Showing papers on "Vehicle dynamics published in 1989"

Automotive Powertrain Modeling for Control

Abstract: A dynamic model of an automotive powertrain system is developed by the use of eight states and two time-delays in the continuous-time domain, with careful attention given to the dynamics and kinematics of a four-stroke spark-ignition engine, an automatic transmission, and rubber tires. The model is relatively simple, yet it predicts the important dynamics quite well when compared to experimental data. The model is well suited for developing powertrain controllers and can also be used for studying the dynamic behavior of a powertrain system

Planning mobile manipulator motions considering vehicle dynamic stability constraints

Abstract: The high-speed motions of mobile manipulators can dynamically disturb their vehicles, even to the point where they can cause a vehicle to tip over. A planning method is presented which insures that such dynamic disturbances do not exceed the capabilities of a vehicle, and compromise its stability, while permitting a mobile manipulator to perform its tasks quickly. The method is an extension of an algorithm for fixed-base manipulators and has been implemented in a CAD system with extensive computer graphics. The technique can also determine if any proposed manipulator motion plan, optimal or conventional, results in dynamic forces which exceed the capabilities of a vehicle and result in either a statistically or dynamically unstable system. The technique is applied to a representative system in which there is significant friction between the vehicle and ground. The results suggest that the algorithm may be an effective planning tool for such mobile manipulators. The technique has also been found to be effective for planning the motions of spacecraft-mounted manipulators. >

An application of generalized predictive control to rotorcraft terrain-following flight

Abstract: Generalized predictive control (GPC) describes an algorithm for the control of dynamic systems in which a control input is generated which minimizes a quadratic cost function consisting of a weighted sum of errors between desired and predicted future system output and future predicted control increments. The output predictions are obtained from an internal model of the plant dynamics. The GPC algorithm is first applied to a simplified rotorcraft terrain-following problem, and GPC performance is compared to that of a conventional compensatory automatic system in terms of flight-path following, control activity and control law implementation. Next, more realistic vehicle dynamics are utilized and the GPC algorithm is applied to simultaneous terrain following and velocity control in the presence of atmospheric disturbances and errors in the internal model of the vehicle. The online computational and sensing requirements for implementing the GPC algorithm are minimal. Its use for manual control models appears promising. >

Modelling, design and analysis of an autopilot for submarine vehicles

Abstract: This work presents the modelling, analysis, preliminary design and build-up of a prototype of a submarine autopilot. The autopilot is designed to perform two different missions: depth­ keeping near the sea surface and depth changing control. The vehicle dynamics are simulated by a non-linear model, whose coefficients are evaluated by the equivalent ship method. A solution of the control problem is obtained using optimal control techniques. The system state is estimated using the Kalman filter asso­ ciated with the dynamical model compensation technique. A simplified filter was also used for real time state estimation. The prototype consists of a microcomputer with analog-digital inter­ faces for input-output signals. A digital simulation of submarine manoeuvres was done and the results indicate a good performance for the autopilot, even under severe conditions. Other tests showed the accuracy of the non-linear model and the technical feasibility of the prototype.

Longitudinal Control of a Platoon of Vehicles I: Linear Model

Abstract: This paper presents a systematic analysis of a longitudinal control law of a platoon of vehicles using a linear model to represent the vehicle dynamics of each vehicle within the platoon Recent advances in communication and measurement are employed in the study of longitudinal control of a platoon of vehicles

Kinematics, Dynamics, and Control of Omnidirectional Vehicles with Mecanum Wheels

Abstract: Vehicles equipped with so-called mecanum wheels can translate in any direction and rotate on the spot without slippage though the axes of the wheels are fixed in the vehicle body. This paper presents an analysis of the kinematics, dynamics, and control of such vehicles.

A Discrete-Time Robust Vehicle Traction Controller Design

Abstract: A discrete-time robust vehicle traction control algorithm, which includes anti-skid braking and anti-spin acceleration, is proposed. It is a nonlinear feedback scheme and can be designed via classical digital control theory. From a practical viewpoint, it is easy to tune and to modify to incorporate higher order dynamics, which may be unique in particular hardware setup. The robust controller in this paper provides stable and reliable performance under a vast amount of uncertainties involved in the vehicle/brake system, which are either difficult to measure or costly to obtain. The effectiveness of this new scheme is demonstrated by experiments on anti-skid braking.

