Clutch Slip Control Research Articles

Optimal Clutch Slip Control of AMT to Improve Vehicle Drivability

Optimal Clutch Slip Control of AMT to Improve Vehicle Drivability

Dry Clutch Control of Two-Speed Electric Vehicles by Using an Optimal Control Scheme With Persistent Time-Varying Disturbance Rejection

A novel two-speed inverse automatic mechanical transmission (I-AMT) is proposed to eliminate the torque interruption in conventional AMT and improve the working performance of electric vehicles (EVs). However, due to the intrinsic structural characteristics of I-AMT, the requirements for clutch slip control are different from current AMT. Besides, clutch slip control is sensitive to internal uncertainties and external persistent time-varying disturbances during gear shifting. This study proposes a unified framework to build a clutch slip model for gear upshift and downshift. A high-order disturbance observer-based optimal controller is developed to reject persistent time-varying disturbances in a dry clutch system. During controller deduction, a novel multiplier function λ is introduced, and the optimal control law is presented as a feedback form of system states, the disturbance, and the derivatives of the disturbance. The controller is then applied to the clutch slip processes during gear shifting of an EV equipped with I-AMT. Simulation and experimental results under gear upshift and downshift demonstrate that the controller guarantees consistent performance under various working scenarios with different kinds of disturbances. The rapidity and smoothness of the clutch slip process are ensured without large speed or torque fluctuation, thus improving the overall gear shift quality.

Coordinated clutch slip control for the engine start of vehicles with P2-hybrid automatic transmissions

The disconnect clutch can be used to start the engine through slipping for vehicles having P2-hybrid automatic transmissions. However, the driver is easily disturbed by the starting process because of driveline vibration. We develop a multiphase control strategy for slip coordination between the disconnect clutch and shifting clutch to improve the driving comfort during engine start. A detailed dynamic model of the whole powertrain, including the engine (ICE), P2-hybrid automatic transmission, dual-mass flywheel (DMF), electric motor (EM), and driving resistance, is established to support the development of the control strategy and analyze the transient behavior of the engine starting process. Simulations are performed using a co-simulation platform based on “SimulationX” software for the dynamic model and “Simulink” software for the developed control strategy. Experiments are carried out on a plug-in hybrid vehicle. Both simulation and experiment results show that the driveline oscillation can be effectively reduced through slip coordination between the disconnect clutch and shifting clutch.

An Output Regulator With Rejection of Time-Varying Disturbance: Experimental Validation on Clutch Slip Control

Time-varying disturbances may severely deteriorate control performance. For instance, the time-varying vehicle mass and the clutch friction coefficient may make automated manual transmission vehicle fail to startup on a slope. A quadratic output regulator is proposed in this brief to deal with time-varying disturbances, and the unmeasurable disturbances are estimated by a disturbance observer. To derive the control law, a novel form of multiplier function $\lambda $ is introduced, and the control law is represented as a feedback form of the system states, the disturbances and their derivatives. The system is guaranteed to be input-to-state stable, which will significantly relax the dependence of the controller on modeling accuracy. Eventually, the proposed control law is validated on clutch slip control. Although the performance of clutch slip control is susceptible to the uncertainties in dry clutch system and the disturbances from external environment, the simulation and experimental results demonstrate that the control law is robust enough and has strong ability in rejecting time-varying disturbances, and the vehicle can be launched successfully with high performance through clutch slip control under various working scenarios.

Accurate Clutch Slip Controllers During Vehicle Steady and Acceleration States

Over the past years, the control of the clutch clamping force has been studied to guarantee a smooth/fast and low-wear engagement. Recent studies have highlighted the interest in controlling the clutch clamping force in order to limit vibrations in vehicle drivelines. However, the major risk with any clutch clamping control strategy is an unexpected clutch opening due to the ignorance of the nonlinear and time-varying relationship between clutch clamping and clutch slip. Inspite of improvements, an accurate clutch slip control currently remains a challenge due to high nonlinear dynamics, uncertain parameters, and noisy environments, which render the clutch slip control more complex. In line with this challenging premise, this study presents two accurate clutch slip controllers used during vehicle steady states (constant engine speed) and vehicle acceleration states (increasing engine speed). The first controller, based on punctual least square adaptations of a clutch slip relation, yielded accurate clutch slip tracking results only in the vehicle steady state. In contrast, the second controller, based on a nearly continuous least mean square adaptation of the clutch slip relationship in parallel with a proportional-integral compensator, yielded accurate clutch slip tracking results both in vehicle steady and acceleration states.

Improved clutch slip control for automated transmissions

Clutch slip control of the inertia phase during the clutch-to-clutch shift process is the key to ensure good drive quality in automated transmissions. Addressing the problem of unpleasant driveline jerk and clutch overwear, a novel control scheme consisting of a linear quadratic controller and two compensators is proposed. The compensators are designed to deal with the challenges involving the disturbances and discontinuity in the drivetrain torque during the inertia phase. Compared to the conventional proportional–integral–derivative and classical linear quadratic approaches, the proposed control scheme demonstrates a significant better shift performance in terms of the slipping tracking error and jerk level during shift. The influences of various reference inputs and disturbances are investigated, where the proposed control scheme shows advantages. The proposed control scheme can be adaptable to various engine torque and vehicle load torque with improved control robustness.

