Printer Carriage Motion Control LaboratoryPrinter Carriage Motion ControlLearning ObjectivesBy the end of this laboratory experiment, the experimenter should be able to:- Use a quad push-pull driver chip for bi-directional DC motor control with an Arduino.- Use reflective photo-switches, opto-interrupter switches, and micro-switches for limit sensing- Explain how and why limit switches are used to prevent over-travel of moving components.ComponentsQty. Item1 Arduino Duemilanove board w/ ATmega328 microcontroller1 USB A to B cable1 Solderless breadboard1 Printer carriage assembly1 Optical-interrupter switch (Fairchild H21LTB)1 Photo-reflective opto sensor (Fairchild QRB1134)2 Roller lever momentary switch (Omron SS-5GL2)1 SN754410 (Quad Half-H driver) or L293D (Quad Push-Pull driver with diodes)1 74LS04 hex inverterOverviewThe purpose of this lab is to help you learn how construct a system with multiple sensors and an actuator, and interface these with the Arduino/ATmega328. Figure 1 shows how all the components come together to complete the printer carriage motion system. The procedure below will guide you in building and testing pieces of the system and then integrating them into a complete system.Figure 1. Printer carriage system. The printer carriage system contains: two sensors: a photo-reflective opto sensor and photo-interrupter switch; a power interface (the SN754410 and 1/6 of the 74LS04); the carriage motor, and two SPST switches to provide fail-safe end-of-travel limits. The connections between the modules and Arduinoare made through 5-way binding posts on the printer carriage assembly. The opto sensors and the SN754410 need +5 V to operate, whereas +7 V will be applied to the VS pin of the SN754410 to power the motor.IntroductionSwitches are common devices that permit or interrupt the flow of current. In addition to simply controllingelectrical power to a device (such as a motor or light), they can be used in motion control to detect whetheror not a movable element has reached a predetermined position.San José State University Department of Mechanical and Aerospace Engineering rev 1.2 13MAR2011 Arduino/ ATmega328IN 1IN 2EN 1SN75441074LS04+5V10 kOUT 1OUT 2motorreflective optooptointerrupterLimitSW 1LimitSW 2tact switch+5VOPTO POWEROPTO GND+7V+5VD8D9D2Page 1 of 7Printer Carriage Motion Control LaboratoryMechanical switches come in a variety of designs. They are categorized by the number of poles and throws they have. The number of poles represents the number of separate circuits that can be completed by the same action of the actuating lever or button. The number of throws represents the number of individual contacts for each pole. The most common types are shown in Figure 2 below.Figure 2. Examples of different switch configurations. The number of poles represents the number of separate circuits that can be completed by the same action of the movable contact(s) inside the switch. The number of throws represents the number of individual contacts for each pole. Micro-switches typically refer to mechanical switches of small size that have a spring-loaded, momentary contact, operated by a push-button directly or via a pivoted cantilever. Micro-switches find use in many consumer products such as notebook computers, appliances (to detect if a cover is closed), etc. Switches are comprised of moving or sliding mechanical elements are designed to operate for thousands to hundreds of thousands of on-off cycles.Optical switches (e.g. opto-interrupters, opto-reflectors, etc.) are non-mechanical switches made up of a light-emitting diode (LED) and a phototransistor. As shown in Figure 3, light from the LED shines toward the base of a photransistor across a gap in the housing of the switch. The output of the photransistor will indicate whether or not something is blocking the light from the LED. Opto-interrupters are often used in mechatronic devices to indicate that a movable element has reached a specific position or an end-of-travel limit. Devices that use optical switches include printers, copiers, and manufacturing automation systems. Opto-interrupters are attractive to use, because they are solid-state, reliable, relatively inexpensive, and are straightforward to interface with logic circuits. Since they operate without physical contact, they have the advantages of longer lifetime, higher reliability, and faster actuation time compared to mechanical switches.You are going to use two types of optical switches, a reflective (Fairchild QRB1134) and an interrupter-type (Fairchild H21LTB) on a printer mechanism and use them in driving a printer carriage between preset limits. You will also use two SPST microswitches to provide a fail-safe limit on the end-of-travel of the carriage in case one of the opto-switches fails. Figure 3. Opto switch schematic. The opto interrupters used on the printer carriage are solid state devices consisting of an infared-LED and an NPN transistor. When the LED shines on the phototransistor, this causes a current to flow from the base to the emitter. The base-to-emitter current in turn can control current from collector-to-emitter assuming that there is a circuit connected to the collector from a voltage source. Assembling the SystemAs we have done in past expermiments, we will again construct the system in a modular way by building and testing pieces of the system as we go. This is always a good general approach in any kind of engineering, whether it be electronic work, system design, or computer programming. Avoid the temptation to wire everything up first and hope that it will all work the first time. Such an approach is doomed to fail, San José State University Department of Mechanical and Aerospace Engineering rev 1.2 13MAR2011 Single-pole/single-throw (SPST) Single-pole/double-throw (SPDT) Double-pole/double-throw (DPDT) Double-pole/single-throw (DPST) Page 2 of 7Printer Carriage Motion Control Laboratoryand you will end up spending more time trying to figure out what is not working than if you simply build and testing each individual subsystem as you go along.First you will work with the sensors and make sure that they are working properly. Then you will connect the sensors to the Arduino. Next, you will work with the SN754410 chip, and finally you will pull everything together to complete the printer system.Get a printer carriage assembly from your lab instructor. The next three sections will guide you through some tests to ensure