Engineering Topics From Electric Power Steering to the Airbag System Essay Example

Engineering Topics: From Electric Power Steering to the Airbag System Essay Electric power steering (EPS or EPAS) uses an electric motor to assist the driver of a vehicle. Sensors detect the position and torque of the steering column, and a computer module applies assistive torque via the motor, which connects to either the steering gear or steering column. This allows varying amounts of assistance to be applied depending on driving conditions. Engineers can therefore tailor steering-gear response to variable-rate and variable-damping suspension systems, optimizing ride, handling, and steering for each vehicle. 15] On Fiat group cars the amount of assistance can be regulated using a button named CITY that switches between two different assist curves, while most other EPS systems have variable assist. These give more assistance as the vehicle slows down, and less at faster speeds. In the event of component failure that fails to provide assistance, a mechanical linkage such as a rack and pinion serves as a back-up in a manner similar to that of hydraulic syste ms.Electric systems have an advantage in fuel efficiency because there is no belt-driven hydraulic pump constantly running, whether assistance is required or not, and this is a major reason for their introduction. Another major advantage is the elimination of a belt-driven engine accessory, and several high-pressure hydraulic hoses between the hydraulic pump, mounted on the engine, and the steering gear, mounted on the chassis. This greatly simplifies manufacturing and maintenance. By incorporating electronic stability control electric power steering systems can instantly vary torque assist levels to aid the driver in corrective maneuvers. 16] Electric Power Steering (EPS) is favored over hydraulic power steering in most new vehicles. Eliminating the power steering pump can reduce weight and improve fuel economy. EPS also offers greater handling and steering feel while improving vehicle safety by adapting the steering torque to the vehicles speed and providing active torque in criti cal driving situations. The central electronic elements of todays electric power steering systems are modern 16- and 32-bit MCUs designed for safety-critical applications.Freescales 16-bit and Qorivva 32-bit single and dual-core MCU provide enhanced computing power and specialized peripherals for complex electric motor control functions. Integrated power supply solutions are also important elements of a power steering control unit. They provide connectivity to automotive busses, such as CAN and LIN. For MOSFET power stages control, integrated pre-drivers are typically used to interface with the MCU directly or via SPI. DUAL FUEL ENGINES (CO) and non-methane hydrocarbon (NMHC) emissions is required.Cummins and Dual Fuel Cummins will produce dual fuel engines for well servicing applications. The engines using Cummins Dual Fuel technology substitute diesel fuel with natural gas in the combustion process, reducing the amount of diesel fuel required to operate frac equipment. The first e ngine in the Cummins Dual Fuel portfolio for well servicing will be the QSK50, followed by dual fuel for land-based drilling applications, with other QSK Series engines to follow, including engines capable of meeting worldwide emissions regulations.Dual-Fuel engines operate on both natural gas and diesel fuel simultaneously, majority of fuel burned being natural gas. Diesel fuel acts essentially as a ‘spark plug’ as it auto ignites under compression and then ignites the gas. The use of diesel fuel allows the retention of the diesel compression ratio and its efficiency while the natural gas contributes to economy and is responsible for lowering emissions. The Fumigation Principle Natural Gas can be introduced to the combustion chamber by either mixing it with the airflow or injecting it into the manifold/chamber.In the Fumigation process, the gas is blended with air and both enter the inlet together in correct proportion whereas in direct injection the gas is introduced into the engine just prior to burning. The latter is an expensive and complex process whereas the fumigation method is not. More importantly, gas is not the primary fuel in a dual fuel engine and therefore the fumigation process works perfectly well, even for very large engines. GAS to DIESEL Ratio The EXCLAIM kit has operated at a replacement ratio of 92%.However, the average substitution of diesel by gas ranges between 50% to 80%. Power The EXCLAIM kit will not derate an engine if used with standard Natural gas or LPG. The kit ensures that full power remains available by adjusting ratios and providing necessary BTU energy to the engine. In gases such as LPG where the BTU content is higher than normal, dual fuel operation provides superior energy efficiencies whereas when the gas being used has a low heat value (coal gas, biogas or other gases having BTU content of less than 800) there is a proportional de-rating of the engine.Temperatures Unlike dedicated natural gas engines, dual fuel engines do not run hotter. Indeed, in some cases engines may actually run a few degrees cooler. Changeover between fuels The EXCLAIM kit is designed to switch seamlessly between full diesel and dual fuel operation without any surge or loss of power, frequency or speed. Maintenance costs Because gas is a better, cleaner fuel, the engine oil life is extended. Oil and filter change