Search Results
146 items found for ""
- 6 Line Follower
Small Robot : 6 Line Follower # . < < < Previous List All Next > > > . Introduction A Line Follower is self controlled Robot, which follows a thick line. Many types of sensors are used to read the line. The Small Robot uses IR (Infra-Red) sensors, to read the line. Five pairs of IR LEDs and IR sensors (shaped as LED) are used here to read the Line. All the five IR sensing pairs are arranged in a row, perpendicular to the line path. The Small Robot always try to position symmetrical to the line, by following the middle IR sensing pair (out of 5 IR pairs in a row). To have more input pins (at least 5 inputs are required for IR sensors), in small size, ATTNY84 micro-controller is selected, which have 14 pins. Out of 14 pins, five pins are used for sensing the line and four pins are required to control the two motors, through the motor driver (L293D). (refer Small Robot Base Frame for motor control codes). In general Line Followers are set to follow the line and complete target distance as soon as possible without leaving the line. The programming is either target for fast line follower, with smooth curves, or complicated line follower with various types of obstacles. The Small Robot is programmed here to follower various line types, like, sharp bends, sharp turns, sharp curves, crossings, gaps in lines, zig-zag lines, double lines, stop identification etc. A model path used to test the Small Robot is shown below, having various line shapes. About Line Sensing: Most of the Line Followers use IR (Infra-red) sensing system to read the presence of line. An IR LED emits IR light on the bottom surface (where the line is drawn). The IR light reflects from the surface and falls on an IR sensor (in LED shape), placed near to the IR LED. The IR sensor is connected in reverse biased, which varies its internal resistance, depending on the brightness of reflected IR light. The internal resistance of the IR sensor decreases with increase in falling IR light. So, when the surface below the IR sensor is white, more reflected light falls on the IR sensor, which makes least internal resistance. Similarly, if the surface is black, least light reflects on the IR sensor, which makes highest internal resistance. Due to change in the resistance of IR sensor, the voltage at the junction of the IR sensor and fixed resistance varies, which are connected in series with power supply and ground. A typical IR LED + IR sensor pair arrangement with the circuit diagram is shown below. Total 5 such IR sensing pairs are required for Small Robot, and soldered on a PCB, then fixed in front of the Small Robot. All the IR LEDs and IR sensors are 3 mm size. Maintain the gap between. the two successive IR sensors should be just less than the line width. The IR sensor PCB, with 5 IR pairs, shall be fitted in front of the Small Robot, with a clearance adjustment arrangement (from surface) , to adjust the sensitivity with black and white surfaces. Working of Line Follower: Making of Small Robot as Line Follower is simple and easy. One PCB is required for IR sensing board, with 5 pairs of IR LEDs and IR sensors explained above. Another PCB with micro-controller ATTINY84 is used as control system for the Line Follower based on the varying voltages obtained from five IR senors. The varying voltages from the IR sensor board are read as five digital inputs by the micro-controller. Then, the programmed logic makes the Small Robot to follow middle IR sensor. In case, the Small Robot reads the line from any other IR sensors, the required output code is sent through the four motor control pins, to turn the Small Robot accordingly, else Small Robot moves in straight line. In case of sharp turns, gaps, crossings, junctions or stop blocks etc., the Small Robot moves little further and then takes necessary movement accordingly. The complete circuit diagram of Control Board with ATTINY84, is available below. Use jumper wires to connect S1…S5 pins from Sensor Board to Control board consecutively. The shorting jumper J1 is provided to select the line colour as BLACK or WHITE. Either Red or Yellow LED glows by selecting the shorting jumper position, for Black or White line. A button switch, SW1, is useful to start the Line Follower, after switching ON the power supply to the Control Board. All the Best Download LF HEX file Contact for Source Code Download file from above link and remove .TXT extension. . < < < Previous Once Small Robot's Base Frame is made, then, various control systems for Small Robot are developed and available for selection, using 'Previous ' and 'Next ' buttons here. Next > > > .