Electro-mechanical clutch actuator control based on output switched Takagi- Sugeno controller

This paper aims to present a methodology to control the position of the clutch actuator. The objective is to improve the position reference tracking in order to get better performances and accuracy on the clutch slip control. The originality of this work is to use a model that takes into account the nonlinear characteristic of the stiffness of the clutch diaphragm. Instead of robustness approach, the nonlinearity is managed using the quasi-LPV Takagi-Sugeno representation and, additionally, because the nonlinearity is switching, the developed control law is, consequently, a nonlinear switching one. Moreover, in order to use unmeasured values in the controller, such as the current of the electric motor, a Takagi-Sugeno switching observer is designed. Some simulation results highlight the efficiency of the proposed approach.

Optimal Servo Design for Lock-Up Slip Control for Torque Converter—Nonlinear Output Regulation Approach

It is well known that slip control of lock-up clutch in automatic transmission systems is a crucial technology for improving fuel economy and driving comfort. However, plant parameters rapidly vary according to turbine speed, making the slip control challenging. For this problem, we apply nonlinear output regulation theory for the system represented as a linear parameter-varying system with the turbine speed as the parameter. In this framework, it is possible to design a servo controller that is optimally scheduled according to the turbine speed. The effectiveness of the proposed method is confirmed by experiments compared with an $H_{\infty }$ controller, which is one of the most advanced methods employed in the field of lock-up clutch slip control.

Shift control of Dual Clutch Transmission using Triple-Step nonlinear method

The shift control, especially clutch slip control in inertia phase, is considered as a key issue of dual clutch transmission for improving driving comfort. For the shift is a complex nonlinear dynamic process combining engine states and road information, and these are often variable, so the clutch control system can be described as a nonlinear parameter-varying model. Moreover, a novel nonlinear approach is proposed for clutch control of shift process, the control objective is to obtain smooth gearshift in the limited shift time by making clutch slipping speed difference tracking the planned reference. The proposed method can be formalized as a triple-step procedure and this procedure provides a concise design process so that the derivation of the control law is simplified and straightforward. Finally, the simulation results in the environment of AMESim with a complete vehicle model show the efficiency of the proposed approach.

Fuzzy logic and slip controller of clutch and vibration for hybrid vehicle

This paper is the second part of the paper titled “Simulation and Control of Hybrid Electric Vehicles” published in IJCAS, Vol. 10(2)/2012 where the model predictive control has been built to handle the clutch engagement between the combustion engine and the electrical motor. In this research, a fuzzy logic and slip controller of clutch and vibration of the hybrid vehicle have been considered and tested as a second control strategy. The use of the fuzzy logic control can avoid the need of the complex and rigorous mathematical modeling since the fuzzy logic can work very successfully on the uncertain and imprecise information. The clutch slip controller is implemented in an experimental test vehicle for the critical vibration reduction.

Nonlinear feedforward–feedback control of clutch-to-clutch shift technique

To improve the shift quality of the vehicle with clutch-to-clutch gear shifts, a nonlinear feedforward–feedback control scheme is proposed for clutch slip control during the shift inertia phase. The feedforward control is designed based on flatness in consideration of the system nonlinearities, and the linear feedback control is given to accommodate the model errors and the disturbances. Lookup tables, which are widely used to represent complex nonlinear characteristics of powertrain systems, appear in their original form in the designed feedforward controller, while the linear feedback controller is calculated through linear matrix inequalities such that the control system is robust against the parameter uncertainties. Finally, the designed controller is tested on an AMESim powertrain simulation model, which contains a time-variant model of clutch actuators.

Design of Clutch-Slip Controller for Automatic Transmission Using Backstepping

To improve the shift quality of vehicles with clutch-to-clutch gearshifts, a nonlinear controller using backstepping technique is designed for the clutch-slip control. Model uncertainties including steady-state errors and unmodeled dynamics are also considered as additive disturbance inputs, and the controller is designed such that the error dynamics is input-to-state stable. Lookup tables, which are widely used to represent complex nonlinear characteristics of engine systems, appear in their original form in the designed nonlinear controller. Finally, the designed controller is tested on an AMESim power train simulation model. Comparisons with an existing linear algorithm are given as well.

Design of Observer-based Output Feedback Clutch Slip Controller for Automatic Transmission

AbstractIn this paper, an observer-based output feedback controller is designed for clutch slip control of automatic transmission where not all states are measurable. The control system consists of a reduced-order observer and a nonlinear state feedback controller. The main contribution of this paper is that an integral action of the tracking error is introduced to reducing the steady-state error of the system. Robustness of the tracking error system is discussed in the framework of Input-to-State Stability (ISS) theory, where the disturbance inputs are considered as estimation error from the observer and unmodelled dynamics respectively. Moveover, lookup tables, which are widely used to represent complex nonlinear characteristics of engine systems, appear in their original form in the designed controller. Finally, the designed controller is tested on an AMESim powertrain simulation model to demonstrate the effectiveness of the proposed control scheme.

