Vehicle dynamics
Encyclopedia
Vehicle dynamics refers to the dynamics
of vehicle
s, here assumed to be ground vehicles. Vehicle dynamics is a part of engineering
primarily based on classical mechanics
but it may also involve chemistry
, solid state physics, electrical engineering
, communication
s, psychology
, control theory
, etc.
This article applies primarily to automobile
s. For single-track vehicle
s, specifically the two-wheeled variety, see bicycle and motorcycle dynamics
. For aircraft
, see aerodynamics
. For watercraft
see Hydrodynamics.
. These include:
. These include:
and its distribution. These include:
. These include:
s. These include:
s on which they travel. These include:
system, through a three-degree of freedom (DoF) bicycle model, to a large degree of complexity using a multibody system simulation
package such as MSC ADAMS
or Modelica
. As computers have gotten faster, and software user interfaces have improved, commercial packages such as CarSim
have become widely used in industry for rapidly evaluating hundreds of test conditions much faster than real time. Vehicle models are often simulated with advanced controller
designs provided as software in the loop (SIL) with controller design software such as Simulink
, or with physical hardware in the loop (HIL).
Vehicle motions are largely due to the shear forces generated between the tires and road, and therefore the tire model is an essential part of the math model. The tire model must produce realistic shear forces during braking, acceleration, cornering, and combinations, on a range of surface conditions. Many models are in use. Most are semi-empirical, such as the Pacejka Magic Formula model.
Racing car games or simulators
are also a form of vehicle dynamics simulation. In early versions many simplifications were necessary in order to get real-time performance with reasonable graphics. However, improvements in computer speed have combined with interest in realistic physics, leading to driving simulators
that are used for vehicle engineering using detailed models such as CarSim
.
It is important that the models should agree with real world test results, hence many of the following tests are correlated against results from instrumented test vehicles.
Techniques include:
Dynamics (mechanics)
In the field of physics, the study of the causes of motion and changes in motion is dynamics. In other words the study of forces and why objects are in motion. Dynamics includes the study of the effect of torques on motion...
of vehicle
Vehicle
A vehicle is a device that is designed or used to transport people or cargo. Most often vehicles are manufactured, such as bicycles, cars, motorcycles, trains, ships, boats, and aircraft....
s, here assumed to be ground vehicles. Vehicle dynamics is a part of engineering
Engineering
Engineering is the discipline, art, skill and profession of acquiring and applying scientific, mathematical, economic, social, and practical knowledge, in order to design and build structures, machines, devices, systems, materials and processes that safely realize improvements to the lives of...
primarily based on classical mechanics
Classical mechanics
In physics, classical mechanics is one of the two major sub-fields of mechanics, which is concerned with the set of physical laws describing the motion of bodies under the action of a system of forces...
but it may also involve chemistry
Chemistry
Chemistry is the science of matter, especially its chemical reactions, but also its composition, structure and properties. Chemistry is concerned with atoms and their interactions with other atoms, and particularly with the properties of chemical bonds....
, solid state physics, electrical engineering
Electrical engineering
Electrical engineering is a field of engineering that generally deals with the study and application of electricity, electronics and electromagnetism. The field first became an identifiable occupation in the late nineteenth century after commercialization of the electric telegraph and electrical...
, communication
Communication
Communication is the activity of conveying meaningful information. Communication requires a sender, a message, and an intended recipient, although the receiver need not be present or aware of the sender's intent to communicate at the time of communication; thus communication can occur across vast...
s, psychology
Psychology
Psychology is the study of the mind and behavior. Its immediate goal is to understand individuals and groups by both establishing general principles and researching specific cases. For many, the ultimate goal of psychology is to benefit society...
, control theory
Control theory
Control theory is an interdisciplinary branch of engineering and mathematics that deals with the behavior of dynamical systems. The desired output of a system is called the reference...
, etc.
