Development of alternative steering models for ev bus: a preliminary study on the conversion of hydraulic to electric power steering

This study aims to develop alternative steering models for the EV bus. The EV bus uses its energy source from the main 384 VDC 300 Ah battery and the secondary battery with a capacity of 25.8 VDC 100 Ah. The use of energy in this electric bus is divided into the main components, namely the BLDC motor as the main drive of 200 kW, 15 kW of air conditioning, 7.5 kW of hydraulic power steering, a compressor for the air braking system of 4 kW, and accessory components. The other is 2.4 kW. It is expected that this 7.5 kW electric power can be reduced by an electric system by up to 20 %. This research will study the steering system with an electric power system (EPS) to convert the hydraulic steering system (HPS). With this EPS system, it is hoped that controlling the vehicle’s motion towards the steer by wire will be easier. Initially, data were collected from the types of large vehicles from various well-known brands about the steering system used. A large commercial vehicle that purely uses EPS is not yet found. The model developed for EPS on this electric bus is through the reverse engineering method by redrawing all the components involved in the previous steering system. Because this type of EV bus is included in the upper mid-size class, this paper proposes two new EPS models, namely the addition of an assist motor on the drag link and on the steering rack. The links involved in this system are wheel drive, steering column, lower steering column, rack and pinion gear, assist motor, drop link, drag link, drop link extension, drag link extension, tie rod, knuckle, kingpin, tire, axle beam and several others. The values of stiffness, inertia, and damping of each link will affect the driver’s torque and the assist motor as a wheel speed function on this electric bus. The steering structure of the EV bus consists of a truss structure and a frame structure with a kinematic structure consisting of two four-bar linkages joined together

Design and Optimization of Suspension and Steering System of Efficycle – Human Powered Hybrid Tricycle

Suspension is a system of tires, springs, shock absorbers, and linkages that connects a vehicle’s chassis to its wheels and allows relative motion between the two. Steering is a mechanism that provides a direction to the vehicle, it basically consists of gears, shaft, joints, steering column, steering wheel, and furthermore. The main objective of this paper is to design a system of suspension and steering for a three-wheeled human-electric hybrid trike. A system of directly actuated double wishbone suspension system is chosen for the front and a pushrod actuated 2-link trailing arm suspension system for the rear. The steering system used is a type of Single tie rod and drag link system. A knuckle-to-knuckle drag link provides continuity to the wheels and a tie rod to the bell crank provides steering rotation. This paper also talks about the single nut hub-shaft system which is being used in the front suspension system. Based on the research using various input parameters, the inboard and outboard suspension hardpoints are decided to maximize the tire contact patch at every vehicular motion (mainly during body roll). Forces and stresses are calculated with the help of Free Body Diagrams (FBD) and Multi-Body Dynamics (MBD) software LOTUS Shark. The paper discusses the calculations regarding the roll and ride rates and for the custom springs of specific stiffness used in front and rear shock absorbers and the variation of roll steer and bump steer on changing various parameters of the steering system. Key points also include the procedure of selections of various types of bearings, rod ends, and bolts. This paper also talks about laser-cut jigsaw uprights that are used in the front wheel assembly. The finite element method was used to analyze the designs using DS Solidworks and Ansys Workbench. Static structural and explicit dynamics analysis was performed on the wheel assembly components both individually and assembled

