presented By:
Y.Sreenu
Ch.V.Raghavendra Kumar

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ABSTRACT
Imagine you control all the systems around just by a simple gesture and the things respond to you as if it was some magic. This could be possible with embedded systems.
The term ‘embedded systems’ is quite a complex one. Simply put, it is a combination of hardware and software that performs the component of a larger system. A few years ago embedded technology existed in stand alone devices such as vending machines and copiers that did their jobs with little regards for what went on around them. But as technology advance to connect devices to the internet and to each other, the potential of embedded technology has increased. Home appliances, mobile phones, cars, tiny micro chips, avionics etc.., are all using embedded technology.
High-profile embedded chips are scaleable, generate small amounts of heat, and consume less power. These are generally preferred for their speed, accuracy and reliability. As they are compact in size and ability to perform time-critical and task specific operators, embedded devices find application in all segments of industrial and commercial market places and home appliances.
In recent years,it became apparent that control systems as integral components of larger systems, should be developed and designed concurrently with mechanics, hydraulics, and electronics. It is important that engineers have a good understanding of the implications of software technology embedded into traditional engineering systems. Current machines consist of physical components providing the means and a control system employing those means to fulfill the machine’s function. Together, they build up the controlled machine, which can also be called an embedded system. . New innovative applications in different areas will make embedded systems as one of the fastest developing technology of the near future.
This paper deals with concepts and developments of embedded systems in control of machines and gives a general overview of the basic components of control systems, ranging from sensors to actuators.
Embedded Systems
An embedded system employs a combination of hardware & software (a “computational engine”) to perform a specific function; is part of a larger system that may not be a “computer”; works in a reactive and time-constrained i.e is real-time environment.
Software is used for providing features and flexibility
Hardware = {Processors, ASICs, Memory...} is used for performance (& sometimes security)
The term ’embedded system’ can be used for a wide range of applications and devices. A useful definition is not easy to formulate. Boasson mentioned one characteristic that applies to all embedded systems: Neither the computer system without the special environment in which it is embedded, nor the environment without the computer system has any significance in itself.
An embedded system employs a combination of hardware & software (a “computational engine”) to perform a specific function; is part of a larger system that may not be a “computer”; works in a reactive and time-constrained environment.
Basics of Embedded systems
An embedded systems typically comprises the hardware, embedded RTOS, device drivers, communication stacks and embedded application software.
Embedded hardware: The embedded hardware mainly consists of a microcontroller with various peripheral ICs. A fixed size volatile memory such as DRAM or SRAM and non volatile memory such as Flash or EPROM, connected to the microcontroller, are an integral part of the device. Depending on the targeted application of the device, the peripheral can include communication device such as serial controller, Ethernet controller, or a wireless communication controller and other application-specific ICs (ASICs). Many handheld devices these days also have sensors, actuators, keypads and graphical LCD screens as user interfaces.
The only way a embedded machine control system can get information about its surroundings, is through the use of sensors and/or sensor systems. Control signals from the embedded control are converted into power and/or movement through Actuators.
Sensors: During the past years a shift has taken place from mechanization towards automation. This implies the extensive use of sensors (and actuators) in order to be able to actually control (and influence) the actions that are performed by the controlled system.In principle the task of a sensor is fairly simple. It transforms an input signal that usually is difficult to handle in its original form to a more manageable form. Between input and output of the sensor a number of processes take place to obtain the desired result, as schematically shown in Figure.
Actuators: Actuators come in many forms and shapes. They act as the ’arms and legs’ of the machine. Actuators convert control signals into power and/or movement,as schematically shown in Figure below. Control signals do not have to be of electrical nature, also other kinds are possible. The power conversion can be done in a number of ways.
The most common energy sources for actuators are:
• Compressed air, pneumatics
• Pressured oil, hydraulics
• Electricity, electro mechanics
Embedded RTOS: The concept of real-time operating system (RTOS) is inseparable when we talk about embedded systems. All intelligent devices that perform complex functions have an embedded operating system inside. A real-time operating system (RTOS) is built for specific applications and guarantees response to an external event with in a specified time constraint. This operating system is typically real time in nature, i.e. it is capable of responding deterministically to time-critical external events.
For example, when you suddenly apply brakes for your car to avoid an accident, the ‘intelligent gad-get’ responds immediately. Imagine the plight of a driver if there is no response… the result is obvious