CAR&D

Dictionary

Angles

The suspended mass of a vehicle has a position defined by three angles whose correct names are: roll, pitch, yaw around xyz axis.

Decarbonized or decarbonated

The chemical term was used in 2008 in the US to refer to vehicles that consume little or no fossil fuel (oil, gas) but can consume biofuel; and /or generate little C0 (low greenhouse gas emissions).

Decoupled

Originally describes a vibration mode of a single mass. By extension a device for obtaining decoupled modes, e.g. independent stiffness in heave, roll, or pitch.

Degree of Freedom

DoF (DdL in french), number of independent variables of the mathematical model of a system, to get an idea of the fineness of its description, do not forget, however, the linear nature whether these variables .

Demonstrator

A vehicle with basic functions covered by development that can "lean" to show, without the components a final process or additional functions.

Dynamics

Study the vehicle movements subjected to forces, including the time response to commands or disturbances.

Embedded

An approach to road safety board that assesses the present situation from the vehicle’s perspective with respect to the road and the environment.

Ergonomics

Ability to be used by a human being.

Ground Bond

"Suspension" is a simple term that does not include steering, drive or tires and then impossible to apply to vehicles without a dedicated suspension (e.g. a kart) but facing to comfort, traction, maneuverability, handling, stability issues. The term Ground Bond reflects better what happens between the main sprung mass and the ground, see further explanation here.

Hybrid

A combination of two things of unlike nature. With respect to motor vehicles, a combination of two types of motors e.g. Eaton bus with an engine and hydraulic motor. Unless otherwise indicated, a hybrid engine includes an internal combustion engine with at least one electric motor.

See a more detailled explanation here.

Hybrid Simulation

Simulation where elements of different natures interact, for instance a vehicle dynamics software and a human driver (=simulator); an electronic unit (=Hardware-in-the-loop); an engine test bench (=hybrid test bench, cf publication n23).

Kinematics

Study of movement independent of causes (forces) or time cues.

Linear

In the reality, rare are the linar phenomena. A test tube of metal deforms gradually with the applied effort, then breakage. A suspension sinks gradually with the load then puts itself in abutment. A tyre derives gradually then bursts brutally. On the other hand, the linear phenomena or the linear portions of the phenomena are easier to analyze.

A little as the story of the alcoholic which looks for its keys under a streetlight. " It is that you lost them? " Ask for an acute passer-by. " Not, but here, I see clearly!

Mode

In a system with multiple masses and springs, refers to a particular movement where all bodies move at the same frequency but not necessarily in the same direction or phase.

Model

Mathematical representation of a physical system.

Model, it is to simplify, because the physical models are not often very simple. It is thus essential to make validation (see farther). For example the behavior of the human being (decision-making, actions) is difficult to model, and for it it seems sometimes interesting to surround a real driver in an environment of simulation, what we call simulator.

The model can be solved in a literal way, frquentielle, or temporal.

The word "simulation" (see farther) is reserved for the temporal answer to entrances.

Numerical Simulation

Numerical computation of time-response of the state and derived variables for a system with inputs and/or disturbances, enabling a "what-if" situation and optimization of the system’s set of parameters (see below).

Parametric set

Very useful neologism for distinguish clearly the part " set of numerical values " from the model cleanly spoken, which is constituted by its degrees of freedom and its equations.

Pendular

Type of chassis-suspension organization linking roll angle toward the inside and theturn, like a motorcycle. Contrary of Tabular.

Pragmatism

Applied to technology, anti-dogmatic approach to the result, implicitly recognizing that we do not know everything and should experiment.

This method is not very appreciated in France. Conversely, it has enabled Mercedes in the preparation of the 190 model in the 1980 attempt on a simple tubular frame all types of rear suspensions and possible and proceed directly to the old suspension kinematics to 5 rods known and used, for example Formula 1 year 1970 and has since become the standard for all luxury vehicles.

This approach is very relevant in the field of automotive technology R & D is not necessarily generalizable to other fields (philosophy, etc.).

"whether the cat is black or white, what matters is it catches mice", Chinese proverb.

Simulator

A specific environment in which vehicle dynamics are simulated and a human driver is in the loop. The goal is to provide the driver with relevant information (visual, haptic, sound, etc) and ascertain his/her reactions.

Steady-State

Study of a stabilized response for a solid body in motion. Constant acceleration for longitudinal movement with variable speed; for lateral dynamics, the corner is stabilized at lateral acceleration and the longitudinal speed is constant. In both cases, the stabilized state is computed but rarely the time response, which is constant. The French term statico-dynamique is less appealing than the Italian "in regime" and English steady-state.

Tabular

Type of chassis-suspension organization inducing roll toward the outside when turning, like a standard car. Contrary of Pendular.

Validation

A problematic because of its imprecision. For vehicle dynamics, it means comparing a model and a test that provides real data on an instrumented vehicle.

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