Xingyong Song

Pressure-Based Clutch Control for Automotive Transmissions Using a Sliding-Mode Controller

Clutch shift control is critical for efficient and high-performance transmission designs, including automatic, dual clutch, and hybrid transmissions. To ensure a smooth clutch to clutch shift, appropriate controls for two consecutive processes are critical. One is the precise coordination between the on-coming and off-going clutches, which requires the on-coming clutch to be filled and ready for engagement at the predetermined time (clutch fill). The other is the proper torque control during clutch engagement. In this paper, we will investigate the closed-loop “wet” clutch control enabled by a pressure sensor in the clutch chamber. The main challenges of the pressure-based “wet” clutch control lie in the complex nonlinear dynamics due to the interactions between the fluid and the mechanical systems, the ON/OFF behavior of the clutch assembly, the time-varying clutch loading condition, the required short time duration for a precise and robust clutch shift, and the lack of the displacement information. To enable precise and robust pressure-based control, this paper focuses on the following three aspects. First, a clutch dynamic model is constructed and validated, which precisely captures the system dynamics in a wide pressure range. Second, a sliding-mode controller is designed to achieve robust pressure control while avoiding the chattering effect. Finally, an observer is constructed to estimate the clutch piston motion, which is not only a necessary term in the nonlinear controller design but also a diagnosis tool for the clutch fill process. To validate the proposed methods, a transmission clutch fixture has been designed and built in the laboratory. The experimental results demonstrate the effectiveness and robustness of the proposed controller and observer.

Time-Varying Internal Model-Based Control of a Camless Engine Valve Actuation System

This paper focuses on the motion control of a camless engine valve actuation system during both steady state and transient engine operation. The precise tracking performance obtained using controllers based on the internal model principle for the constant speed case motivates the investigation under engine speed transients. The cyclic but aperiodic reference signal to be tracked is modeled using two different methods, i.e., as a combination of frequency varying sinusoids in the time domain or as a repetitive (periodic) signal in the rotational angle domain. The recently developed time-varying internal model-based controller is ideally suited for both the approaches. The details associated with the design of the controller for each of the approaches are first documented. A quantitative analysis comparing various performance metrics for both the approaches helps to highlight the relative advantages of each method. The experimental results from a prototype camless engine valve actuation system are then presented to help in validating the overall effectiveness of the proposed control method.

Robust stabilizer design for linear time-varying internal model based output regulation and its application to an electrohydraulic system ☆

Abstract This paper focuses on the design of a low order robust stabilizer for the tracking/disturbance rejection problem based on the internal model principle in the time-varying setting and its application to the hydraulic pressure tracking with varying frequency. The problem of this kind known as output regulation generally consists of two major parts: internal model unit construction and stabilizer design. While the construction of the time-varying internal model unit is non-trivial by itself and a very recent research outcome enables its synthesis for a class of linear time-varying systems, the effective stabilization of the augmented system (internal model unit and plant) for practical applications remains a challenge. This is due to the need to stabilize the high order time-varying augmented system using a low order stabilizer in a robust fashion and with desirable transient performance. While directly applying the stabilization approaches for a general LTV system will result in a high order stabilizer, a new method is proposed in this paper that overcomes this bottleneck by taking advantage of the unique structure of the internal model based control system. Instead of using a dynamic stabilizer with high order, this approach uses a sequence of time-varying gains that are directly injected into the internal model unit. A critical issue addressed is how to avoid the non-convex optimization associated with the time-varying gain synthesis and then convert the stabilizer design into a series of Linear Matrix Inequalities (LMIs). The proposed control approach is then demonstrated on an electrohydraulic system.

Robust stabilizer design for Linear time varying internal model based control

This paper focuses on the design of a low order robust stabilizer for the tracking/disturbance rejection problem based on the internal model principle in the time varying setting. The existing stabilization approaches are either lack of robustness or results in a high order design, which limits the potential for broad application. The method proposed in this paper overcomes this bottleneck by taking advantage of the unique structure of the time varying internal model based control system. Instead of using a dynamic stabilizer with high order, this approach uses a sequence of time varying gains that are injected into the internal model unit. A critical issue addressed is how to avoid the non-convex optimization associated with the time varying gain synthesis and then convert the stabilizer design into a series of convex Linear Matrix Inequality (LMI) constraints. The approach is then validated on an experimental system and demonstrated to be robust and computationally efficient.

Automotive transmission clutch fill optimal control: An experimental investigation

Clutch to clutch shift control technology, which is the key enabler for a compact and low cost automotive transmission design, is important for both automatic and hybrid transmissions. To ensure a smooth clutch to clutch shift, precise synchronization between the on-coming and off-going clutches is critical. This further requires the on-coming clutch to be filled and ready for engagement at the predetermined time. To optimize this process, the clutch fill was formulated as an optimization problem in our previous work and a customized dynamic programming method was proposed as a solution. Following this idea, this paper presents the clutch fill experimental setup and the optimal control implementation. First, a clutch fill dynamic model, which captures the key dynamics in the clutch fill process, is constructed and analyzed. Second, the customized DP method is implemented to obtain the optimal pressure profile subjected to specified constraints. To validate the proposed method, a transmission clutch fixture has been designed and built in the laboratory. Finally, the experiment is conducted to track the optimal input pressure for clutch fill.