intervals are normally extended to generate additional savings. DUAL-FUEL TECHNOLOGY BENEFITS Attractive operating economics; replaces expensive diesel with low cost gas. * Greatly reduced emissions * Retains torque and power characteristics of the original diesel engine * Emergency diesel fallback for safety * Excellent long term reliability record * Same heat rejection as diesel GPS GLOBAL POSITIONING SYSTEM The Global Positioning System (GPS) is a space-based satellite navigation system that provides location and time information in all weather conditions, anywhere on or near the Earth where there is an unobstructed line of sight to four or more GPS satellites.The system provides critical capabilities to military, civil and commercial users around the world. It is maintained by the United States government and is freely accessible to anyone with a GPS receiver. The GPS project was developed in 1973 to overcome the limitations of previous navigation systems,[1] integrating ideas from several predecessors, including a number of classified engineering design studies from the 1960s. GPS was created and realized by the U. S. Department of Defense (DoD) and was originally run with 24Â  satellites.It became fully operational in 1994. Bradford Parkinson, Roger L. Easton, and Ivan A. Getting are credited for inventing it. Advances in technology and new demands on the existing system have now led to efforts to modernize the GPS system and implement the next generation of GPS III satellites and Next Generation Operational Control System (OCX). [2] Announcements from Vice President Al G ore and the White House in 1998 initiated these changes. In 2000, the U. S. Congress authorized the modernization effort, GPS III.In addition to GPS, other systems are in use or under development. The Russian Global Navigation Satellite System (GLONASS) was developed contemporaneously with GPS, but suffered from incomplete coverage of the globe until the mid-2000s. There are also the planned European Union Galileo positioning system, Chinese Compass navigation system, and Indian Regional Navigational Satellite System. Basic concept of GPS A GPS receiver calculates its position by precisely timing the signals sent by GPS satellites high above the Earth.Each satellite continually transmits messages that include * the time the message was transmitted * satellite position at time of message transmission The receiver uses the messages it receives to determine the transit time of each message and computes the distance to each satellite using the speed of light. Each of these distances and satellites locations define a sphere. The receiver is on the surface of each of these spheres when the distances and the satellites locations are correct. These distances and satellites ocations are used to compute the location of the receiver using the navigation equations. This location is then displayed, perhaps with a moving map display or latitude and longitude; elevation or altitude information may be included, based on height above the geoid (e. g. EGM96). Many GPS units show derived information such as direction and speed, calculated from position changes. In typical GPS operation, four or more satellites must be visible to obtain an accurate result. Four sphere surfaces typically do not intersect. a] Because of this, it can be said with confidence that when the navigation equations are solved to find an intersection, this solution gives the position of the receiver along with the difference between the time kept by the receivers on-board clock and the true time-of-day, the reby eliminating the need for a very large, expensive, and power hungry clock. The very accurately computed time is used only for display or not at all in many GPS applications, which use only the location. A number of applications for GPS do make use of this cheap and highly accurate timing.These include time transfer, traffic signal timing, and synchronization of cell phone base stations. Although four satellites are required for normal operation, fewer apply in special cases. If one variable is already known, a receiver can determine its position using only three satellites. For example, a ship or aircraft may have known elevation. Some GPS receivers may use additional clues or assumptions such as reusing the last known altitude, dead reckoning, inertial navigation, or including information from the vehicle computer, to give a (possibly degraded) position when fewer than four satellites are visible. 45][46][47] Structure The current GPS consists of three major segments. These are the space segment (SS), a control segment (CS), and a user segment (US). [48] The U. S. Air Force develops, maintains, and operates the space and control segments. GPS satellites broadcast signals from space, and each GPS receiver uses these signals to calculate its three-dimensional location (latitude, longitude, and altitude) and the current time. [49] The space segment is composed of 24 to 32 satellites in medium Earth orbit and also includes the payload adapters to the boosters required to launch them into orbit.The control segment is composed of a master control station, an alternate master control station, and a host of dedicated and shared ground antennas and monitor stations. The user segment is composed of hundreds of thousands of U. S. and allied military users of the secure GPS Precise Positioning Service, and tens of millions of civil, commercial, and scientific users of the Standard Positioning Service (see GPS navigation devices). Applications While originally a milit ary project, GPS is considered a dual-use technology, meaning it has significant military and civilian applications.GPS has become a wide ly deployed and useful tool for commerce, scientific uses, tracking, and surveillance. GPSs accurate time facilitates everyday activities such as banking, mobile phone operations, and even the control of power grids by allowing well synchronized hand-off switching. [49] Control segment Ground monitor station used from 1984 to 2007, on display at the Air Force Space amp; Missile Museum. The control segment is composed of 1. a master control station (MCS), 2. an alternate master control station, 3. four dedicated ground antennas and 4. six dedicated monitor stationsDRIVERLESS OR SELF-DRIVING An autonomous car,[1] also known as a robotic car,[2] or informally as driverless or self-driving, is an autonomous vehicle capable of fulfilling the human transportation capabilities of a traditional car. As an autonomous vehicle, it is capable of sensing its e nvironment and navigating without human input. [3] Robotic cars exist mainly as prototypes and demonstration systems, but are likely to become more widespread in the near future. Autonomous vehicles sense their surroundings with such techniques as radar, lidar, GPS, and computer vision.Advanced control systems interpret sensory information to identify appropriate navigation paths, as well as obstacles and relevant signage. [4] Some autonomous vehicles update their maps based on sensory input, allowing the vehicles to keep track of their position even when conditions change or when they enter uncharted environments. The earliest quasi-autonomous demonstration systems date back to the 1930s. [5] Since the 1980s, when Mercedes-Benz and Bundeswehr University Munich built the worlds first modern driverless car,[6] significant advances have been made in both technology and legislation relevant to autonomous cars.Numerous major companies and research organizations have developed working pr ototype autonomous vehicles, including Mercedes-Benz, General Motors, Google, Continental Automotive Systems, Autoliv Inc. , Bosch, Nissan, Toyota, Audi, and Oxford University. [6][7][8][9][10][11][12] As of 2013, three U. S. states have passed laws permitting autonomous cars: Nevada, Florida and California.. Vehicular communication systems Individual vehicles may benefit from information obtained from other vehicles in the vicinity, especially information relating to traffic congestion and safety hazards.Vehicular communication systems use vehicles and roadside units as the communicating nodes in a peer-to-peer network, providing each other with information. As a cooperative approach, vehicular communication systems can allow all cooperating vehicles to be more effective. According to a 2010 study by the National Highway Traffic Safety Administration, vehicular communication systems could help avoid up to 81 percent of all traffic accidents. [82] In 2012, computer scientists at the University of Texas in Austin began developing smart intersections designed for autonomous cars.The intersections will have no traffic lights and no stop signs, instead using computer programs that will communicate directly with each car on the road. [83] Public opinion surveys In a 2011 online survey of 2,006 consumers in the US and the UK conducted by Accenture, 49% of those surveyed said they would be comfortable using a driverless car. [84] According to a 2012 survey of 17,400 vehicle owners conducted by J. D. Power and Associates, 37% of all survey responders initially said they would be interested in purchasing a fully autonomous car. 85] However, that figure dropped to 20% once they learned the technology would cost an additional $3,000. With an additional cost of $3,000, 25% of the male vehicle buyers were willing to pay for a fully autonomous vehicle, while only 14 percent of women wanted the feature. [85] AIRBAG SYSTEM An airbag is a part of the safety restraint system in cars. Airbags are bags that rapidly fill with air when an accident happens. That way they can prevent injuries that occur because the driver hit a hard object. An airbag is a useful vehicle safety device.Airbags are used in the world increasingly because in accidents, it can help passengers reduce shock. When the sensor feels a strong shock, the gas device explodes. This gas fills the bag immediately. An airbag, also known as a Supplementary/Secondary Restraint System (SRS) or as an Air Cushion Restraint System (ACRS), is a flexible membrane or envelope, inflatable to contain air or some other gas. Air bags are most commonly used for cushioning, in particular after very rapid inflation in the case of an automobile collision. History of airbagsAn American inventor, Dr. Allen S. Breed, invented and developed a key component for automotive use. Breed Corporation then marketed this innovation first in 1967 to Chrysler. A similar Auto-Ceptor crash-restraint, brandon, developed by Eaton, Yale ;amp; Towne Inc. for Ford was soon offered as an automatic safety system in the USA. The Italian Eaton-Livia company offered a variant with . The first patent on an inflatable crash-landing device for airplanes was filed during World War II. In the 1980s, the first commercial airbags appeared in automobiles.Since model year 1990, all new cars sold in the United States have been required to have airbags on both driver and passenger sides. To date, statistics