- 2 Keypad Control
Small Robot : 2 Keypad Control # . < < < Previous List All Next > > > . Introduction To control Small Robot, a simple and easy concept is explained here. Four buttons are used to control the Small Robot, in all the four directions. To make the Robot control small and simple, ATTINT13 (8 pin micro controller) is used for both transmitter and receiver boards. A Transmitter board, is designed with a micro-controller (ATTINY13) , which receives four inputs from the small buttons and converts to 4 bit data. Then sends the 4 bit data as serial data. The serial data is sent through a wireless transmitter module. Similarly, Receiver board, is also designed to receive the serial data, through a wireless receiver module. Then, the micro-controller (ATTINY13) decodes the serial data, to four bit parallel data, used as input to motor driver IC (L293D). Thus, motor driver controls the two motors of the Small Robot, for required movement, in all the directions, depending on the keyboard input(s). Keypad Transmitter: For the Keypad Transmitter board, four keys are used to control the direction of motion of Small Robot. Every two keys have parallel connection with two voltage divider resistances. So, by default, the micro-controller receives, mid voltage of power supply (i.e., 2.5V), as input. Two such inputs are used for four input buttons. Both the inputs are connected to the micro-controller's ADC (Analog-to-Digital Converter) pins. So, when no button is pressed, the micro-controller reads mid value of ADC from both the pins. When, any input button is pressed, the ADC value is set as, either maximum or minimum, depending on the button press. So, the micro-controller always checks the ADC input voltage and converts the ADC value to four bit digital data. Then, the four bits are sent through a pin as serial in encoded form. (Refer Base Frame for four bit data) Any RF (Radio Frequency) Transmitter may be used, to transmit the Serial data, from the micro-controller to wireless radio wave. A 433 MHz RF transmitter module is used here for the purpose. A 7805 is used to convert 9V battery supply to 5VDC power supply for the circuit. Keypad Receiver: For the Keypad Receiver Board, the serial data is received by the RF receiver module, and sent to the micro-controller (ATTINY13). The micro-controller decodes the received data, and converts to four bit parallel data. Then the four bits are sent to the base frame through the 6 pin connector, which in turn controls the movement of the Small Robot. The 5VDC power supply for Receiver board is derived from the Main board of Base Frame, through 6 pin connector. Download TX HEX file Download RX HEX file Contact for Source Code Download files from above link and remove .TXT extension. . < < < Previous Once Small Robot's Base Frame is made, then, various control systems for Small Robot are developed and available for selection, using 'Previous ' and 'Next ' buttons here. Next > > > .
- 1 Base & IR follower
Slim-Bot 1 Base & IR follower Introduction .. As the name indicates, SLIM-BOT, is a small, simple, compact robot, which may be moved or controlled using various inputs, without using any micro-controller. There is no need of programming language or coding to make and control the Slim-Bot. This is the basic project for those, who don’t have any knowledge in micro-controllers and programming. The various controls for the Slim-Bot is completely based on the electronic circuits only. To make Slim-Bot, smaller and compact, two numbers of servo motors are modified to make continuous rotation. You may use SG90 or MG90 servo motors for the purpose. Two small wheels are used as drive wheels, connected on either side (at rear), to the modified servo motors, and a small castor wheel is used at the front for the Slim-Bot. To make the Robot compact, a 3.7V flat Li-Ion cell, (normally available in old cell phones), is used and positioned below the main PCB. The size of the main PCB is also made small, which will accommodate mainly, motor controller IC (L293D), power switch, an 8 pin connector for data and power supply, an indicator LED etc. The pinouts of 8 pin female connector is shown below. A shorting jumper is used to connect the DC power supply to both the motors (through L293D) at Vmot to Vcc pin. But, a separate power supply may be used for Vcc pin, if required, in future control systems. About Base Board : The base board is a small PCB, which holds the basic required electronic components and connections. The main component on the base board is, motor driver IC, L293D . similarly, the main connection is a 8 pin female berg strip. Out of 8 pins, 4 pins are data input pins for motor control and DC power supply pins on one side and motor power supply side on other side. The shorting jumper J1 is connected to get the power supply at Vcc pin (power supply to external PCB, if any) also, along with Vmot pin (for motor power supply) and Logic power supply (VccL) of motor driver IC. The logical data inputs, D0, D1, D2 and D3 , are connected to 4 inputs, ip1, ip2, ip3 and ip4 pins of motor driver IC. Whereas, the output pins, op1, op2, op3 and op4 are connected to two modified servo (DC) motors, for movement control of the Slim-Bot. So, for movement control of the Slim-Bot, four bit signal(s) are used at D0 to D3 pins on the 8 pin berg strip. The Slim-Bot uses three wheels, out of which two small wheels are directly mounted on the modified servo motor shaft, and the third one is a small castor wheel, which is fixed at the front side of the Slim-Bot. For quick testing of motor movement, the D0 to D3 pins may be connected sequentially to Vcc pin, through a series resistor (about 1K). For each pin connection of D0 to D3, one out of the two motors, rotates either Clockwise or Anti-clockwise. About IR follower : IR or Infra-Red sensor LED is sensitive to the IR light falling on its surface. The resistance between the Anode and Cathode pins varies due to intensity of IR light falling on it. The resistance decreases, as the IR light falling on it is high and vice-versa. The IR sensor LED should be connected in reverse polarity (i.e., cathode towards positive power supply and anode towards ground or negative power supply), for its proper functioning. Two 5mm size, IR LEDs are used here, to control the Slim-Bot using IR light. Both the IR LEDs are connected in reverse polarity as shown in the circuit diagram below. The Cathode (C) pins are connected to Vcc and Vmot, and Anode (A) pins are connected to D0 and D3 in crossed manner. Note that, the Anode pins of both the IR LEDs should not touch each other. A small opaque medium (block or barrier) is introduced between the two IR LEDs, to reduce the IR light interference on each other. Now, when, an IR light is falling on the left side IR sensor LED, the signal goes to right side data pin (D3) and right side motor rotates accordingly. This makes Slim-Bot to have left side turn, towards the IR light. Similarly, the right side IR light makes, the Slim-Bot to take right turn. When the IR light falls on both the IR sensor LEDs (if the IR light source is in front of Slim-Bot), then both the motors rotates and the Slim-Bot moves forward.
