fabrication of Automated guided Vehicle<br />Mini Project Report 2011<br />Submitted By<br />ARVIND S.A<br />SOORAJ.V.R<br />ANKITHA SHARMA<br />ALKA MOHAN PHILIP<br />VISHNU MURALI MENON<br />Department of Production Engineering<br />Government Engineering College, Thrissur<br />FABRICATION OF Automated GUIDED Vehicle<br />Mini Project Report 2011<br />Submitted By<br /> ARVIND S.A<br /> SOORAJ.V.R<br />ANKITHA SHARMA<br />ALKA MOHAN PHILIP<br />VISHNU MURALI MENON<br />Department of Production Engineering<br />Government Engineering College, Thrissur<br />DEPARTMENT OF PRODUCTION ENGINEERING<br />2011<br />CERTIFICATE<br />This is to certify that the Mini-Project Report entitled<br />Fabrication of Automated Guided Vehicle<br />was presented by<br />ARAVIND S.A<br />SOORAJ.V.R<br />ANKITHA SHARMA<br />ALKA MOHAN PHILIP<br />VISHNU MURALI MENON<br />Of the Sixth Semester Production Engineering in partial fulfillment of the requirement for the award of the Degree of Bachelor of Technology in Production engineering under the University of Calicut in the year 2011<br />Staff in Charge<br />Prof.Dr. Sathish K P Prof. P V Gopinathan<br />Dept. of Production Head of the department<br /> Dept. of Production <br />Place: Thrissur<br />Date: <br />ABSTRACT<br /> <br />Automated Guided vehicle is a robot that can deliver the materials from the supply area to the technician automatically. This is faster and more efficient.. The robot can be accessed wirelessly. I.e. a technician can directly order the robot to deliver the components rather than order it via a human operator (over phone, computer etc. who has to program the robot or ask a delivery person to make the delivery). To avoid collision with human workers, a proximity detector has been added which causes the robot to stop as long as there is an obstacle in its way, thus avoiding accidents.<br />ACKNOWLEDGEMENT<br />We express our deep sense of gratitude and indebtedness to Prof. P V Gopinathan, Head, Department of Production Engineering for her valuable advice, constant encouragement and constructive criticism during the course of the project and also during the preparation of this manuscript, We place on record the valuable suggestions and numerous constructive comments rendered by Prof.Dr.Sathish K P, Lecturer, Department of Production Engineering and for being our internal guide in the design and implementation of our project<br />We are highly indebted to all the staff members of Production Department for their wholehearted support and co-operation. <br />We also express our sincere thanks to all the classmates for their support and co-operation in completing the project work.<br />Above all, we should express our supreme gratitude to almighty God for making this project a reality. <br />TABLE OF CONTENTS<br /> <br />1.INTRODUCTION <br />2.AVG COMPONENTS <br />3.BLOCK DIAGRAM <br />4.MECHANICAL DESIGN <br />5.ELECTRICAL AND ELECTRONICS COMPONENTS <br />6.COMPUTER <br />7.PATH PLANNING <br />8.PROJECT COST <br />9.CONCLUSION <br />10.BIBLIOGRAPHY <br />11.APPENDIX<br />LIST of tables<br />Chassis specification (3.1)<br />Steering specification table (3.2)<br />Load Test (3.3)<br />Transmitter receiver specification (4.1)<br />Atemega16 Technical specification (4.2)<br />Connections of atmega16 (4.3)<br />L293d Technical specification (4.4)<br />Motor Technical specification (4.5)<br />Connections of USB Bridge (4.6)<br />Model Costs (7.1)<br />LIST of figures<br />Differential steering 3.2<br />Spinning by differential steering 3.3<br />Small radius turning 3.4<br />Large radius turning 3.5<br />Transmitter receiver pair 4.1<br />H-Bridge 4.2<br />Circuit diagram of Motor driver 4.3<br />PWM 4.4<br />USB Bridge 4.5<br />Programming algorithm 4.6<br />Example of path planning 6.1<br />Introduction<br />Automated Guided vehicle<br />An automated guided vehicle or automatic guided vehicle (AGV) is a mobile robot that follows markers or wires in the floor, or uses vision or lasers. They are most often used in industrial applications to move materials around a manufacturing facility or a warehouse<br />Automated guided vehicles