the first unit track; The acceleration, the speed, the position coordinates, the time and the attitude angle of the vehicle in the first unit track section are calculated using the geometric information about the first initial value and the unit track, and the first initial value and the calculated result are included in a table. A second step of storing; Until the calculation for all the unit tracks input by the user is completed, the result value calculated in the previous unit track section is input as the second initial value of the next unit track, and the input second initial value and each unit track A third step of calculating an acceleration, a speed, a position coordinate, a time, and an attitude of the vehicle by using the geometric information and storing the same in a table; A fourth step of calculating an angular change rate by using a posture angle obtained by linearly interpolating a time interval of each unit track module at a predetermined sampling interval when calculation of all unit tracks is completed; And a fifth step of performing a simulation by using the acceleration, the speed, the position coordinate, the time, the attitude angle, and the calculated angular change rate of the vehicle stored in the table for each unit track.

Preferably, after the calculation of one unit track is completed, if the error is found by performing the validity of the unit track, the method further comprises the step of notifying the user of the error occurrence.

Preferably, validation of each unit track is made by calculating the kinetic energy, the potential energy and the loss energy and comparing it with the energy that the vehicle had at the beginning of each unit track section.

Also preferably, the attitude angle is calculated using the dot product calculation of the vector, and the change in the calculated angle is continuously accumulated during the simulation so that the attitude angle is expressed.

In addition, the present invention, in the computer to simulate the track vehicle in real time, in the state divided into several unit tracks according to the type of track, the form of the entire track by the combination of the unit track is input, A first step of receiving a first initial value; The acceleration, the speed, the position coordinates, the time and the attitude angle of the vehicle in the first unit track section are calculated using the geometric information about the first initial value and the unit track, and the first initial value and the calculated result are included in a table. A second step of storing; Until the calculation for all the unit tracks input by the user is completed, the result value calculated in the previous unit track section is input as the second initial value of the next unit track, and the input second initial value and each unit track A third step of calculating an acceleration, a speed, a position coordinate, a time, and an attitude of the vehicle by using the geometric information and storing the same in a table; A fourth step of calculating an angular change rate by using a posture angle obtained by linearly interpolating a time interval of each unit track module at a predetermined sampling interval when calculation of all unit tracks is completed; And a program for executing a fifth step of performing a simulation using the acceleration, the speed, the position coordinate, the time, the attitude angle, and the calculated angular change rate of the vehicle stored in the table for each unit track. To provide.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a flowchart of the entire process of a real-time simulation method of a tracked vehicle according to the present invention.

First, in the present invention, in order to calculate the motion of the tracked vehicle by unit tracks, eight types of straight sections, tunnel sections, uphill hills, downhill hills, left curves, right curves, loops, and twists are divided into different unit tracks. In the curve, uphill, and downhill tracks, some tracks of different sizes are added to be divided into 14 unit tracks, and each unit track is assigned a unique code (101). When the user determines the shape of the desired entire track by combining the unit tracks while looking at the shape of the divided unit tracks, the determined total track shape is stored 102 and an initial state is input from the user (103). In addition, the geometric information of the first unit track is received (104). When the initial state and the geometric information are input, the selected unit modules are sequentially performed to calculate and store the acceleration, the speed, the position coordinates, and the attitude angle of the vehicle in each unit track (105).

The shape data of the track for each unit track is determined by the input value of the exercise model. In order to graphically express each unit track, the position coordinates x, y, z for each sampled point and the rotation angles φ, θ, and ψ on each axis are calculated, and are formed and stored in a data table for each unit track. At this time, since the coordinate system of the graphic coordinate system and the motion model are different, the coordinates should be converted and calculated on the same coordinate system.

Looking at the calculation process in each unit track in more detail as follows.