This article applies primarily to automobile
Automobile
An automobile, autocar, motor car or car is a wheeled motor vehicle used for transporting passengers, which also carries its own engine or motor...
s. For single-track vehicle
Single-track vehicle
A single-track vehicle is a vehicle that leaves a single ground track as it moves forward. Single-track vehicles usually have little or no lateral stability when stationary but develop it when moving forward or controlled...
s, specifically the two-wheeled variety, see bicycle and motorcycle dynamics
Bicycle and motorcycle dynamics
Bicycle and motorcycle dynamics is the science of the motion of bicycles and motorcycles and their components, due to the forces acting on them. Dynamics is a branch of classical mechanics, which in turn is a branch of physics. Bike motions of interest include balancing, steering, braking,...
. For aircraft
Aircraft
An aircraft is a vehicle that is able to fly by gaining support from the air, or, in general, the atmosphere of a planet. An aircraft counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines.Although...
, see aerodynamics
Aerodynamics
Aerodynamics is a branch of dynamics concerned with studying the motion of air, particularly when it interacts with a moving object. Aerodynamics is a subfield of fluid dynamics and gas dynamics, with much theory shared between them. Aerodynamics is often used synonymously with gas dynamics, with...
. For watercraft
Watercraft
A watercraft is a vessel or craft designed to move across or through water. The name is derived from the term "craft" which was used to describe all types of water going vessels...
see Hydrodynamics.
Components
Components, attributes or aspects of vehicle dynamics include:- Automobile layoutAutomobile layoutIn automotive design, the automobile layout describes where on the vehicle the engine and drive wheels are found. Many different combinations of engine location and driven wheels are found in practice, and the location of each is dependent on the application the vehicle will be used for...
- Electronic Stability ControlElectronic Stability ControlElectronic stability control is a computerized technology that may potentially improve the safety of a vehicle's stability by detecting and minimizing skids. When ESC detects loss of steering control, it automatically applies the brakes to help "steer" the vehicle where the driver intends to go...
(ESC) - SteeringSteeringSteering is the term applied to the collection of components, linkages, etc. which will allow a vessel or vehicle to follow the desired course...
- SuspensionSuspension (vehicle)Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. Suspension systems serve a dual purpose — contributing to the car's roadholding/handling and braking for good active safety and driving pleasure, and keeping vehicle occupants...
- Traction control systemTraction control systemA traction control system , also known as anti-slip regulation , is typically a secondary function of the anti-lock braking system on production motor vehicles, designed to prevent loss of traction of driven road wheels...
(TCS)
Aerodynamic specific
Some attributes or aspects of vehicle dynamics are purely aerodynamicAerodynamics
Aerodynamics is a branch of dynamics concerned with studying the motion of air, particularly when it interacts with a moving object. Aerodynamics is a subfield of fluid dynamics and gas dynamics, with much theory shared between them. Aerodynamics is often used synonymously with gas dynamics, with...
. These include:
- Automobile drag coefficientAutomobile drag coefficientThe drag coefficient is a common metric in automotive design pertaining to aerodynamic effects. As aerodynamic drag increases as the square of speed, a low value is preferable to a high one...
- Automotive aerodynamicsAutomotive aerodynamicsAutomotive aerodynamics is the study of the aerodynamics of road vehicles. The main concerns of automotive aerodynamics are reducing drag , reducing wind noise, minimizing noise emission, and preventing undesired lift forces and other causes of aerodynamic instability at high speeds...
- Center of pressureCenter of pressureThe center of pressure is the point on a body where the total sum of a pressure field acts, causing a force and no moment about that point. The total force vector acting at the center of pressure is the value of the integrated vectorial pressure field. The resultant force and center of pressure...
- DownforceDownforceDownforce is a downwards thrust created by the aerodynamic characteristics of a car. The purpose of downforce is to allow a car to travel faster through a corner by increasing the vertical force on the tires, thus creating more grip....
- Ground effect in carsGround effect in carsGround effect is term applied to a series of aerodynamic effects used in car design, which has been exploited to create downforce, particularly in racing cars. This has been the successor to the earlier dominant aerodynamic theory of streamlining...
Geometry specific
Some attributes or aspects of vehicle dynamics are purely geometricGeometry
Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ....
