Large motion mountain biking dynamics

A bond graph model of a mountain bike and rider is created to develop baseline predictions for the performance of mountain bikes during large excursion maneuvers such as drops, jumps, crashes and rough terrain riding. The model assumes planar dynamics, a hard-tail (front suspension only) bicycle and a rider fixed to the bicycle. An algorithm is developed to allow tracking of a virtual tire-ground contact point for events that separate the wheels from the ground. This model would be most applicable to novice mountain bikers who maintain a nearly rigid relationship between their body and the bicycle as opposed to experienced riders who are versed in controlling the bicycle independent of the body. Simulations of a steep drop are performed for various initial conditions to qualitatively validate the predictions of the model. Results from this model are to be compared to experimental data and more complex models in later research, particularly models including a separate rider. The overarching goals of the research are to examine and understand the dynamics and control of interactions between a cyclist and mountain bike. Specific goals are to understand the improvement in performance afforded by an experienced rider, to hypothesize human control algorithms that allow riders to perform manoeuvres well and safely, to predict structural bike and body forces from these maneuvers and to quantify performance differences between hard-tail and full suspension bicycles.     

Large motion mountain biking dynamics

A bond graph model of a mountain bike and rider is created to develop baseline predictions for the performance of mountain bikes during large excursion maneuvers such as drops, jumps, crashes and rough terrain riding. The model assumes planar dynamics, a hard-tail (front suspension only) bicycle and a rider fixed to the bicycle. An algorithm is developed to allow tracking of a virtual tire-ground contact point for events that separate the wheels from the ground. This model would be most applicable to novice mountain bikers who maintain a nearly rigid relationship between their body and the bicycle as opposed to experienced riders who are versed in controlling the bicycle independent of the body. Simulations of a steep drop are performed for various initial conditions to qualitatively validate the predictions of the model. Results from this model are to be compared to experimental data and more complex models in later research, particularly models including a separate rider. The overarching goals of the research are to examine and understand the dynamics and control of interactions between a cyclist and mountain bike. Specific goals are to understand the improvement in performance afforded by an experienced rider, to hypothesize human control algorithms that allow riders to perform manoeuvres well and safely, to predict structural bike and body forces from these maneuvers and to quantify performance differences between hard-tail and full suspension bicycles.     

Nonlinear Design Approach to Four-Wheel-Steering Systems Using Neural Networks

Four-wheel-steering (4WS) systems have been studied and developed with remarkable success from the viewpoint of vehicle dynamics. Most of the control methods require a linearized bicycle model of the actual vehicle system which is however strongly influenced by tire nonlinearity. This paper proposes a new method to design the 4WS system taking into account the nonlinear characteristics of tires and suspensions. For this purpose integration of artificial neural network and linear control theory is introduced for the identification and control of a nonlinear vehicle model structured using a software for multi-body dynamic analysis (ADAMS). This model takes into account the nonlinear characteristics of actual vehicles with tires modeled by “magic formula“. The results of computer simulations show that the proposed nonlinear approach is efficient in improving the handling and stability of vehicles.     

两相位交叉口机非冲突对机动车饱和流率的影响研究

通过分析直行自行车与右转和左转机动车之间的冲突规律,采用冲突区占有率方法,研究了直行自行车对机动车饱和流率的修正系数,建立了直行自行车与右转机动车对冲突区占有率的关系模型,结果表明直行自行车对冲突区的占有率随着流量的增加而增加,进而标定了其对机动车饱和流率的影响系数。针对左转机动车,通过分析车流运行特性和通行规则,建立了直行机动车对冲突区的占有率模型,并以此为基础标定了直行自行车对左转机动车饱和流率的修正系数。本文的研究成果为机非混行条件下交叉口的通行能力计算和信号配时方案设计提供了依据。     

非拥挤路段自行车交通流特性研究

自行车是城市居民出行的主要方式之一，研究自行车交通流的特性对于合理规划道路交通资源，提高白行车交通服务水平具有重要意义。针对白行车交通流与机动车交通流的不同特征，提出了以单位面积车道上车辆集散程度定义白行车交通流密度的新方法，并基于调查数据，研究了非拥挤状态下自行车交通流密度、车速和流率3个参数的相关性，发现非拥挤自行车流的速度总是分布在接近期望车速的范围内，且与流率、密度无关，而速度的离散程度随着密度的增大而减小。最后，分析了车道、宽度与交通流3个参数的相关性，并建立了相应的回归模型，模型可用于在给定自行车交通需求以及服务水平条件下自行车道的设计宽度。     

大客车车身结构动力学建模与随机响应分析

建立了某型全承载式车身结构大客车包括蒙皮和固定玻璃在内的完整的动力学有限元模型,合理地模拟了该车使用的空气弹簧悬架,通过与理论模型求解结果对比,验证了模型的正确性。运用结构动力学的频域求解方法,在模态分析、频率响应分析的基础上,进行了大客车整车结构的动应力随机响应分析。     

