• 대한기계학회논문집A
• /
• 제32권2호
• /
• pp.170-176
• /
• 2008

Anti roll bar model for real time multibody vehicle dynamics model has been proposed using kinematic constraint. Anti roll bar have been modeled by kinematic relationship, and mass properties are neglected. Relative angle of torsion bar spring is computed by constraint about drop-link using Newton-Raphson iteration, and then the torque of torsion bar spring can be computed with the angle and torsion spring stiffness. Finally anti roll bar force acting on both knuckle can be calculated. To validate the proposed method, half car simulations of McPherson strut suspension and full car simulations are also carried out comparing with the ADAMS vehicle model with anti roll bar. CPU times are also measured to see the real-time capabilities of the proposed method.

• International Journal of Aeronautical and Space Sciences
• /
• 제14권2호
• /
• pp.152-161
• /
• 2013

This paper presents a control effectiveness analysis of the hawkmoth Manduca sexta. A multibody dynamic model of the insect that considers the time-varying inertia of two flapping wings is established, based on measurement data from the real hawkmoth. A six-degree-of-freedom (6-DOF) multibody flight dynamics simulation environment is used to analyze the effectiveness of the control variables defined in a wing kinematics function. The aerodynamics from complex wing flapping motions is estimated by a blade element approach, including translational and rotational force coefficients derived from relevant experimental studies. Control characteristics of flight dynamics with respect to the changes of three angular degrees of freedom (stroke positional, feathering, and deviation angle) of the wing kinematics are investigated. Results show that the symmetric (asymmetric) wing kinematics change of each wing only affects the longitudinal (lateral) flight forces and moments, which implies that the longitudinal and lateral flight controls are decoupled. However, there are coupling effects within each plane of motion. In the longitudinal plane, pitch and forward/backward motion controls are coupled; in the lateral plane, roll and side-translation motion controls are coupled.

• Journal of Mechanical Science and Technology
• /
• 제15권8호
• /
• pp.1090-1096
• /
• 2001

In this paper, new methods for efficiently solving linear acceleration equations of multibody dynamic simulation exploiting sparsity for real-time simulation are presented. The coefficient matrix of the equations tends to have a large number of zero entries according to the relative joint coordinate numbering. By adequate joint coordinate numbering, the matrix has minimum off-diagonal terms and a block pattern of non-zero entries and can be solved efficiently. The proposed methods, using sparse Cholesky method and recursive block mass matrix method, take advantages of both the special structure and the sparsity of the coefficient matrix to reduce computation time. The first method solves the η$\times$η sparse coefficient matrix for the accelerations, where η denotes the number of relative coordinates. In the second method, for vehicle dynamic simulation, simple manipulations bring the original problem of dimension η$\times$η to an equivalent problem of dimension 6$\times$6 to be solved for the accelerations of a vehicle chassis. For vehicle dynamic simulation, the proposed solution methods are proved to be more efficient than the classical approaches using reduced Lagrangian multiplier method. With the methods computation time for real-time vehicle dynamic simulation can be reduced up to 14 per cent compared to the classical approach.

• 대한기계학회논문집A
• /
• 제24권7호
• /
• pp.1878-1884
• /
• 2000

In multibody dynamic analysis, one of the most important problems is to reduce computation times for real time simulation. In this paper, a symbolic computation method is implemented and tested for each dynamic analysis step. Applying symbolic formulations to the vehicle dynamics program AutoDyn7, the effectiveness of the symbolic computation method is verified.

• Journal of Mechanical Science and Technology
• /
• 제19권spc1호
• /
• pp.395-402
• /
• 2005

This paper deals with modeling and computer simulation of a full multibody vehicle model for a driving simulator. The multibody vehicle model is based on the recursive formulation and a corresponding simulation code is generated automatically from AUTOCODE, which is a symbolic computation package developed by the authors using MAPLE. The paper describes a procedure for automatically generating a highly efficient simulation code for the full vehicle model, while incorporating realistically modeled components. The following issues have been accounted for in the procedure, including software design for representing a mechanical system in symbolic form as a set of computer data objects, a multibody formulation for systems with various types of connections between bodies, automatic manipulation of symbolic expressions in the multibody formulation, interface design for allowing users to describe unconventional force-and torque-producing components, and a method for accommodating external computer subroutines that may have already been developed. The effectiveness and efficiency of the proposed method have been demonstrated by the simulation code developed and implemented for driving simulation.

