H-Bridge is an electronic circuit which will control the mechanical of the robot.
The H-Bridge is the link between digital circuitry and mechanical action. The computer sends out binary commands, and high powered actuators do stuff. Most often H-bridges are used to control rotational direction of DC motors. And unless you buy a potentially expensive motor-driver, you need an H-bridge to control any robot with a motor.
This is a quickly sketched H-Bridge circuit with supporting circuitry.
First lets talk about what a transistor is. These nifty chips revolutionized the electronics industry and you would be hardpressed to find something electronic that does not have at least a few thousand of these in them. So what do they do? They can control a flow of electrons by applying a voltage to them. The plumbing equivalent would be a water valve. By rotating the valve, a very large flow of water can easily be controlled.
Motor servo has high value of torque, with this motor you will able to control your robot movement easily… just very easy… the disadvantage of using “ex” motor servo just one… yaeh… the velocity is very low… but do not afraid, just change the robot wheel with the large one and then you will see your robot running fast…
I have built 2 line follower robot and 1 firefighting robot just using modified motor servo… and great, the robot is very easy to be controled…
Here the my first line follower robot using modified motor servo (old picture):
The robot’s movement is very slow, added more voltage and increase the wheel’s size is very important to increase the robot speed.
Here the tutorial how to make hexapod robot using 3 servo motors:
Download Hexapod Robot Tutorial:
hexapod.pdf
Download The video:
hexapod video.wmv
PIC18CXXX/PIC16CXXX DC Servomotor Application Note:
Download the tutorial:
DC servomotor application of PIC.pdf
Stepper motors:
A stepper motor’s shaft has permanet magnets attached to it. Around the body of the motor is a series of coils that create a magnetic field that interacts with the permanet magnets. When these coils are turned on and off the magnetic field causes the rotor to move. As the coils are turned on and off in sequence the motor will rotate forward or reverse. This sequence is called the phase pattern and there are several types of patterns that will cause the motor to turn. Common types are full-double phase, full-single phase, and half step. To make a stepper motor rotate, you must constantly turn on and off the coils. If you simply energize one coil the motor will just jump to that position and stay there resisting change. This energized coil pulls full current even though the motor is not turning. The stepper motor will generate a lot of heat at standstill. The ability to stay put at one position rigidly is often an advantage of stepper motors. The torque at standstill is called the holding torque.
Line Follower ROBOT
Plermjai Inchuay, plermjai@loxinfo.co.th
Award winner from VingPeaw Competition 2543, the robot built with 2051, L293D, and four IR sensors. Simple circuit and platform, quick tracking and easy-understand program using C language.
I designed my Robot, which use two motors control rear wheels and the single front wheel is free. It has 4-infrared sensors on the bottom for detect black tracking tape, when the sensors detected black color, output of comparator, LM324 is low logic and the other the output is high.Microcontrollor AT89C2051 and H-Bridge driver L293D were used to control direction and speed of motor.
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Line Follower Robot ...
Robot kinematics is the study of the motion (kinematics) of robots. In a kinematic analysis the position, velocity and acceleration of all the links are calculated without considering the forces that cause this motion. The relationship between motion, and the associated forces and torques is studied in robot dynamics. One of the most active areas within robot kinematics is the screw theory.
Robot kinematics deals with aspects of redundancy, collision avoidance and singularity avoidance. While dealing with the kinematics used in the robots we deal each parts of the robot by assigning a frame of reference to it and hence a robot with many parts may have many individual frames assigned to each movable parts. For simplicity we deal with the single manipulator arm of the robot. Each frames are named systematically with numbers, for example the immovable base part of the manipulator is numbered 0, and the first link joined to the base is numbered 1, and the next link 2 and similarly till n for the last nth link.
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Robot Kinematics ...
The SCARA acronym stands for Selective Compliant Assembly Robot Arm or Selective Compliant Articulated Robot Arm.
In general, traditional SCARA’s are 4-axis robot arms, i.e., they can move to any X-Y-Z coordinate within their work envelope. There is a fourth axis of motion which is the wrist rotate (Theta-Z). The ‘X’, ‘Y’ and the ‘Theta-Z’ movements are obtained with three parallel-axis rotary joints. The vertical motion is usually an independent linear axis at the wrist or in the base. SCARA robots are used in assembly operations where the final move to insert the part is a single vertical move. Component insertion into printed circuit boards is an example. This is often called “vertical assembly”.
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SCARA Robot ...
Mechatronics is the synergistic combination of mechanical engineering (“mecha” for mechanisms, i.e., machines that ‘move’), electronic engineering (“tronics” for electronics), and software engineering. The purpose of this interdisciplinary engineering field is the study of automata from an engineering perspective and serves the purposes of controlling advanced hybrid systems.
Author: Gordon Petten
The word robot comes from the Czech word “robota”, meaning “forced labor.” The stuff of science fiction robotics in the 21st century is different than your parents or your grandparents’ ideas of robotics. What used to be thought of as futuristic improbability is now becoming a reality.
There are, theoretically, three Laws of Robotics. The Laws of Robotics were developed by a small group of scientists who believe that robotics is the wave of the future. The first law, referred to as law zero, is that a robot may not injure humanity, or, though inaction, allow humanity to come to harm. The second law states that a robot may not injure a human being, or, through inaction, allow a human being to come to harm, unless this would violate a higher order law. This law was created so that mankind would seek not to create robots that would harm people. The third law is that a robot must obey orders given it by human beings, except where such orders would conflict with a higher order law. And finally the final law is that a robot must protect its own existence as long as such protection does not conflict with a higher order law. These were used in a recent Hollywood movie however many people don’t know that the Laws of Robotics actually exists.
