Design and Analysis of Electric Bikes for Local Commutes

In today’s society, those who do not take advantage of public transportation services typically drive personal vehicles to school, work, and other locations of interest. Due to the required amount of physical exertion, walking or riding a bike is often avoided. This is concerning given that a large percentage of carbon and hazardous emissions emanate from motor vehicles. This creates a need for an alternative means of travel for shorter commutes with electric bikes (e-bikes) one potential solution. They have zero tailpipe emissions and significantly lower overall emissions relative to motorized vehicles; however, their cost often prevents them from being readily marketable. In order to address this issue, two undergraduate capstone design teams have constructed e-bikes using recycled and donated parts over the past two years. In the first year, the runner from a pickup truck was scavenged from a junkyard and employed as the frame to provide for the greatest environmental benefit. However, this resulted in an odd bicycle shape because of limited material availability. As a result, the second years team decided to use a donated chrome moly tube as the frame while focusing on ergonomics and aesthetics. This second bike was designed so that a male rider of average height (5′10″ – 1.78 m) could complete commutes of several miles in relative comfort. Both e-bikes employ a direct drive motor (first year – front wheel; second year – back wheel) to provide assistance when needed, leaving the rider less fatigued. To promote further development in electric bike design, each team has made a considerable effort to record the design process with highlights presented in this effort. Furthermore, e-bike testing results are presented including center of mass calculations, braking distances, turning radii, and overall efficiencies quantified by the miles traveled using the same battery pack. This information will be used to compare the bikes against each other in order to illustrate bike attributes that are desired when an electric motor is employed. The result is an appealing, cost-effective, and efficient electrical bike that will greatly reduce traffic related emissions should it become widely implemented. Given the issues related to transportation at a university (e.g., available parking) including the reticence of students to traverse long distances across campus to attend classes, it is believed that this effort can serve as a model example to other universities who might see e-bikes as a potential solution to reducing congestion and improving student attendance.

A Wireless-Communication-Based Active Safety System for Articulated Heavy Vehicles

This paper presents an active trailer steering (ATS) system using a wireless communication link to facilitate exchanging information among vehicle units of articulated heavy vehicles (AHVs). A challenge for developing and implementing the wireless-communication-based ATS system is to address the problems of delay and packet-loss. Embedding wireless communication transceivers on an AHV may introduce delays for data exchange, and the transmitted data may be lost. Many reasons may lead to the delay and packet-loss, e.g., channel fading, noise burst, interference, etc. The proposed ATS system may prevent unstable motion modes of AHVs if the sensor data reach the controllers/actuators in real-time with an acceptable level of delay and packet-loss. In order to ensure the performance of the ATS control, a Kalman-filter-based estimator is introduced. The estimator uses the available dynamic data to estimate the current states of the AHV in case some sensor information is not available due to a delay or an outage in the wireless communication link. To investigate the effect of the time delay due to the wireless communication on the performance of the ATS control, co-simulations are conducted. The wireless network is modeled using TrueTime toolbox, the ATS controller is designed in SimuLink package, and the AHV model is constructed in TruckSim software. Integrating the wireless network modeled in TrueTime, the ATS controller designed in SimuLink, and the AHV model constructed in TruckSim leads to the co-simulation platform. Under the emulated double lane-change test maneuver, the effects of the wireless communication with two schemes on the direction performance of the AHV are examined.

Lateral Motion Control of a Vehicle Using the Rear Steer: Simulation Study

The lateral motion control is a key element for automated driving vehicle technology. Typically, the front steering system has been used as the primary actuator for vehicle lateral motion control. Alternatively, this paper presents a new method of the lateral motion control using a rear steer. When combined with the front steer actuator, the rear steer can generate more dynamically responsive turning of the vehicle. In addition, the rear steer can be used as a secondary back up actuator when the front steer actuator fails to operate during automated driving mode. Similar to the prior research that has used the front steer actuator for the lateral control, the control methodology presented in this paper maintains the same hierarchical framework, i.e., sensor fusion, path prediction, path planning, and motion control. Since the rear steer is in play for the vehicle lateral motion control, the equations for the path prediction and vehicle dynamics are re-derived with non-zero front steer and rear steer angles. Combined with the rear steering dynamics, the model predictive control (MPC) technique is applied for motion error minimization. This paper describes the theoretical part of the algorithm, and provides simulation results to show effectiveness of the algorithm. Future work will include vehicle implementation, testing, and evaluation.

