Category Archives: Robotics

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Line Following Robot using AVR ATmega8

One of the most basic autonomous robot you can build is a line following robot(LFR). This type of robot is run over a white surface which has an arbitrary path drawn over it by using back paint. The task of the robot is to run exactly along this painted path. You may note that the surface may also be black(or any other dark colour), in that case the path is a light colour like white. Please watch the following video for a LFR in action. Designing an LFR At minimum our LFR design require the following components. A sensor to detect the line on the surface.(It can be a simple IR Reflectance Sensor or an high end camera!). We will use a simple IR based sensor, it is cheap and easy to build and use. This article describe how to make a line sensor array. A microprocessor to run the code that takes inputs from the sensor and control the motion of robot. We will use a cheap single chip computer called an microcontroller (MCU). A popular family of microcontroller is AVR series from Atmel. A member of the popular family is ATmega8. ATmega8 is chosen because it has just the required amount of resources and is very low cost. The MCU cannot drive the motors (used to actually make […]

Making a Line Sensor using IR Receiver

A line follower robot, or a LFR in short, is a simple autonomous robot that optically tracks a line made on the surface of the floor. That means you have an arbitrary line drawn on the floor and the robot tracks it by moving right along it! The line is sensed using a piece of hardware called a line sensor. A line sensor can be easily made using a low cost IR Rx/Tx pair. The IR Rx emmits IR radiation and the Rx helps in receiving the waves. See the figure below for working of line sensor. Working of Line Sensor Schematic for Line Sensor. Line Sensor Schematic   Actual IR Rx Tx Pair. Line Sensor Array. Actually a group of such sensor units as described above is required to make a line follower robot. We generally use 3 or 5 such sensor unit to make a line sensor array. The complete steps are described below. You need small piece of veroboard (general purpose PCB). Actual IR Rx Tx Pair. We will fit the sensor at the castor mount of the metal chassis. So we carefully mark the location we need drilling. Mark drilling location.   Mark the drilling location. You can make the hole easily by using a pair of scissor. Just press and rotate. Make hole using scissor. […]

PC Controlled Robot

In this tutorial we will discuss a simple PC controlled robot. The Robot PC link will be a RS232 serial line. The robot will have only five commands. Move forward (RS232 char ‘F’ or ‘f’) Move backward (RS232 char ‘B’ or ‘b’) Turn Left (RS232 char ‘L’ or ‘l’) Turn Right (RS232 char ‘R’ or ‘r’) Stop (RS232 char ‘S’ or ‘s’) To keep things as simple as possible, in this example we will use terminal software RealTerm for sending commands to the robot. Later on a dedicated software can be written on PC end to control the robot. The Robot’s Hardware The robot’s hardware will be a simple differential drive using two 200RPM DC Gear motor mounted on a HQ Metal Chassis with a front castor wheel. On the back motors we have mounted plastic wheels. More about differential drive is explained in this tutorial. Gear Motors   Wheels   Metal Chassis   Remove motor’s nut   Insert the motor   Fasten the nuts again   Both motors installed   Front Castor wheel   Installing the front castor   Mounting hole for wheels screw   Mounting the wheels   Chassis is ready! The Electronics The robot is controlled using xBoard v2.0 which has ATmega32 as main CPU and integrated motor drivers. We have connected xBoard v2.0 with PC using […]

Tracked Wheel Robotics Platform

Tracked Robot, Chain Links   Tracked Robot, Chain Links   Chain Links Connected   Metal Connecters   How to connect chain links.   Complete Tracks with 18 links These tracks then can be fitted on the wheels. The track wheel set comes with the chain links, metal connecter and four plastic wheels. For more details check out Track Wheel Set for hobby robotics. Tracked Wheels   A complete mobile platform. The above platform is a four wheel drive, using 200 RPM Gear DC Motors on all four wheels. Bottom View   Gear motor for robots Other wise if you want to control the cost you may use dummy motor in place of two front motors. Dummy Motor Shaft The platform was built over the High Quality Metal Chassis. The Chassis

Obstacle Avoiding Robot using AVR ATmega32 – Part III

Hello All, Welcome to the third part of the Obstacle Avoiding Robot Tutorial. Till now we have completed the mechanical construction and made the sensor for our robot. I have shown you how to control the motors and read values from sensor in last two parts of the tutorial. In this tutorial we create the master program for our robot. The job of the program is simple, to read values from the sensors, make a decision and command two motors. In this way our robot will roam about the room avoiding obstacles in its path. In our program we define three constants, namely RTHRES,CTHRES and LTHRES in the following way :- //Threshold Values For Sensor Triggering #define RTHRES 195 #define CTHRES 275 #define LTHRES 195 The constant value next to them is the triggering values. You can get this values as described in previous tutorial. Simply run the IR Sensor Test program and bring any obstacle near the sensor at about 15cm (6 inches) and note down these values against respective sensor threshold values. Do same for all three sensor. Now the program knows when the value comes near this threshold value, the sensor has a obstacle in front of it. Note that the value shown above is may not match with the values you obtained, that OK. In our […]

Obstacle Avoiding Robot using AVR ATmega32 – Part II

Hello and Welcome back to the second part of Obstacle Avoiding Robot Tutorial. In the last part we studied the drive system and the mechanical construction of our robot. In this part we will make the sensor part. The sensors will help our robot detect obstacle in its path. The sensor system is of very basic type of infrared(IR) reflectance sensor. It is made up of an IR Transmitter and an IR receiver. The IR transmitter is an IR LED which emits light in IR spectrum that is invisible to human eye. The IR receiver can detect those rays. A Matching Pair of IR Rx and Tx, The Blue One is Tx (LED). The IR Sensor Element The IR Sensor element is made up of an IR Tx,IR Rx and few resistors. The schematic is given below. We need three such elements mounted in front of the robot to sense obstacles in front of it. IR Reflectance sensor schematic. As you can see the sensor element has two pins for power supply and an Output pin. The output is a variable voltage between 0 and 5v depending on the type and distance of the obstacle. It tends to 5v as some obstacle comes near it. IR Sensor Construction Guidelines. The value of R1 is 150 ohms and R2 is 22K. […]

Obstacle Avoiding Robot using AVR ATmega32 – Part I

Hi and Welcome All, In this tutorial series I will show you how to make a simple obstacle avoiding robot using the xBoard v2.0 microcontroller board. xBoard v2.0 is well suited for developing small intelligent robots as it is compact in size, has four DC motor controller, can be programmed using USB Port and many other features. It is also very easy to learn and use. The xAPI, which is a set of C functions which makes complex programming tasks such as PWM ,LCD, Remote Control etc very easy for beginners. You can buy it from here http://shop.extremeelectronics.co.in/product_info.php?cPath=23&products_id=111 Its design is open so if you don’t want to buy the board you can make it yourself at home by the help of its schematic. The Robo’s Task The task of our robo is simple. To move randomly in an area avoiding obstacles, that’s it ! Though the task is simple, its a complete autonomous robot in itself. It has a brain which reads sensors and makes decisions and command the motors. In the course of making the robot you will learn various basic techniques which will be of great use for your further projects. Our Final Robot will look like this. AVR ATmega32 Based Obstacle Avoiding Robot The following Video Demo Shows the Robo in Action The following Video was […]