基于元胞自动机(CA)的自行车流建模及仿真

为研究城市复杂的混合交通，通过分析自行车的行驶特性，建立了包括元胞尺寸、速度、状态空间及属性、元胞的邻域与局部元胞演变规则的单向自行车二维CA模型。理论分析和数字仿真表明，该模型不仅能灵活有效地描述自行车流，而且其速度-密度特性和最大通行能力的数值范围均符合实际或经验数值。利用该模型还分析并仿真了车道数对单车道自行车通行能力的影响：随着车道宽度的增加，单车道通行能力随之增加，但幅度呈递减趋势，且车道数增长到一定时，通行能力不再继续增长。     

美国的电动自行车安全立法研究

电动自行车在美国的普及率并不高,但联邦与各州都极为重视其交通安全问题。在《联邦电动自行车法》颁布后,美国加快了统一规范电动自行车安全的步伐。通过一系列的立法,美国已经基本建立起了相对统一的电动自行车安全法律体系,主要包括电动自行车的界定、管理、安全装置与通行规则4个方面的内容。及时、科学、完备的立法有力地保障了电动自行车的交通安全．值得我们借鉴。     

Identification of linear handling models for road vehicles

This study reports the identification of linear handling models for road vehicles starting from structural identifiability analysis, continuing with the experiments to acquire data on a vehicle equipped with a sensor set and data acquisition system, and ending with the estimation of parameters using the collected data. The model structure originates from the well-known linear bicycle model that is frequently used in handling analysis of road vehicles. Physical parameters of the bicycle model structure are selected as the unknown parameter set that is to be identified. Global identifiability of the model structure is analysed, in detail, and concluded according to various available sensor sets. Physical parameters of the bicycle model structure are estimated using prediction error estimation method. Genetic algorithms are used in the optimisation phase of the identification algorithm to overcome the difficulty in the selection of initial values for parameter estimates. Validation analysis of the identified model is also presented. The identified model is shown to track the system response successfully.     

Validation of Railway Vehicle Lateral Dynamics Models

SUMMARY

The general form of the railway vehicle lateral dynamic predictions seems to have been proven. If wheels are coned, rails are of uniform cross-section, and suspensions are linear, then good predictions can be obtained. If wheels are not coned, and rail sections vary, but the suspension is relatively linear, as in modern vehicles, it is still possible to obtain good predictions of critical speed for flexible suspensions. The situation with “stiff” vehicles remains unproven. In each case dynamic response calculations will be only as good as the knowledge of the track input including the rolling line term. The validity of making calculations to predict critical speeds of very non-linear vehicles has not yet been convincingly demonstrated. Validation experiments for the more difficult case of time history representation suggest the possibility of correct prediction for easily comprehensible vehicles, but even this requires an enormous amount of supportive experimental work.     

Validation of Railway Vehicle Lateral Dynamics Models

The general form of the railway vehicle lateral dynamic predictions seems to have been proven. If wheels are coned, rails are of uniform cross-section, and suspensions are linear, then good predictions can be obtained. If wheels are not coned, and rail sections vary, but the suspension is relatively linear, as in modern vehicles, it is still possible to obtain good predictions of critical speed for flexible suspensions. The situation with “stiff” vehicles remains unproven. In each case dynamic response calculations will be only as good as the knowledge of the track input including the rolling line term. The validity of making calculations to predict critical speeds of very non-linear vehicles has not yet been convincingly demonstrated. Validation experiments for the more difficult case of time history representation suggest the possibility of correct prediction for easily comprehensible vehicles, but even this requires an enormous amount of supportive experimental work.     

公共电动自行车系统运营模式设计模型

当前对传统公共自行车系统运营模式的研究主要是定性分析,各种方法标准不一,且研究结论与实际差别较大,不能直接用于资金、设施等要求更高的公共电动自行车系统的运营模式设计问题.因此,提出了一种定量设计模型,利用0-1混合整数规划模型对系统的经营主体进行筛选,再利用动态规划模型分配资源.利用算例进行模拟分析,结果表明:①与以资金多和收益好为优的常规的定性分析法相比,定量模型能更合理配置系统构成要素,降低政府的财政负担,分别为政府节省18.68%和23.09%的资金.②在公共电动自行车系统建设和运营过程中,宜采用政企合作模式.③相对于系统运营而言,系统建设期间对政府投入的资金反应更灵敏,因此政府有必要加大建设期的资金投入.      

基于蚁群算法的公共自行车站间调度优化

公共自行车系统在实际运行中存在借车难、还车难等问题,站间自行车调度不合理、不及时是主要原因。根据自行车调度的实际情况,考虑公共自行车系统特殊的调度车容量约束和下一站点补给约束,建立公共自行车站间调度的数学模型。通过改进常规旅行商问题求解的蚁群算法,以满足自行车调度的约束条件。在Matlab中编程实现改进的蚁群算法,并以武汉市关山光谷片区的24个自行车站点为例,用改进的蚁群算法求解调度回路,结果表明该算法可以求解得到最优调度回路。     

A Model for Determining Rider Induced Energy Losses in Bicycle Suspension Systems

The energy dissipated by the suspension systems used for off-road bicycles is a major concern due to the limited power source in cycling. Rider induced energy losses are those that arise from the muscular action of the rider. The purpose of this study was to develop and verify a dynamic model of a seated cyclist riding an off-road bicycle up a smooth road. With the absence of terrain irregularities, all suspension motion was rider induced. Knowing the stiffness and dissipative characteristics of the suspension elements, the power dissipated by the suspensions was calculated.