increase efficiency and reduce costs by helping to automate a manufacturing facility or warehouse. The AGV can tow objects behind them in trailers to which they can autonomously attach. The trailers can be used to move raw materials or finished product. The AGV can also store objects on a bed. The objects can be placed on a set of conveyor and then pushed off by reversing them. Some AGVs use fork lifts to lift objects for storage. AGVs are employed in nearly every industry, including, pulp, paper, metals, newspaper, and general manufacturing. Transporting materials such as food, linen or medicine in hospitals is also done.<br />An AGV can also be called a laser guided vehicle (LGV) or self-guided vehicle (SGV). Lower cost versions of AGVs are often called Automated Guided Carts (AGCs) and are usually guided by magnetic tape. AGCs are available in a variety of models and can be used to move products on an assembly line, transport goods throughout a plant or warehouse, and deliver loads to and from stretch wrappers and roller conveyors.<br />AGV applications are seemingly endless as capacities can range from just a few kgs to hundreds of tons. The Aim of the project is to design and fabricate such a AGV<br />AGV components<br />Mechanical <br />The Mechanical components include chassis and the steering system.<br />Functions of chassis<br />
Act as a frame for attaching other components
Carry the load of other components and the payload.
Act as sacrificial component to prevent damage of expensive payload in case of accidents
Steering system is for steering the AGV <br />Electrical<br />Electrical components include the motor and the power supply for the motor itself.<br />Electronic<br />Electronic components provide sensing, logical decision and control of the vehicle. It includes microprocessor for the decision logic, the motor driver as both sensing and control of motor.<br />Computer<br />The Computer acts as a viable substitute for a central computer that provide the AGV’s with the path to proceed.<br />Block Diagram<br />274320153822600274320051250850012763504591685MICRO CONTROLLER00MICRO CONTROLLER56197552679600-4476754886960RECEIVER00RECEIVER468736550107860038550854934585MOTOR DRIVER00MOTOR DRIVER474662555257700055054504886960MOTOR00MOTOR48196501105535RADIO TRANSMITTER00RADIO TRANSMITTER43053001438910033337501133475BRIDGE00BRIDGE2876550154368501076325800735CENTRAL COMPUTERPROGRAM INSTRUCTION00CENTRAL COMPUTERPROGRAM INSTRUCTION552450143891000-4095751022350SIGNAL00SIGNAL<br />Mechanical Design<br />Chassis<br />The chassis is fabricated from Aluminum alloy sheet metal. This is done for ease of fabrication. It was designed in ProE, part of fabrication was outsourced due to unavailability of precision cutting tools. The Bending was done in then college workshop. The chassis was designed to take a static load of 10kg minimum. <br />The Top part of chassis has lots of drilled holes which serves as holes for bolting other parts and reduce the weight of the chassis. The Holes are arranged in a zigzag linear arrangement so that the decrease in strength of chassis is not considerable.<br />The flange which holds the motor was designed in a way that there is at least 10mm so that it can safely accommodate any bending due to loading above the designed value. The chassis incorporates mounting holes for both Ackermann steering and Differential steering system<br />Technical Data for Chassis (Table 3.1)<br />FeatureDataLength:194mmBreadth:105mmHeight:42mmMaterial:Al AlloyAesthetics:Power CoatingMaximum static load:12.6KgMaximum dynamic load:6.3KgMaximum impact load:1.2Kg from 1000mmMounting Holes:4×13mmø Holes for motor1×18mmø Hole for castor>50×5mm Holes for general mounts<br />Steering system<br />The steering system used in the model is of differential type. A differential wheeled vehicle is a vehicle whose movement is based on two separately driven wheels placed on either side of the body. It can thus change its direction by varying the relative rate of rotation of its wheels and hence does not require an additional steering motion. It allows the turning center to be on the vehicle body thus the ability to rotate on the point<br />Fig 3.1: Differential Steering<br />If both wheels rotate at the same speed and in the same direction, the robot will move in a straight line.