Mohd Azrin Mohd Zulkefli

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.

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

Energy management strategy for a power-split hydraulic hybrid wheel loader

Energy management strategies for a power-split hydraulic hybrid wheel loader are studied in this paper. The differences between the powertrain and the energy management system for on-road vehicles and the powertrain and the energy management system for off-road vehicles are first identified. Unlike on-road vehicles where the engine powers only the drivetrain, the engine in a wheel loader powers both the drivetrain and the working hydraulic system. In a non-hybrid wheel loader, the two subsystems interfere with each other since they share the same engine shaft. By using a power-split powertrain, this not only allows for optimal engine operation and regenerative braking but also greatly reduces the interference between the drivetrain and the working functions. An energy management strategy based on dynamic programming is developed to give full system optimization including both the drivetrain and the working functions. Both a long loading cycle and a short loading cycle are studied in this paper. The dynamic-programming-based strategy is compared with a rule-based strategy using simulation studies.

Investigation on the energy management strategy for hydraulic hybrid wheel loaders

Energy management strategies for a hydraulic hybrid wheel loader are studied in this paper. The architecture of the hydraulic hybrid wheel loader is first presented and the differences of the powertrain and the energy management system between on-road vehicles and wheel loaders are identified. Unlike the on-road vehicles where the engine only powers the drivetrain, the engine in a wheel loader powers both the drivetrain and the working hydraulic system. In a non-hybrid wheel loader, the two sub-systems interfere with each other since they share the same engine shaft. By using a power split drivetrain, it not only allows for optimal engine operation and regenerative braking, but also eliminates interferences between driving and working functions, which improve the productivity, fuel efficiency and operability of the wheel loader. An energy management strategy (EMS) based on dynamic programming (DP) is designed to optimize the operation of both the power split drivetrain and the working hydraulic system. A short loading cycle is selected as the duty cycle. The EMS based on DP is compared with a rule-based strategy through simulation.Copyright

Modeling, Analysis, and Optimal Design of the Automotive Transmission Ball Capsule System

Clutch shift control is critical for the performance and fuel economy of automotive transmission, including both automatic and hybrid transmissions. Among all the factors that influence clutch shift control, clutch fill and clutch engagement are crucial to realize a fast and smooth clutch shift. When the clutch is not engaged, the fluid held by the centrifugal force inside of the clutch chamber, which introduces additional pressure that will affect the subsequent clutch fill and engagement processes, should be released. To realize this function, a ball capsule system is introduced and mounted on the clutch chamber. When the clutch is ready to be filled for engagement, the ball capsule needs to close quickly and remain closed until the clutch is disengaged. Its also desirable to have appropriate closing velocity for the ball capsule to minimize noise and wear. In this paper, we will model the ball capsule dynamics and reveal its intrinsic positive feedback structure, which is considered to be the key to realize a fast response, and design the optimal shape of the capsule to achieve the desired performance.

Hybrid Powertrain Optimization With Real-Time Traffic Information

Combining hybrid powertrain optimization with traffic information has been researched before, but tradeoffs between optimality, driving-cycle sensitivity and speed of calculation have not been cohesively addressed. Optimizing hybrid powertrain with traffic can be done through iterative methods such as Dynamic Programming (DP), Stochastic-DP and Model Predictive Control, but high computation load limits their online implementation. Equivalent Consumption Minimization Strategy (ECMS) and Adaptive-ECMS were proposed to minimize computation time, but unable to ensure real-time charge-sustaining-operation (CS) in transient traffic environment. Others show relationship between Pontryagin’s Minimum Principles (PMP) and ECMS, but iteratively solve the CS-operation problem offline. This paper proposes combining PMP’s necessary conditions for optimality, with sum-of State-Of-Charge-derivative for CS-operation. A lookup table is generated offline to interpolate linear mass-fuel-rate vs net-power-to-battery slopes to calculate the equivalence ratio for real-time implementation with predicted traffic data. Maximum fuel economy improvements of 7.2% over Rule-Based is achieved within a simulated traffic network.© 2013 ASME

Modeling, analysis, and optimal design of the automotive transmission ball capsule system

Clutch shift control is critical for the performance and fuel economy of automotive transmission, including both automatic and hybrid transmissions. Among all the factors that influence clutch shift control, clutch fill and clutch engagement are crucial to realize a fast and smooth clutch shift. When the clutch is not engaged, the fluid held by the centrifugal force inside of the clutch chamber, which introduces additional pressure that will affect the subsequent clutch fill and engagement processes, should be released. To realize this function, a ball capsule system is introduced and mounted on the clutch chamber. When the clutch is ready to be filled for engagement, the ball capsule needs to close quickly and remain closed until the clutch is disengaged. Its also desirable to have appropriate closing velocity for the ball capsule to minimize noise and wear. In this paper, we will model the ball capsule dynamics and reveal its intrinsic positive feedback structure, which is considered to be the key to realize a fast response, and design the optimal shape of the capsule to achieve the desired performance.

A Novel Automotive Transmission Clutch Control Mechanism

Clutch fill control is critical for automotive transmission performance and fuel economy, including both automatic and hybrid transmissions. To ensure proper function of the transmission systems, it is important to have a precise and robust clutch fill process. Current clutch fill control is realized in an open loop fashion, due to the lack of a pressure or position sensor in the clutch chamber. To improve the accuracy and robustness of this system, a new clutch control mechanism is proposed, which includes an internal feedback structure without a pressure or position sensor. First, the design and working principles of the new mechanism are presented. Second, the advantages of the internal feedback mechanism are analyzed and shown to be superior to the traditional clutch fill mechanism. To this end, the dynamic model of the new mechanism is formulated. Through a series of simulations and case studies, the new clutch control mechanism is demonstrated to be effective, efficient, and robust for solving the clutch fill and engagement control problem.Copyright