- 5 Wireless Joystick Control
Slim-Bot 5 Wireless Joystick Control Introduction .. As the name indicates, SLIM-BOT, is a small, simple, compact robot, which may be moved or controlled using various inputs, without using any micro-controller. There is no need of programming language or coding to make and control the Slim-Bot. This is the basic project for those, who don’t have any knowledge in micro-controllers and programming. The various controls for the Slim-Bot is completely based on the electronic circuits only. Now, the Slim-Bot may be controlled wirelessly using a Joystick. A joystick has a knob to control in all the four directions (Up-Down-Right-Left), which is easy for manoeuvering the Slim-Bot. As the joystick generates analog values, op-amps are used for conversion of analog to digital values. Then the digital values are fed to Encoder IC and then transmitted wirelessly using RF transmitter. The serial data is received by the RF receiver, sends to Decoder IC (HT12D). The Decoder IC, decodes the received serial data, back in to 4 bit data. The 4 bit data is used to control the movement of the Slim-Bot. About Joystick ADC : The joystick used here is normally available in the market as joystick module. Generally, this joystick module contains, three outputs, viz., dx, dy and SW. The dx and dy are connected to mid-pins of two variable resistors, perpendicular to each other. When the knob is moved horizontally(left-right), the resistance value in dx varies. Similarly, when the knob is moved vertically(up-down), the resistance value in dy varies. So, when the joystick module is connected to 5VDC power supply (between the Vcc and ground pins), the dx and dy values are set at 2.5VDC approximately, by default. When the knob is moved left and right or up and down, the voltage at dx and dy varies accordingly. The SW pin is connected to a button switch below the knob and gets activated (switched on), when the knob is pressed down. Hence, the output of dx and dy are analog voltages, which varies in between 0V to 5V (up to Vcc). To convert the analog to digital voltage, 4 numbers of OP-AMPs are used here. So, 2 numbers of LM358 dual op-amp ICs are used to convert dx and dy analog values, to four digital values, as shown in the circuit below. About Joystick TX and RX: The digital values are fed to Encoder IC (HT12E), as explained earlier in Keypad control system. Then, the digital code is encoded by the Encoder IC (HT12E) and outputs the code in serial format. Then the serial output of the encoder is transmitted by an RF transmitter. The connections between digital outputs from op-amps to Encoder IC, HT12E, are shown at the bottom of the page. ( CLICK HERE to know more about working of HT12E and RF transmitter, from wireless keypad control) There is NO CHANGE in Receiver Board or Slim-Bot, w.r.t. Keypad control. Once the Transmitter module is ready, then switch ON the power supply to Transmitter and Slim-Bot, for easy control of Slim-Bot using joystick. (Refer Keypad Control system for Receiver circuit diagram) CLICK HERE to know, how to make BASE for SLIM-BOT.
