The development of a multidimensional scale to evaluate motor vehicle dynamic qualities

Advances in motor vehicle engineering will allow greater refinement of the dynamic qualities of passenger cars in the near future. This paper describes the development and initial validation of a reliable and valid multidimensional scale to assess these parameters based upon a technique previously developed to evaluate aircraft handling qualities. The scaling methodology developed emphasizes the interaction between the vehicle's dynamic behaviour and the category of vehicle (e.g. sports car, executive saloon). This three-part study describes the initial extraction and the subsequent verification of the scale dimensions from an analysis of the opinions of circa 500 drivers, followed by an evaluation of the sensitivity and diagnosticity of the scale to distinguish between the road behaviour exhibited by vehicle types. The results suggest that the scale shows both content and construct validity, being able to distinguish both between broad categories of vehicle and different models of vehicle within a particular category in a consistent and meaningful manner.     

The rescheduling arc routing problem

In this paper, the rescheduling arc routing problem is introduced. This is a dynamic routing and scheduling problem that considers adjustments to an initial routing itinerary when one or more vehicle failures occur during the execution stage and the original plan must be modified. We minimize the operational and schedule disruption costs. Formulations based on mixed‐integer programming are presented to compare different policies in the rerouting phase. A solution strategy is developed when both costs are evaluated and it is necessary to find a solution quickly. Computational tests on a large set of instances compare the different decision‐maker policies.     

A Wheelchair Steered through Voice Commands and Assisted by a Reactive Fuzzy-Logic Controller

This paper describes new results with a Reactive Shared-Control system that enables a semi-autonomous navigation of a wheelchair in unknown and dynamic environments. The purpose of the reactive shared controller is to assist wheelchair users providing an easier and safer navigation. It is designed as a fuzzy-logic controller and follows a behaviour-based architecture. The implemented behaviours are three: intelligent obstacle avoidance, collision detection and contour following. Intelligent obstacle avoidance blends user commands, from voice or joystick, with an obstacle avoidance behaviour. Therefore, the user and the vehicle share the control of the wheelchair. The reactive shared control was tested on the RobChair powered wheelchair prototype [6] equipped with a set of ranging sensors. Experimental results are presented demonstrating the effectiveness of the controller.     

The ANFIS approach applied to AUV autopilot design

This paper describes the application of neurofuzzy techniques in the design of autopilots for controlling the yaw dynamics of an autonomous underwater vehicle. Autopilots are designed using an Adaptive-Network-based Fuzzy Inference System (ANFIS), a chemotaxis tuning methodology and a fixed fuzzy rule-based approach. To describe the yaw dynamic characteristics of an autonomous underwater vehicle, a realistic simulation model is employed. Results are presented which demonstrate the superiority of the ANFIS approach. It is concluded that the approach offers a viable alternative method for designing such autopilots.     

A second generation adaptive autostabilization system for airborne vehicles

The paper is concerned with the initial evaluation of a self adaptive autostabilization system for an airborne vehicle whose dynamic behaviour may vary rapidly and over a wide range during normal operation. The basic design approach could be applied to any airborne vehicle which warranted adaptive control operation, but it is evaluated here in relation to the control of a high performance missile during an 80 second mission. This mission includes a rocket boost phase with accompanying large variations in the model parameters caused by changes in dynamic pressure, mach number, altitude and mass. The adaptive system can be considered as a ‘second generation’ adaptive scheme in the sense that it provides a logical self-adaptive successor to the well known ‘schedule adaptive’ systems used heretofore.     

Development of a heavy truck semi-active suspension control

The article describes the control design, the development process and the overall performance of a semi-active suspension control for a heavy truck. The control software is developed, debugged and preliminarily tuned within a dedicated Matlab/Simulink environment, in time and frequency domain, utilising a simplified vehicle model. After a preliminary virtual evaluation, the system performance is then tested on a real prototype truck, owing to the rapid prototyping technique application. A fine tuning of the system is realised through of an experimental test activity focused both on the comfort and the handling behaviour of the vehicle.     

