THE LINE FOLLOWING ROBOT

[Audio] This presentation explains the line following robot.

[Audio] Group members. GROUP MEMBERS : ADNAN A.M.M.S. (E/19/010) AHMETH M.M. (E/19/011) AKRAM A.W.M. (E/19/013) AZHAR H.M. (E/19/031) FARMAN M.H.M. (E/ 19/105) FASEEH M.F.M. (E/19/106) Group : MI - T6.

[Audio] A line following robot is an autonomous vehicle which is capable of following a given path. We expect to make a line following robot which consists of a chassis, IR sensors, microcontrollers, DC motors and motor driver. This project tries to implement PID controller on the line following robot and thus trying to reduce the errors while moving. The robot consists of a " sun founder line following module" which consists of array of 8 IR sensors through which the robot detects the black line and follows the path. The PID is implemented so that the robot will be able to follow the given black line effectively and smoothly..

[Audio] DEVELOPMENT OF THE PROGRAM FLOW 1. Inter-Integrated Communication Bus ( IIC Bus) The IIC communication bus is very popular and broadly used by many electronic devices because it can be easily implemented in many electronic designs which require communication between a master and multiples slave devices. The easy implementation comes with the fact that only two wires are required for communication between up to almost 128 devices when using 7-bit addressing and up to almost 1024 devices when using 10 - bit addressing. Each device has a unique device address so the master can choose with which device will be communicating. The two lines are called Serial Clock ( SCL) and Serial Data ( SDA). The SCL line is the clock signal which synchronizes data transfer between the devices on the IIC bus and it is generated by the master device. The other line is SDA line which carries the data. For the two-line, pull-up resistors are needed to them so that the lines are active high, because the devices on the IIC bus are active low. Commonly used values for the resistors are from 2 kiloΩ for a higher speed at about 400 kbps second, up to 10 KiloΩ for lower speed at about 100 kilobyte per second. Let's see the data protocol of the IIC bus. The data signal is transferred in sequences of 8 bits. The first 8 bits sequence which indicates the address of the slave to which the data is being sent. After each 8 bits sequence follows a bit called Acknowledge. After the first Acknowledge bit, another addressing sequence comes for the internal registers of the of slave device. After the both addressing sequences follows the 8-bit data sequence. We will use the Arduino Wire Library to interact with IIC. Firstly, we need to define the sensor address and internal register addresses. Then, the " Wire.begin()" function is used to initiate the Arduino wire library and the serial communication. After the addressing, the data transfer sequences begin either from the master or the slave depending on the selected mode at the R/W bit. After the data is completely sent, the transfer will end with a stop condition which occurs when the SDA line goes from low to high while the SCL line is high..

[Audio] 2. Sunfounder IR Sensors ( 8 channels) The robot uses Sunfounder IR sensor module to sense the BLACK LINE. It consists of an array of 8 IR sensors faced towards the ground. The communication between the module and the Arduino is done by IIC bus. Both the IR LED and Photodiode are placed in parallel, facing both in the same direction. Therefore, when an object is kept in front of the IR pair, the IR light gets reflected by the object and gets received by the photodiode. Make sure that the object should not be black in colour, as black coloured objects absorb IR light and does not reflect. To avoid reflection from the surrounding objects other than the object placed In Front, the sensors could be enclosed properly by black plastic tape..

[Audio] Calibration Of the Line Follower Sensor Module Calibration is the process of configuring an instrument to provide a result for a sample within an acceptable range. The goal of calibration is to minimise any measurement uncertainty by ensuring the accuracy of test equipment. Calibration quantifies and controls errors or uncertainties within measurement processes to an acceptable level. We need to calibrate the output from the IR sensor array since every sensor doesn't give the same maxima and minima value. Therefore, individual sensors are calibrated to return a maximum and minimum value ranging from 0 to 1000, so that it can be found that which sensor detects the black line, helps to move, and correct the position of the robot. Below flowchart shows, how calibration process works. Once the values have been noted down, the individual values from the sensors for black and white readings will be mapped to a common range. An analogue signal is obtained in the output, based on the amount of reflected light, and is fed to the comparator and the digital signal is sent to the microcontroller. Here, the analogue signal is converted into digital by the IR array module..

