Diagnosis Model for the Intelligence of Dual-Clutch Transmission Control Systems Based on Utility Weights

This paper focuses on the dynamic modeling and analysis of dry dual clutch transmissions (DCTs) during vehicle launch and shifts. The system model incorporates the clutch torque control strategies for DCT vehicle launch and shifts. This model is capable of quantitatively analyzing and predicting dual clutch transmission dynamic characteristics and performance metrics, such as launch response and shift patterns, thus providing an analytical tool for DCT torque control and calibration. The model is applied for a test vehicle equipped with a dry dual clutch transmission. The simulation data on vehicle launch and shift dynamic characteristics are highly agreeable to the data obtained on the test vehicle.

The clutch control in the starting process is a main core and difficulty of control technology of dual clutch transmission(DCT). Without a hydraulic torque converter, the DCT achieves a smooth start only by the slipping of clutches and the DCT slipping control in the starting process becomes a key point. The torque transfer characteristics of the wet clutch is very complex and affected by many factors. An intelligent starting control strategy of DCT is introduced in this paper. The method of determining the starting gear is illustrated and it inducts the control stragety with two forward gears involved in the starting process. The control flow of the starting process is used to illustrate the DCT operation. Some vehicle tests are carried out to verify the strategy effectiveness. The result shows that the stragety has good robustness and adaptability, and can also response to various changes in parameters quickly, which can increase the clutch life and ensure the ride comfort.

This paper is aimed at the problem that the subjective drivability evaluation by experienced test drivers is limited in time efficiency and is of high cost and poor repeatability. In this article, an intelligent drivability objective evaluation tool (I-DOET) for passenger cars with dual-clutch transmission (DCT) is developed and verified by real vehicle testing. First, the signal denoising method and its key parameters, which are suitable for drivability evaluation, are selected based on analytic hierarchy process (AHP) and technique for order preference by similarity to ideal solution (TOPSIS). Besides, combined with the uncertainty characteristics of subjective judgment, a mathematical model of the objective drivability evaluation FARODE (fuzzy AHP-RS based on objective drivability evaluation) is proposed by using the fuzzy comprehensive assessment (FCA) method. The AHP and rough set (RS) method are used to calculate the subjective and objective weights of the drivability evaluation, respectively, and the proportion of subjective and objective weights is determined by the principle of minimum relative information entropy. The fuzzy matrix is built by membership function of the evaluation indexes. Finally, the static gearshift condition focused on by the subjective evaluation experts is taken as a case study. The predictability score is obtained by combining the drivability quantization lever vector, comprehensive weight, and fuzzy matrix. The experimental results indicate that the proposed method is applicable for objective drivability evaluation in passenger cars with DCT.

<div class="section abstract"><div class="htmlview paragraph">This paper defines the shifting quality evaluation index in detail for DCT (Dual Clutch Transmission) from the perspective of control. The vehicle model for DCT is built using MATLAB / Simulink tools, including the models of driver, load, controller, engine, clutch, transmission (synchronizer), actuators, and vehicle dynamics model. And then a control quality evaluation system is designed. The AHP (Analytic Hierarchy Process) is used to determine weights of the control quality evaluation index and the shifting quality control objectives through the co-simulation of vehicle system model and evaluation system, namely expected control range of each evaluation index, which provides reference and guidance for shifting control strategy and control algorithm of DCT. During the process of shifting control, we apply the strategy of fuzzy control and select the highest shifting quality rating scale as the objective function to optimize clutch engagement speed and engine throttle which influences the shifting quality. Then the optimal solution of fuzzy control rules is obtained. Based on the model of vehicle and the simulation platform of evaluation system about DCT, the simulation result about shifting quality before and after the optimization is observed. Simulation results show that the shifting quality of the vehicle is significantly improved after the optimization of shifting fuzzy control rules.</div></div>

Increasing functionality and complexity of automotive embedded system have led to more risks from systematic faults and random hardware faults. This makes it necessary to perform the functional safety process throughout the safety lifecycle of these systems. In addition, the appearance of the new functional safety standard ISO 26262 also make the consideration of functional safety as part of the design and implementation process for these systems is growing in importance. This paper presents a comprehensive functional safety analysis approach based on functional model. The process of functional modeling and safety analysis is outlined and the comprehensive functional safety analysis approach is applied to Dual Clutch Transmission (DCT) control system and the analysis results are integrated. A method for the automotive safety integrity level (ASIL) determination is put forward based on severity, probability of exposure and controllability.