Directional Dynamics Considerations for Multi-Articulated, Multi-Axled Heavy Vehicles

Abstract: Directional performance characteristics of heavy truck combinations are reviewed with respect to the influences of multiple axles and articulation points The performance characteristics considered include steady turning, directional stability, and forced responses in obstacle avoidance maneuvers The review provides useful insights to engineers interested in the handling and safety qualities of these types of vehicles (A) For the covering abstract of the conference see IRRD 860578

Dynamic model and self-tuning adaptive control of an underwater vehicle

Abstract: An adaptive controller is designed for the position control of an underwater vehicle used in the exploitation of combustible gas deposits at high depths. A mathematical model of the vehicle dynamics is introduced for the verifications of the project choices. The design of the adaptive control is obtained by application of a self-tuning controller with the minimisation of an appropriate cost function. Performance of the controller is determined by simulation tests, corresponding to different environment and loading conditions. The results indicate that an adaptive controller is an efficient solution for the real implementation of the position control of the vehicle.

Adaptive Identification and Control of an Autonomous Underwater Vehicle

Abstract: An adaptive controller for dive maneuvering of a submersible is presented. Main feature is that it performs adaptive pole placement of the closed loop system, based on the estimated dynamics. While the linear compensator adapts in the presence of changing operating conditions, a nonlinear controller along the lines of the Variable Structure (VS) approach guarantees robustness in the presence of nonlinearities and unmodelled dynamics.

Formulation of a Basic Building Block Model for Interaction of High Speed Vehicles on Flexible Structures

Abstract: In traditional analyses of vehicle/structure interaction, especially when there are constraints between vehicule masses and the structure, vehicle nominal motion is prescribed a priori, and therefore unaffected by the structure flexibility. In this paper, a concept of nominal motion is defined. General nonlinear equations of motion of a bulding block model, applicable to both wheel-on-rail and magnetically levitated vehicles, are derived

Modeling, Sliding Mode Control Design, and Visual Simulation of Auv Dive Plane Dynamic Response

Abstract: A sliding mode autopilot for depth control of an Autonomous Underwater Vehicle (AUV) is designed. The controller is evaluated for a linear model and optimized by a series of numerical experiments for a number of depth changing maneuvers. The effects of varying control parameters is discussed. Controller performance is assessed by visual simulation of AUV dynamic response based on the full six degree of freedom nonlinear equations of motion. This graphical simulation provides an efficient testbed for control design assessment. The robustness of the sliding mode control law is demonstrated by comparison between predicted and actual vehicle response characteristics. Suggestions for design improvement and directions for future research are indicated. Finally, the presentation includes a video of the diving performance obtained as seen through the visual simulator.

Nonlinear Longitudinal Control of a Supermaneuverable Aircraft

Abstract: This paper describes a technique which can be used for design of feedback controllers for high performance aircraft operating in flight conditions in which nonlinearities significantly affect performance. Designs are performed on a math model of the longitudinal dynamics of a hypothetical aircraft similar to proposed supermaneuverable flight test vehicles. Nonlinear controller designs are performed using truncated solutions of the Hamilton-Jacobi-Bellman equation. Preliminary results show that the method yields promising results.

Design and Experimental Verification of a Model Based Compensator for Rapid Auv Depth Control

Abstract: A model based autopilot for rapid depth control of an autonomous underwater vehicle is designed and installed in a small model experimental vehicle. The compensator is evaluated and verified by a series of experiments for a number of depth changing maneuvers. A systematic series of tests is performed to assess the effects of varying hydrodynamic parameters and control gains. The influence of the heave-pitch coupling is described in terms of the least squares fit of model to experimental open loop responses, which then form the basis of the closed loop antopilot design. The influence of sensor bias, parameter mismatch, and disturbances are discussed. The paper presents the design parameters of the small model vehicle and the presentation includes a video of the diving performance obtained when the compensator is properly designed. A conclusion is that control performance will be further enhanced by the incorporation of parameter adaption, as presented in a companion paper.