. These include:
- Ackermann steering geometryAckermann steering geometryAckermann steering geometry is a geometric arrangement of linkages in the steering of a car or other vehicle designed to solve the problem of wheels on the inside and outside of a turn needing to trace out circles of different radius...
- Axle trackAxle trackThe axle track in automobiles and other wheeled vehicles which have two or more wheels on an axle, is the distance between the centreline of two roadwheels on the same axle, each on the other side of the vehicle...
- Camber angleCamber anglethumb|100px|From the front of the car, a right wheel with a negative camber angleCamber angle is the angle made by the wheels of a vehicle; specifically, it is the angle between the vertical axis of the wheels used for steering and the vertical axis of the vehicle when viewed from the front or...
- Caster angleCaster anglethumb|250px|θ is the caster angle, the red line is the pivot line, and the grey area is the tire.Caster angle or castor angle is the angular displacement from the vertical axis of the suspension of a steered wheel in a car, bicycle or other vehicle, measured in the longitudinal direction...
- Ride heightRide heightRide height is the amount of space between the base of an automobile tire and the underside of the chassis; or, more properly, to the shortest distance between a flat, level surface, and any part of a vehicle other than those parts designed to contact the ground...
- Roll centerRoll centerThe roll center of a vehicle is the notional point at which the cornering forces in the suspension are reacted to the vehicle body.-Theory:There are two definitions of roll center...
- Scrub radiusScrub radiusThe scrub radius is the distance in front view between the king pin axis and the center of the contact patch of the wheel, where both would theoretically touch the road....
- Steering ratioSteering ratioSteering ratio refers to the ratio between the turn of the steering wheel or handlebars and the turn of the wheels .The steering ratio, is the amount of degrees you have to turn the steering wheel, for the wheels to turn an amount of degrees.In motorcycles and bicycles, the steering ratio is...
- ToeToe (automotive)In automotive engineering, toe, also known as tracking, is the symmetric angle that each wheel makes with the longitudinal axis of the vehicle, as a function of static geometry, and kinematic and compliant effects. This can be contrasted with steer, which is the antisymmetric angle, i.e. both...
- WheelbaseWheelbaseIn both road and rail vehicles, the wheelbase is the distance between the centers of the front and rear wheels.- Road :In automobiles, the wheelbase is the horizontal distance between the center of the front wheel and the center of the rear wheel...
Mass specific
Some attributes or aspects of vehicle dynamics are purely due to massMass
Mass can be defined as a quantitive measure of the resistance an object has to change in its velocity.In physics, mass commonly refers to any of the following three properties of matter, which have been shown experimentally to be equivalent:...
and its distribution. These include:
- Center of massCenter of massIn physics, the center of mass or barycenter of a system is the average location of all of its mass. In the case of a rigid body, the position of the center of mass is fixed in relation to the body...
- Moment of inertiaMoment of inertiaIn classical mechanics, moment of inertia, also called mass moment of inertia, rotational inertia, polar moment of inertia of mass, or the angular mass, is a measure of an object's resistance to changes to its rotation. It is the inertia of a rotating body with respect to its rotation...
- Roll momentRoll momentIn a vehicle suspension, roll moment is the moment of inertia of the vehicle's sprung mass . The roll moment is the product of the sprung mass and the square of the distance between the vehicle's roll center and its center of mass...
- Sprung massSprung massIn a vehicle with a suspension, such as an automobile, motorcycle or a tank, sprung mass is the portion of the vehicle's total mass that is supported above the suspension, including in most applications approximately half of the weight of the suspension itself...
- Unsprung mass
- Weight distributionWeight distributionWeight distribution is the apportioning of weight within a vehicle, especially cars, airplanes, and trains.In a vehicle which relies on gravity in some way, weight distribution directly affects a variety of vehicle characteristics, including handling, acceleration, traction, and component life...
Motion specific
Some attributes or aspects of vehicle dynamics are purely dynamicAnalytical dynamics
In classical mechanics, analytical dynamics, or more briefly dynamics, is concerned about the relationship between motion of bodies and its causes, namely the forces acting on the bodies and the properties of the bodies...