The existing state of dual clutch transmission (DCT) starting control technique is summarized from starting kinetic model of clutch, control strategy of clutch engaging speed and tracking performance of clutch actuator respectively, moreover, a method which can further improve the starting performance is put forward. Shift scheduling is summarized to four kinds, which are based on experience, constraint condition, intelligent compensating and comprehensive intelligence respectively, then, the relative merits of every shift scheduling are analyzed, fur- thermore, methods which can optimize the comprehensive intelligence shift scheduling is presented. Methods which have applied to increase shift quality are summarized, besides, approaches which can further improve the shift quality are put forward. At last, progress of digital simulation which has been applied in the performance of DCT research is summarized, in addition, application method that hardware in the loop(HIL) applied to study DCT control system is analyzed.

Cognitive wireless network (CWN) is expected as one of the most efficient transmission methods to solve today’s wireless problems like the lack of wireless bands or the efficient usage of limited wireless resources. However, CWN have not established effective transmission methods considered with QoS or user-oriented transmission methods. In this paper, selective transmission control method in CWN considering with end-to-end QoS based on user policies is proposed. First, at the observation stage, the physical data such as electric field strength, bit error rate, jitter, latency, packet error rate, and throughput are observed. Then, at the decision stage, analytic hierarchy process (AHP) with user policy is applied for decision making process with those parameters. Finally, the action stage, one of the suitable links is chosen and changed links and networks. Also, the route selecting method is proposed based on extended AODV protocols. When route changes come to need, considerable wireless routes are listed by AODV protocol including network conditions. Then, the following three methods are used for route selection: (1) Route selection so that Maximizing End-to-End network conditions among all of the routes. (2) Route selection so that applying End-to-End AHP selection among all of the routes. (3) Route selection so that using min-max methods for the results of the policy based AHP. In our simulation, ns2 is used for the computational results to the effectiveness of the suggested transmission methods in CWNs. The results showed the effectiveness of the proposed methods.

This paper presents a gear shift method for the dual clutch transmission (DCT) with integrated electric motor in pure electric drive mode. In contrast to clutch-to-clutch shift in conventional DCT, a good gear shifting process relies on the coordinated control of the motor and synchronizer in electric drive mode of the hybrid DCT. To shorten the torque interruption time and reduce the wear of the synchronizer during engagement, the key point is to adjust the oncoming gear speed to the output shaft speed rapidly. This study provides a speed regulation control framework based on model predictive control (MPC) and disturbance observer (DO), where the MPC controller is designed to achieve a good tracking performance and the DO is to eliminate effects from exogenous disturbances. Simulation and experimental results demonstrate that the proposed approach can attain a rapid and robust gear shifting performance.

