IOT (Actuators) Flashcards
what is an actuator? tell the characteristics
An actuator can be considered as a machine or system’s component that can affect the
movement or control the said mechanism or the system. The system activates the actuator through a control signal, which may be digital or analog. It elicits a response from the actuator, which is in the form of some form of mechanical motion.
The control system of an actuator can be a mechanical or electronic system, a software-based system, a human, or any other input.
discuss the the working of a actuator
A remote user sends commands to a processor. The processor instructs a motor controlled robotic arm to perform the commanded tasks accordingly. The processor is primarily responsible for converting the human commands into sequential machine-language
command sequences, which enables the robot to move. The robotic arm finally moves the designated boxes, which was its assigned task
Actuator Types
Hydraulic actuators
Pneumatic actuators
Electric actuators
Thermal or magnetic actuators
Mechanical actuators
Soft actuators
Shape memory polymers
explain Hydraulic actuators
-A hydraulic actuator works on the principle of compression and decompression of fluids.
-These actuators facilitate mechanical tasks such as lifting loads through the use of hydraulic power derived from fluids in cylinders or fluid motors
-The mechanical motion applied to a
hydraulic actuator is converted to either linear, rotary, or oscillatory motion
-incompressible property of liquids is used in hydraulic actuators for exerting significant force
also known as as stiff systems
disadvantages –The actuator’s limited
acceleration restricts its usage.
Pneumatic actuators
-A pneumatic actuator works on the principle of compression and decompression of gases.
-These actuators use a vacuum or compressed air at high pressure and convert it into either linear or rotary motion.
-Pneumatic rack and pinion actuators are commonly used for valve controls of water pipes.
-characterized by the quick response to starting and stopping signals
- Small pressure changes
can be used for generating large forces through these actuators
–Pneumatic actuators are
responsible for converting pressure into force
Electric actuators
electric motors are used to power an electric actuator by generating mechanical
torque. This generated torque is translated into the motion of a motor’s shaft or for switching
Thermal or magnetic actuators
-The use of thermal or magnetic energy is used for powering this class of actuators
-These actuators have a very high power density and are typically compact, lightweight, and economical
-These actuators do not require electricity for actuation
-They are not affected by vibration and can work with liquid or gases
Mechanical actuators
- the rotary motion of the actuator is converted into linear motion to
execute some movement.
-The use of gears, rails, pulleys, chains, and other devices are necessary for these actuators to operate.
-. The best example of a mechanical actuator is a rack and pinion mechanism
-The hydroelectric generator convert the water-flow induced rotary motion of a turbine into electrical energy or the mechanical switches uses the mechanical motion of the switch to switch on or off an
electrical circuit
Soft actuators
-Soft actuators (e.g., polymer-based) consists of elastomeric polymers that are used as embedded fixtures in flexible materials such as cloth, paper, fiber, particles, and others
-The conversion of molecular level microscopic changes into tangible macroscopic deformations is the primary working principle of this class of actuators
-These actuators have a high stake in modern-day robotics. They are designed to handle fragile objects such as agricultural fruit harvesting, or performing precise operations like manipulating the internal
organs during robot-assisted surgeries.
Shape memory polymers
Shape memory polymers (SMP) are considered as smart materials that respond to some external stimulus by changing their shape, and then revert to their original shape once the affecting stimulus is removed
-Features such as high strain recovery, biocompatibility, low density, and biodegradability characterize these materials. SMP-based actuators function
similar to our muscles
-Photopolymer/light-activated polymers (LAP) are a particular type of SMP, which require light as a stimulus to operate.
-Using only the variation of light frequency or its intensity, LAPs can be controlled
remotely without any physical contact. The polymer retains its shape after removal of the activating light.
Actuator Characteristics
Actuators perform the physically heavier tasks in an IoT deployment; tasks which require moving or changing the orientation of physical objects, changing the state of objects, and other such activities The correct choice of actuators is necessary for the long-term sustenance and continuity of operations, as well as for increasing the lifetime of the actuators themselves
A set of four characteristics can define all actuators :
-weight
-power
-torque is to weight ratio
-stiffness
Weight
-The physical weight of actuators limits its application scope.
-the use of heavier actuators is generally preferred for industrial applications and applications requiring no mobility of the IoT deployment.
-In contrast, lightweight actuators typically find common usage in portable systems in vehicles, drones, and home IoT applications.
-Heavier actuators also have selective usage in mobile systems, for example, landing gears and engine motors in aircraft.
power rating
This helps in deciding the nature of the application with which an actuator
can be associated
-The power rating defines the minimum and maximum operating power an
actuator can safely withstand without damage to itself
Torque to Weight Ratio
The ratio of torque to the weight of the moving part of an instrument/device is referred to as its torque/weight ratio.
-Higher is the weight of the moving part; lower will be its torque to weight ratio
for a given power.
Stiffness and Compliance
-The resistance of a material against deformation is known as its
stiffness, whereas compliance of a material is the opposite of stiffness
-Stiffness can be directly
related to the modulus of elasticity of that material
-Stiff systems are considered more accurate
than compliant systems as they have a faster response to the change in load applied to it
-hydraulic systems are considered as stiff and non-compliant, whereas pneumatic
systems are considered as compliant.