show that airbags reduce the risk of dying in a direct frontal crash by about 30 percent. Today, some cars have six or even eight airbags. How airbags work First, moving objects have momentum (the product of the mass and the velocity of an object). If no outside force acts on an object, the object will continue to move at its present speed and direction (because of inertia). Cars consist of several objects, including the vehicle itself, loose objects in the car and, of course, passengers.If these objects are not restrained, they will continue moving at whatever speed the car is traveling at, even if the car is stopped by a collision. Stopping an objects momentum requires force acting over a period of time. When a car crashes, the force required to stop an object is very great because the cars momentum has changed instantly while the passengers has not (there is not much time to work with). The goal of any supplemental restraint system is to help stop the passenger while doing as little damage to him or her as possible.What an airbag wants to do is to slow the passengers speed to zero with little or no damage. The constraints that it has to work within are huge. The airbag has the space between the passenger and the steering wheel or dashboard and a fraction of a second to work with. Even that tiny amount of space and time is valuable, however, if the system can slow the passenger evenly rather than forcing an abrupt halt to his or her motion. Motorcycle airbag In 2006 the airbag was set up for a motor cycle. This was in the Gold Wing by Honda. 1] Air bags supplement the safety belt by reducing the chance that the occupants head and upper body will strike some part of the vehicles interior. They also help reduce the risk of serious injury by distributing crash forces more evenly across the occupants body. One recent study concluded that as many as 6,000 lives have been saved as a result of airbags. However, the exact number of lives saved is almost impossible to calculate. SPECIAL VEHICLES (EARTH MOVERS/ EXCAVATORS) Excavators are heavy construction equipment consisting of a boom, stick, bucket and cab on a rotating platform (known as the house).The house sits atop an undercarriage with tracks or wheels. A cable-operated excavator uses winches and steel ropes to accomplish the movements. They are a natural progression from the steam shovels and often called power shovels. All movement and functions of a hydraulic excavator are accomplished through the use of hydraulic fluid, with hydraulic cylinders and hydraulic motors. Due to the linear actuation of hydraulic cylinders, their mode of operation is fundamentally different from cable-operated excavators.Excavators are heavy construction equipment consisting of a boom, stick, bucket and cab on a rotating platform (known as the house). The house sits atop an undercarriage with tracks or wheels. A cable-operated excavator uses winches and steel ropes to accomplish the movements. They are a natural progression from the steam shovels and often called power shovels. All movement and functions of a hydraulic excavator are accomplished through the use of hydraulic fluid, with hydraulic cylinders and hydraulic motors.Due to the linear actuation of hydraulic cylinders, their mode of operation is fundamentally different from cable-operated excavators. Configurations Excavators come in a wide variety of sizes. The smaller ones are called mini or compact excavators. Caterpillars smallest mini-excavator weighs 2,060 pound s (930Â  kg) and has 13 hp; their largest model is the largest excavator available (a record previously held by the Orenstein ;amp; Koppel RH400) the CAT 6090, it weighs in excess of 2,160,510 pounds (979,990Â  kg), has 4500Â  hp and has a bucket size of around 52. m? depending on bucket fitted. Engines in excavators drive hydraulic pumps; there are usually 3 pumps: the two main pumps are for supplying oil at high pressure (up to 5000 psi) for the rams, swing motor, track motors, and accessories, and the third is a lower pressure (700 psi) pump for Pilot Control, this circuit used for the control of the spool valves, this allows for a reduced effort required when operating the controls. The two main sections of an excavator are the undercarriage and the house.The undercarriage includes the blade (if fitted), tracks, track frame, and final drives, which have a hydraulic motor and gearing providing the drive to the individual tracks, and the house includes the operator cab, counter weight, engine, fuel and hydraulic oil tanks. The house attaches to the undercarriage by way of a center pin, allowing the machine to slew 360Â ° unhindered. The main boom attaches to the house, and can be one of several different configurations: * Most are mono booms: these have no movement apart from straight up and down. Some others have a knuckle boom which can also move left and right in line with the machine. * Another option is a hinge at the base of the boom allowing it to hydraulically pivot up to 180Â ° independent to the house; however, this is generally available only to compact excavators. * There are also triple-articulated booms (TAB). Attached to the end of the boom is the stick (or dipper arm). The stick provides the digging force needed to pull the bucket through the ground. The stick length is optional depending whether reach (longer stick) or break-out power (shorter stick) is required.On the end of the stick is usually a bucket. A wide, large capacity (mud) bu cket with a