|
Hans Bastiaan Pacejka (born 1934) is an expert in vehicle system dynamics and particularly in tire dynamics, fields in which his works are now standard references. He is Professor emeritus at Delft University of Technology in Delft, Netherlands. ==The Pacejka "Magic Formula" tire models== Pacejka has developed a series of tire design models over the last 20 years. They were named the 'magic formula' because there is no particular physical basis for the structure of the equations chosen, but they fit a wide variety of tire constructions and operating conditions. Each tire is characterized by 10-20 coefficients for each important force that it can produce at the contact patch, typically lateral and longitudinal force, and self-aligning torque, as a best fit between experimental data and the model. These coefficients are then used to generate equations showing how much force is generated for a given vertical load on the tire, camber angle and slip angle. The Pacejka tire models are widely used in professional vehicle dynamics simulations, and racing car games, as they are reasonably accurate, easy to program, and solve quickly.〔http://www.tut.fi/plastics/tyreschool/moduulit/moduuli_10/hypertext/index.html MF is "easy to handle, accurate, low effort"〕 A problem with Pacejka's model is that when implemented into computer code, it doesn't work for low speeds (from around the pit-entry speed), because a velocity term in the denominator makes the formula diverge.〔Beckman, Brian (2007) (''Brian Beckman: The Physics in Games - Real-Time Simulation Explained'' ), at ''channel9.msdn.com'', Jun 08, 2007, (min. 29:53-33:45 ) quotation: 〕 An alternative to Pacejka tire models are brush tire models, which can be analytically derived, although empirical curve fitting is still required for good correlation,〔Jacob Svendenius, Björn Wittenmark (2003) (''Brush Tire Model with increased Flexibility'' ), In ''European Control Conference'', September 2003.〕〔(''Modelling of tyres'' )〕 and they tend to be less accurate than the MF models.〔http://www.tut.fi/plastics/tyreschool/moduulit/moduuli_10/hypertext/index.html "These models are not expected to give a very accurate correspondence with measurement but should predict the qualitative trends."〕 The general form of the magic formula is: where ''b'', ''c'', ''d'' and ''e'' represent fitting constants and ''R'' is a force or moment resulting from a slip parameter ''k''. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Hans B. Pacejka」の詳細全文を読む スポンサード リンク
|