Autonomous Obstacle Avoiding and Path Following Rover

Transcription

1 Volume 114 No , ISSN: (printed version); ISSN: (on-line version) url: Autonomous Obstacle Avoiding and Path Following Rover ijpam.eu Sandeep Polina 1, Pavan Kumar Barathula 2 and K P Prasad Rao 3 Department of Electrical and Electronics Engineering K L University, Vaddeswaram , Andhra Pradesh, India. sandeep.polina@gmail.com Abstract. With the advancement of automation technology, the industries are adopting automated robots in workplace instead of humans. This paper deals with designing and implementing the basic prototype of line follower robot with obstacle avoiding capabilities. The basic line follower robot follows the path either black or white colour in inverted surface but having an obstacle in its path becomes a reasonable issue effects its utilization in workplaces. This prototype of the robot follows line, detects obstacle and take necessary actions to avoid it. The 3 sets of IR transmitter-receiver and ultra-sonic sensors are implemented in this prototype to detect path and obstacles respectively. The Arduino Uno board is the control system of this robot. The design includes two modules- line following and obstacle detection, both modules and its algorithm are implemented individually and at final both are combined in such a way that the robot performs specified task. Arduino motor shield and sensors are connected to control system and power is taken from 12V battery. Keywords: Robot, obstacle, sensors, ultra-sonic, IR transmitterreceiver. 1 Introduction Robot is usually a machine controlled by a computer program or electronic circuitry. These are designed mainly to reduce the work of a human. In most of the situations where humans are under risks. So, to reduce the risk factors as well as to increase the comfort these are developed. And by using it we can achieve more efficient outputs with in a low span of time. In olden days machines are only used to reduce the human effort they don t have any capability of making decisions. But now, the world is moving towards the autonomous in every aspect. By incorporating a little amount 271

2 of knowledge to the robots they can take a bounded decision on its own without any human involvement. We have designed a robot that performs additional tasks along with following a path. It avoids an obstacle in its path and continuous to follow its path after the obstacle been avoided. We can set the gap between the robot and intrusion at that point which the robot take its deviation from the path. Our robot follows the black line if it was removed from the black line it stops and while following the line if any obstacle was present in its path it detects the object from a distance which we set in programme. When the distance between obstacle and robot is reduced to minimum value the robot control instructions transfers from line following module to the obstacle avoiding module. When the robot avoids the obstacle, and detects the black line again the control sent back to the line follower module. Our robot contains single ultra-sonic sensor mounted on the servo motor helps to detect obstacles around in front of robot 2. BLOCK DIAGRAM This is the block diagram of line follower. The direction of the arrow indicates the signal flow. The connection between Arduino board and Arduino motor shield is bi directional. Since we are using three motors (2 dc and 1 servo) it is easy and comfortable to use the motor shield in controlling the speed of the motors and if we want the four-wheel drive we can increase the number of dc motor to four for heavy loads with the help of motor shield. Fig1. Block Diagram of Specimen model The signal from IR sensors are the input to the Arduino board. This signal helps in determining the position of the robot with respect to the black line and Arduino gives the necessary commands to the motor shield to adjust the motors speeds in controlling the robots position. This loop continuous unless any obstacle was detected. The ultra-sonic sensor detects the obstacle and sent the data to the Arduino, based on the data the Arduino calculates the distance between the obstacle and robot. 272