. These include:
- Body flexBody flexBody flex is a lack of rigidity in a motor vehicle's chassis. It is often something to be avoided by car manufacturers as higher levels of body flex is a sign of structural weakness, and means that the vehicle's suspension cannot work as efficiently - the body takes up some of the 'slack', rather...
- Body rollBody rollOn wheeled or tracked vehicles, body roll is a reference to the load transfer of a vehicle towards the outside of a turn. When a vehicle is fitted with a suspension package, it works to keep the wheels or tracks in contact with the road, providing grip for the driver of vehicle to control its...
- Bump SteerBump SteerBump steer is the term for the tendency of a wheel to steer as it moves upwards into jounce. It is typically measured in degrees per metre or degrees per foot....
- Directional stabilityDirectional stabilityDirectional stability is stability of a moving body or vehicle about an axis which is perpendicular to its direction of motion. Stability of a vehicle concerns itself with the tendency of a vehicle to return to its original direction in relation to the oncoming medium when disturbed away from...
- Critical speed
- Noise, vibration, and harshnessNoise, Vibration, and HarshnessNoise, vibration, and harshness , also known as noise and vibration , is the study and modification of the noise and vibration characteristics of vehicles, particularly cars and trucks...
- Pitch
- Ride qualityRide qualityRide quality refers to the degree of protection offered vehicle occupants from uneven elements in the road surface, or the terrain if driving off-road. A car with very good ride quality is also a comfortable car to ride in. Cars which disturb vehicle occupants with major or minor road...
- Roll
- Speed wobbleSpeed wobbleWobble, shimmy, tank-slapper, speed wobble, and even death wobble are all words and phrases used to describe a quick oscillation of primarily just the steerable wheel of a vehicle. Initially, the rest of the vehicle remains mostly unaffected, until translated into a vehicle yaw oscillation of...
- Understeer, oversteerUndersteerUndersteer and oversteer are vehicle dynamics terms used to describe the sensitivity of a vehicle to steering. Simply put, oversteer is what occurs when a car turns by more than the amount commanded by the driver...
, lift-off oversteerLift-off oversteerLift-off oversteer is a form of oversteer in an automobile that occurs when the vertical load on the tires shifts from the rear to the front quickly due to throttle release while cornering...
, and fishtailingFishtailingFishtailing is a vehicle handling problem which occurs when the rear wheels lose traction, resulting in oversteer. This can be caused by low friction surfaces... - Weight transfer and load transferWeight transferWeight transfer and load transfer are two expressions used somewhat confusingly to describe two distinct effects: the change in load borne by different wheels of even perfectly rigid vehicles during acceleration, and the change in center of mass location relative to the wheels because of...
- Yaw
Tire specific
Some attributes or aspects of vehicle dynamics can be attributed directly to the tireTire
A tire or tyre is a ring-shaped covering that fits around a wheel rim to protect it and enable better vehicle performance by providing a flexible cushion that absorbs shock while keeping the wheel in close contact with the ground...
s. These include:
- Camber thrustCamber thrustCamber thrust and camber force are terms used to describe the force generated perpendicular to the direction of travel of a rolling tire due to its camber angle and finite contact patch...
- Circle of forcesCircle of forcesThe circle of forces, traction circle, friction circle, or friction ellipse is a useful way to think about the dynamic interaction between a vehicle's tire and the road surface. In the diagram below we are looking at the tire from above, so that the road surface lies in the x-y plane...
- Contact patchContact patchContact patch is the portion of a vehicle's tire that is in actual contact with the road surface. It is most commonly used in the discussion of pneumatic tires, , where the term is strictly used to describe the portion of the tire’s tread that touches the road surface...
- Cornering forceCornering forceCornering force or side force is the lateral force produced by a vehicle tire during cornering.Cornering force is generated by tire slip and is proportional to slip angle at low slip angles. The rate at which cornering force builds up is described by relaxation length...