- 02 Omni Robo Joystick
Previous < Back Next desc about joystick control Intro to joystick and control
- 4 Wireless Keypad Control
Slim-Bot 4 Wireless Keypad Control Introduction .. As the name indicates, SLIM-BOT, is a small, simple, compact robot, which may be moved or controlled using various inputs, without using any micro-controller. There is no need of programming language or coding to make and control the Slim-Bot. This is the basic project for those, who don’t have any knowledge in micro-controllers and programming. The various controls for the Slim-Bot is completely based on the electronic circuits only. A robot may be controlled wirelessly in many ways. Here, the Slim-Bot is wirelessly controlled using a 4 button keypad. Four buttons are used as input system to control the movement of the Slim-Bot, which generates 4 bit code. Then the code is encoded using an Encoder IC (HT12E) and outputs the code in serial format. Then the serial output of the encoder is transmitted by an RF transmitter. The serial data is received by the RF receiver and send the data to Decoder IC (HT12D). The Decoder IC, decodes the received serial data, back in to 4 bit data. The 4 bit data is used to control the movement of the Slim-Bot. About Keypad Transmitter: For simplicity and easy understanding of working of a keypad, a simple four direction keypad is made here. Four numbers of two pin tactile button switches are arranged in North-South-East-West (for Forward-Backward-Right Turn-Left Turn movements respectively) format and the connected as shown below. The Backward, Right turn and Left Turn button press signals are directly fed to the Encoder IC (HT12E). Whereas for Forward movement, two diodes are connected from North button, to right and left buttons, to have movement of both right and left motors forward, thus the Slim-Bot moves forward. The Encoder IC, HT12E, has 12 inputs, i.e., 8 address pins A0 to A7 and 4 data pins AD8 to AD11 . All the 8 address pins are internally connected to logic high. To make a specific 8 bit address (or code to select matching Decoder IC, HT12D), required pins may be connected to ground. Here, all the pins are left open to get address as 11111111 binary code (= FF hexadecimal). The TE pin (pin 14), Transmit Enable, is connected to ground for continuous transmission of the button code. The 4 bit button press code is fed to AD8 to AD11 pins of Encoder IC, HT12E, and the encoder generates, a serial data at Dout pin (pin 17), which contains the 8 bit address code and 4 bit data code sequentially. The serial data is then sent to an RF (Radio Frequency) module. You may use either 433MHz or 315MHz RF module for the purpose. A good antenna increases transmission range of radio frequency. About Receiver Board: The radio frequency is received by an RF receiver module (should match the RF transmitter frequency 433MHz or 315MHz), and the 12 bit serial code is sent to Din pin of Decoder IC, HT12D. Similar to the Encoder IC, the Decoder IC (HT12D) also has 8 bit address pins (A0 to A7) and 4 bit data pins (AD8 to AD11) . The 8 bit address pins of decoder IC, shall match the address code pattern of the encoder IC, i.e., the same pins of decoder IC should be connected to ground, matching to encoder IC. Then, the 4 bit data is available at AD8 to AD11 pins of Decoder IC. The VT pin (Valid Transmission) goes high, whenever the received data is matching to the set address pattern at A0 to A7 pins. As the 8 address pins of Encoder IC are left open (not connected to ground) for the transmitter, here also the 8 address pins of Decoder IC are left open, to match the address, i.e., binary code = 11111111 (= FF hexadecimal). So, the 4 bit signal data available at AD8 to AD11 pins are connected to the D0 to D3 pins of base board on Slim-Bot as shown below, to control the movement of the Slim-Bot. Here, the Decoder IC and RF receiver module may be directly soldered on the Base Board (PCB) of the Slim-Bot, or soldered on a separate board, then insert in to the 8 pin berg-strip available on the Base Board. A separate 3.7V Li-Ion battery may be used for the power supply of Decoder IC and RF module, to reduce interference to RF signals and isolate from the motors power supply. Additional battery is connected between the Vcc and ground, through a switch in series as shown in the circuit and the shorting jumper shall be disconnected on the base board. CLICK HERE to know, how to make BASE for SLIM-BOT .
- 9 Obstacle Avoider
Small Robot : 9 Obstacle Avoider # . < < < Previous List All Next > > > . Introduction: An Obstacle Avoider is also a self controlled Robot, which will recognize obstacle (like wall) and avoids collision with the vertical surfaces. Many types of sensors may be used for finding obstacle, like IR distance sensor, Ultrasonic Distance sensor, pressure switches etc. But, using Ultrasonic sensor is simple and reasonable to recognize the obstacle. One Ultrasonic distance sensor is fitted on front side of the Small Robot to measure the distance of obstacle. The distance is read from the ultrasonic sensor by the micro-controller (ATTINY84), then analyzed to take turn accordingly, based on the 4 bit motor control data, through the motor driver IC (L293D) on base board. (refer Small Robot Base Frame for motor control codes). The concept of Obstacle Avoider Robot is to avoid flat vertical obstacles. Basically, the Obstacle Avoider periodically sends an ultrasonic wave and measures the distance of obstacle by the time taken to receive its reflected wave from the obstacle. If the distance measured is less than the set distance value, then takes turn accordingly. Here, the Small Robot is programmed to take a right or left turn, when it founds any obstacle within its set distance, else moves forward continuously. About Obstacle Sensing: Here, the Obstacle Avoider uses one ultrasonic sensor module, HC-SR04 (readily available) to read the presence of obstacle in front of it. The ultrasonic sensor module, consists of a ultrasonic wave generator and ultrasonic wave receiver, with required on-board electronic circuit. The ultrasonic sensor module is available with four pinouts, i.e., Vcc, Ground, Trigger and Echo. The ultrasonic sensor module is connected to 5VDC supply across Vcc and Ground pins. Whenever the Trigger pin goes HIGH ( logic 1 ), for 10 micro-seconds, the ultrasonic wave generator sends ultrasonic waves, about 40 KHz, which is not audible to human ears. Then the ultrasonic wave receiver starts listening for the reflected ultrasonic wave. Then, a high pulse is generated from Echo pin, proportional to the time