In the motion of the tracked vehicle, the only forces acting on the vehicle body are gravity and frictional forces, and since the vehicle is in motion constrained to the shape of the track, the shape of the track soon determines the motion of the vehicle. The translation and rotation of the vehicle are directly determined by the shape of the track, and the vehicle's movement appears as a mixture of the two. Since the motion of the vehicle can be seen as a single degree of freedom confined to the track, the position and attitude of the vehicle every hour is determined by the shape of the track. Basically, the system in which gravity acts is the absolute reference coordinate, and to convert it to the force acting on the vehicle, the body coordinate system is defined using the definition of Euler rotation transformation as shown in Equation 1 below. Must be converted to

By using the inverse transformation of the rotation matrix in Equation 1, the force acting on the vehicle in the fuselage coordinate system can be calculated. The force acting on the mass in the inertial system is defined by Newton's second law (F = ma), so if you know the force and mass, you can find the acceleration. The acceleration thus obtained is the acceleration acting on the vehicle in the fuselage coordinate system. In this case, the friction force between the track and the vehicle can be considered as the vehicle progresses on the track. The frictional force is a force acting opposite to the traveling direction of the vehicle in the fuselage coordinate system and can be expressed as Equation 2. The coefficient of friction μ is a value that can vary depending on the material of the track.

In other words, the force term in Newton's second law can be obtained by the inverse transformation of Equation 1, wherein the propagation direction component applies the friction force as in Equation 2. Since the movement of the vehicle is constrained to the track, no effective force is applied except in the direction of travel. After all, the force component in Newton's second law can be expressed as Equation 3. Since the whole vehicle is regarded as a quality, substituting Equation 3 in Newton's second law and dividing both sides by mass leaves only the acceleration term.

This is an acceleration component that affects the vehicle, and since it is a value in the body coordinates of the vehicle, the translational acceleration of the vehicle can be known by converting it into an absolute reference coordinate system. By integrating this, the speed and position of the vehicle can be known at every reference time.

Acceleration acting on one material point becomes tangential acceleration in the absolute reference coordinate system. The distance between the nth and n + 1th points is called s and the coordinates of each point and the initial velocity at the minute interval can be made as shown in Equation 4.

The solution of Equation 4 is obtained as Equation 5 below.

Since the acceleration can be known from Newton's second law and equation (3), it is possible to know the traveling direction speed of the vehicle in the minute section as shown in equation (6).

Velocity is also a tangential velocity, so if it is converted into a velocity component in absolute reference coordinates,

By multiplying each velocity component of Equation 7 by the time required in Equation 5, the positions in the x, y, and z-axis directions can be known.

In a curve track, when the vehicle moves, yaw, which is a rotational movement in the z-axis direction, and rolling, which is a rotational movement in the y-axis direction, occur together, and the centrifugal force, gravity and the vertical drag on the track's vehicle Since the force balance should be achieved, the following relation is established.

In Equation 8, v is the entry speed of the curve section, ρ is the radius of curvature of the curve section, g is the gravitational acceleration. By using Equation 8, a bank angle of a curve section may be obtained.

In the present invention, the calculation type of the unit track is largely divided into four types: a curve, an uphill, a downhill, and a twist. Here, the twist is a very complex motion, especially where all three axes of rotation are used, so the modeling of the twisted track is configured differently than the modeling of any other unit track. In the case of track, uphill, and downhill tracks, the types are divided according to the track size. In this case, if the graphics data is changed to a different track size and a motion operation is attempted, the tracks having different sizes are used. Can implement the movement.

When the values for each unit track are calculated and stored in this way, the unit tracks must now be integrated. What is important when integrating into full modeling using modules modeled by unit track is the interconnection of the data between the unit tracks. Since the last position of the preceding unit track is the initial position of the later unit track, these values must be connected to each other. In order to connect the two unit tracks with each other, the vehicle's position, attitude, direction of rotation and travel time must be considered.

The attitude of the vehicle is determined by the shape of the track. However, in order to determine the attitude value for each train position, it is necessary to newly calculate the attitude angles φ, θ, and ψ using the position coordinates (105). Although the motion model of the track vehicle was modeled as a 1 degree of freedom motion, the actual vehicle motion is a motion in which all 6 degree of freedom behaviors realized by the track are expressed.