- Ground pressureGround pressureGround pressure is the pressure exerted on the ground by the tires or tracks of a motorized vehicle, and is one measure of its potential mobility, especially over soft ground. Ground pressure is measured in pascals which corresponds to the EES unit of pounds per square inch...
- Pacejka's Magic Formula
- Pneumatic trailPneumatic trailPneumatic trail or trail of the tire is a trail-like effect generated by compliant tires rolling on a hard surface and subject to side loads, as in a turn...
- Relaxation lengthRelaxation lengthRelaxation length is a dynamic property of pneumatic tires that describes the delay between when a slip angle is introduced and when the cornering force reaches its steady-state value....
- Rolling resistanceRolling resistanceRolling resistance, sometimes called rolling friction or rolling drag, is the resistance that occurs when a round object such as a ball or tire rolls on a flat surface, in steady velocity straight line motion. It is caused mainly by the deformation of the object, the deformation of the surface, or...
- Self aligning torqueSelf aligning torqueSelf aligning torque, also known as aligning torque, SAT, or Mz, is the torque that a tire creates as it rolls along, which tends to steer it, i.e. rotate it around its vertical axis...
- Slip angleSlip angleIn vehicle dynamics, slip angle or sideslip angle is the angle between a rolling wheel's actual direction of travel and the direction towards which it is pointing...
- Slip (vehicle dynamics)Slip (vehicle dynamics)In vehicle dynamics, slip is the relative motion between a tire and the road surface it is moving on. This slip can be generated either by the tire's rotational speed being greater or less than the free-rolling speed , or by the tire's plane of rotation being at an angle to its direction of...
- Steering ratio
- Tire load sensitivityTire load sensitivityTire load sensitivity describes the behaviour of tires under load. Conventional pneumatic tires do not behave as classical friction theory would suggest...
Roadway specific
Some attributes or aspects of vehicle dynamics can be attributed directly to the roadRoad
A road is a thoroughfare, route, or way on land between two places, which typically has been paved or otherwise improved to allow travel by some conveyance, including a horse, cart, or motor vehicle. Roads consist of one, or sometimes two, roadways each with one or more lanes and also any...
s on which they travel. These include:
- Banked turnBanked turnA banked turn is a turn or change of direction in which the vehicle banks or inclines, usually towards the inside of the turn. The bank angle is the angle at which the vehicle is inclined about its longitudinal axis with respect to its path....
, cross slopeCross slopeCross slope is a geometric feature of pavement surfaces; the transversal slope [%] with respect to the horizon. It is a very important safety factor. One task is to make water run off the surface to a drainage system, as Cross Slope is the main contributor to Pavement Drainage gradient. Very low...
, drainage gradientDrainage gradientDrainage gradient is a term in road technology, defining the resulting vector of a road surface cross slope and longitudinal gradient .If the DG is too low, rain and melt water drainage will be insufficient...
, and cant or superelevationCant (road/rail)The cant of a railway track or a road is the difference in elevation between the two edges... - Road slipperinessRoad slipperinessRoad slipperiness or skid resistance is the technical term for the cumulative effects of snow, ice, water, loose material and the road surface on the traction produced by the wheels of a vehicle...
and Split frictionSplit frictionA special road safety problem is Split friction or μ - split; when the friction significantly differs between the left and the right wheelpath. The road may then not be perceived as hazardous when accelerating, cruising or even braking softly. But in a case of hard braking, the car will start to... - Surface roughness, International Roughness IndexInternational Roughness IndexThe International Roughness Index is the roughness index most commonly obtained from measured longitudinal road profiles. It is calculated using a quarter-car vehicle math model, whose response is accumulated to yield a roughness index with units of slope...
, ProfilographProfilographThe profilograph is a device used to measure pavement surface roughness. In the early 20th century, Profilographs were low speed rolling devices. Today many Profilographs are advanced high speed systems with a laserbased height sensor in combination with a inertial system that creates a large...
, TextureTexture (roads)Road surface texture are deviations from a planar surface, affecting the vehicle/tyre interaction. Pavement texture is divided into:* Microtexture with wavelengths from 0 mm up to 0.5 mm* Macrotexture with wavelengths from 0.5 mm up to 50 mm...