taken to receive the reflected ultrasonic wave by the ultrasonic wave receiver. The Echo pulse time ( or Time of Flight ) is measured by the micro-controller (ATTINY84) and converted to distance by using suitable formula. If the distance obtained by the formula is less than the set distance (means obstacle is near to the Obstacle Avoider or within critical distance), then, the Obstacle Avoider takes turn accordingly, else moves forward. The Concept of working of Ultrasonic sensor is shown below. As the generated Ultrasonic wave moves in a narrow path, sometimes the ultrasonic sensor module may not recognize thin obstacles (like wires etc.) and obstacles above or below the ultrasonic wave path. The ultrasonic sensor module may not recognize the obstacle with inclined surfaces, as the ultrasonic wave may get diverted its path and the ultrasonic receiver may not receive the reflected ultrasonic wave. To avoid such errors, multiple ultrasonic sensor modules are to be used at various directions. Working of Obstacle Avoider: Two versions of Obstacle Avoider are developed. The first version uses a bracket to hold the ultrasonic sensor module at fixed position. So, to check the obstacles at sides, the Small Robot takes right and left turns, at regular intervals. In the first version, only the ultrasonic sensor module is connected to the control board, using jumper wires. The distance of obstacle is measured continuously by the micro-controller (ATTINY84), then takes turn, if the obstacle is found within the critical distance, else moves forward. In this version, the movement of Small Robot is slow, with intermittent brakes, since it takes small turn at regular intervals, to find obstacles at sides. In the second version, a servo is fitted on the bracket and used to swing the ultrasonic sensor module on its horn. The servo motor is also controlled by the micro-controller (ATTINY84) and set to swing right and left side. So, the obstacle distance is read continuously from right, left and forward. The Small Robot takes turn according to the obstacle found, else moves forward. Here, the searching angle for obstacle is high and movement of the Small Robot is also improved. On the control board, no shorting jumper should be used (existing shorting jumper should be removed, if any). Then, the RED LED glows, when the obstacle is found within critical distance, else YELLOW LED glows. This is simple and very useful indication, to know the working status of ultrasonic sensor module. A button switch, SW1 on control board, is useful to start the Obstacle Avoider, after switching ON the power supply to the Control Board. The SW1 switch should be pressed twice in first version, to search the obstacle in both sides, else the Small Robot will search for obstacle in forward direction only. The complete circuit diagram of Control Board with ATTINY84, is available below. Use separate jumper wires to connect ultrasonic sensor module and servo motor to Control board. Omit servo motor and its connections in first version. Download OA1 HEX file Download OA2 HEX file Contact for Source Code Download file(s) from above link and remove .TXT extension. . < < < Previous Once Small Robot's Base Frame is made, then, various control systems for Small Robot are developed and available for selection, using 'Previous ' and 'Next ' buttons here. Next > > > .
- 1 Base Frame
Small Robot : 1 Base Frame # . < < < Previous List All Next > > > . Introduction The following are the General Requirements of a basic robot: 1. Chassis – 1no. 2. Motors – 2nos 3. Wheels – 2nos 4. Castor wheel – 1no 5. Battery and power supply circuit – 1 no. 6. Motor driver – 1no. 7. Controller Board (Microcontroller or other) – 1no (minimum) 8. Display / status indicators – as per requirement 9. Sensors / other input devices – as per requirement 10. Programmer (to load code to microcontroller) – 1no. 11. Software(s) – as per requirement. 12. logic development skills. Out of above listed 12 points, first 6 points are common and hardly change the items. These are mainly hardware items and does not require any software skills. Same robot can be modified to required configuration by changing micro-controller / sensors / inputs / displays / software / logic. The Small Robot is simple in construction, compact design and have mainly two parts. The first part , Palm Robot – Base Frame, contains the 1 to 6 items of the above list and second part, Small Robot – Control, contains the 7 to 12 items of the above list. By using Small Robot Base Frame, time is saved to develop logic using various micro-controller(s) and software(s). The Small Robot control systems are designed/developed using AVR microcontrollers here. But, the same logic can be developed using PIC or other microcontroller(s) and the output of the logic can be used to control the Small Robot Base Frame. About Base Frame: The Small Robot – Base Frame, contains two B.O. motors with 200 rpm are attached to a chassis on either side and two suitable wheels are mounted on it. A castor wheel with bracket is fixed on front side of the chassis. A 7.4V Li-ion battery is placed between two B.O.motors. 4 or 6 nos of long bolts may be suitably arranged on top of the chassis to hold circuit boards. A circuit board, called Main Board, with motor driver IC (L293D) and two separate 5VDC regulated power supplies are fixed on top of the chassis, which hardly covers half of the chassis and makes room for adding microcontroller board of one’s choice. One of the 5VDC supply may be used for microcontroller board and sensors. The other 5VDC supply or 7.4VDC from the battery may be used for motors by selecting jumper J1. Due to separate 5VDC supplies, the microcontroller board have least impact of voltage fluctuations due to motors. A six pin berg strip is available on the Main Board. Out of 6 pins 2 pins are Ground and 5VDC supply for Microcontroller board and remaining 4 pins are data input pins (D3, D2, D1, D0) for motor control. The logic for control of motors are as follows: Circuit Diagram of Main Board A PCB is required to assemble all the components shown below in the circuit diagram. For Small Robot, the PCB is fitted on the top of the chassis, where as motors (with wheels), castor wheel and battery is fitted below the chassis. Good Day to you Download 4 bit code Contact for Source Code Making Base Frame is mandatory to add various types of controls. . < < < Previous Once Small Robot's Base Frame is made, then, various control systems for Small Robot are developed and available for selection, using 'Previous ' and 'Next ' buttons here. Next > > > .
