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Ayalew, Beshah
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A Fuzzy Inference System for Understeer/Oversteer Detection Towards Model-Free Stability Control

SAE International Journal of Passenger Cars - Mechanical Systems

Clemson Univ.-Beshah Ayalew
Ford Motor Co.-Benjamin Hirche
  • Journal Article
  • 2016-01-1630
Published 2016-04-05 by SAE International in United States
In this paper, a soft computing approach to a model-free vehicle stability control (VSC) algorithm is presented. The objective is to create a fuzzy inference system (FIS) that is robust enough to operate in a multitude of vehicle conditions (load, tire wear, alignment), and road conditions while at the same time providing optimal vehicle stability by detecting and minimizing loss of traction. In this approach, an adaptive neuro-fuzzy inference system (ANFIS) is generated using previously collected data to train and optimize the performance of the fuzzy logic VSC algorithm. This paper outlines the FIS detection algorithm and its benefits over a model-based approach. The performance of the FIS-based VSC is evaluated via a co-simulation of MATLAB/Simulink and CarSim model of the vehicle under various road and load conditions. The results showed that the proposed algorithm is capable of accurately indicating unstable vehicle behavior for two different types of vehicles (SUV and Sedan). The algorithm can do this without any significant parameter adjustment, illustrating its robustness against the considered uncertainty.
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Control Allocation for Multi-Axle Hub Motor Driven Land Vehicles

SAE International Journal of Alternative Powertrains

Clemson University-Qian Wang, Beshah Ayalew
US Army, TARDEC-Amandeep Singh
  • Journal Article
  • 2016-01-1670
Published 2016-04-05 by SAE International in United States
This paper outlines a real-time hierarchical control allocation algorithm for multi-axle land vehicles with independent hub motor wheel drives. At the top level, the driver’s input such as pedal position or steering wheel position are interpreted into desired global state responses based on a reference model. Then, a locally linearized rigid body model is used to design a linear quadratic regulator that generates the desired global control efforts, i.e., the total tire forces and moments required track the desired state responses. At the lower level, an optimal control allocation algorithm coordinates the motor torques in such a manner that the forces generated at tire-road contacts produce the desired global control efforts under some physical constraints of the actuation and the tire/wheel dynamics. The performance of the proposed control system design is verified via simulation analysis of a 3-axle heavy vehicle with independent hub-motor drives.
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A Model-Free Stability Control Design Scheme with Active Steering Actuator Sets

SAE International Journal of Passenger Cars - Mechanical Systems

Clemson Univ.-Beshah Ayalew
Ford Motor Co.-Benjamin Hirche
  • Journal Article
  • 2016-01-1655
Published 2016-04-05 by SAE International in United States
This paper presents the application of a proposed fuzzy inference system as part of a stability control design scheme implemented with active steering actuator sets. The fuzzy inference system is used to detect the level of overseer/understeer at the high level and a speed-adaptive activation module determines whether an active front steering, active rear steering, or active 4 wheel steering is suited to improve vehicle handling stability. The resulting model-free system is capable of minimizing the amount of model calibration during the vehicle stability control development process as well as improving vehicle performance and stability over a wide range of vehicle and road conditions. A simulation study will be presented that evaluates the proposed scheme and compares the effectiveness of active front steer (AFS) and active rear steer (ARS) in enhancing the vehicle performance. Both time and frequency domain results are presented.
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Coordinated Electric Supercharging and Turbo-Generation for a Diesel Engine

