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Technical Paper

Improved Potential Field-Based Collision Avoidance Control for Autonomous Vehicles

Limiting factors for autonomous vehicle (AV) to be widely used are not only technical, but also psychological. Considering the psychological feelings of drivers during switching manned to unmanned driving status, this paper proposes an algorithm about avoiding collisions combining driver psychological feelings for AVs. The confidence-limit-distance of the driver is experimentally obtained by many real track tests which require the test driver to approach the obstacle as close as possible. The confidence-limit-distance from driver is defined as the distance between the obstacle and the last steering point allowed for the psychological limit of the driver to avoid collisions. Based on Artificial Potential Field (APF), a road potential field is accordingly established to characterize the characteristics and boundary constraints of the real road.
Technical Paper

Adaptive Optimal Management Strategy for Hybrid Vehicles Based on Pontryagin’s Minimum Principle

The energy management strategies (EMS) for hybrid electric vehicles (HEV) have a great impact on the fuel economy (FE). The Pontryagin's minimum principle (PMP) has been proved to be a viable control strategy for HEV. The optimal costate of the PMP control can be determined by the given information of the driving conditions. Since the full knowledge of future driving conditions is not available, this paper proposed a dynamic optimization method for PMP costate without the prediction of the driving cycle. It is known that the lower fuel consumption the method yields, the more efficiently the engine works. The selection of costate is designed to make the engine work in the high efficiency range. Compared with the rule-based control, the proposed method by the principle of Hamiltonian, can make engine working points have more opportunities locating in the middle of high efficiency range, instead of on the boundary of high efficiency range.
Technical Paper

Internal Model Control during Mode Transition Subject to Time Delay for Hybrid Electric Vehicles

With the rapid development of series-parallel hybrid electric vehicles (SPHEVs), mode transition from pure electrical drive to hybrid drive has attracted considerable attention. The presence of time delay due to response capacity of actuators and signal transmission of communication may cause decrease of speed tracking accuracy, even instable dynamics. Consequently, drivability of the SPHEV is unacceptable, and durability of the components is reduced. So far, plenty of control strategies have been proposed for mode transition, however, no previous research has been reported to deal with the time delay during mode transition. In this paper, a dynamic model with time delay of hybrid electric system is established. Next, a mode transition time-delay controller is proposed based on a two degree of freedom internal model controller (2-DOF-IMC).
Technical Paper

A High Reliable Automated Percussive Riveting System for Aircraft Assembly

Percussive riveting is a widely used way of fastening in the field of aircraft assembly, which used to be done manually. Nowadays, replacing the traditional percussive riveting with automated percussive riveting becomes a trend worldwide, which improves the quality of riveting significantly. For the automated riveting system used in aircraft assembly, reliability is of great importance, deserving to be deeply researched and fully enhanced. In this paper, a high reliable automated percussive riveting system integrated into a dual robot drilling and riveting system is proposed. The riveting system consists of the hammer part and the bucking bar part. And both parts have been optimized to enhance the reliability. In the hammer side, proximity switches are fully used to detect the state of rivet insertion.
Technical Paper

Simultaneous Measurement of the Flame Lift-Off Length on Direct Injection Diesel Sprays Using High Speed Schlieren Imaging and OH Chemiluminescence

Lift-off length is defined as the distance from injector hole to the location where flame stabilized on a high injection pressure direct injection (DI) diesel spray. In this paper we used the high-speed (40 kHz) Schlieren and time-averaged OH chemiluminescence imaging technique to simultaneously measure the flame lift-off locations on a DI diesel spray in an optically accessible and constant-volume combustion vessel. The time-resolved development of the diesel spray acquired from the high-speed Schlieren imaging system enabled us to observe the instantaneous spray structure details of the spray flames. The OH chemiluminescence image obtained from a gated, intensified CCD video camera with different delay and width settings was used to determine the quiescent lift-off length. Experiments were conducted under various ambient temperatures, ambient gas densities, injection pressures and oxygen concentrations.
Technical Paper

On-Line Non-Destructive Measurement for Interference-Fit Riveting Based on Force-Deformation Data Analysis

