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From Automotive Control Systems: For Engine, Driveline, and Vehicle, Second Edition

This Chapter describes various approaches for the estimation and observation of variables which are not directly measurable. Section 9.1 presents two methods of obtaining the vehicle velocity in the inertial co-ordinate system, a Kalman filter approach and a fuzzy estimator. In Section 9.2 these methods are also employed for the estimation of the yaw rate. In Section 9.4, various approaches for estimating the friction characteristics, and the mass moments of inertia. In Section 9.5, approximation formulas are given for the wheel ground contact forces. The tire side slip constants are adapted with a simple nonlinear approximation equation. Based on the wheel ground contact forces, the roll and pitch angles are approximated. In Section 9.6 the vehicle body side slip angle is estimated using a nonlinear observer. Section 9.7 presents two methods for road gradient estimation.

9.1 Vehicle Velocity Estimation

The vehicle velocity v CoG is obtained via a fusion of the data from all rotational wheel velocities v Rij and the longitudinal acceleration sensor. Via integration of the acceleration a fifth estimate for the vehicle velocity is made available. The estimation must be very accurate, as a basis for the wheel slip calculation (see Section 8.3.2). Some systems only select the maximum rotational wheel speed as the estimate for the vehicle velocity. When all four wheels happen to lock simultaneously, this approach is very inaccurate.

Two alternative estimation methods for the vehicle velocity are regarded, the Kalman filter and the fuzzy estimator.

9.1.1 Sensor Data Preprocessing

All sensors...

Products & Services
Electric Brakes
Electric brakes are assemblies consisting of electrical elements for the slowing or stopping of shafts in equipment drives. Electrical power is required to activate the brake.
Automatic Guided Vehicles (AGV)
Automatic Guided Vehicles (AGV) are designed to perform their operations without direct human guidance. They are used in a wide variety of industrial applications and can be laser, inertially or Cartesian-guided.
Differentials and Axles

A differential is a mechanical connection that translates rotational motion from a source to two axles. The driveshaft generally runs the length of the vehicle, from the energy input (a motor) to the energy output (the wheels). The axle of the driving wheels is split, with the driveshaft transferring motion through gearing arrangements to maintain a uniform direction and speed of the (live) axles. This arrangement is very common in rear-wheel drive cars and trucks, but is also employed in aircraft, production machinery and equipment, trains, and ships.

Wheels
Wheels are solid discs or rigid circular rings that attach to assemblies such as casters to allow movement. They are connected to a hub and designed to turn around an axle.
Brake Controllers
Brake controllers are used to control braking systems. They can simply engage and disengage the brake, or control the speed of engagement, breakaway torque, and other variables.

Topics of Interest

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5.1 Introduction The output error method discussed in Chapter 3 is perhaps the most widely used approach for parameter estimation. It has several nice statistical properties and is relatively easy...

9.2 FIXED-POINT SMOOTHING The objective in fixed-point smoothing is to obtain a priori state estimates of xj at times j + 1, j + 2, …, k, k + 1, …. We will use the notation j, k to refer...

INTRODUCTION This book discusses mathematical approaches to the best possible way of estimating the state of a general system. Although the book is firmly grounded in mathematical theory, it should...

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