Search Results

This paper analyzes different concepts for storage and recuperation of kinetic energy during braking operation in a forklift truck application. The reduction of fuel consumption is one of the challenges for on and off-road vehicles. Starting from a conventional hydrostatic transmission, secondary hydraulic control and a hybrid solution are investigated. Wasting kinetic energy during braking operation of mobile working machines in cyclic applications and converting it into heat energy instead of reusable energy is a very inefficient principle still used in industry. Rising energy costs, enhanced government guidelines and increased environmental awareness require more efficient drive concepts for the next decades. Recuperation of kinetic energy during braking operation provides the opportunity of increasing the efficiency of mobile working machines. Efficient recuperation of kinetic energy requires a proper application and a low-loss system design.

A new hydraulic brake utilizing a self-energizing effect is developed at the Institute for Fluid Power Drives and Controls (IFAS). In addition to a conventional hydraulic braking actuator, it features a supporting cylinder conducting the braking forces into the vehicle undercarriage. The braking force pressurizes the fluid in the supporting cylinder and is the power source for pressure control of the actuator. The new brake needs no external hydraulic power supply. The only input is an electrical braking force reference signal from a superior control unit. One major advantage of the SEHB concept is the direct control of the actual braking torque despite friction coefficient changes. The prototype design, presented in this paper, is done in two phases. The first prototype is based on an automotive brake caliper. It is set up to gain practical experience about the hydraulic self-energisation and to prepare the laboratory automation environment.

Intelligent convoy consisting of heavy duty vehicles is an implementation of IVHS believed to be one of the most practicable proposals to come into reality in the near feature. Control Strategy in the context of Autonomous Intelligent Vehicle Platoon is different from that in other “Lane-keeping” IVHS systems which have been well studied. In this paper, an Autonomous Platoon consisting two articulated commercial vehicles is studied and a model of tractor-trailer type commercial vehicles suitable for control studies is derived based on a single track three-axle bicycle model. The authors give perspectives on the implementation of intelligent convoy of articulated vehicles emphasizing safety issues in emergency situations, as opposed to normal following of the lead vehicle. An initial integrated braking and steering control is developed to avoid spinout or jack-knifing when specific axles are locked during braking process.

In order to comply with demanding Greenhous Gas (GHG) standards, future automotive engines employ advanced engine technologies including waste heat recovery (WHR) systems. A waste heat recovery system converts part of engine wasted exergies to useful work which can be fed back to the engine. Utilizing this additional output power leads to lower specific fuel consumption and CO2 emission when the total output power equals the original engine output power. Engine calibration strategies for reductions in specific fuel consumption typically results in a natural increase of NOx emissions. The utilization of waste heat recovery systems provides a pathway which gives both reduction in emissions and reduction in specific fuel consumption. According to DOE (Department of Energy), US heavy-duty truck engines’ technology need to be upgraded towards higher brake thermal efficiencies (BTE). DOE target is BTE>55% for Class-8 heavy-duty vehicles in the United States.

This research compares the responses of a vehicle modeled in the 3D vehicle simulation program SIMON in the HVE simulation operating system against instrumented responses of a 3-axle tractor, 2-axle semi-trailer combination. The instrumented tests were previously described in SAE 2001-01-0139 and SAE 2003-01-1324 as part of a continuous research effort in the area of vehicle dynamics undertaken at the Vehicle Research and Test Center (VRTC). The vehicle inertial and mechanical parameters were measured at the University of Michigan Transportation Research Institute (UMTRI). The tire data was provided by Smithers Scientific Services, Inc. and UMTRI. The series of tests discussed herein compares the modeled and instrumented vehicle responses during quasi-steady state, steady state and transient handling maneuvers, producing lateral accelerations ranging nominally from 0.05 to 0.5 G's.

Using neural networks, an algorithm has been developed to steer a wheel loader vehicle. Mathematical functions have been used in the past in an attempt to model a human in their operation of many types of vehicles. Since such functions can typically only be derived for situations in which the problem domain is thoroughly understood, research continues in an effort to develop a complete “operator model”. Neural Network algorithms were utilized in an attempt to determine the feasibility of accurately modeling the operator of a wheel loader construction vehicle. These algorithms were also used to determine how the control of different vehicle functions might be automated on a wheel loader.

Virtual reality technology permits engineers to assess visibility of virtual machines interactively in a virtual environment. Use of a virtual prototyping system allows one to investigate, in three dimensions, the effect of design changes on the visibility of critical machine components, such as the working tool. Although there have been successful applications of virtual prototyping systems to visibility assessment, there still exist system limitations that need to be overcome.

In this paper we demonstrate our work to date on our underactuated two link robot called the Pendubot. First we will overview the Pendubot's design, discussing the components of the linkage and the interface to the PC making up the controller. Parameter identification of the Pendubot is accomplished both by solid modeling methods and energy equation least squares techniques. With the identified parameters, mathematical models are developed to facilitate controller design. The goal of the control is to swing the Pendubot up and balance it about various equilibrium configurations. Two control algorithms are used for this task. Partial feedback linearization techniques are used to design the swing up control. The balancing control is then designed by linearizing the dynamic equations about the desired equilibrium point and using LQR or pole placement techniques to design a stabilizing controller.

