Actuator in IoT

An actuator is a component of a machine or system  that moves or controls the mechanism or the system.

An actuator is the mechanism by which a control system acts upon an environment

An actuator requires a control signal and a source of energy.

Upon receiving a control signal, the actuator tor responds by converting the energy into mechanical motion.

The control system  can be simple (a fixed mechanical or electronic system), software-based (e.g. a printer driver, robot control system), a human, or any other input.

Actuator Types

• Hydraulic
• Pneumatic
• Electrical
• Thermal/Magnetic
• Mechanical

Hydraulic Actuators 

• A hydraulic actuator consists of a cylinder or fluid motor that uses hydraulic power to facilitate mechanical operation.
• The mechanical motion is converted to linear, rotary or oscillatory motion.
• Since liquids are nearly impossible to compress, a hydraulic actuator exerts considerable force.
• The actuator's limited acceleration restricts its usage.

Pneumatic Actuators :

• A pneumatic actuator converts energy formed by vacuum or compressed air at high pressure into either linear or rotary motion.
• Pneumatic rack and pinion actuators are used for valve controls of water pipes.
• Pneumatic energy quickly responds to starting and stopping signals.
• The power source does not need to be stored in reserve for operation.
• Pneumatic actuators enable large forces to be produced from relatively small presure changes (e.g., Pneumatic brakes can are very responsive to small changes in pressure applied by the driver).
• It is responsible for converting pressure into force.

Electric Actuators

• An electric actuator is generally powered by a motor that converts electrical energy into mechanical torque.
• The electrical energy is used to actuate equipment such as solenoid valves which control the flow of water in pipes in response to electrical signals.
• Considered as one of the cheapest, cleanest and speedy actuator types available.

Thermal or Magnetic Actuators

• These can be actuated by applying thermal or magnetic energy.
• They tend to be compact, lightweight, economical and with high power density.
• These actuators use shape memory materials (SMMs), such as shape memory alloys (SMAs) or magnetic shape-memory alloys (MSMAs).
• Some popular manufacturers or these devices are Finnish Modti Inc. and American Dynalloy.

Mechanical Actuators

• A mechanical actuator converts rotary motion into linear motion to execute some movement.
• It involves gears, rails, pulleys, chains and other devices to operate.
• Example : rack and pinion

Soft Actuators

• Soft actuators (e.g. polymer based) are designed to handle fragile objects like fruit harvesting in agriculture or manipulating the internal organs in biomedicine.
• They typically address challenging tasks in robotics.
• Soft actuators produce flexible motion due to the integration of microscopic changes at the molecular level into a macroscopic deformation of the actuator materials.

Shape Memory Polymers

• Shape memory (SMP) actuators function similar to our muscles, even providing a response to a range of stimuli such as light, electrical, magnetic, heat, PH, and moisture changes.
• SMP exhibits surprising features such a low density, high strain recovery, biocompatibility, and biodegradability.

Light Activated Polymers

• Photopolymer/light activated polymers (LAP) are a special type of SMP that are activated by light stimuli.
• The LAP actuators have instant response.
• They can be controlled remotely without any physical contact, only using the variation of light frequency or intensity.