What is motor & how we use it in robotics:
according to Wikipedia, An electric motor is an electrical machine that converts electrical energy into mechanical energy. In robotics, motors convert the electrical energy that powers the robot into mechanical energy that allows the robot to do work.
Motors are mainly used to move a part of a robot. In a word, Motors and actuators give life to a robot. There are many kinds of motors that can be used in robotic applications. Each type of motor is used for a different purpose. Motors can be attached to wheels that drive a robot around or might work as a joint in a robot arm to move.
Motors commonly used in robotics:
basically, in simple robotics, motors are used as its wheels, limbs, legs, arms, fingers, or to move any part into any direction or at any speed. Generally, there are different types of motors used for a different purpose. Some of the most common motors are given below.
- Brushed DC motor
- Brushless DC motor
- Geared DC motor
- Servo motor
- Stepper motor
- Pager motors
- AC motor
- DC Linear Actuator
Brushed DC motor:
Brushed DC motors that run on DC voltage are probably the least complex kind of engines that keep on being utilized for an electrical drive, cranes, paper machines, steel moving factories, hairdryer, and Almost everywhere. It exists.
A brushed DC engine is comprised of 4 essential parts; the stator, the rotor (
armature ), brushes, and commutator.
How does it work?
A Brush DC Motor contains two magnets going up against a similar heading, incorporating two circles of wire that abide in the Brush DC Motor, around a rotor.
The brushes and contacts of a motor, which is called the Commutator, is an interesting arrangement if you think about it converts the DC input to AC over the coil because as the rotor turns, it flips the Polarity over the coil. This generates a magnetic field, which ultimately pushes the coils away from the magnets they face and causes the rotor to turn. The current shut off at the rotor and makes a 180-degree turn, making every rotor face the contrary magnet. As the current turns on again, the electricity flows oppositely, sending another pulse that causes the rotor to turn once again. The brushes located within the Brush DC Motor turn it off and on when instructed by transferring the electricity from the rotor.
Executing Brushed DC Motor Control :
The brushed DC engine's speed is constrained by the voltage applied to the armature and the force by the armature current. The motion and the force can undoubtedly be controlled independently. This is the fundamental rule on which all the advanced control techniques currently depend.
Brushless DC motor:
we can assume as of now by its name that this kind of electric engine has no brushes as we have just found in our past article about the working rule of DC engines the brushes are sliding gadgets which permit the power to stream into the copper coil of the motor the brushless engines have no sliding components on the authority so this totally takes care of the issue of upkeep and substitution of brushes and other electrical contacts. To make the activity more dependable, more productive also, less boisterous, the ongoing pattern has been to utilize brushless dc engines. They are likewise lighter contrasted with brushed engines with a similar force yield. The brushes in regular dc engines wear out over the long run and may cause starting. In this way, the brushed dc engine should never be utilized for tasks requiring long life and dependability.
How does it work?
This sort of the engine features a rotor with perpetual magnets it couldn't be during a ny case since there are not any contacts on the rotor and its stator has electromagnets energized by windings and loops this is often a big contrast contrasted with the traditional brushes DC motor since the last can have both stator and rotor made out of electromagnets to expand the attractive fields and during this manner have a better mechanical force thickness by unit of weight of the engine the force of the brushless motor is due to the attractive collaboration forced by the electromagnets on the perpetual magnets there's a particular succession of excitation of the electromagnets which forces to the lasting magnets in rakish development which is consistently an identical way and it's as steady as conceivable under an identical excitation clearly the grouping is recurrent and therefore the rotor proceeds with its turn until it's fueled rehashing the arrangement every once in a while to be more explicit the succession of excitation of the electromagnets inside the stator is with the top goal that the magnets of the rotor are pulled in to the electromagnets while never contacting them because the excitation is consistently and just of these loops not yet ventured when power streams into curl one the contrary posts of the rotor and stator are pulled in to at least one another when the rotor is approaching to the curl one the facility streams within the loop to when the rotor is approaching to the loop to the facility streams within the curl three later within the curl one the facility will stream again yet with inverse extremity this cycle is rehashed persistently inside the motor guaranteeing a gentle revolution of the rotor.
Why brushless?
We can summarize the main strength points of the brushless DC motor is noiseless it is reliable and has a shallow MTBF boundary, which is the predicted elapsed time between its inherent failures it provides low energy costs, does not require any maintenance it can likewise be utilized in combustible conditions it has more competitive cost than traditional brush motors of a similar force anyway the brushless engine has additionally its constraints like requires an electronic driver, to control the correct excitation grouping, utilizes lasting magnets the particular force is by and large lower than the regular engines outfitted with stator and rotor.
Geared DC motor:
A gear motor is a combination of a motor and a gearbox. The addition of a gear head to a motor reduces the speed while increasing the torque output. The most important parameters about gear motors are speed (rpm), torque (lb-in), and efficiency (%). To pick the foremost suitable gear motor for your application, you want to compute the load, speed, and torque requirements for your application.