Driving techniques
Driving techniques which relate to, or improve the stability of vehicle dynamics include:- Cadence brakingCadence brakingCadence braking or stutter braking is an advanced driving technique used to allow a car to both steer and brake on a slippery surface. It is used to effect an emergency stop where traction is limited, to reduce the effect of skidding from road wheels locking up under braking...
- Threshold brakingThreshold brakingThreshold braking or limit braking is a driving technique most commonly used in motor racing, but also practiced in road vehicles to slow a vehicle at the optimum rate using the brakes....
- Double declutching
- Drifting (motorsport)Drifting (motorsport)Drifting refers to a driving technique and to a motorsport where the driver intentionally over steers, causing loss of traction in the rear wheels through turns, while maintaining vehicle control and a high exit speed...
- Handbrake turnHandbrake turnThe handbrake turn is a driving technique used to deliberately slide a car sideways, either for the purpose of negotiating a very tight bend quickly, or for turning around well within the vehicle's own turning circle....
- Heel-and-ToeHeel-and-toeHeel-and-toe is a driving technique used mostly in performance driving, although some drivers use it on the road in everyday conditions in the interest of effectiveness. It involves operating the throttle and brake pedals simultaneously with the right foot, while facilitating normal activation of...
- Left-foot brakingLeft-foot brakingLeft-foot braking is the technique of using the left foot to operate the brake pedal in an automobile, leaving the right foot dedicated to the throttle pedal...
- Opposite lockOpposite lockOpposite lock, also commonly known as counter-steering, is a colloquial term used to mean the steering associated with the deliberate use of oversteer to turn a vehicle rapidly without losing momentum. It is typified by the classic rallying style of rear-wheel drive cars, where a car appears to...
- Scandinavian flickScandinavian flickThe Scandinavian flick, Finnish flick, Manji Drifting, or Pendulum turn, is a technique used in rallying. While approaching the turn the driver applies a slight steering input to the opposite direction of the turn, then steering into the turn, while sharply lifting off the throttle and lightly...
Analysis and simulation
The dynamic behavior of vehicles can be analysed in several different ways. This can be as straightforward as a simple spring massTuned mass damper
A tuned mass damper, also known as an active mass damper or harmonic absorber, is a device mounted in structures to reduce the amplitude of mechanical vibrations. Their application can prevent discomfort, damage, or outright structural failure...
system, through a three-degree of freedom (DoF) bicycle model, to a large degree of complexity using a multibody system simulation
Multibody system
A multibody system is used to model the dynamic behavior of interconnected rigid or flexible bodies, each of which may undergo large translational and rotational displacements.- Introduction :...
package such as MSC ADAMS
MSC Software
-History:MSC.Software Corporation was formed in 1963 under the name MacNeal-Schwendler Corporation . The company developed its first structural analysis software called SADSAM at that time, and was deeply involved in the early efforts of the aerospace industry to improve early finite element...
or Modelica
Modelica
Modelica is an object-oriented, declarative, multi-domain modeling language for component-oriented modeling of complex systems, e.g., systems containing mechanical, electrical, electronic, hydraulic, thermal, control, electric power or process-oriented subcomponents.The free Modelica languageis...
. As computers have gotten faster, and software user interfaces have improved, commercial packages such as CarSim
Carsim
CarSim is a commercial software package that predicts the performance of vehicles in response to driver controls in a given environment...
have become widely used in industry for rapidly evaluating hundreds of test conditions much faster than real time. Vehicle models are often simulated with advanced controller
Electronic Stability Control
Electronic stability control is a computerized technology that may potentially improve the safety of a vehicle's stability by detecting and minimizing skids. When ESC detects loss of steering control, it automatically applies the brakes to help "steer" the vehicle where the driver intends to go...
designs provided as software in the loop (SIL) with controller design software such as Simulink
Simulink
Simulink, developed by MathWorks, is a commercial tool for modeling, simulating and analyzing multidomain dynamic systems. Its primary interface is a graphical block diagramming tool and a customizable set of block libraries. It offers tight integration with the rest of the MATLAB environment and...