3 The servo motor helps in rotating the head of the robot (ultra-sonic sensor) through to find the obstacles is present in other direction. 3. LINE FOLLOWER MODULE The IR sensors mounted under the robot near the caster wheel helps in the detecting the black line. The line following strategy can be achieved by minimum two sets of IR transmitter and receiver to increase preciseness and smoothness in operation we use three sets of them. Line follower works on the principle that light reflects on white surface and doesn t reflect on black. IR transmitter transmits IR waves on to the surface receiver sends the information about the presence of black line to the Arduino board based on the reflection of the IR wave, based on the information Arduino sends signal to the motor shield to control the speed of the motors to take turning. The direction of the robot making a turn depends of the individual speed of left and right motors. If the speed of the left motor was more than the speed of the right motor the robot takes right turn and vice versa. To move the robot in straight forward both motors should be in same speed. 3.1 FLOW CHART OF LINE FOLLOWER This flow-chart explains how the robot movement related to the sensor inputs. Fig 2. Flow chart for Line Follower Number 0 and 1 under respective sensor indicates the logical high or low value. When the wave is reflected that means surface is white so, sensor output is logical high (1) value and if the surface is black then the wave will not be reflected so the sensor output is logical low (0) value. 273

4 F indicates the label hence the robot should continuously check for the black line and calibrate its position per path the process should continuously run in the loop. 3.2 PSUEDO CODE FOR LINE FOLLOWER Following code is used to explain how the coding is done on Arduino to make the robot to follow the line. Include AFMotor library Define left sensor to A0 Define middle sensor to A1 Define right sensor to A2 Assign right motor to the 3 rd motor slot of Arduino motor shield. Assign left motor to the 4 th motor slot of Arduino motor shield. Firstly: Set left sensor(a0) as input. Set middle sensor(a1) as input Set right sensor (A2) as input to the Arduino. Set the speed of left motor and right motor Initially make the both motors stop. Here loop starts: If left sensor and right sensor is on white and middle sensor is in black (case 1) Make both motors to run forward //it makes motor to move forward.. If middle sensor and right sensor is on white and left sensor is on black (case 2) Stop left motor and make the right motor to run //this makes robot to turn left If middle sensor and left sensor is on white and right sensor is on black (case 3) Stop the right motor and make left motor to run //this makes robot to turn right If all the sensors is on the black (case 4) Stop the both motors //this indicates the robot is at finish point. If all the sensors is on white (case 5) Stop the both motors //this indicates robot is out of track. If left sensor is on white and right sensor and middle sensor is on black (case 6) Stop right motor and run the left motor //it makes robot to turn right If right sensor is on white and left sensor and middle sensor is on back (case 7) Stop left motor and run the right motor //it makes robot to turn left If left sensor and right sensor is on black and middle sensor is on white (case 8) Stop both the motors //it indicates invalid path Go back to the loop. The entire loop executes repeatedly until the robot stops Even we use the analog pins of Arduino board we read the sensor inputs as digitally. 274

5 4. OBSTACLE AVOIDING MODULE In this module, we make the circuit and explain the strategy followed by robot to avoid the obstacle present in its path and continue following the path. The robot head turns 180 degrees to check the obstacle in three directions. Arduino is the brain of this robot it takes the data from the ultra-sonic sensor and calculate the distance between obstacle and robot. From the angle of the servo motor Arduino gets the direction of obstacle. By knowing the speed of the wave and time delay between triggered wave and echo the distance is calculated by formula. Distance =(speed*time)/2 When obstacle is present it path it check the distance in both directions and prefer the direction where there is a large gap. It travels in that direction leaving the path and travels through the boundary of an obstacle until it finds a black line. After finding the black line it continues its path. The threshold distance is set in the program when the gap between the object and the robot is below the threshold distance then the obstacle avoiding module gets activated. 4.1 FLOW-CHART OF OBSTACLE AVOIDING MODULE 275

6 Fig 3. Flow chart of obstacle avoiding module. The above flow chart repeats continuously in a loop measures the distances and take its course. 4.2 PSUEDO CODE FOR OBSTACLE AVOIDING MODULE Following code is for the obstacle avoiding module and shows the connection between the line follower module and this module by calling the line follower functions (discussed under 5 th heading) at certain constraints. Include servo library Include AFMotor library Set servo to pin 9 Set trig pin to A3 Set echo pin to A4 Initially make the robot stop. Check weather left distance is greater than right distance. If left distance is greater than right Make robot to turn left Step 1: make robot to move forward delay for some time check right greater than max distance. If right greater than max distance Make Robot to turn right. Step 2: Make robot to move 276 forward