Quad-Tilting Rotor Convertible MAV: Modeling and Real-Time Hover Flight Control

This paper describes the modeling, control and hardware implementation of an experimental tilt-rotor aircraft. This vehicle combines the high-speed cruise capabilities of a conventional airplane with the hovering capabilities of a helicopter by tilting their four rotors. Changing between cruise and hover flight modes in mid-air is referred to transition. Dynamic model of the vehicle is derived both for vertical and horizontal flight modes using Newtonian approach. Two nonlinear control strategies are presented and evaluated at simulation level to control, the vertical and horizontal flight dynamics of the vehicle in the longitudinal plane. An experimental prototype named Quad-plane was developed to perform the vertical flight. A low-cost DSP-based Embedded Flight Control System (EFCS) was designed and built to achieve autonomous attitude-stabilized flight.     

Evaluation of antilock braking system with an integrated model of full vehicle system dynamics

Antilock braking system (ABS), traction control system, etc. are used in modern automobiles for enhanced safety and reliability. Autonomous ABS system can take over the traction control of the vehicle either completely or partially. An antilock braking system using an on–off control strategy to maintain the wheel slip within a predefined range is studied here. The controller design needs integration with the vehicle dynamics model. A single wheel or a bicycle vehicle model considers only constant normal loading on the wheels. On the other hand, a four wheel vehicle model that accounts for dynamic normal loading on the wheels and generates correct lateral forces is suitable for reliable brake system design. This paper describes an integrated vehicle braking system dynamics and control modeling procedure for a four wheel vehicle. The vehicle system comprises several energy domains. The interdisciplinary modeling technique called bond graph is used to integrate models in different energy domains and control systems. The bond graph model of the integrated vehicle dynamic system is developed in a modular and hierarchical modeling environment and is simulated to evaluate the performance of the ABS system under various operating conditions.     

Evaluation of antilock braking system with an integrated model of full vehicle system dynamics

Antilock braking system (ABS), traction control system, etc. are used in modern automobiles for enhanced safety and reliability. Autonomous ABS system can take over the traction control of the vehicle either completely or partially. An antilock braking system using an on–off control strategy to maintain the wheel slip within a predefined range is studied here. The controller design needs integration with the vehicle dynamics model. A single wheel or a bicycle vehicle model considers only constant normal loading on the wheels. On the other hand, a four wheel vehicle model that accounts for dynamic normal loading on the wheels and generates correct lateral forces is suitable for reliable brake system design. This paper describes an integrated vehicle braking system dynamics and control modeling procedure for a four wheel vehicle. The vehicle system comprises several energy domains. The interdisciplinary modeling technique called bond graph is used to integrate models in different energy domains and control systems. The bond graph model of the integrated vehicle dynamic system is developed in a modular and hierarchical modeling environment and is simulated to evaluate the performance of the ABS system under various operating conditions.     

Experimental Evaluation and Formal Analysis of High‐Level Tasks with Dynamic Obstacle Anticipation on a Full‐Sized Autonomous Vehicle

Certifying the behavior of autonomous systems is essential to the development and deployment of systems in safety‐critical applications. This paper presents an approach to using a correct‐by‐construction controller with the probabilistic results of dynamic obstacle anticipation, and validates the approach with experimental data obtained from Cornell's full‐scale autonomous vehicle. The obstacle anticipation (used to calculate the probability of collision with dynamic obstacles around the vehicle) is abstracted to a set of Boolean observations, which are then used by the synthesized controller (a state machine generated from temporal logic task specifications). The obstacle anticipation, sensor abstraction, and synthesized controller are implemented on a full‐scale autonomous vehicle, and experimental data are collected and compared with a formal analysis of the probabilistic behavior of the system. A comparison of the results shows good agreement between the formal analysis and the experimental results.     

Modelling and analysis of the dynamics of a tilting three-wheeled vehicle

To understand the handling behaviour of a three-wheeled tilting vehicle, models of the vehicle with different level of detail, corresponding to specific fields of investigation, have been developed. Then the proposed kinematics of the three-wheeler are assessed and optimized with respect to desired dynamic properties by applying a detailed multibody system model. The partially unstable nature of the motion of the vehicle suggests the application of an analytically derived, simplified model, to allow for focusing on stability aspects and steady-state handling properties. These investigations reveal the necessity of employing a steer-by-wire control system to support the driver by stabilizing the motion of the vehicle. Thus, an additional basic vehicle model is derived for control design, and an energy-efficient control strategy is presented. Numerical simulation results demonstrate the dynamic properties of the optimized kinematics and the control system, approved by successful test runs of a prototype.     