, or with physical hardware in the loop (HIL).
Vehicle motions are largely due to the shear forces generated between the tires and road, and therefore the tire model is an essential part of the math model. The tire model must produce realistic shear forces during braking, acceleration, cornering, and combinations, on a range of surface conditions. Many models are in use. Most are semi-empirical, such as the Pacejka Magic Formula model.
Racing car games or simulators
Sim racing
Sim racing is the collective term for computer software that attempts to simulate accurately auto racing , complete with real-world variables such as fuel usage, damage, tire wear and grip, and suspension settings...
are also a form of vehicle dynamics simulation. In early versions many simplifications were necessary in order to get real-time performance with reasonable graphics. However, improvements in computer speed have combined with interest in realistic physics, leading to driving simulators
Driving simulator
Driving simulators are used for entertainment as well as in training of driver's education courses taught in educational institutions and private businesses...
that are used for vehicle engineering using detailed models such as CarSim
Carsim
CarSim is a commercial software package that predicts the performance of vehicles in response to driver controls in a given environment...
.
It is important that the models should agree with real world test results, hence many of the following tests are correlated against results from instrumented test vehicles.
Techniques include:
- Linear range constant radius understeerBundorf analysisA Bundorf analysis is a way of describing the characteristics of a vehicle that govern its understeer balance. The understeer is measured in units of degrees of additional yaw per g of lateral acceleration.-An imaginary example:...
- Fishhook
- Frequency responseFrequency responseFrequency response is the quantitative measure of the output spectrum of a system or device in response to a stimulus, and is used to characterize the dynamics of the system. It is a measure of magnitude and phase of the output as a function of frequency, in comparison to the input...
- Lane change
- Moose testMoose testA moose test or elk test is a test to determine how a certain vehicle acts when the driver evades a suddenly appearing obstacle...
- Sinusoidal steering
- SkidpadSkidpadA skidpad or skidpan is a large, circular area of flat pavement used for various tests of a car's handling. The most common skidpad use is testing lateral acceleration, measured in g....
- Swept path analysisSwept path analysisSwept Path Analysis is the calculation and analysis of the movement and path of different parts of a vehicle when that vehicle is undertaking a turning maneuver. At a basic level this includes calculating the path taken by each wheel during the turn and also calculating the space needed by the...
See also
- Automotive suspension designAutomotive suspension designAutomotive suspension design is an aspect of automotive engineering, concerned with designing the suspension for cars and trucks.The process entails*selecting appropriate vehicle level targets*selecting a system architecture...
- Hunting oscillationHunting oscillationHunting oscillation is an oscillation, usually unwanted, about an equilibrium. The expression came into use in the 19th century and describes how a systems 'hunts' for equilibrium...
- Important publications in vehicle dynamics
- Multi-axis shaker tableMulti-axis shaker tableA multi-axis shaker table or MAST is an automotive test system specifically designed for the high-frequency testing of vehicle components. These test systems consist of hexapod platform with a low resonance table on top. The test system can be used to simulate any kind of vibration in all six...
- Vehicle metricsVehicle metricsThere are a broad range of metrics that denote the relative capabilities of various vehicles. Most of them apply to all vehicles while others are type-specific....
- 4-poster4-posterA 4-poster or four poster automotive test system is specifically designed for the testing of vehicles . These test systems consist of 4 hydraulic actuators on top of which the wheels of the vehicle are placed. Movements of the actuators simulate the road surface and forces exerted by the road on...
- 7 post shaker7 post shakerThe 7 post shaker is a piece of test equipment used to perform technical analysis on racecars. A 7 post shaker can apply all vertical forces acting on the car on the racetrack, emulating some of the effects of driving. The shaker has many controls for the hydraulic system and sensors to measure...
External links
- http://white-smoke.wetpaint.com/page/What+is+reality%2C+simulation+and+how+to+model+the+real+world An open resource and wiki for information on the vehicle dynamics of racing cars.