Design, Modeling, and Control of a Novel Automotive Transmission Clutch Actuation System

Clutch fill control is the key enabler for a smooth clutch-to-clutch shift, which is critical for the performance and fuel economy of both automatic and hybrid transmissions. While a precise and robust clutch fill is crucial, its control is very challenging as the traditional approach is still in the open-loop fashion due to the lack of a feedback sensor. To address this challenge, a new clutch actuation mechanism is proposed, which realizes an internal feedback structure without any sensor measurement. The proposed mechanism is novel as it embeds all the control elements in the orifice area regulation, which successfully solves the precise and robust control of the hydraulic system with nonlinear dynamics. In this paper, we first present the working principle of the new clutch actuation mechanism. Then, the mechanical system design is shown and the system dynamic model is built. To this end, the proposed internal feedback control mechanism is fabricated and validated in a transmission testing fixture. The new mechanism performance is finally presented through a series of simulation and experimental results.

Robust stabilization of discrete linear time varying internal model based system

This paper focuses on a low order robust stabilizer design for linear time varying (LTV) internal model based system in the discrete time domain. While adopting the output feedback gain injection based stabilization structure for continuous LTV systems, the discrete stabilization synthesis has its unique challenges, and the approach formulated in the continuous domain cannot be directly applied. Therefore, in this paper, the stabilization for LTV internal model based control in the discrete setting is formulated. Its challenges are revealed and methods to convert it into a convex optimization based synthesis are proposed. The approach is then validated through simulation analysis and experimental investigations.Copyright

Transmission Clutch Fill Control Using a Customized Dynamic Programming Method

Clutch fill control is critical for automotive transmission performance and fuel economy, including both automatic and hybrid transmissions. The traditional approach, by which the clutch fill pressure command is manually calibrated, has a couple of limitations. First, the pressure profile is not optimized to reduce the peak clutch fill flow demand. Moreover, it is not systematically designed to account for uncertainties in the system, such as variations of solenoid valve time delay and parameters of the clutch assembly. In this paper, we present a systematic approach to evaluate the clutch fill dynamics and synthesize the optimal pressure profile. First, a clutch fill dynamic model is constructed and analyzed. Second, the applicability of the conventional numerical Dynamic Programming (DP) algorithm to the clutch fill control problem is explored and shown to be ineffective. Thus we developed a new customized DP method to obtain the optimal and robust pressure profile subject to specified constraints. After a series of simulations and case studies, the new customized DP approach is demonstrated to be effective, efficient, and robust for solving the clutch fill optimal control problem.Copyright

A new stabilizer for ltv internal model based system and its application to camless engine valve actuation

This paper focuses on the stabilization of an internal model based control system for reference tracking/disturbance rejection, where the physical plant is linear time invariant while the generating dynamics of the reference/disturbance is time varying. Given the inevitable linear time varying (LTV) nature of the internal model unit resulting from the time varying generating dynamics, a critical problem to be addressed is the design of a low order and robust stabilizer for the entire augmented system. While a parameter-dependent output injection based stabilizer was introduced in our previous work, the new method proposed in this paper reduces the conservativeness in the control synthesis and thus enables a more effective control design especially for the problem involving LTI physical plant with LTV internal model dynamics. The proposed approach is then validated through experimental investigations on a camless engine valve actuation system, where robust and precise tracking performance is demonstrated.

Hybrid powertrain control with a rapid prototyping research platform

As one of the most promising approaches for reducing automotive fuel consumption, hybrid powertrain has inspired extensive research efforts on system control and energy optimization. However, the time and cost of constructing or modifying a physical hybrid powertrain seriously affects the experimental investigation of the complicated system dynamics, so as to limit the development of the precise hybrid powertrain control and optimization. To provide an accurate and flexible hybrid powertrain emulation tool for developing the hybrid control methodologies, a rapid prototyping hybrid powertrain research platform, which employs a transient hydrostatic dynamometer to emulate the dynamics of various hybrid power sources and different hybrid architectures, is constructed. In this research platform, a three-level closed-loop control system is designed for realizing the hybrid powertrain emulation. With respect to the high/middle/low level systems, a suite of hybrid powertrain controllers including an adaptive driver model, an energy optimization strategy, a virtual hybrid torque controller and a dynamometer torque controller are designed and, further, their interactions are analyzed. Experimental results demonstrate that the proposed control system can achieve the precise emulation of the typical hybrid powertrain operation.