The method of calculating the attitude angle uses an inner product operation of a vector. The angle between two vectors is obtained by applying vector product calculations, and the change of the calculated angle is continuously accumulated during the simulation to express the attitude angle. For example, continuously add angles such as 0 ° to 360 °, 370 °, 400 °, and 500 ° so that the amount of change between angles changes continuously so that the amount of change in the angle is evenly calculated when calculating the angular rate. .

In addition, in order to represent the phenomenon in which rolling and yawing occur together in the track of the curve, the method of determining the direction angle ψ is selected using the calculation result of the turning angle φ. When the direction angle ψ is 45 °, the turning angle φ is obtained so that the best value is obtained, and the turning angle is inversely proportional to the turning radius ρ and is proportional to the entry speed ν of the curve section. In addition, the angle of rotation is limited so as not to exceed a certain value to implement the curve motion safely. Finally multiply the Proportional Gain to adjust the degree of turning angle. Therefore, using the turning angle obtained from Equation 8, the turning motion algorithm is performed as shown in Equation 9 together with the direction angle ψ. Through the above process, the position coordinates x, y, z of the vehicle, the attitude angles φ, θ, ψ of the vehicle, and the translational acceleration a _x , a _y , a _z and the attitude angles of the vehicle using the coordinate transformation A total of 13 variable values of the angular velocity p, q, r, which is the rate of change of, and the running time t are obtained through the calculation.

In this way, the calculation module of the unit track is sequentially performed according to the type of the entire track input by the user. At this time, the calculated result of the previous unit track module becomes the first input value of the next unit track module. Validation 106 of each unit track is performed immediately after the calculation of the unit track module is completed, and if the validation passes, the operation of the next unit track is started (108). If an error is found in the validation check, the user is notified that an error has occurred (107), and new track shape information is input from the user (102). If no error is found as a result of validation of each unit track, a calculation for the next unit module is performed (108).

Looking at the validation, as can be seen from the mathematical model of the vehicle, both the friction force to counter the movement of the vehicle and the vertical force acting in the vertical direction to the vehicle are the reaction force that the track gives to the vehicle. These vector forces can be summed up to calculate the load (F _struc ) the vehicle acts on the track structure upside down. In addition, since the speed and height of the vehicle (the difference between the initial position and the current position of the vehicle) are known in the minute section of the unit track, the kinetic energy and the position energy can be calculated. And, if the energy lost is calculated separately and all the energy (kinetic energy, potential energy, and lost energy) is added, it must be equal to the energy that the vehicle originally had. Using this principle, the energy that is the source of energy-vehicle movement originally possessed by the vehicle has a relationship with the sum of all the energies calculated in the current state of the vehicle and the following equation (10).

This principle is used to validate unit tracks. If the verification result is an error, the user is notified. There may be various methods such as a screen display and a sound display.

In the above calculation method, the length of the minute section is known and the time required to pass the section is obtained. However, since the time intervals are not all constant, the interpolation should be performed at a constant sampling interval through linear interpolation (109). The interpolation process is necessary because the data calculated in the exercise module must be transferred to another system at regular time intervals. In the interpolation process, the motion information of a certain section is calculated based on the time axis based on the motion information of the vehicle. This data is then passed to other subsystems that make up the simulator around the movement model, which is then synchronized to the dynamics system, the visual system, and the motion system. If so, the simulation is performed (110, 111).

In order to know how accurate and how reliable the simulation result according to the present invention was, the result data was compared and verified in terms of quantitative and qualitative. In the quantitative sense, the friction between track and vehicle was not considered. Considering the law of conservation of energy in the first BIG SLOPE drop to ground, the height of the big hill is 210m, so the speed should be 64.189 [m / s] when the vehicle descends to the ground. Extracting the simulation results into the data table, it was confirmed that the velocity at the ground became 64.289 [m / s], which had a quantitative error of 0.156 (%). Qualitatively, since there is graphics data for the track, it can be seen that the trend is the same as in FIG.