Robust and Simplified Design of Slip Control System for Torque Converter Lock-Up Clutch

A torque converter lock-up clutch slip control system, which is designed to improve fuel economy, must be able to precisely regulate slip speed. Also the system must have a high level of robustness for coping with changes in the operating conditions and any deterioration in the automatic transmission fluid and the clutch. Moreover, to reduce the design time, the design process must be as simple as possible. In this paper, we first propose a loop shaping that aims to optimize complementary sensitivity function of the control system, while satisfying the abovementioned requirements of performance and robustness. Next, a method for simplifying the design process is proposed, that is, a model and a controller are expressed by interpolation. A controller set, which has a relationship of duality to the interpolation parameters of the model, is created in advance so that the construction of a new control system can be realized by identifying the characteristic parameters only. From application to the actual design process for a vehicle, we verified that the design time was reduced to less than 1∕3 of that required for the conventional method. This new method has already been adopted for the design and fitting of new products.

Two-Degree-of-Freedom Controller Design for Clutch Slip Control of Automatic Transmission

Two-Degree-of-Freedom Controller Design for Clutch Slip Control of Automatic Transmission

CLUTCH-TO-CLUTCH SHIFT CONTROL OF AN AUTOMATIC TRANSMISSION WITH PROPORTIONAL PRESSURE CONTROL VALUES

For a new kind of automatic transmissions using proportional pressure valves to control the clutches directly, a two-degree-of-freedom controller is designed for clutch slip control during the inertia phase of the shift process. The controller is designed based on a low order linear model which is derived from dynamics of the proportional pressure control valve and the vehicle drive line. The feedback gain is calculated by robust pole assignment methods while the feed-forward compensator aims to improve system response. Finally, the designed controller is tested on an AMESim powertrain simulation model. Simulation results show that the rotational speed difference of clutch can track the desired trajectory well, and shift shock can be reduced by designing suitable feed-forward compensator.

Simplified Design Method of Slip Control System for Torque Converter Lock-up Clutch (2nd Report, Controller Design Method)

A model-based control such as H-infinity one makes it possible to make a robust controller design taking non-linearity and characteristic variation of the plant into consideration. There is, however, a problem of requiring much time to perform the procedure from the modeling to the designing of the control system because of the need for a strict analysis of the phenomena to obtain a practicable model. In previous paper we proposed new design method and explained the modeling technique. This method enables to shorten the design time by representing the plant model by interpolation of vertex characteristics and construct the control system on an onboard ECU when it is possible to determine the plant characteristics from the data and knowledge accumulated in the past. In this paper we aim at controller design based on the above method, and show that the total time for design has been shortened greatly as compared with the conventional method in torque converter lock up clutch slip control systems.

Robust Stabilization of Slip Control System for Torque Converter Lock-up Clutch Using H-Infinity Control Theory (2nd Report, Evaluation Test on Vehicle)

In previous paper, H-infinity control theory was applied in order to establish high reliability of a torque converter lock-up clutch slip control system. In this paper, evaluation test on vehicle is done after the controller is transformed so as to maintain the designed characteristics for implementation into an onboard ECU. As a result it is confirmed that robust stability against large variation under vehicle operating conditions and variation induced by aging deterioration is ensured. However it is found that there is a limit of improvement in performance with the controller adopting fixed gain because of the large variation in the system. So we propose characteristic variation compensating which compensates for the variation with only a few parameters in order that the characteristics of plant realized by feedback controller become invariant, so that the high performance can be achieved. The result in the system shows that the proposed filter makes the performance improve several times.

On-Line Design Method of Feedback Controller for Automatic Transmission System

This paper presents a new design method, which reduces the developing and design time for a feedback controller in various automotive electronic control systems. To achieve this problem, “On-line Design Method” hasbeen developed, which first acquires data and sets up a model at the same timeusing onboard ECU so that it can next output the controller directly, by representing the characteristics of thecontrolled system with only two parameters. The new method has been applied to Automatic Transmission lock-up clutch slip control system, and realized over 50% reduction of design time as compared with the conventional method.

DESIGN OF A FEEDBACK CONTROLLER FOR TORQUE CONVERTER CLUTCH SLIP SYSTEM IN PASSENGER CAR AUTOMATIC TRANSMISSION

Most vehicles equipped with automatic transmissions use torque converter clutches to reduce the fuel consumption, and recently its slip control scheme is studied for the expansion of the operating region of the torque converter clutch and thus for the further improvement of the fuel economy of vehicles. In this article, the analysis of the torque converter clutch system including the line pressure control unit of the automatic transmission and the actuating hydraulic control unit of the torque converter clutch is performed, and a feedback controller for its slip control is designed. The performance of the designed slip controller is verified by simulations and experiments, and the effect of the torque converter clutch slip control on the fuel economy is examined using a driving cycle simulation.