Modelling the nonlinear dynamic behaviour of a boiler‐turbine system using a radial basis function neural network

Building an appropriate mathematical model that describes the system behaviour with a certain degree of satisfaction is quite challenging owing to the uncertain and volatile nature of thermodynamic constants and geometric parameters. In this paper, we present a technique to approximate and validate the dynamic behaviour of the Aström–Bell boiler‐turbine power plant based on an RBFNN over a large operating range. The proposed RBFNN is applied to solve the parametric identification problem for nonlinear and complex systems using an optimiser based on a hybrid genetic algorithm. This optimiser is composed of the gradient descent optimiser and a genetic algorithm for fast convergence. Two simulations were performed to show the effectiveness of the proposed technique under different situations with several boiler‐turbine input variables. The optimal structure and parameters of the obtained RBFNN‐based model emulates well the dynamic behaviour of the Aström–Bell boiler‐turbine system. Copyright © 2013 John Wiley & Sons, Ltd.     

Stochastic optimal control of vehicle suspension with preview on an irregular surface

An active suspension system with preview under stochastic optimal control of a vehicle travelling on an irregular surface is discussed. The vehicle is modelled as a mass-damper-spring system with two degrees of freedom and the dynamic behaviour of the irregular surface is described by a first-order system subject to a gaussian white random input. The acceleration of the vehicle and the irregular quantity of the surface ahead of the vehicle are in a noisy environment measured using sensors mounted on the vehicle. The state variables of the vehicle dynamics and the dynamic behaviour of the irregular surface are estimated using the Kalman filter. The stochastic optimal control is determined by minimizing the given performance index, and is composed of the weighted linear combination of the estimated state variables of the vehicle dynamics and the dynamic behaviour of the irregular surface. A numerical example shows the effectiveness of the proposed active suspension system with preview.     

A dynamic model of an underwater vehicle with a robotic manipulator using Kane's method

Development of a robust autonomous Underwater Robotic Vehicle (URV) is a key element to the exploitation of marine resources. An accurate dynamic model is important for both controller design and mission simulation, regardless of the control strategy employed. In this paper, a dynamic model for an underwater vehicle with an n-axis robot arm is developed based on Kane's method. The technique provides a direct method for incorporating external environmental forces into the model. The model developed in this paper includes four major hydrodynamic forces: added mass, profile drag, fluid acceleration, and buoyancy. The model derived is a closed form solution which can be utilized in modern model-based control schemes.     

TextWiki: a superlative resource

Although superlatives are commonly used in natural language, so far there has been no large-scale computational investigation of the types of comparisons they express. This article describes a comprehensive annotation scheme for superlatives, which classifies superlatives according to their surface forms and motivates an initial focus on so-called “ISA superlatives”. This type of superlative comparison is especially suitable for a computational approach because both their targets and comparison sets are explicitly realised in the text, and the proposed annotation scheme offers guidelines for annotating the spans of such comparative elements. The annotations are tested and evaluated on 500 tokens of superlatives with good inter-annotator agreement. In addition to providing a platform for investigating superlatives on a larger scale, this research also introduces a new text-based Wikipedia corpus in which all superlative instances have been annotated according to the proposed annotation scheme, and which has been used to develop a tool that can reliably distinguish between different superlative types, and identify the comparative components of ISA superlatives.     

Experimental Verification of a Drift Controller for Autonomous Vehicle Tracking: a Circular Trajectory Using LQR Method

This study develops an autonomous vehicle control method that enables it to perform a drift maneuver which is an expert driving technique consisting of sliding the rear wheel intentionally for fast cornering. By developing an autonomous control algorithm for such an agile maneuver, the safety of the future autonomous vehicle on extreme conditions such as slippery road, will be increased. Drift equilibrium states are derived to find the suitable feedforward control input for the scale car to enter the drifting region. In addition, a feedback controller is designed based on the linear quadratic regulator method in order to track the circular trajectory and maintain drift equilibrium states. To validate the performance of the developed control algorithm a 1:10 scale car experimental platform is developed with on-board control and sensor system. The feasibility of the developed method for the autonomous vehicle is confirmed through both simulation and experiments following circular trajectories while maintaining the desired equilibrium states.