- 7 Path Follower
Small Robot : 7 Path Follower # . < < < Previous List All Next > > > . Introduction: A Path Follower is self controlled Robot, which follows in a path, which is a wide white or black line. The width of the path is generally more than the width of the Robot. Like Line Follower, here also, many types of sensors may be used to read the path. The Small Robot uses IR (Infra-Red) sensors, to read the path. Four pairs of IR LEDs and IR sensors (shaped as LED) are used here to read the Path. All the four IR sensing pairs are arranged in a row, perpendicular to the path, two on each side of the Small Robot. The Small Robot always try to position within the path, by following the edge of the path. To read four input pins for IR sensors, ATTNY84 micro-controller is selected, which have 14 pins. Out of 14 pins, four pins are used for sensing the line and four pins are required to control the two motors, through the motor driver (L293D). (refer Small Robot Base Frame for motor control codes). In general, Path Followers are used in industries for material handling. The robot moves within the two lines earmarked for its movement. The programming is to move the Robot within two thick lines, which forms as a path, which may have sharp and smooth curves. The Small Robot is programmed here to follow various path shapes, like sharp bends, sharp turns, sharp curves etc. The coding may be modified for individuals requirement. A model path used to test the Small Robot is shown below, having various line shapes. About Path Sensing: The Path Follower uses IR (Infra-red) sensing system to read the presence of Path. An IR LED emits IR light on the bottom surface. The IR light reflects from the surface and falls on an IR sensor (in LED shape), placed near to the IR LED. The IR sensor is connected in reverse biased, which varies its internal resistance, depending on the brightness of reflected IR light. The internal resistance of the IR sensor decreases with increase in falling IR light. So, when the surface below the IR sensor is white, more reflected light falls on the IR sensor, which makes least internal resistance. Similarly, if the surface is black, least light reflects on the IR sensor, which makes highest internal resistance. Due to change in the resistance of IR sensor, the voltage at the junction of the IR sensor and fixed resistance varies, which are connected in series with power supply and ground. A typical IR LED + IR sensor pair arrangement with the circuit diagram is shown below. Total four such IR sensing pairs are required for Path Following Small Robot, and soldered on a PCB, then fixed in front of the Small Robot. All the IR LEDs and IR sensors are 3 mm size. Maintain the gap between. the two successive IR sensors at each extreme end should be just less than the line width of the path. The distance between the mid of the two extreme IR sensors shall be approximately equal to the width of the path. So, that, the Path Follower tries to keep the itself within the path. The IR sensor PCB, with 4 IR pairs, shall be fitted in front of the Small Robot, as shown below, with a clearance adjustment arrangement (from surface) , to adjust the sensitivity with black and white surfaces. Working of Path Follower: Making of Small Robot as Path Follower is simple and easy. One PCB is required for IR sensing board, with 4 pairs of IR LEDs and IR sensors explained above. Another PCB with micro-controller ATTINY84 is used as control system for the Path Follower based on the varying voltages obtained from four IR sensors. The varying voltages from the IR sensor board are read as four digital inputs by the micro-controller. Then, the programmed logic makes the Small Robot to follow middle two IR sensor. In case, the Small Robot reads that, any IR sensor is out of path, the required output code is sent through the four motor control pins, to turn the Small Robot accordingly, else Small Robot moves in straight path. Similarly, in case of sharp turns, smooth turns, the Small Robot turns accordingly. The complete circuit diagram of Control Board with ATTINY84, is available below. Use jumper wires to connect S1, S2, S3 & S4 pins from Sensor Board to Control board consecutively. The shorting jumper, J1 is provided to select the path colour as BLACK or WHITE. Either Red or Yellow LED glows by selecting the shorting jumper position, for White or Black path. A button switch, SW1 on control board, is useful to start the Path Follower, after switching ON the power supply to the Control Board. Best of Luck Download PF HEX file Contact for Source Code Download file from above link and remove .TXT extension. . < < < Previous Once Small Robot's Base Frame is made, then, various control systems for Small Robot are developed and available for selection, using 'Previous ' and 'Next ' buttons here. Next > > > .