REDUCING STRUCTURAL ERROR IN FUNCTION GENERATING MECHANISMS VIA THE ADDITION OF LARGE NUMBERS OF FOUR-BAR MECHANISMS

This paper presents a methodology for synthesizing planarlinkages to approximate any prescribed periodic function. Themechanisms selected for this task are the slider-crank and thegeared five-bar with connecting rod and sliding output (GFBS),where any number of drag-link (or double crank) four-bars areused as drivers. A slider-crank mechanism, when comparing theinput crank rotation to the output slider displacement, producesa sinusoid-like function. Instead of directly driving the inputcrank, a drag-link four-bar may be added that drives the crankfrom its output via a rigid connection between the two. Drivingthe input of the added four-bar results in a function that is lesssinusoid-like. This process can be continued through the additionof more drag-link mechanisms to the device, slowly alteringthe curve toward any periodic function with a single maximum.For periodic functions with multiple maxima, a GFBS is usedas the terminal linkage added to the chain of drag-link mechanisms.The synthesis process starts by analyzing one period ofthe function to design either the terminal slider-crank or terminalGFBS. A randomized local search is then conducted as thefour-bars are added to minimize the structural error between thedesired function and the input-output function of the mechanism.Mechanisms have been “grown” in this fashion to dozens of linksthat are capable of closely producing functions with a variety ofintriguing features.

The Synthesis of Function Generating Mechanisms for Periodic Curves Using Large Numbers of Double-Crank Linkages

This paper presents a methodology for synthesizing planar linkages to approximate anyprescribed periodic function. The mechanisms selected for this task are the slider-crankand the geared five-bar with connecting rod and sliding output (GFBS), where any numberof double-crank (or drag-link) four-bars are used as drivers. A slider-crank mechanism,when comparing the input crank rotation to the output slider displacement,produces a sinusoid-like function. Instead of directly driving the input crank, a drag-linkfour-bar may be added to drive the crank from its output via a rigid connection betweenthe two. Driving the input of the added four-bar results in a function that modifies thesinusoid-like curve. This process can be continued through the addition of moredrag-link mechanisms to the device, progressively altering the curve toward any periodicfunction with a single maximum. For periodic functions with multiple maxima, a GFBS isused as the terminal linkage added to the chain of drag-link mechanisms. The synthesisprocess starts by analyzing one period of the function to design either the terminal slidercrankor terminal GFBS. MATLAB’s fmincon command is then utilized as the four-bars areadded to reduce the structural error between the desired function and the input–outputfunction of the mechanism. Mechanisms have been synthesized in this fashion to includea large number of links that are capable of closely producing functions with a variety ofintriguing features

The Synthesis of Function Generating Mechanisms for Periodic Curves Using Large Numbers of Double-Crank Linkages

This paper presents a methodology for synthesizing planar linkages to approximate any prescribed periodic function. The mechanisms selected for this task are the slider-crank and the geared five-bar with connecting rod and sliding output (GFBS), where any number of double-crank (or drag-link) four-bars are used as drivers. A slider-crank mechanism, when comparing the input crank rotation to the output slider displacement, produces a sinusoid-like function. Instead of directly driving the input crank, a drag-link four-bar may be added to drive the crank from its output via a rigid connection between the two. Driving the input of the added four-bar results in a function that modifies the sinusoid-like curve. This process can be continued through the addition of more drag-link mechanisms to the device, progressively altering the curve toward any periodic function with a single maximum. For periodic functions with multiple maxima, a GFBS is used as the terminal linkage added to the chain of drag-link mechanisms. The synthesis process starts by analyzing one period of the function to design either the terminal slider-crank or terminal GFBS. matlab's fmincon command is then utilized as the four-bars are added to reduce the structural error between the desired function and the input–output function of the mechanism. Mechanisms have been synthesized in this fashion to include a large number of links that are capable of closely producing functions with a variety of intriguing features.

Reducing Structural Error in Function Generating Mechanisms via the Addition of Large Numbers of Four-Bar Mechanisms

This paper presents a methodology for synthesizing planar linkages to approximate any prescribed periodic function. The mechanisms selected for this task are the slider-crank and the geared five-bar with connecting rod and sliding output (GFBS), where any number of drag-link (or double crank) four-bars are used as drivers. A slider-crank mechanism, when comparing the input crank rotation to the output slider displacement, produces a sinusoid-like function. Instead of directly driving the input crank, a drag-link four-bar may be added that drives the crank from its output via a rigid connection between the two. Driving the input of the added four-bar results in a function that is less sinusoid-like. This process can be continued through the addition of more drag-link mechanisms to the device, slowly altering the curve toward any periodic function with a single maximum. For periodic functions with multiple maxima, a GFBS is used as the terminal linkage added to the chain of drag-link mechanisms. The synthesis process starts by analyzing one period of the function to design either the terminal slider-crank or terminal GFBS. A randomized local search is then conducted as the four-bars are added to minimize the structural error between the desired function and the input-output function of the mechanism. Mechanisms have been “grown” in this fashion to dozens of links that are capable of closely producing functions with a variety of intriguing features.