GREATER ease of servicing is one of the ultimate goals in the development of dry-type air cleaners. The authors acknowledge, however, that the oil-bath cleaner is a rugged proved component that has done a good job for the farmers who serviced it properly. This paper describes studies made in Illinois of oil-bath and dry air cleaners in field service. At the same fuel/air ratios, the maximum horsepower of a test engine was greater with the dry-type filter than with the oil-bath cleaner. It was found that with AC fine dust and steady airflow, the oil-bath cleaners had significantly lower efficiencies than the dry-type filter. At less than rated airflow the efficiency of the oil-bath cleaner decreased while that of the dry filter remained high.

An overview of enrollment trends and curricular changes in engineering education in the past ten years. Comments are made about the implications of lower enrollment on quality of education and availability of engineers for the employment market. Discussions of curricular variations summarizes changes such as computerization of engineering studies, expansion of high school preparation, and selection of major studies for students.

This paper describes the University of Illinois machining system research program. This program focuses on the development of mechanistic models for machining process simulation and the use of these models for the simultaneous engineering of products and processes. Models are presented for end milling, face milling, and cylinder boring which take into account the cutting conditions, tool geometry, workpiece geometry, and system element dynamics. Furthermore, these models explicitly recognize the presence of machining process noise factors such as cutter runout and tool wear. Representative applications for these models are given. A methodology is described for the simultaneous engineering of products and manufacturing processes which incorporates models for the unit manufacturing processes, the manufacturing system, and the product to be produced.

Yield potential was predicted and mapped for three corn fields in Central Illinois, using digital aerial color infrared images. Three methods, namely statistical (regression) modeling, genetic algorithm optimization and artificial neural networks, were used for developing yield models. Two image resolutions of 3 and 6 m/pixel were used for modeling. All the models were trained using July 31 image and tested using images from July 2 and August 31, all from 1998. Among the three models, artificial neural networks gave best performance, with a prediction error less than 30%. The statistical model resulted in prediction errors in the range of 23 to 54%. The lower resolution images resulted in better prediction accuracy compared to resolutions higher than or equal to the yield resolution. Images after pollination resulted in better accuracy compared to images before pollination.

A programmable, four way directional control valve, with the versatility to operate in any type of hydraulic system and perform any function, was designed with functional variations to be made in the control software, rather than the hardware. This paper reports on the first reduction to practice, along with the development of a new “inferred flow feedback” concept. The initial prototype has shown promising results, in spite of hardware limitations encountered: flow forces and valve dynamics. Pressure control is especially encouraging, with nearly perfect regulation of pressure across the flow range of the programmable relief valve.

Physics-based models in a closed-loop feedback control of a premixed charge compression ignition (PCCI) engine can improve the combustion efficiency and potentially reduce harmful NOx and soot emissions. A stand-alone multi-zone combustion model has been proposed in the literature using a physics-based mixing approach. The scalar dissipation rate emerged as the determining parameter in the model for mixing among different zones in the mixture fraction space. However, the calculation of the scalar dissipation rate depends on three approaches: three-dimensional computational fluid dynamics (3-D CFD) combustion simulations based on representative interactive flamelet (RIF) model, tabulation, or an empirical algebraic model of the scalar dissipation rate fitted for the given operating conditions of the engine. While the 3-D CFD approach provides accurate results, it is computationally too expensive to use the multi-zone model in closed-loop control.

Electrification is a key enabler to reduce emissions levels and noise in commercial vehicles. With electrification, Batteries are being used in commercial hybrid vehicles like city buses and trucks for kinetic energy recovery, boosting and electric driving. A battery management system monitors and controls multiple components of a battery system like cells, relays, sensors, actuators and high voltage loads to optimize the performance of a battery system. This paper deals with the development of modular control architecture for battery management systems in commercial vehicles. The key technical challenges for software development in commercial vehicles are growing complexity, rising number of functional requirements, safety, variant diversity, software quality requirements and reduced development costs. Software architecture is critical to handle some of these challenges early in the development process.

Powertrain electrification is becoming increasingly common in the transportation sector to address the challenges of global warming and deteriorating air quality. This paper introduces a novel “Build Your Hybrid” approach to experience and test various hybrid powertrain concepts. This approach is applied to the light commercial vehicles (LCV) segment due to the attractive combination of a Diesel engine and a partly electrified powertrain. For this purpose, a demonstrator vehicle has been set up with a flexible P02 hybrid topology and a prototype Hybrid Control Unit (HCU). Based on user input, the HCU software modifies the control functions and simulation models to emulate different sub-topologies and levels of hybridization in the demonstrator vehicle. Three powertrain concepts are considered for LCVs: HV P2, 48V P2 and 48V P0 hybrid. Dedicated hybrid control strategies are developed to take full advantage of the synergies of the electrical system and reduce CO2 and NOx emissions.