- 00 Omni Wheel
Previous < Back Next desc about omni wheel Intro to omni wheel
- 1 ELECTRICITY
< Previous Next > :STATIC ELECTRICITY: Static electricity is a stationary electric charge, produced due to an imbalance between positive and negative charges in an object or two near-by objects. Generally, this charge is build up on the surface of the object. To release the charge (or discharge) on the object, an electric path has to be created between positive and negative surfaces, through a circuit or an electric conductor (eg. copper wire). Some materials that tend to gain or lose electrons easily, when comes in contact with other materials, like human hair, human skin, wool, cloth, silk, nylon, plastic sheet etc. Due to Static electricity, some times you feel mild electric shock and may feel nuisance. Static Electricity has some advantages / applications , which are used in photo-copying machines for toner transfer, air pollution control systems using electro-static discharge concept, paint sprayers etc. So, our hands (skin) may develop a mild static electricity when rubbing with glass or aluminum or silk cloth etc., which may be harmful (or damage) some sensitive ICs (Integrated Circuits). So, we should discharge static electricity from our hand before working with some ICs. We have to just touch (do not rub) to some metallic sheet to discharge Static electricity from our hand, before working on static electricity sensitive electronic components. Static electricity discharge pads are also available. The main difference between the Static Electricity and Current Electricity are, In Static Electricity, the charges are at rest and in Current Electricity, the electrons are moving. The Static Electricity may be observed on the surface of insulator, where as Current Electricity means moving of electrons inside the conductor. Coulomb(s): Coulomb is unit of electrical charge and its symbol is C. A quantity of 1C is equal to approximately 6.24 x 10^18 electrons (its charge). (need not worry about these definitions. This is to just have an idea only) :CURRENT ELECTRICITY: Have you heard riddle “Which city has electrons” Answer is ELECTRICITY. The explanation below is to easily understand the term Electricity and its relative terms. In reality, understanding electricity and flow of electricity is a vast subject. In theory, Electricity means flow of electrons from higher potential to lower potential in conductors. You may be wondering, how electrons flow? What is conductor? . . . Do you remember basics of Quantum Physics? For quick recap, an atom consists of Protons(positively charged), Neutrons(no charge) and Electrons(negatively charged) particles. Protons and Neutrons occupy centre of the atom called neucleus and electons revolve around it. The quanity of Protons and Electrons always matches for an atom, so, the overall charge of the atom becomes ZERO. Most of the physics and chemistry depends on the behaviour of outer-most electrons and distance from the neuclies of the atom. Same with the electricity also. The (electric) Conductors, normally have one electron in the outer-most shell and/or loosly bound to the neuclies, i.e., very less energy is required to separate the outer-most electron from the atom. As the electron is negatively charged, it gets repelled by another negatively charged particle (electron) or gets attracted to positively charged particle (proton) of another atom. If an electron is separated from an atom, as the number of protons remains same, the atom becomes positively charged by 1, which is called cat-ion. These cat-ions have attraction towards negatively charged particles, i.e., electrons again to balance the overall charge of the atom. As per electron cloud theory, the loosely bound electrons form as electron cloud within the conductor (say metals) and move in haphazardly within the conductor. Electro Motive Force (e.m.f.): Coming to electricity, some (electrical) force is required to push the loosly-bound electron from the metal. As the electron moves out of the atom, it repels the loosly-bound electron of the nearest atom. The positively charged atom (cat-ion) attracts the next electron coming from the (electrical) force. This chain continues to create a flow of electrons. On the other side, the (electrical) force attracts and collects the flowing electrons. So, the (electrical) force must have positively charged elements to attract the electrons in the loop. The electrical force which makes the loop to create flow of electrons is called as Electro-Motive-Force (E.M.F.). So, an e.m.f. is required to generate flow of electrons in the conductor, pushes free electrons (loosly-bound electrons) on one side from its negative pole and attracts the free electrons on the other side, i.e. positive pole. In other words, electrons are negatively charged and carry their charge through the conductor, from one end to other end. So, electricity may be considered as moving the electrical charge through the conductor. The electrical charge cannot continue, unless the continuous contact of the conductor is available from beginning of the e.m.f. to receiving end of the e.m.f. i.e., the flow of charge will be disturbed, if the connectivity from any one of the ends of e.m.f. is lost. So, the continuation (or stoppage) of electricity may be controlled by a switch, which makes or breaks the continuity of the chain. So, e.m.f. is considered as the energy supplied to the conductor to have flow of electrons or electric charge, which is measured at end points of e.m.f. generator, like, battery, dynamo, solar cells etc. KEYWORDS: Potential Difference (P.D.) : Potential energy is the position possesed by electric particle due to location in an electric field. This may