The Analysis Function of the US-CERT Control Systems Security Center (CSSC) at the Idaho National Laboratory (INL) has prepared this report to document cyber security incidents for use by the CSSC. The description and analysis of incidents reported herein support three CSSC tasks: establishing a business case; increasing security awareness and private and corporate participation related to enhanced cyber security of control systems; and providing informational material to support model development and prioritize activities for CSSC. The stated mission of CSSC is to reduce vulnerability of critical infrastructure to cyber attack on control systems. As stated in the Incident Management Tool Requirements (August 2005) ''Vulnerability reduction is promoted by risk analysis that tracks actual risk, emphasizes high risk, determines risk reduction as a function of countermeasures, tracks increase of risk due to external influence, and measures success of the vulnerability reduction program''. Process control and Supervisory Control and Data Acquisition (SCADA) systems, with their reliance on proprietary networks and hardware, have long been considered immune to the network attacks that have wreaked so much havoc on corporate information systems. New research indicates this confidence is misplaced--the move to open standards such as Ethernet, Transmission Control Protocol/Internet Protocol, and Web technologies is allowing hackers to take advantage of the control industry's unawareness. Much of the available information about cyber incidents represents a characterization as opposed to an analysis of events. The lack of good analyses reflects an overall weakness in reporting requirements as well as the fact that to date there have been very few serious cyber attacks on control systems. Most companies prefer not to share cyber attack incident data because of potential financial repercussions. Uniform reporting requirements will do much to make this information available to Department of Homeland Security (DHS) and others who require it. This report summarizes the rise in frequency of cyber attacks, describes the perpetrators, and identifies the means of attack. This type of analysis, when used in conjunction with vulnerability analyses, can be used to support a proactive approach to prevent cyber attacks. CSSC will use this document to evolve a standardized approach to incident reporting and analysis. This document will be updated as needed to record additional event analyses and insights regarding incident reporting. This report represents 120 cyber security incidents documented in a number of sources, including: the British Columbia Institute of Technology (BCIT) Industrial Security Incident Database, the 2003 CSI/FBI Computer Crime and Security Survey, the KEMA, Inc., Database, Lawrence Livermore National Laboratory, the Energy Incident Database, the INL Cyber Incident Database, and other open-source data. The National Memorial Institute for the Prevention of Terrorism (MIPT) database was also interrogated but, interestingly, failed to yield any cyber attack incidents. The results of this evaluation indicate that historical evidence provides insight into control system related incidents or failures; however, that the limited available information provides little support to future risk estimates. The documented case history shows that activity has increased significantly since 1988. The majority of incidents come from the Internet by way of opportunistic viruses, Trojans, and worms, but a surprisingly large number are directed acts of sabotage. A substantial number of confirmed, unconfirmed, and potential events that directly or potentially impact control systems worldwide are also identified. Twelve selected cyber incidents are presented at the end of this report as examples of the documented case studies (see Appendix B).

Downshift decision and process optimal control of dual clutch transmission for hybrid electric vehicles under rapid braking condition

The key to the launching control of a dual-clutch transmission (DCT) lies in the coordination control of the engine and dual clutches, along with the accurate closed-loop control of the torque transmitted by each clutch and the output torque of the engine. The implementation feasibility and precision of the clutch torque closed-loop control are completely dependent on the effective real-time estimation of the clutch torque, which cannot be directly measured. Therefore, the high-order sliding-mode observer and unknown input observer are used to estimate the transmitted torque of the twin clutches on the basis of the self-designed control strategy and estimation of the vehicle drag torque. First, for the launching clutch slipping phase, an improved engine constant speed control is proposed based on the dynamic equations of a dry DCT with dual intermediate shafts, and the minimum value principle is applied to achieve the optimum launching control of the clutches. Meanwhile, the separating conditions of the separated clutch and the torque distribution are determined to ensure approximate friction work and avoid power cycle, and the target curve of the clutch-transmitted torque is obtained according to different conditions. Then, the vehicle drag torque is estimated using the recursive least-square method with a double forgetting factor, the angular acceleration of the engine and output shaft is refactored utilizing a high-order sliding-mode observer algorithm, and the transmitted torque of the twin clutches are estimated using the unknown input observer. Then, the DCT launching process is simulated under different driving conditions on the MATLAB/Simulink software platform. Finally, the bench test is conducted to verify the effectiveness of the self-designed clutch torque estimation method. The simulation and hardware-in-the-loop (HIL) test results show that the proposed methods of high-order sliding-mode observer and unknown input observer can effectively estimate the clutch-transmitted torque and lay a solid foundation for the subsequent development of the launching control strategy for a real vehicle with a DCT.