As described above, it was found that the present invention can be simulated to some degree. Next, the trajectory of the vehicle's motion is considered in FIG. 3 considering the frictional force, and the acceleration, attitude angle, and angular velocity in the motion are shown in FIGS. 4, 5, and 6, respectively.

Therefore, the present invention as described above, by expressing a number of vehicles in one rigid body, by expressing the six degrees of freedom motion of the rigid body to express the dynamic characteristics of the vehicle by the motion of the material point having one degree of freedom, one of the six differential equations By expressing the differential equation and the five algebraic equations, the three-dimensional motion of a rigid body can be expressed with equal fidelity. As a result, the present invention enables a simulation in which a real-time time constraint condition is satisfied even in a general PC, and can present the accuracy required to a track vehicle, a training or a recreation simulator.

1 is an overall processing flow diagram of a simulation method according to the present invention.

Figure 2 is a graph showing the verification results of the simulation using the present invention.

Figure 3 is a graph showing the motion trajectory of the vehicle according to the present invention.

Figure 4 is a graph showing the translational acceleration in the fuselage coordinate system of the vehicle motion according to the present invention.

5 is a graph showing the accumulated attitude angle of the vehicle motion according to the present invention.

Figure 6 is a graph showing the angular velocity in the fuselage coordinate system of the vehicle motion according to the present invention.

Claims (6)

In a real-time simulation method of a tracked vehicle using a computer system, A first step of inputting a shape of all tracks by a combination of the unit tracks and receiving a first initial value for the first unit track in a state in which the unit tracks are divided into several unit tracks according to the type of tracks; The acceleration, the speed, the position coordinates, the time and the attitude angle of the vehicle in the first unit track section are calculated using the geometric information about the first initial value and the unit track, and the first initial value and the calculated result are included in a table. A second step of storing; Until the calculation for all the unit tracks input by the user is completed, the result value calculated in the previous unit track section is input as the second initial value of the next unit track, and the input second initial value and each unit track A third step of calculating an acceleration, a speed, a position coordinate, a time, and an attitude of the vehicle by using the geometric information and storing the same in a table; A fourth step of calculating an angular change rate by using a posture angle obtained by linearly interpolating a time interval of each unit track module at a predetermined sampling interval when calculation of all unit tracks is completed; And And a fifth step of performing simulation using the acceleration, the speed, the position coordinate, the time, the attitude angle, and the calculated angular change rate of the vehicle stored in the table for each unit track. The method of claim 1, After the calculation of one unit track is completed, the step of performing the validation of the calculation of the completed unit track, further comprising the step of notifying the user that the error occurred if an error is found, wherein the validation of the unit track And calculating the kinetic energy, the potential energy and the lost energy in any unit track section, and comparing the kinetic energy with the potential energy and the lost energy at the beginning of any unit track. Real time simulation method of tracked vehicle. delete The method of claim 2, The attitude angle is calculated using a dot product calculation of a vector, and the change of the calculated angle is continuously accumulated during a simulation so that the attitude angle is represented. delete On a computer to simulate a tracked vehicle in real time, A first step of inputting a shape of all tracks by a combination of the unit tracks and receiving a first initial value for the first unit track in a state in which the unit tracks are divided into several unit tracks according to the type of tracks; The acceleration, the speed, the position coordinates, the time and the attitude angle of the vehicle in the first unit track section are calculated using the geometric information about the first initial value and the unit track, and the first initial value and the calculated result are included in a table. A second step of storing; Until the calculation for all the unit tracks input by the user is completed, the result value calculated in the previous unit track section is input as the second initial value of the next unit track, and the input second initial value and each unit track A third step of calculating an acceleration, a speed, a position coordinate, a time, and an attitude of the vehicle by using the geometric information and storing the same in a table; A fourth step of calculating an angular change rate by using a posture angle obtained by linearly interpolating a time interval of each unit track module at a predetermined sampling interval when calculation of all unit tracks is completed; And And a program for executing a fifth step of performing a simulation using the acceleration, the speed, the position coordinate, the time, the attitude angle, and the calculated angular change rate of the vehicle stored in the table for each unit track.