be compared as the position of an object on the earth w.r.t. distance from the centre of the earth, gravitational force on the object. Higher the altitutude means higher position and vice-versa. So, the difference between the potential energy of electrical particles in the circuit may be considered as Potential Difference. Voltage : Voltage is the energy required to move unit charge from one point to another, while electric charge is flowing. Voltage is measuring unit of Potential Difference between any two points or across a passive element of the electrical charge circuit. The sum of Voltages across all the passive elements in series is equal to the e.m.f. of the circuit. Volt(s) : Volt is the electrical unit of voltage and its symbol is V). One Volt is defined as energy consumption of one joule per electric charge of one coulomb. i.e., 1V = 1J/C. (don't worry or confuse about the definition right now). as per OHM's law, One volt is equal to current of 1 amp flows through resistance of 1 ohm: 1V = 1A ⋅ 1Ω ( formulated as V = I . R ) Current : The quantity of electrical charge moving between two points at any moment, due to e.m.f. is called current. The current may be considered as number of electrons flowing parallel to each other at an instant. It means, higher the electrons flowing across the conductor at a time is considered as higher current is flowing. Ampere(s) : Ampere is the electrical unit of Current and its symbol is A. One Ampere is defined as the current that flows with electric charge of one Coulomb per second. 1A = 1C/sec. (don't worry or confuse about the definition right now). as per OHM's law, One Ampere is equal to the current flows through resistance of 1 ohm across 1 volt: 1A = 1V / 1Ω ( formulated as I = V / R ) The fundamentals of Electricity is to be known before going through the next pages. The basics and keywords are frequently used in the future explanations. More details are available in the next pages, wherever applicable.
- 4 IR Remote Control
Small Robot : 4 IR Remote Control # . < < < Previous List All Next > > > . Introduction Another way to control the Small Robot is, using an IR (infra Red) remote. Here, a handy remote with direction markings is selected for controlling the Small Robot. The IR remote sends a specific pattern of digital signal through its IR LED, based on the button press. An IR receiver module (TSOP 1738) receives the IR signal from the IR remote and sends to the micro-controller (ATTINY13). Then, the micro-controller decodes the signal and converts it to 4 bit binary code, which is available as D0,D1,D2 & D3 at 6 pin connector. Then, the 4 bit code is received by the motor driver IC (L293D) on the Base Frame, to drive the two B.O. motors accordingly. (refer Small-Robot Base Frame for motor control codes) A small 8 pin micro-controller (ATTINY13) is used in Receiver circuit. As the transmitter is IR remote, so there is no need of Transmitter board and micro-controller. Any IR remote may be used to control the Small Robot. But, the signal generated by the IR remote should be decoded and then it shall be converted to, required 4 bit binary code, to control the Small Robot. Similarly, any IR receiver with 38KHz carrier frequency may be used, like TSOP1838, TSOP98138, TSOP38328, TSPO38438 etc. The pinouts should match with the circuit. IR (Infra Red) Transmitter: The IR remote used in the project is clone to Panasonic Audio remote control, which is easily available at affordable price (The original Panasonic remote is costly and not advisable for our project). The main advantage with this IR remote is, it has the four direction keys on a handy size. The front two buttons used for volume control are used to rotate the Small Robot in Clockwise and Counter-Clockwise directions. Most of the IR remotes use 38 KHz carrier frequency. It means, the IR LED of the remote glows on/off for 38000 times per second, which is called as Carrier Frequency. Again, the time of 38 KHz IR LED frequency varies for code generation. Say, to send a digital code '1' , the 38 KHz frequency is available for more time, compared to send code '0', before stopping the Carrier Frequency. So, a specific pattern of digital code is sent by the IR remote, on each key press. To differentiate or identify the IR code from each IR remote manufacturer, a header code is sent initially and the digital time also varies. (The header code ignored in our case). IR (Infra Red) Receiver: In the IR Receiver Board, the IR receiver, TSOP1738, is used, for easy identification of its pin-outs. One of its pin, out of 4 pins, is absent, which makes the pin identification fool proof. (Refer the circuit diagram below for better understanding). So, the Infra-red signals received by the IR receiver, TSOP1738, filters the Carrier Frequency and sends the digital code to the micro-controller (ATTINY13). An LED is provided to show the status of data reception from the IR receiver. The micro-controller decodes the received data, and converts to four bit parallel data. Then the four bits are sent to the base frame through the 6 pin connector, which in turn controls the movement of the Small Robot. In case, to use different remote, the IR pattern has to be studied and the Source code is to be modified accordingly (modify the getIRcode() function as required). The 5VDC power supply for Receiver board is derived from the Main board of Base Frame, through 6 pin connector. Good Luck Download IR HEX file Contact for Source Code Download file from above link and remove .TXT extension. . < < < Previous Once Small Robot's Base Frame is made, then, various control systems for Small Robot are developed and available for selection, using 'Previous ' and 'Next ' buttons here. Next > > > .