The clutch characteristics of dual clutch transmission (DCT) will change as the service time increases, which will lead to the deterioration of gearshift performance. To reduce the influence of the change in clutch characteristics on the gearshift performance, an adaptive gearshift control method based on the extended state observer and H∞ robust control is proposed. First, the gearshift problem of the DCT is transformed into the reference trajectory tracking problem, and the gearshift reference trajectory is designed using the minimum principle. The uncertain term related to the change in clutch characteristics in the DCT gearshift dynamic model is defined, and an extended state observer is designed to estimate the uncertain term. On this basis, the gearshift controller is designed using the backstepping method, and H∞ robust control is introduced to further improve the adaptation effect of the controller, then the adaptive control laws of the clutch pressure and engine torque are obtained. Finally, the adaptation effect of the proposed method was verified by both simulation and experiment. The results show that the proposed adaptive gearshift control method can effectively avoid the gearshift delay caused by the change in clutch characteristics, and the gearshift jerk in the simulation and experiment is reduced by 55.01% and 34.8%, respectively.

Based on a certain manual transmission of a heavy duty truck, a dual clutch transmission (DCT) structure was proposed and the simulation model was built by means of Matlab/Simulink. The control strategy, that the engine speed was controlled to follow the target speed, was put forward. Exact mathematical model of DCT is difficult to gain, thus fuzzy controller was adopted to control the engine throttle and oil pressure. After analysis of the shortcomings of traditional fuzzy control, improved fuzzy control method was proposed to improve the launch performance. The integral term is added as an offset to the system to accelerate the movement of the process towards set point and eliminate the residual steady-state error. Simulation results show that improved fuzzy control method can yield better launch quality. The simulation model can provide a useful analytical tool for further development of such gearboxes.

This paper suggested a shift control algorithm for improving the shift quality(SQ) by modeling a dual clutch transmission(DCT)-type 2-speed transmission system for an electric vehicle(EV). In 2-speed transmission system, the driving comfort decreased when the driveshaft torque of the vehicle fluctuated by shifting gear, unlike with the existing single-gear ratio EV. To improve this, a shift control algorithm was proposed that controlled two units of shift actuators and a unit of a driving motor for the subject DCT. To evaluate the proposed shift control algorithm, a shift performance simulator based on MATLAB/Simulink that consisted of a motor, DCT, actuator, and vehicle model was developed by modeling a DCT-type EV with 2-speed transmission system. The SQ improvement was verified by reducing the overshoot torque of the driveshaft during inertia phase.

<div class="htmlview paragraph">Dual Clutch Transmissions (DCTs) are providing the full shift comfort of traditional step automatics but offer significantly improved full efficiency and performance.</div> <div class="htmlview paragraph">With up to 15% better fuel efficiency compared to planetary-ATs, the DCTs are the first automatics to provide better values than manual transmissions. Higher top speed and, more important in everyday driving, better acceleration compared to planetary-ATs and CVTs are additional benefits.</div> <div class="htmlview paragraph">DCTs are also the first automatic transmissions well suited for high torque Diesels and high revving gas engines alike.</div> <div class="htmlview paragraph">The DCT concept was originally developed in the 1940's but it took until recently that high volume production solutions were made possible and allowed for the mainstream vehicle market entry.</div> <div class="htmlview paragraph">Beside the electronic hard- and software the key enablers for the DCT are the dual wet clutch and the electrohydraulic transmission control module.</div> <div class="htmlview paragraph">On the clutch side new friction elements have been designed. Combined with an enhanced transmission fluid more than two million shifts per clutch and a consistent launch quality over the transmission lifetime are achieved.</div> <div class="htmlview paragraph">The dual clutch design itself supports very responsive clutch engagements and disengagements as well as good controllability under slipping conditions.</div> <div class="htmlview paragraph">On the controls side the electronics, sensors and electrohydraulics have been integrated into a mechatronic module for minimized tolerance bands and improved reliability.</div> <div class="htmlview paragraph">Low hysteresis, direct acting solenoids enable the precise and fast clutch control that is the key for the DCT function.</div>