Controllability and Stability Aspects of Actively Controlled 4WS Vehicles

Abstract: Four wheel steering (4WS) of passenger cars has become a topic of interest in recent vehicle dynamics literature. In the present work, a linear two -degree of freedom (L2DF) model has been used to examine controllability and stability aspects of various 4WS algorithms. Yaw rate r and lateral velocity v were used as model degrees of freedom, and as state feedback variables for the implementation of 4WS controllers of various types. With controllers developed using the L2DF model, investigations were performed into the performance of such controllers when implemented using a nonlinear three-degree of freedom (N3DF) model which included roll and the possibility of tire saturation. Desirable steady-state properties for y and r can be obtained using the robust controllers developed through the use of the L2DF model. Finally, the stability of the system is shown to depend upon tire cornering stiffness, and is examined both qualitatively and quantitatively.

Planning Movements for Several Coordinated Vehicles

Abstract: This paper describes a two-level controlling system for a set of non-holonomic vehicles moving in a dynamic universei.e. among static and moving objects-. The higher level is concerned with planning a trajectory for each vehicle whereas the execution of the plan is distributed at the level of each vehicle. This paper focuses on the higher level i.e. the global planner. Our approach consists in first assigning priorities to the vehicles and then in planning motions one vehicle at a time. For that purpose, we make use of a path/velocity decomposition and of techniques to deal with the kinematic constraints of the vehicles. Planning the velocity parameters is then achieved by temporally allocatiiig “conflict regions” to the vehicles. In order to deal with the uncertainty introduced by the changes of the universe, tlic globill p1;iniicr operatos periodidly on a given interval of time.

Energy based stability analysis of a fuzzy roll controller design for a flexible aircraft wing

Abstract: A fuzzy-logic-based roll controller design is presented for the experimental advanced technology wing (ATW). The ATW integrated active controls with flexible structural dynamics for enhanced performance. The authors initially designed and tested controllers using classical control design concepts, but the high level of model uncertainties and the many approximations in the real-time system dynamics led them to investigate a fuzzy-logic-based system. The design, performance simulation, controller performance, and stability analysis of the fuzzy controller are described. The stability analysis considers a continuous-time dynamic model combined with a discrete-time fuzzy controller. An energy-based technique using Lyapunov theory is then applied. The analysis shows that the control system is stable. >

Development and validation of a general vehicle dynamics simulation (NUCARS)

Abstract: NUCARS (New and Untried Car Analytic Regime Simulation) is a general-purpose program for modeling rail vehicle transient and steady-state response. NUCARS models the interaction of an arbitrary number of rigid or flexible bodies joined by suspension-element-type connections. Means are provided for varying the number and identity of the degrees of freedom chosen for each body. The potential choices include all translational and rotational body degrees of freedom and the first flexible modes (for all bodies, excluding the wheelsets) in twist and in vertical and lateral bending. All connections must be assigned a stiffness and/or damping characteristic. Rigid connections are given large stiffnesses. The representation of connection location and of forces through the connections is chosen to minimize the program memory required. NUCARS is coded in Fortran 77 for use on IBM-compatible personal computers. Three vehicle dynamics applications are presented, including results of validation testing with a lightweight, two-axle, intermodal car. >

Bandwidth-Limited Robust Nonlinear Sliding Control of Pointing and Tracking Maneuvers

Abstract: It is shown in this paper how multiaxial spacecraft tracking and pointing maneuvers, with known control bandwidth and given tracking error bounds, can be implemented by variable structure control, in the presence of uncertain vehicle and target dynamics. To this end, it is shown how to select a nonlinear sliding surface relating attitude and rate variables, as well as a Lyapunov function in the surface variables that absorbs multiplicative model uncertainties, thereby simplifying the computation of control corrections. It is then shown how a boundary layer envelope can be designed, within which the components of the surface error dynamics can be modeled as the outputs of designer-selected decoupled low pass filters. Closed loop stability conditions, accounting for the coupling between the attitude error dynamics and the surface error dynamics are then obtained.

Sliding Mode Control of Automotive Powertrains with Uncertain Actuator Models

Abstract: An alternative formulation of the sliding mode control method for dealing with the uncertainties in actuator or control dynamics is presented in this paper. The advantages of the formulation are in the reduced computational requirements and simplified procedures for meeting robustness and performance requirements. The method is then applied to control an automotive powertrain system, whose dynamics are highly nonlinear. In particular, coordinating engine and transmission control variables to perform clutch-to-clutch shifts is illustrated. The design objectives are to provide smooth transients for passenger comfort and to reduce clutch energy dissipation requirements for component longevity. The robustness and performance characteristics of the designed controller are demonstrated for a case that involves neglected actuator dynamics, whose bandwidth is very close to the frequency of the controlled system dynamics.