[Audio] Weighted Average Algorithm for Line Following A weighted average algorithm can provide a measure of error. Each sensor is already calibrated to return a maximum and minimum value. The midpoint of the Sunfounder IR sensor module is considered as the reference point. Each individual sensor point is given a weighting. Hence, distance of the ith sensor from the reference point is given by, shown equation.

[Audio] Consider the following schematic of the sensor module, Let's assume that when the sensor senses the black line, it reads 0 and when it is off the black line, it reads 1. The microcontroller corresponds to the algorithm, executes the next movement in such a way that the centre most sensors that are L1 and R1, reads 0 and the rest of the sensors read 1000 if the rest of the surface is pure white. In this way, we need to do the calibration process and implement the weighted average algorithm. In below schematic, R1 sensor is our reference sensor..

[Audio] PID Control System A PID controller is a feedback loop system. The basic idea is to guide the robot towards the BLACK LINE based on, "the so far off it is, the more it corrects itself". The basic terminology of the PID control system is as follows: Proportional( P) – The proportional constant directly multiplies the error; therefore, set a reasonable motor speed change for the given the error magnitude. Integral( I) - The integral component multiplies a running sum of the error; therefore, its effect increases the longer the robot is not on track. Differential( D) - The differential component multiplies the change in error; therefore, its effect depends on how quickly the line is changing compared to the instantaneous track of the robot..

[Audio] The process is a feedback loop as shown in the below figure. Such a design allows the robot on the track with the implementation of PID controller..

[Audio] The error is a measure of how far the robot is from the track. The further the car is off the track, the larger the error. More specifically we can say that error is the difference between the current position and the target position. The error will be negative when the car is on the right side of the black line. Similarly, the error will be positive when the car in on the left side..

[Audio] This Figure shows how the speed of the wheel is changed based on the error value obtained..

[Audio] Tuning The PID Constants In this project, we hope to use trial and error approach to design the PID controller. The first step of creating a PID feedback loop is to define our desired position. We need to calibrate the values by simply moving the robot across the line and note its readings We need to add the error value to the output by measuring the centre point deviation of the line. If the robot deviates from the black line, a proportional constant is given to bring the robot back to the black line as quick as possible. But, to prevent the robot from overshooting, a derivative constant is given. This corresponds to the rate of change of error. The integral constant is used to improve the accuracy and smoothness of the movement of the robot. It corresponds to the sum of the recent errors. The terms in the PID equation namely K p-factor, K i-factor, K d-factor is a constant value used to increase or decrease the impact of the proportion, integral and derivative respectively..

[Audio] Here, The Overall Program Flow path is shown in the flow lines..

[Audio] REQUIRED COMPONENTS FOR THE ASSEMBLY Let us discuss about required components. STMicroelectronics L7805ACV, 1 Linear Voltage, Voltage Regulator 1A, 5 V 3-Pin: 1 Nos voltage regulator, any electrical or electronic device that maintains the voltage of a power source within acceptable limits. The voltage regulator is needed to keep voltages within the prescribed range that can be tolerated by the electrical equipment using that voltage..

[Audio] Duracell MN21 12V Alkaline Batteries. 2. Duracell MN21 12V Alkaline Batteries (2 Pack): 1 Nos.

[Audio] Battery Holder AA 2 Cell Wire Leads. Dimensions be like 6.5" that is 165.1mm.

[Audio] 1 kilo Ohm Resistor. 4. 1 k Ohm Resistor: 1 Nos.

[Audio] Two Gebildet DC3V- 12V DC Geared Motor for Four-wheel Robotic Body.

[Audio] Required Male, Female Jumper Wires. 6. Required Male, Female Jumper Wires.

[Audio] EMO 4-wheel 2-layer Robot Smart Car Chassis Kits with Speed Encoder.

[Audio] Arduino UNO board Arduino is an open-source electronics platform based on easy-to-use hardware and software. For our Project, Arduino will be a crucial component to control the whole system. In our project Arduino is used so that it receives the signals from IR sensors, analyses it and controls the movement of the Robot car by giving required output signals to the Motors which run the wheels of the robot car..