Simulation results were compared to suspension deflections that were experimentally measured for a cyclist riding a commercially available dual suspension bicycle up a 6% grade at 6.5m/s. For this particular case, no fork motion was observed in the experiments which was consistent with the simulation results. For the rear suspension, the mean and amplitude of the largest harmonic were experimentally determined to be 6.6 and ±2.7 mm respectively. Simulation results were within 0.7mm of the mean and within 0.3mm of the amplitude. The only major discrepancy between the experiments and the simulations was the presence of a phase lag in the simulation results which was attributed to inter-subject variability. The power dissipated by the rear suspension was calculated to be 6.9 Watts or 1.3% of the total power input by the rider. Given the grade and forward velocity, this translated into an equivalent mass of 1.8 kg. Thus, the bicycle appeared to be roughly 12% heavier than it actually was.     

自行车交通系统政策和规划及实施探讨——以丹麦欧登塞市为例

分析、研究了丹麦欧登塞市发展自行车的政策和规划,包括提高自行车出行比例、安全和质量目标,自行车道路规划、环境控制区、自行车设施和技术措施组成,研究认为,欧登塞市的自行车政策和规划是多项政策与规划的协调集成.政策与规划的制定与实施采用动态循环的政策质量监督管理程序,用行动计划推动实施,通过评估给出实施效果.文章认为,长期战略,综合、集成的政策和规划,完善的政策制度、集成与逐步创新发展自行车政策和规划将给予中国城市最直接的启示.     

Modelling and model predictive control for a bicycle-rider system

This study proposes a bicycle-rider control model based on model predictive control (MPC). First, a bicycle-rider model with leaning motion of the rider’s upper body is developed. The initial simulation data of the bicycle rider are then used to identify the linear model of the system in state-space form for MPC design. Control characteristics of the proposed controller are assessed by simulating the roll-angle tracking control. In this riding task, the MPC uses steering and leaning torques as the control inputs to control the bicycle along a reference roll angle. The simulation results in different cases have demonstrated the applicability and performance of the MPC for bicycle-rider modelling.     

考虑心理潜变量的城市电动自行车用户出行决策行为

为探究电动自行车用户对不同城市电动自行车规范管理政策的行为响应机理,采用问卷调查方法收集用户的社会人口特征、出行特征、心理特征以及在不同政策下的决策,基于心理接受度等潜变量构建了多指标多因素模型,得出了潜变量的拟合值,将潜变量作为解释变量引入到行为决策模型中,构成了混合选择模型来分析社会人口变量、出行特征变量和心理潜变...     

Using an integrated model of TPB and TAM to analyze the pandemic impacts on the intention to use bicycles in the post-COVID-19 period

Due to the rapid increase in bicycle usage during the pandemic, this study aims to ascertain the effects of COVID-19 and the role of psychosocial factors on the intention to cycle in the future. An integrated model of the theory of planned behavior (TPB) and technology acceptance model (TAM) was modified and utilized with a sample of 473 cyclists in Yogyakarta, Indonesia. The results confirm that the awareness change because of the advent of COVID-19, especially related to the environment, negative impacts of motorized vehicles (including road safety burden), and climate change issues, has the strongest power to influence bicycle use intention. The positive effect of COVID-19 also significantly influenced subjective norms and perceived behavioral control. Meanwhile, attitudes toward cycling and its perceived usefulness did not significantly contribute to bicycle use intention. Attitudes to use bicycles also could not mediate the relationship between COVID-19 and the intention to use bicycles. Based on the study findings, a set of policy initiatives was proposed, including cycling campaigns related to environmental issues, promoting bicycle use by public figures, providing a segregated bike lane, and introducing bicycle-specific programs, such as bicycle usage in cultural events.     

可倒骑变速自行车计算优化

将产品经济性、舒适性、可靠性指标融入设计理念,对设计的可倒骑双飞变速自行车部分部件建立数学建模,进行尺寸优化,运用NX Nastrsan对曲柄、车架进行有限元素计算分析,并采用Altair Hyper Opt算法对质量、应力分布迭代优化,使各项指标更加精确。     

基于二元有序概率的共享单车满意度评估方法

城市共享单车是城市绿色交通系统的组成部分,是服务公众短距离出行和公共交通接驳换乘的重要方式,在解决城市交通出行"最后一公里"问题等方面发挥了积极作用.为科学评估城市共享单车服务的满意度,采用问卷调查法和实地踏勘法采集了宁波市1212个共享单车用户有效样本,利用统计学方法构建二元有序概率(bivariate ordere...