Construction and Application of 3D and 2D Type Maps for Linkages

The 3D and 2D type maps for planar four-bar and simply RSSR linkages are constructed with illustration of their application. The criteria determining the rotatability of input or output link are developed or reviewed for both linkages. Three-dimensional type maps are then constructed by integrating the tool for numerical analysis and solid modeling software, e.g. MATLAB and PRO/E. The coordinate axes are mainly three ratios of link lengths. The types are classified based on whether the input or output link can make fully rotation. Each type map is composed of five regions representing different types. They are drag link, crank-rocker, rocker-crank, double-rocker, and unassembled. Any cross sections can be taken readily and arbitrarily from the 3D models along any plane or surfaces to get 2D type maps. The constructed type maps are also combined with curves or surfaces representing performances of transmission ratio. With type maps and related surfaces, the design process can be simplified and expedited substantially.

Fatigue Life Prediction of a Drag Link by Using Finite Element Method

The focus of this study is to find fatigue behavior and fatigue life of a drag link in the different road and loading conditions. Finite element method was used for fatigue analysis and fatigue life of the drag link was predicted. Firstly, the historical changes in the concept of the fatigue and fatigue life calculation methods were explained in the chapter one and two. Factor affecting the fatigue performance was explained. Stress and strain based fatigue analysis methods were described clearly. Finally, fatigue life analysis in the frequency domain which is a new method relative to the others was explained. Then, two different steering drag links of a midibus were examined and fatigue life calculations of these two drag links were made. The fatigue life analysis in the time domain of the drag links were made in the static steering conditions and the results were compared with the test results made by the vendor of the drag links. After that, the drag link which has a greater fatigue life than the other was selected, the road loads were taken from another test report which was made by using the same drag link and the fatigue life of the drag link was computed by using the finite element method in the time domain. Finally, the same road loads were converted in the frequency domain and the fatigue life analysis of the same drag link were made in the frequency domain. The results from the time domain and the frequency domain were compared and the advantages of the fatigue life analysis in the frequency domain were expressed.

Design of Centric Drag-Link Mechanisms for Delay Generation With Focus on Space Occupation

Planar drag-link mechanism is a Grashofian four-bar chain with the shortest link fixed. In practice, the mechanism is used as a coupling between two shafts to convert uniform rotation of the driving shaft into a nonuniform rotation of the driven shaft. The nonuniformity in rotation is characterized by a cyclically increasing and decreasing delay (or advance) in the displacement of the driven shaft relative to that of the driving shaft. Drag-link synthesis problems include synthesizing the mechanism to generate a specified maximum delay. In a drag-link mechanism, the longer links make a full rotation about fixed pivots, which results in a relatively large installation space. This calls for designing drag-link mechanisms with a focus on space occupation, along with the traditional criteria of quality of motion transmission. Using position analysis, we investigate the relationships among mechanism space occupation, extreme transmission angle, and the generated maximum delay. Space occupation is represented by the link-length ratio of input link to fixed link. Given a desired maximum delay, the proposed approach suggests finding a unique extreme transmission angle value for which this link-length ratio is at a minimum. A closed-form solution to drag-link synthesis to generate a specified maximum delay is developed based on a compromise between quality of motion transmission and space occupation. For any drag-link designed by this compromise, the coupler link and the output crank are of the same length. Based on the obtained design equations, a graphical design solution and a method for evaluating space occupation are provided.