A gear motor is also a single component that integrates a gear reducer with either an AC or DC motor. The gear train's inherent advantage is that it functions as a torque multiplier and speed reducer, requiring less motor power to drive a given load. Gear rotors are common in applications that need reduced motor speed and plenty of torque to maneuver heavy loads. Most industrial gear motors incorporate fixed or variable speed AC motors. However, some gear motors use PM DC for BLDC motors, common in applications where quiet operations, high torque density, or variable speed are required. Gear motor designs can combine various motor and kit train types to best fit specific application needs. However, gear housing design, gearing type, gear lubrication, and the precise mode of integration affect gear motor performance. Motor and kit reducer combination examples are planetary and parallel shaft gear trains. Right-angle worm gears can be combined with permanent magnet DC AC induction or brushless DC motors to form an integral care motor unit. However, it's possible to combine many various motors and gear trains. The appliance often determines the best-suited gear motor solution. Certain combinations are more efficient and cost-effective than others. That's why knowing the appliance and getting an accurate estimation of its required torque, and operating speeds are the inspiration for successfully integrating a gear motor into a system. Typically, gear motors outperform other motor gear combinations. More importantly, gear motors simplify design implementation because they save engineers time for integrating motors with separable gear heads, which successively produces engineering costs. If the appliance requirements are known, engineers can order the proper gear motor from a supplier directly. What's more, when the gear motor is sized properly, the proper combination of motor and gearing can prolong design life and boost gear motors' overall design efficiency. It can also eliminate the necessity for couplings and potential alignment problems that accompany those components. Such problems are common when a design includes the connection of a separate motor and gear reducer, which successively increases the potential for misalignment noise or bearing failure.
Servo motor:
A servo motor is a turning actuator or direct actuator that licenses for exact control of precise or straight position, speed, and quickening. It comprises a suitable engine coupled to a sensor for position input. Servo motor applications are most normally used in shut circle frameworks where exact position control is generally found in mechanical and business applications. They're little in size. However, pack a tremendous punch and are very energy-effective. These highlights permit them to be utilized to work distantly controlled or radio-controlled toy vehicles, robots, and planes. Servo engines likewise are used in modern applications, mechanical technology, in-line assembling, pharmaceutics, and food administrations.
working principle:
Servos are constrained by sending an electrical pulse of variable width or pulse width regulation (PWM) through the control wire. There are a base pulse and a reiteration rate. A servo engine can normally just turn 90° one or the other way for a total of 180° development. The engine's nonpartisan position is characterized because the servo has an equal measure of likely pivot in both the clockwise or counter-clockwise heading. The PWM shipped off the motor decides the pole's situation and upheld the length of the beat sent through the control wire; the rotor will address the predefined position. The servo engine hopes to learn a pulse every 20 milliseconds (ms), and subsequently, the length of the beat will decide how far the engine turns. For example, a 1.5ms pulse will make the engine address the 90° position. More limited than 1.5ms moves it inside the counter-clockwise heading toward the 0° position, and anything else than 1.5ms will turn the servo during a clockwise bearing toward the 180° position. When these servos are instructed to move, they will move to the position and hold that position. On the off chance that an outside power pushes against the servo while the servo is holding an edge, the servo will oppose moving out of that position. The most extreme measure of power the servo can apply is named the force rating of the servo. Servos won't hold their position everlastingly; however;, the position beat must be rehashed to teach the servo to stay in position.
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Servo Motors are classified into different types based on their application, such as the AC servo motor and DC servo motor. There are three main considerations to evaluate servos motors. First based on their current type – AC or DC, and secondly on the Commutation used, whether the motor uses brushes. Therefore, the third variety of consideration is that the rotor's motors rotating field, whether the rotation is synchronous or asynchronous.
Stepper motor:
A stepper motor, also known as a step motor or stepping motor, is a brushless DC electric motor that divides a full rotation into several equal steps. It is used for precise positioning with a motor, such as hard disk drives, robotics, antennas, telescopes, and some toys. Stepper motors cannot run at high speeds but have a high holding torque.
working principle:
It has a stationary part (the stator) and a moving part (the rotor). There are teeth on which coils are wired on the stator, while the rotor is either a permanent magnet or a variable reluctance iron core. By energizing one or more of the stator phases, a magnetic field is generated by the current flowing in the coil, and the rotor aligns with this field. By supplying different phases in sequence, the rotor can be rotated by a specific amount to reach the desired final position.
Pager motors:
Pager Motor is simply one more name for the vibration engine that was at first used in the Motorola Pager; however, today typically utilized in cell phones, oscillating brushes, and wearable gadgets for vibration-ready warnings.
There are several types of pager motor, such as :
Coin Pager Motors
SMD Pager Motors
Cylinder Coreless Motor
Linear Resonant Actuators
working principle:
a little weight is attached to the motor. This weight is mounted off-center on the motor's spindle. When the motor spins the load (at approximately 100 to 150 rpm), the off-center mounting causes a strong vibration.
AC motor :
AC motors are driven by AC (alternating current). These motors are rarely used in mobile robots because they are powered with direct current (DC). AC motors are mainly used in industrial environments where very high torque is required. However, these motors could be more widely used in several different robot models to complete many applications.
BY K.M.Mohiuddin
Department of software engineering
Daffodil International University
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