<br />Fig: 3.2 Spinning by differential steering<br />If the wheels rotate at equal speed, but in opposite directions, both wheels will traverse a circular path around a point centered half way between the two wheels. Therefore the robot will pivot, or spin in place. (Figure 3.2)<br />Fig 3.3 Small radius turning<br />If one of the wheels is stopped, while the other continues to rotate, the robot will pivot around a point centered approximately at the mid-point of the stopped wheel. (Figure 3.3)<br />Fig: 3.4 Large radius turning<br />If one wheel rotates faster than the other, the robot will follow a curved path, turning inward toward the slower wheel. (Figure 3.4)<br />Steering Specifications: Table 3.2<br />FeatureDataWheel Base142mmWheel Diameter70mmTurning Radius range0-∞Point of Zero Radius TurnHalfway along Breadth,<br />Load tests<br />The following load tests were made on the chassis and the result<br />Table 3.3<br />Movement under 10Kg LoadPassedMovement under 10Kg load at Front &back edgeloadPassedMovement under 10Kg side edge loadFailedMaximum angle uphill (Unloaded)40degreeMaximum angle downhill (Unloaded)55degreeMaximim side angle (Unloaded)25degree<br />Electrical and electronic components<br />Transmitter-Reciever<br />The transmitter receiver pair transmits and receives electronic signal wireless. It is used for transmitting the path data to the AGV from the central computer. <br />The transmitter Module has 4 pins: Vcc, Data, GND and Antenna. Vcc is connected to +5V. The Data is connected to the TX of the bridge. The Antenna pin is connected to the Antenna.<br />Fig 4.1 Transmitter-Receiver Pair<br />Technical Specification of Transmitter-Reciever Pair, Table 4.1<br />FeatureDataFrequency433Mhz (License free)Speed1200BaudRange3m Indoors10m OutdoorsMax&Min Vcc:5.3/3.7VInterference with Safety epquipment NOEncodingAmplitute Shift Keying<br />The receiver has 8 Pins, 2 Vcc, 3Gnd, 1 Antenna, 2 Data<br />Microcontroller<br />A microcontroller (µC, uC or MCU) is a small computer on a single integrated circuit containing a processor core, memory, and programmable input/output peripherals. Microcontrollers are designed for embedded applications, in contrast to the microprocessors used in personal computers or other general purpose applications. <br />The Microcontroller used in the AGV is ATMEL Atmega 16. The reasons for using atmega 16 are<br />
The Microcontroller is programmed with the required program to accept the data from the wireless transmitter, interpret it , calculate the path in terms of spatial orientation and five logical values to the Motor driver.<br />Specification of ATmega 16: Table: 4.2<br />Type:40Pin Dual Inline PackageWidth:Height:Minimunm/Maximum Voltage:4.5/5.5VMaximum current:20mANumber of PORTS4No of Data Pins per port8Bus width8BitOscillation Speed16MhzUART Receiving Speed1200Baud<br />Connections: Table 4.3<br />PIN NamePin NoConnected to:Vcc10+5VGND11GNDXTAL11216Mhz CrystalXTAL21316Mhz CrystalRXD/PD014Data Pin of RecieverPB43L293DPB54PB65PB76<br />Motor driver<br />It is an electronic circuit which enables a voltage to be applied across a load in either direction. It allows a circuit full control over a standard electric DC motor. That is, with an H-bridge, a microcontroller, logic chip, or remote control can electronically command the motor to go forward, reverse, brake, and coast. The current provided by the MCU is of the order of 20mA and that required by a motor is ~500mA. Hence, motor can’t be controlled directly by MCU and we need an interface between the MCU and the motor.<br />A "double pole double throw" relay can generally achieve the same electrical functionality as an H-bridge, but an H-bridge would be preferable where a smaller physical size is needed, high speed switching, low driving voltage, or where the wearing out of mechanical parts is undesirable. The term "H-bridge" is derived from the typical graphical representation of such a circuit, which is built with four switches, either solid-state (eg, L293/ L298) or mechanical (eg, relays).