The lack of sustainable solutions to mobility and transportation is a major problem in Latin American cities and requires prompt solutions. The main issues in Latin America are the high-cost of solutions, no inclusion of renewable energies, poor energy management, the use of foreign systems not adapted to local contexts, ineffective regional legislation and politics, among others. In this paper the main technical issues concerning the implementation of a bike-sharing system using pedaling-assisted (PAS) electric bicycles for Bogota City are discussed and a solution is proposed. To solve such problems, a methodology to design a tailored solution well suited to Bogota citizen’s needs is developed. Such methodology starts with the development of an on-board-computer (OBC) in order to characterize bike-users by collecting a rider’s data in real-time. Furthermore, the proposed solution develops a low-cost middle-drive (mid-drive) propulsion system for the PAS in the electric bike using brushless-DC (BLDC) motors and by implementing a field-oriented controller (FOC). The reported bike-sharing system also includes the development and implementation of two charging-stations that enable charging the battery on the electric bikes exclusively by using photovoltaic energy. Experimental results are presented and discussed.
Stability of bicycles has been studied by using models that assume both a rider with hands-off and hands-on the handlebars. Some authors have presented a general comparison between the behavior of the modes of vibration which affect stability in the two configurations; nonetheless, a systematic analysis of the influence of several parameters on each configuration has not been addressed. In addition, the concept of self-stability range has been used as a stability indicator especially when analyzing a rider’s hands-off situation. In contrast, in this paper, the stability area concept is used as a stability index given that it provides more information about the vibration modes in a broader speed range. Therefore, this paper has two major aims. First, the different influence on stability indexes of geometrical, compliance and tire parameters of road racing bicycles is analyzed using hands-off and hands-on models previously published in the literature. Numerical results show that some parameters have different effects on the stability of weave and wobble modes in hands-off and hands-on conditions. Second, a trade-off between the stability behavior of weave and wobble modes is found when using the hands-on model. Therefore, a multi-objective optimization problem for maximizing the stability of both modes is addressed. A Pareto front of the stability of weave and wobble modes is found that serves to analyze the stability trade-off.
The effect on stability of mass, geometric and stiffness parameters of a bicycle with compliant frame, fork and wheel is studied. Critical stiffnesses of the structural elements are identified by means of specific experimental tests based on modal analysis and static stiffness measurement. Numerical stability analysis is carried out by means of a MATLAB code and simulations are planned with the design of experiment (DOE) approach. Numerical results show that the rigid body properties that have the main influence on self-stability are front wheel radius, longitudinal position of the center of mass and trail. Compliance of structural elements has a small effect on self-stability, but causes the appearance of a wobble mode that may be unstable at high speed.
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