Estimation of the Geometric Parameters of a Front Double Wishbone Suspension Based on Geometry Formulation

Vehicle suspension stands out as an important subsystem, which allows vertical compliance to the wheels following an uneven road; keeps the proper steer and camber attitudes, resist roll of the chassis and provides comfort for passengers. The suspension subsystem needs to comply with stability, handling and optimum steering based on an appropriate suspension geometry. Nowadays, the use of simulation software in automotive design has increased. However, the cost and complexity of such software can make them unavailable to those working in the domain, especially the young designers working in vehicle’s student competition (Baja SAE®). Thus, this paper aims to propose a methodology for assessing a frontal Double Wishbone suspension, which is based on a set of analytical equations implemented computationally at Matlab®. The formulae are developed considering simple concepts of algebra, trigonometry and geometry. The input data are the Cartesian coordinates (x, y, z) of predefined points, which are obtained from the CAD design and the bound/rebound travel. The main results are the simple analytical formulae, for the most important suspension’s geometric parameters: caster, camber and toe angles. These analytical results are validated with MSC ADAMS®, particularly its add-on specialized for the automotive industry ADAMS/Car®, showing good agreement.

Evaluating the Roll Stability of Articulated Vehicles Using a Phase-Plane Analysis Method

An innovative phase-plane analysis method is proposed to assess the roll stability of articulation vehicles. It is well know that the roll instability of articulated vehicles is one of the most serious problems resulting in loss of life and property for drivers. Hence, it is necessary to develop active anti-roll systems to enhance the roll stability of articulated vehicle systems. In order to actuate the active anti-roll control for the articulated vehicle system, effectively threshold values should be determined. Conventionally, vehicle units’ lateral accelerations are used as the roll-over threshold values for active anti-roll control of articulated vehicles. Considering distinguished configurations and unique dynamic features of articulated vehicles, it is questionable whether the lateral-acceleration-based roll-over threshold of single vehicle is effective to evaluate the roll stability of articulated vehicles. In order to address the problem, case studies will be conducted to assess the roll stability of articulated vehicles using the phase-plane method. To this end, this paper will select a car-trailer system, which is represented by a nonlinear vehicle model generated using the CarSim software package. The phase-plane analysis method is used to examine the following relationships between: 1) the leading unit’s roll angle and roll angular velocity (ϕ – dϕ/dt) and 2) the trailing unit’s roll angle and roll angular velocity (ϕ′ – dϕ′/dt). Built upon the conventional phase-plane analysis method for single-unit vehicles, an innovative phase-plane analysis technique is developed in order to effectively assess the roll stability of articulated vehicles. The applicability and effectiveness of the newly developed technique is examined and demonstrated.

Effect of Vehicle Front End Profile on Pedestrian Kinematics and Biomechanical Responses Using a Validated Numerical Model

Traumatic injuries and biomechanical responses of a pedestrian depend on vehicle front end characteristics as well as the pedestrian anthropometric details in vehicle-pedestrian crashes. A number of laboratory experiments were conducted using post mortem human subjects (PMHS) to understand the biomechanics behind the injuries in a pedestrian crash. However, different vehicular front ends were used in these studies making comparisons among studies impossible. The current research work focuses on validating simulated pedestrian kinematics and accelerations responses of MADYMO full body pedestrian model with the experimental results. In general, overall kinematics of the body for pedestrian models were also compared with that recorded in the video snapshots from the cadaveric experimental tests at 50 ms time intervals. Along with the validation of kinematics of pedestrian, the acceleration responses of head, chest, pelvic and lower leg of the pedestrians were also validated against the corresponding experimental data. Other responses like head angle as well as head impact velocity during primary impact with the hood were analyzed at different impact speeds. Once the responses were validated for a particular front end of the vehicle, a series of numerical parametric studies were further conducted using several front end profiles based off a mid-sized sedan. For the parametric study, different pedestrian models representing three pedestrian sizes, a 50th male, a 5th female, and a 6 years-old child, were used in the simulations. Finite element model of a vehicle front end was changed in terms of the heights of bumper, bonnet leading-edge, and bonnet rear reference-line using a mesh-morphing technique. In most simulations, primary head impact location depends on the pedestrian size, and the secondary impact with ground at the head region is affected by type of vehicle and its front end profile. Kinematics of the pedestrians as well as the angle of primary head impact varies a great deal based upon the front-end profile of the striking vehicle (e.g., raised front-end profile or lowered front-end profile). Leg and pelvis accelerations were found to be high in vehicles with raised front end profiles. Chest and head accelerations were also found to be affected by vehicle front end profile and pedestrian size. However, it should be noted that there were some front-end profiles that help in avoiding pedestrian secondary head impact with the ground.