7 Check right greater than max distance If right greater than max distance Make robot to turn right Step 3: Make robot to move forward. Check for black line If black line is present Make robot to turn left. Go to line follower module Go to step 3 Go to step 2 Go to step 1 Make robot to turn right Step 4: Make robot to move forward Check for left greater than max distance If left is greater than max distance Make robot to turn left Step 5: Make robot to move forward. Check for left greater than max distance If left greater than max distance Make robot to turn left Step 6: Make robot to move forward. Check for black line If black line is present make robot to turn right delay for some time go to line follower module Go to step 6 Go to step 5 Go to step 4 This loop continuous Check:// this function is used to check the left distance is greater than right distance. Turns servo to 0 degrees calculate distance Store the value in left Turn servo to 180 degrees calculate distance Store the value in right Turn servo to 90 degree Compare left and right distances If left is greater Return Boolean true Return Boolean false Distance:// this function is used to calculate distance make trig pin low delay for 2 micro seconds make trig pin high delay for 10 micro seconds 277

8 make trig pin low calculate delay between triggered wave to reflected echo wave calculate distance = duration/58.2; return distance CheckLGM and CheckRGM is the functions works same as check function but compare left distance to threshold and right distance to threshold value respectively. The robot stops controlling is in the line follower module. In line follower module while following the black line the robot check the presence of object in its path once in loop when distance is below set distance then the control is back to the obstacle avoiding module. 5. CIRCUIT Fig 4. Circuit connections of robot. 6. WORKING OF ROBOT Robot follows the black line as per the code of line follower module while following it continuously check for presence of an obstacle in its path. When an obstacle is detected it shifts the robot control to the obstacle avoiding module. After the avoiding obstacle, it sent back control to line follower module. Several functions are used in code to reduce complexity and increase preciseness of robot. The complete function of robot as per the pseudo code that explained above. X. RESULTS Following figures are the results of specimen. It was working fine by detecting obstacles while following the path 278

9 CONCLUSION Fig 5. Working of specimen snapshots The robot that designed has different functionality than other line followers and obstacle avoidance robots. By using servo motor we reduced number of ultra-sonic sensors from 3 to 1 and cover all the three directions by rotation of robot head and we can know in which direction the robot was looking by observing its head. By making some changes in the programming of the robot we can detect the obstacle at each degree around the robot and get the position of the obstacle. By replacing ultrasonic sensor with camera, it can capture the obstacles and take a necessary action. By incorporating some logical commands the robot it can be used for multipurpose. the preciseness of the robot in following line can be increased by increasing number of IR sensors. This robot can be used in industries, hospitals and army applications. This robot can replace conventional conveyor belts. REFERENCES 1. K.H. Ng, C.F. Yeong, E.L.M. Su, T.Y. Lim, Y. Subramaniam, and R.S. Teng, Adaptive Phototransistor Sensor for Line Finding, International Symposium on Robotics and Intelligent Sensors 2012 (IRIS 2012), vol. 41, pp , F.H. Jen and B.T. Mai, Building an autonomous line tracing car, IEEE Intelligent Control and Automation (WCICA), th World Congress on, pp , July M. Engin and D. Engin, Path planning of line follower robot, IEEE Education and Research Conference (EDERC), th European DSP, pp. 1-5, September N.M. Arshad, M.F. Misnan, and N.A. Razak, Single InfraRed Sensor Technique for Line- Tracking Autonomous Mobile Vehicle, Signal Processing and its Applications (CSPA), 2011 IEEE 7th International Colloquium on, pp , March Y. Li, X. Wu, D. Shin, W. Wang, J. Bai1, Q. He1, F. Luo, and W. Zheng, An Improved Line Following Optimization Algorithm for Mobile Robot, IEEE Computing and Convergence Technology (ICCCT), th International Conference on, pp , December

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