• 한국자동차공학회논문집
• /
• 제9권6호
• /
• pp.186-194
• /
• 2001

To meet the challenge of testing increasingly complex automotive control systems, the real-time hardware-in-the-loop(HIL) simulation technology has been developed. In this paper, a strategy for evaluation of semiactive suspension systems using real-time HIL simulation is presented. A multibody vehicle model is adopted to simulate vehicle dynamic motions accurately. Accuracy of the vehicle simulation results is compared to that of the real vehicle field test and proven to be very accurate. The controller and stepping motor to adjust semi-active damper stage are equipped as external hardwares and connected to the real-time computer which has vehicle dynamic model. Open and closed loop test methods are used to evaluate a controlled suspension system and the system's operations are verified it is found that the proposed evaluation methods can be used well for the verification of semi-active suspension systems.

• 로봇학회논문지
• /
• 제15권3호
• /
• pp.233-239
• /
• 2020

The aims of this paper is to develop a modular agricultural robot and its autonomous driving algorithm that can be used in field farming. Actually, it is difficult to develop a controller for autonomous agricultural robot that transforming their dynamic characteristics by installation of machine modules. So we develop for the model based control algorithm of rotary machine connected to agricultural robot. Autonomous control algorithm of agricultural robot consists of the path control, velocity control, orientation control. To verify the developed algorithm, we used to analytical techniques that have the advantage of reducing development time and risks. The model is formulated based on the multibody dynamics methods for high accuracy. Their model parameters get from the design parameter and real constructed data. Then we developed the co-simulation that is combined between the multibody dynamics model and control model using the ADAMS and Matlab simulink programs. Using the developed model, we carried out various dynamics simulation in the several rotation speed of blades.

• 한국공작기계학회논문집
• /
• 제10권2호
• /
• pp.18-28
• /
• 2001

Super computers has been utilized to carry out vehicle dynamics in real time. This research propose an implicit integra-tion method for vehicle state variables. Newton chord method is empolyed to solve the equations of motion and con-straints. The equations of motion and constraints are formulated such that the Jacobian matrix for Newton chord method is needed to be computed only once for a dynamic analysis. Numerical experiments showed that the Jacobian matrix generat-ed at the initial time could have been utilized for the Newton chord iterations throughout simulations under various driving conditions. Convergence analysis of Newton chord method with the proposed Jacobian updating method is carried out. The proposed algorithm yielded accurate solutions for a prototype vehicle multibody model in realtime on a 400 MHz PC compatible.

• 한국자동차공학회논문집
• /
• 제14권4호
• /
• pp.199-206
• /
• 2006

Real time vehicle dynamics models have been developed with the subsystem synthesis method for intelligent vehicle HILS system. Three different models for solving subsystem equations are compared in order to find out the best suitable model for HILS applications. The first model is based on the generalized coordinate partitioning technique, and the second one is on the approximate function approach, and the last one is on the constraint stabilization method. To investigate the theoretical efficiency of three proposed methods, arithmetic operators used in the formulations of three models are counted. Bump run simulations with half-sine bump have also carried out with three different models to measure the actual CPU time to validate theoretical investigation.

• 한국자동차공학회논문집
• /
• 제13권1호
• /
• pp.109-118
• /
• 2005

A functional suspension model is proposed as a kinematic describing function of the suspension that represents the relative wheel displacement in polynomial form in terms of the vertical displacement of the wheel center and steering rack displacement. The relative velocity and acceleration of the wheel is represented in terms of first and second derivatives of the kinematic describing function. The system equations of motion for the full vehicle dynamic model are systematically derived by using velocity transformation method of multi-body dynamics. The comparison of field test results and simulation results of the ADAMS/Car demonstrates the validity of the proposed functional suspension modeling method. This model is suitable for real-time vehicle dynamics analysis.