straight cutting edge is used for cleanup and levelling or where the material to be dug is soft, and teeth are not required. A general purpose (GP) bucket is generally smaller, stronger, and has hardened side cutters and teeth used to break through hard ground and rocks. Buckets have numerous shapes and sizes for various applications. There are also many other attachments which are available to be attached to the excavator for boring, ripping, crushing, cutting, lifting, etc.Before the 1990s, all excavators had a long or conventional counterweight that hung off the rear of the machine to provide more digging force and lifting capacity. This became a nuisance when working in confined areas. In 1993 Yanmar launched the worlds first Zero Tail Swing excavator,[2] which allows the counterweight to stay inside the width of the tracks as it slews, thus being safer and more user friendly when used in a confined space. This type of machine is now widely used throughout the world. There are two main types of Control configuration generally use in excavators to control the boom and bucket, both of which spread the four main digging controls between two x-y joysticks. This allows a skilled operator to control all four functions simultaneously. The most popular configuration in the US is the SAE controls configuration while in other parts of the world, the ISO control configuration is more common. Some manufacturers such as Takeuchi have switches that allow the operator to select which control configuration to use. Excavator attachmentsHydraulic excavator capabilities have expanded far beyond excavation tasks with buckets. With the advent of hydraulic-powered attachments such as a breaker, a grapple or an auger, the excavator is frequently used in many applications other than excavation. Many excavators feature a quick coupler for simplified attachment mounting, increasing the machines utilization on the jobsite. Excavators are usually employed together with loa ders and bulldozers. Most wheeled, compact and some medium-sized (11 to 18-tonne) excavators have a backfill (or dozer) blade.This is a horizontal bulldozer-like blade attached to the undercarriage and is used for levelling and pushing removed material back into a hole COLLISION AVOIDANCE SYSTEMS A considerable amount of research is addressing eSafety systems of the future. Much work is being carried out on technologies such as collision avoidance systems but their usefulness in addressing high-risk crash scenarios typical of most European roads as well as their feasibility has yet to be determined.Research on collision warning and collision avoidance systems is taking place in Japan, the United States and in the European Union within the European Commissions eSafety programme. Very large estimates of the safety potential of such systems have been claimed following laboratory studies, but the range of technical and behavioural issues involved in many of the concepts require full on- road assessment. To be practical, most of the proposed systems require a well controlled traffic situation, such as that found on motorways, but where the casualty reduction potential is relatively low.For an overview of key issues [41]OECD, 2003 Road safety: impact of new technologies. Various systems are under development: Forward Collision Warning Is a system which comprises a visual and audible warning that the driver is too close to the vehicle in front. The warning depends on how long the distance is between the vehicle and the vehicle ahead. The level of warning changes from safe to critical as the following distance decreases. The Reverse Collision Warning System Is a visual and audible system which warns drivers about the likelihood of collision with an object behind the vehicle by means of sensors in the rear bumper.The warning intensifies when the distance between the vehicles rear and the object decreases. Adaptive Cruise Control (ACC) Enhances automatic cruise control f ound in many new vehicles by automatically maintaining a set following distance to the vehicle in front. The distance to the preceding vehicle is measured by radar, laser systems or both. When the speed of the vehicle in front is slower than the adjusted speed, the ACC system adjusts vehicle speed to allow a safe distance to the lead vehicle. Collision Mitigation by brakingIs an evolution of ACC with the addition of a braking system that increases headway by braking; these systems may also detect obstacles within the road and brake accordingly. The speed and separation distance at which the systems operate is determined by the arrangement and type of sensors and the recognition ability of the systems. Lane-Keeping Devices Are electronic warning systems that are activated if the vehicle is about to veer off the lane or the road. Times to collision in safety-critical lane changes are normally much less than one second.Since mean driver reaction time is about one second, there is not s ufficient time for a driver to respond to a warning before crashing. Because there is insufficient time for reaction to a warning, lane change and merging crashes can probably only be avoided by intervening systems. But these have their own problems: how to detect driver intentions and how to intervene. This may be by taking over the steering from the driver or by providing feedback through the steering wheel. The technical and operational feasibility of such systems has still to be demonstrated. Most existing systems are warning only systems.