Strategies for biped gymnastics

Abstract: The author studies the dynamics of a planar cat. He then proposes a few strategies that a cat can use to perform a forward or backward somersault. >

A Modular Computer Model for the Design of Vehicle Dynamics Control Systems1

Abstract: SUMMARY This paper describes a multiport approach to computer-aided modeling of vehicle dynamics. The modeling approach produces models that are suitable for the interactive design and evaluation of complex control strategies. The vehicle model which can be used for ride and handling analysis, is built from modular components. The components are programmed using the syntax of the computer aided control system design (CACSD) program EASYS. Seven modeling components are used to create a three-dimensional vehicle dvnamics model. The model is flexible enoug-h to simulate any suspension design with revolute joints. Each component of the model consists of a FORTRAN subroutine and a main calling module called a macro. To simplify the process of model building, the modeling components in the car model are designed to represent physical elements, such as the spring, damper, link or tire. To create a model, the components, which are represented by blocks, are interconnected through points, located on the blocks, ca...

Trajectory optimization and guidance law development for transatmospheric vehicles

Abstract: The problems of on-board trajectory optimization and real-time guidance law synthesis are addressed for an air-breathing, single-stage-to-orbit vehicle. The particular objective of fuel-optimal ascent is examined in the hypersonic regime using a simple vehicle model representative of the aerospace plane concept. This model includes a dual-mode propulsion system composed of SCRAMJET and rocket engines. An energy state approximation is applied to a four-state dynamic model for flight of a point mass in a vertical plane over a spherical non-rotating Earth. Optimal climb profiles for the unconstrained and dynamic pressure constrained cases result from further reduction in model order. An analytic switching condition is derived for optimal transition to rocket powered flight as orbital velocity is approached. Simple feedback guidance laws for both the unconstrained and dynamic pressure constrained cases are derived via a combination of singular perturbation and feedback linearization techniques. Lastly, the performance of the resulting nonlinear feedback guidance laws is presented in a numerical simulation of ascent to orbit.

Vehicle dynamics model for simulation on a microcomputer

Abstract: Equations of motion are derived for a two–axle, two–wheeled vehicle pulling a one–axle, two–wheeled trailer. Linear and nonlinear tyre side force models are discussed. Examples of computer solutions of the equations are presented for both single vehicle motion and articulated vehicle motion. A comparison of tractor semitrailer manoeuvres with a more elaborate simulation shows excellent results.

Emulation of Vehicle Dynamics on an Engine Test Bench

Abstract: In this paper, the problem of controlling the dynamic brake of a test bench for automotive engines is treated The goal is controlling the brake in such a way that during arbitrary transients of the throttle of the engine, the instantaneous load torque of the engine on the test bench matches the load torque of the engine in a specific car at all instants of time. The system configuration and the control scheme of a dynamic engine test bench are explained. Experimental results for two particular models of the vehicle dynamics are given.

An Integrated Configuration and Control Analysis Technique for Hypersonic Vehicles

Abstract: This paper describes a design analysis methodology for hypersonic vehicles that treats the vehicle configuration and trajectory simultaneously. Vehicle geometry, dynamic discontinuities, and time-dependent control variables are all treated as optimization parameters with respect to a single performance measure. A generalized first order gradient method is used to affect changes in the optimization variables to minimize a performance or cost measure. This is done while maintaining prescribed two-point boundary conditions and any path constraints imposed on the problem. The current research status and projected benefits of these activities are discussed.

Simulation of the interaction between aerodynamics and vehicle dynamics in general unsteady ground effect

Abstract: A method for modelling general unsteady lifting flows and a method for simulating dynamic-aerodynamic interaction is described. The aerodynamic model is general enough to treat multiple, closely coupled lifting components in ground effect. Simulations are computed both in and out of ground effect.

Minimum-Fuel Ascent to Orbit using Air-Breathing Propulsion

Abstract: Single-stage vehicles using air-breathing propulsion hold promise for more economical delivery of payloads to orbit. The characterization of minimum-fuel trajectories over the range of possible engine and aerodynamic performance of such vehicles provides useful feedback to engine and vehicle designers and paves the way for the development of guidance logic. In this paper, the minimum-fuel trajectory problem is formulated, propulsion system and aerodynamic models are presented, a numerical solution approach is described, and some preliminary results are discussed.