The New Rail System

The objective of this study was to define the elements of a rail system capable of achieving a 1000-fold increase in freight throughput, accommodate passenger travel, be capable of a phased implementation, be affordable and have a payback to an adopting railroad of less than seven years. This paper describes a novel New Rail System, “NRS” that achieves the stated objectives. The NRS utilizes existing rail rights-of-way and tracks. It has the capability to accommodate both freight and passenger movement. In its initial implementation it supports speeds of 85 mph. Although no invention is required, three modifications to the railroad infrastructure are required, (1) elimination of at-grade crossings, (2) electrification, and (3) transition from diesel-electric locomotive powered trains to individual electrical powered pallets to allow flexible routing and sorting in the network. The four elements defining NRS are; (1) self-powered 70-foot pallets, (2) freight and passenger payload modules (loadable and unloadable from the pallets), (3) pallet yards, accumulators and transfer stations, and (4) a pallet control system. An initial cost-benefits analysis shows that if BNSF implemented the NRS on its Southern Transcon route between Los Angeles and Chicago a payback of the initial $21.2 billion investment can be achieved in under four-years.

Development of a Virtual Platform to Evaluate the Performance of an Electrical Vehicle

Virtual simulations of electrical vehicle performance help to optimize vehicle design, by studying and predicting the effects of parameter variations on the vehicle performance, in order to find an optimum balance between the cost and benefit of design decisions. In this work, the development of a virtual platform to evaluate the performance of an electrical vehicle is presented and applied to the study of public urban transportation. The aim is to analyze the requirements and optimize specifications for a light weight, energy efficient, autonomous vehicle without energy supply along the trajectory, except in the stations. Virtual platforms for vehicle performance have been developed before, and in many cases characteristic velocity profiles are used as a reference, according to the traffic environment in which the vehicle will operate. Vehicle analysis and design is focused on feasibility of the vehicle to be able to follow the prescribed velocity profile. In the present study, the evaluation is instead based on the cost/benefit relationship for an urban transport vehicle on traffic-free trajectories, enabling to adjust and optimize the velocity profiles in order to optimize the energy use while minimizing travel time. Therefore, the virtual platform is focused on the calculation of the net energy usage, the travel time and the system cost corresponding to an electrical vehicle with different battery and ultra-capacitor energy storage capacities, regeneration and storage of brake energy and an automatic governor for autonomous vehicle control. The influence of design parameters, such as the installed motor power, energy storage capacity, vehicle weight, passenger load and vehicle control strategy on the time schedule and energy efficiency is studied. However, the effort does not aim for a straight forward optimization of efficiency or minimization of travel time. In fact, energy optimization often conflicts with the travel time optimization. Therefore, both are analyzed simultaneously in order to assist in the search for an optimum compromise. In addition, the results are interpreted in terms of the overall obtained benefits of travel time reduction or optimization of the energy use, in contrast with the corresponding increment of the investment cost of the vehicle related to the implementation of the studied parameter variation. Specific trajectory profiles, including height profiles can be defined for optimization of the vehicle system for application in specific locations with specific geographic conditions.

Jet-A Combustion in an Indirect Injection Compression Engine Versus a Direct Injection Compression Engine at Same Load and Speed

This study compares combustion of Jet-A in an indirect injection (IDI) compression ignition engine and a direct injection (DI) compression ignition engine at the same load and speed. The Jet-A was blended (75Jet-A): 75% Jet-A and 25% Ultra Low Sulfur Diesel # 2 (ULSD) by mass. Both engines had a load of 4.5 bars Indicated Mean Effective Pressure (IMEP) and were run at 2000 RPM. The IDI engine configuration was very similar to that used in High Mobility Multipurpose Wheeled Vehicles (HMMWV). The research showed that combustion pressure in the IDI engine separate combustion chamber was 81 bars versus 71 bars in the main combustion chamber showing high gas-dynamics losses at transfer passages while in the DI engine the peak pressure reached 65 bars. The Apparent Heat Release Rate (AHRR) in the IDI engine has both the premixed and diffusion stage combined while in the DI classical combustion there are visible both the premixed and diffusion burn stages. The results show that in both engines there is a Low Temperature Heat Release (LTHR) region before top dead center (BTDC). The mass averaged instantaneous temperature reached 1750 K in the direct injection engine being the same for both fuels and for the IDI engines reached 1700 K in main combustion chamber and 1950 K in the separate combustion chamber for both fuels. The study showed that there are significant differences in the shape of the AHRR between the engines, nevertheless, the Jet-A has very similar combustion characteristics with ULSD in both combustion systems making a viable option as a substitute fuel to use in High Mobility Multipurpose Wheeled Vehicles (HMMWV).