Clemson Univ.-Prasad Sajjan Divekar, Beshah Ayalew, Robert Prucka
Published 2010-04-12 by SAE International in United States
Exhaust gas turbo-charging helps exploit the improved fuel efficiency of downsized engines by increasing the possible power density from these engines. However, turbo-charged engines exhibit poor transient performance, especially when accelerating from low speeds. In addition, during low-load operating regimes, when the exhaust gas is diverted past the turbine with a waste-gate or pushed through restricted vanes in a variable geometry turbine, there are lost opportunities for recovering energy from the enthalpy of the exhaust gas. Similar limitations can also be identified with mechanical supercharging systems.This paper proposes an electrical supercharging and turbo-generation system that overcomes some of these limitations. The system decouples the activation of the air compression and exhaust-energy recovery functions using a dedicated electrical energy storage buffer. Its main attributes fast speed of response to load changes and flexibility of control. A causal simulation model of the proposed system, including that of the Diesel engine, electrically driven compressor, energy buffer battery and power electronics, and the turbo-generation system are developed and analyzed. A coordinated control scheme is then implemented for the electric…
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Hydrostatic Wheel Drives for Vehicle Stability Control

SAE International Journal of Passenger Cars - Mechanical Systems

Clemson Univ.-Sisay Molla, Justin Sill, Beshah Ayalew
  • Journal Article
  • 2010-01-0105
Published 2010-04-12 by SAE International in United States
Hydrostatic (hydraulic hybrid) drives have demonstrated energy efficiency and emissions reduction benefits. This paper investigates the potential of an independent hydrostatic wheel drive system for implementing a traction-based vehicle lateral stability control system. The system allows an upper level vehicle stability controller to produce a desired corrective yaw moment via a differential distribution of torque to the independent wheel motors. In cornering maneuvers that require braking on any one wheel of the vehicle, the motors can be operated as pumps for re-generating energy into an on-board accumulator. This approach avoids or reduces activation of the friction brakes, thereby reducing energy waste as heat in the brake pads and offering potential savings in brake maintenance costs.For this study, a model of a 4×4 hydrostatic independent wheel drive system is constructed in a causal and modular fashion and is coupled to a 7 DOF vehicle handling dynamics model. The integrated system model is then used to first verify component selection and hybrid control threshold settings for the independent drive system. Then, a vehicle stability controller is set…
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Independent Torque Distribution Strategies for Vehicle Stability Control

Clemson University-Indrasen Karogal, Beshah Ayalew
Published 2009-04-20 by SAE International in United States
This paper proposes and compares torque distribution management strategies for vehicle stability control (VSC) of vehicles with independently driven wheels. For each strategy, the following feedback control variables are considered turn by turn: 1) yaw rate 2) lateral acceleration 3) both yaw rate and lateral acceleration. Computer simulation studies are conducted on the effects of road friction conditions, feedback controller gains, and a driver emulating speed controller. The simulation results indicated that all VSC torque management strategies are generally very effective in tracking the reference yaw rate and lateral acceleration of the vehicle on both dry and slippery surface conditions. Under the VSC strategies employed and the test conditions considered, the sideslip angle of the vehicle remained very small and always below the desired or target values.This study forms an essential step in the design and selection of actuators (e.g., in-wheel motors) for vehicle dynamics control of vehicles with independently driven wheels. Applications include certain powertrain architectures for pure electric or series hybrid electric and hydraulic hybrid vehicles with independent all wheel drives.
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Compliant Link Suspension

BMW Group USA-Andreas Obieglo
Clemson University-John C. Ziegert, Beshah Ayalew, Vincent Lee, Souharda Raghavendra
Published 2009-04-20 by SAE International in United States
This paper discusses a compliant link suspension concept developed for use on a high performance automobile. This suspension uses compliant or flexible members to integrate energy storage and kinematic guidance functions. The goal of the design was to achieve similar elasto-kinematic performance compared to a benchmark OEM suspension, while employing fewer components and having reduced mass and complexity, and potentially providing packaging advantages. The proposed suspension system replaces a control arm in the existing suspension with a ternary supported compliant link that stores energy in bending during suspension vertical motion. The design was refined iteratively by using a computational model to simulate the elasto-kinematic performance as the dimensions and attachment point locations of the compliant link were varied, until the predicted performance closely matched the performance of the benchmark suspension. A mock-up of the proposed compliant link suspension was built together with an adjustable test fixture, and experiments were carried out to validate the results from simulations. The new suspension is less complex and weighs less than the original suspension without sacrificing basic elasto-kinematic performance.
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