<br />Fig: 4.2 H Bridge<br />Fig: 4.3 Circuit of Motor Driver<br />To control motor speed we can use pulse width modulation (PWM), applied to the enable pins of L293 driver. PWM is the scheme in which the duty cycle of a square wave output from the microcontroller is varied to provide a varying average DC output.<br />Fig: 4.4 PWM.<br />Technical Specification of L293D Table 4.4<br />Type:16Pin Dual Inline packageMax Logic Voltage:5VMax Supply Voltage:36VChannels:2Current per channel:600mA<br />Motor<br />Gear motor is used in this machine because it deliver more torque and full rotation compared to servo motor.Actuator that converts electrical signal to rotational motion.Contrary to usual belief it is an open loop control, A new technology of Back Emf interference is used to approximate a closed loop.<br />Technical specification of Motor: Table 4.5<br />Speed200rpmRated voltage12 VNo load current60mAFull load current500mAStall current580mABack emf interference range300 to 500uAtorque2 kg cm<br />USB-UART Bridge<br />As the Compter has 64/32Bit Data and the microcontroller and 8Bit data, A USB-UART bridge is used to convert the 64/32Bit data to 8Bit data. It also converts the USB Protocol to UART Protocol which is recognized by the Microcontroller:<br />Fig: 4.5 Bridge<br />Connections: Table 4.6 Connections of Bridge<br />Bridge:Transmitter+5VVccGNDGNDTXData<br />PCB Development Board<br />To aid in the Ease of construction a PCB development board has been used which allows easy change in circuit if necessary.<br />Fig: 4.6 Development Board<br />Computer<br />Programming algorithm used<br />Fig: 5.1 Programming Algorithm<br />Featured codes<br />Establishing Connection:<br />s = serial.Serial(‘COM8’,1200)<br />Sending data to the Bridge<br />s.write(‘f’)<br />Going forward 3 Units<br />self.do(‘3’)<br />Turning right 90<br />s.write(‘r’)self.do(‘90’)<br />Path planning<br />Spatial graph theory<br />Fig 6.1: Example of path planning<br />Let us assume the factory machines arranged in grids. The Blue Lines represent the pathway through which the AGV can move. For reaching the destination, the AGV has to go 6 Units right and 4 units forward.<br />For ease, let us denote going up as ‘u’ and right as ‘r’. Therefore the path shown above is r r r r u u u u r r r<br /> By Using Permutations and combination the different combinations for the path is equal to<br />10!6!4!=210<br />Therefore to move x units in one direction and y units in another perpendicular direction to reach the destination, a AGV has <br />x+y!x!y!<br />Ways. The ways are still less when more than one AGV is used as the path allotted to an AGV is subject to the following considerations<br />
The path is not currently in use by other AGV
The path does not cross the lines being used by other AGV.
Formulas used<br />For straight line motion between x1,y1 and x2,y2<br /> m1=x2-x1y2-y1<br />For straight line between x2,y2 and x3,y3<br /> m2=x3-x2y3-y2<br />Formula for taking a turn<br /> tanø = (m2-m11+m1m2) m2>m1<br /> ø = tan-1(m2-m11+m1m2)<br />Formula for calculating distance<br />X2-X12+Y2-Y12<br />Run tests<br />Speed<br />Accuracy<br />Power consumption per unit load<br />7. Project costs<br />Model costs<br />Table 7.1 <br />Microprocessor Board1110Bridge900Microprocessor210Transmitter-Reciever Pair500Motor350Chassis400Motor Driver50Tyres130Battery500 (Lead), 900(LiPo)<br />Load dependent costs<br />Motor, chassis, driver, tyres etc are dependent on the payload. The cost per unit load is 350+400+50+130+900/10 = 183Rs per Kg payload. It is estimated that these loads vary linearly.<br />CONCLUSION<br />The AGV is an productivity increasing feature in a factory that has the following advantages<br />
The Advantages of the AGV far shadow over the disadvantages and hence it is concluded that in a mass production factory with large area, a AGV will definitely increase productivity, decrease expenditure<br />BIBLIOGRAPHY<br />
Automation production systems, and computer integrated manufacturing by Mikell P.Groover