     

Modeling and controlling the mobile harbour crane system with virtual prototyping technology

Virtual simulation of the real behaviour of mobile harbour crane (MHC) without using the traditional build-and-test method is an imperative approach to the design stage that can increase the quality of the product by reducing manufacturing cost and errors. This paper introduces an engineering model that describes the mechanical behaviour of MHC, and the control design for increasing the position accuracy. Based on a concept of the MHC, a virtual mechanical model was created using SOLIDWOKS, which was then exported to the Automatic Dynamic Analysis of Mechanical System (ADAMS) environment. This model was simulated to investigate the dynamic behaviour of the MHC system. In addition, an adaptive siding mode PID controller was also developed in MATLAB/Simulink to control the crane trolley position and suppress the swing angle of the load. This co-simulation demonstrates the reliability of the mechanical and control functionalities of the developed system.     

Visual Exploration of Dynamic Multichannel EEG Coherence Networks

Electroencephalography (EEG) coherence networks represent functional brain connectivity, and are constructed by calculating the coherence between pairs of electrode signals as a function of frequency. Visualization of such networks can provide insight into unexpected patterns of cognitive processing and help neuroscientists to understand brain mechanisms. However, visualizing dynamic EEG coherence networks is a challenge for the analysis of brain connectivity, especially when the spatial structure of the network needs to be taken into account. In this paper, we present a design and implementation of a visualization framework for such dynamic networks. First, requirements for supporting typical tasks in the context of dynamic functional connectivity network analysis were collected from neuroscience researchers. In our design, we consider groups of network nodes and their corresponding spatial location for visualizing the evolution of the dynamic coherence network. We introduce an augmented timeline‐based representation to provide an overview of the evolution of functional units (FUs) and their spatial location over time. This representation can help the viewer to identify relations between functional connectivity and brain regions, as well as to identify persistent or transient functional connectivity patterns across the whole time window. In addition, we introduce the time‐annotated FU map representation to facilitate comparison of the behaviour of nodes between consecutive FU maps. A colour coding is designed that helps to distinguish distinct dynamic FUs. Our implementation also supports interactive exploration. The usefulness of our visualization design was evaluated by an informal user study. The feedback we received shows that our design supports exploratory analysis tasks well. The method can serve as a first step before a complete analysis of dynamic EEG coherence networks.     

Visual—Manual Feedback Mechanism in Human Vehicular Performance

Abstract

This research reports the first experimental cybernetic analysis of the visual manual feedback mechanism in human driving. Cybernetic concepts describe driving behaviour as a dynamic closed-loop feedback-regulated driver-vehicle-road tracking system. Three levels of sensory feedback, reactive, instrumental and operational, are suggested for the functional integration of human motor activities in vehicle operation. The dynamic operational feedback, registered as the spatial difference between the roadway and the positional as well as directional changes of the vehicle in motion, was the main concern of this study. Clear vision of the front and rear ends of an automobile was hypothesized to be a critical and essential factor in human vehicular control and guidance. Three experiments, on backing, parallel parking and forward driving, were designed with both clear and obstructed vision of operational feedback. Results confirmed the theoretical assumptions. The implications of the feedback concepts on driving behaviour are discussed. A behavioural evaluation of current automobile window designs is suggested     

Nonlinear control with integral sliding properties for circular aerial robot trajectory tracking: Real‐time validation

A nonlinear control algorithm for tracking dynamic trajectories using an aerial vehicle is developed in this work. The control structure is designed using a sliding mode methodology, which contains integral sliding properties. The stability analysis of the closed‐loop system is proved using the Lyapunov formalism, ensuring convergence in a desired finite time and robustness toward unknown and external perturbations from the first time instant, even for high frequency disturbances. In addition, a dynamic trajectory is constructed with the translational dynamics of an aerial robot for autonomous take‐off, surveillance missions, and landing. This trajectory respects the constraints imposed by the vehicle characteristics, allowing free initial trajectory conditions. Simulation results demonstrate the good performance of the controller in closed‐loop system when a quadrotor follows the designed trajectory. In addition, flight tests are developed to validate the trajectory and the controller behavior in real time.