自行車騎行動力學理論與安全性分析

The Riding Dynamics and Safety Analysis of a Bicycle

賴大渭(Lai, David)

指導教授 ： 宋震國

國立清華大學/工學院/動力機械工程學系/博士(2009年)

https://doi.org/10.6843/NTHU.2009.00792

摘要

本文探討自行車的煞車安全性，經由建立騎行動力學的數學模型與參數模擬分析，來獲得提昇煞車性能的關鍵因素。由於自行車是以人力來驅動，因此行進間的操控安全性，無不以煞車性能為最重要的指標。文中首先建立煞車安全性的理論分析模型，在不同路面的摩擦係數下，由前後輪可達到之最大減加速度，獲得最大煞車力以及最短的煞車距離，此為同步理想煞車重要的分析結果。
在剛性自行車架的數學模型建立與模擬分析方面，本文分別以直線運動以及二維與三維轉彎模型，來推導直線行進與轉彎運動的理論數學方程式；在全避震自行車的分析方面，首先建立運動參數理論模型，其中包含前、後輪與車架避震系統，再以拉格朗齊法建立整車運動方程式。文中同時建立騎行力學相關模擬條件，作為直線煞車與轉彎運動參數模擬與分析的基礎。
對整車煞車安全性之模擬分析方面，可由本文理論所推導的結果，來探討剛性與全避震自行車的騎行與煞車安全性問題。文中運用理想煞車性能分佈曲線，獲得前後輪煞車力最佳化分配，達到同步理想煞車，以提高自行車之煞車性能；此外於避震車的直線騎行動態響應模擬，亦利用理想同步煞車觀念來改善過大煞車力的情形。最後探討在一般騎行時，以前後輪煞車力分配與時間延遲來避免其中一輪先鎖死，所得模擬結果，可作為同步理想煞車器，於工程實務設計的參考依據。

關鍵字

煞車安全 ； 自行車動力學 ； 同步理想煞車

並列摘要

Bicycles are driven by manpower, therefore, the brake safety is considered to be the most crucial index for high-quality bicycles. This paper focused on establishing mathematical model and then conducting parametric analysis of the riding dynamics for both rigid and fully suspended bicycle frames. The key factors for improving the brake performance of a bicycle can be obtained from the analyses of various friction coefficients of road surfaces, the types of bicycle frames, and the methods of brake forces applied.
This paper employed the linear motion (1D), 2-D and 3-D turning conditions to establish the physical models of riding dynamics of the rigid bicycle frame and then derive the mathematical equations, which was used as a foundation of parametric analysis for linear brake and turning movement. Regarding the analysis of a fully suspended bicycle, a theoretical model that consisted of a front wheel, a rear wheel and a frame equipped with suspensions was established first. After that, the Lagrange method was used to derive the equations of motion for the bicycle, which led to the analysis of various riding parameters.
Regarding the simulation and analysis of brake safety, the issues of riding and brake safety on rigid and fully suspended bicycles were discussed based on the results derived from the theoretical derivation. In the paper, the distribution curve of ideal brake force was used to obtain the optimal ratio of braking force for front and rear wheels, so ideal synchronization brake could be achieved and the brake performance of a bicycle could be improved. In addition, the simulation of dynamic response to linear riding of suspension bicycle also used the concept of ideal synchronization brake to improve the difficulty of excessive brake force. Discussion was implemented on braking force for front and rear wheels in using time delay during applying brake force, which prevents dead lock on one wheel. The simulation results obtained can be used as reference of practical engineering design on the ideal synchronization brake.

並列關鍵字

brake safety ； bicycle riding dynamics ； ideal synchronization brake

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