Search results

The purpose of this study is to improve vehicles’ brake stability, the problem of constraint control for an antilock braking system (ABS) with asymmetric slip ratio constraints is concerned. A nonlinear control method based on barrier Lyapunov function (BLF) is proposed not only to track the optimal slip ratio but also to guarantee no violation on slip ratio constraints.

A quarter vehicle braking model and Burckhardt’s tire model are considered. The asymmetric BLF is introduced into the controller for solving asymmetric slip ratio constraint problems.

The proposed controller can implement ABS zero steady-state error tracking of the optimal wheel slip ratio and make slip ratio constraints flexible for various runway surfaces and runway transitions. Simulation and experimental results show that the control scheme can guarantee no violation on slip ratio constraints and avoid self-locking.

The slip rate equation with uncertainties is established, and BLF is introduced into the design process of the constrained controller to realize the slip rate constrained control.

The Purpose of this study is to prove the possibility of developing low cost mechanical anti – lock braking system (ABS) for the passenger’s safety.

The design methodology of the proposed newer mechanical ABS comprises of two units, namely, the braking unit and wheel lock prevention unit. The braking unit actuates the wheel stopping as and when the driver applies the brake, whereas the wheel lock prevention unit initiates wheel release to prevent locking and subsequent slip/skidding. The brake pedal with master cylinder assembly and double-arm cylinder forms the braking unit, brake pad cylinder, movable brake pad, solenoid valve and dynamo forms the wheel lock prevention unit. The dynamo coupled with the rotor energises/de-energises the solenoid values to direct airflow for applying brake and release it, which makes the system less energy-dependent.

The braking unit aids in vehicle stops, by locking the disc with the brake pad actuated by a double-arm cylinder. The dynamo energises the solenoid valve to activate the brake pad cylinder piston for applying the brake on the disc. Instantaneously, on applying the brake the dynamo de-energises the solenoid to divert the pneumatic flow for retracting the brake pad thereby minimizing the braking torque. The baking torque reduction revives the wheel rotating and prevents slip/skidding.

Mechanical ABS preventing wheel lock by torque reduction principle is a novel method that has not been evolved so far. The system was designed with repair/replacement of the parts and subcomponents to support higher affordability on safety grounds.

In late 2009 Toyota became the subject of media and U.S. government scrutiny after multiple deaths and injuries were attributed to accidents resulting from the unintended and uncontrolled acceleration of its cars. Despite Toyota's voluntary recall of 4.2 million vehicles for floor mats that could jam the accelerator pedal and a later recall to increase the space between the gas pedal and the floor, the company insisted there was no underlying defect and defended itself against media reports and regulatory statements that said otherwise. As the crisis escalated, Toyota was further criticized for its unwillingness to share information from its data recorders about possible problems with electronic throttle controls and sticky accelerator pedals, as well as braking problems with the Prius. By the time Toyota Motor Company president Akio Toyoda apologized in his testimony to the U.S. Congress, Toyota's stock price had declined, in just over a month, by 20 percent---a $35 billion loss of market value.

Understand the strategic and reputational nature of crises Recognize the challenges of managing a crisis Learn the requirements for building trust in a crisis Understand the challenges of managing a crisis that may not be the company's fault Identify the strategic business problem in a crisis Understand how corporate structure may help or hinder effective crisis management Understand the media landscape and its impact on crisis management