Interference-fit riveting is a critical fastening technique in the field of aerospace assembly. The fatigue and sealing performance of the rivet joint are determined by the interference-fit level of the rivet joint. As a result, it is of great importance to measure the interference-fit level accurately and effectively. Conventional interference-fit level measurement methods can be divided into direct measurement (destructive test on test-piece) and indirect measurement (off-line dimensional measurement of upset rivet head). Both methods cannot be utilized in automatic riveting. In this paper, an on-line non-destructive measurement method is developed to measure the interference-fit level. By taking full advantage of servo-driving riveting integrated with force measurement, the force-deformation data of the deformed rivet can be obtained in real time. The recognized feature points from the force-deformation data can reflect the height of the upset rivet head.
Technical Paper

Lateral State Estimation for Lane Keeping Control of Electric Vehicles Considering Sensor Sampling Mismatch Issue

Vehicle lateral states such as lateral distance at a preview point and heading angle are indispensable for lane keeping control systems, and such states are normally estimated by fusing signals from an onboard vision system and inertial sensors. However, the sampling rates and measurement delays are different between the two kinds of sensing devices. Most of the conventional methods simply neglect measurement delay and reduce sampling rate of the estimator to adapt to the slow sensors/devices. However, the estimation accuracy is deteriorated, especially considering the delay of visual signals may not be constant. In case of electric vehicles, the actuators for steering and traction are motors that have high control frequency. Therefore, the frequency of vehicle state feedback may not match the control frequency if the estimator is infrequently updated. In this paper, a multi-rate estimation algorithm based on Kalman filter is proposed to provide lateral states with high frequency.
Technical Paper

A New Clutch Actuation System for Dry DCT

Dry dual clutch transmission (DCT) has played an important role in the high performance applications as well as low-cost market sectors in Asia, with a potential as the future mainstream transmission technology due to its high mechanical efficiency and driving comfort. Control system simplification and cost reduction has been critical in making dry DCT more competitive against other transmission technologies. Specifically, DCT clutch actuation system is a key component with a great potential for cost-saving as well as performance improvement. In this paper, a new motor driven clutch actuator with a force-aid lever has been proposed. A spring is added to assist clutch apply that can effectively reduce the motor size and energy consumption. The goal of this paper is to investigate the feasibility of this new clutch actuator, and the force-aid lever actuator's principle, physical structure design, and validation results are discussed in details.
Journal Article

Study on Vehicle Stability Control by Using Model Predictive Controller and Tire-road Force Robust Optimal Allocation

The vehicle chassis integrated control system can improve the stability of vehicles under extreme conditions using tire force allocation algorithm, in which, the nonlinearity and uncertainty of tire-road contact condition need to be taken into consideration. Thus, An MPC (Model Predictive Control) controller is designed to obtain the additional steering angle and the additional yaw moment. By using a robust optimal allocation algorithm, the additional yaw moment is allocated to the slip ratios of four wheels. An SMC (Sliding-Mode Control) controller is designed to maintain the desired slip ratio of each wheel. Finally, the control performance is verified in MATLAB-CarSim co-simulation environment with open-loop manoeuvers.
Journal Article

Estimation on the Location of Peak Pressure at Quick Start of HEV Engine Employing Ion Sensing Technology

In this paper an estimation method on location of peak pressure (LPP) employing flame ionization measurement, with the spark plug as a sensor, was discussed to achieve combustion parameters estimation at quick start of HEV engines. Through the cycle-based ion signal analysis, the location of peak pressure can be extracted in individual cylinder for the optimization of engine quick start control of HEV engine. A series of quick start processes with different cranking speed and engine coolant temperature are tested for establishing the relationship between the ion signals and the combustion parameters. An Artificial Neural Network (ANN) algorithm is used in this study for estimating these two combustion parameters. The experiment results show that the location of peak pressure can be well established by this method.
Technical Paper

A Novel Integrated Chassis Controller Design Combining Active Suspension and 4WS

In this paper, we proposed a novel integrated vehicle chassis control configuration, which is based on the combination of vehicle vertical and lateral motion controls. Focusing on the improvement of vehicle handling and riding performance, particularly the active safety under critical driving condition, the purpose of Active Suspension (AS) in the integrated system is to achieve ride comfort quality and to provide more tyre cornering ability near the cornering force saturation regions, while the effect of Four Wheel Steering (4WS) is expected to eliminate the body side slip angle and to achieve an ideal yaw rate model following.