Servo Drivers: The Prime Mover of Automated Devices

A servo driver is developed to regulate the position and velocity of various automated devices such as industrial machines, medical equipment and robots. Electromechanical elements such as servo motors help these devices to achieve their desired motion and servo drivers work as electronic amplifiers to these motors.

Servo control systems are pitch control solutions that monitor feedback signals of servo motors and constantly regulate motions to prevent any deviation from the anticipated behavior of machines. They address a lot of mechanical requirements for reducing voltage fluctuations, diminishing loading parameters sensitivity, decreasing steady state errors as well as enhancing the transitory response timing.

Servo systems upturn the bandwidth of the system. Faster response times enable higher machine productivity. Decreasing steady state errors result in high accuracy of servo systems. Lastly, reducing loading parameters sensitivity guarantees that servo systems withstand fluctuations in the output as well as the input parameters.

Servo amplifier

Servo is the name of the motor used to control and manage the mechanical performance of particular machines. In engineering terms it refers to an automatic device and applies this control theory to provide the actual power for the whole mechanism to work. These electric motors have inbuilt motion sensors to control applications for highly controlled motion.

Servo motor control is focused at sensing errors in the mechanism which will then send instant negative feedback or signals to correct this error and enable smooth uninterrupted functioning. These signals can correct multiple parameters from speed to mechanical position.

Controlling a mechanical position with servo amplifier –

Servo mainly uses electric motor to create mechanical force. The concept of servo motor control lies on two factors – there is an actual position and there is a desired position within the mechanism. The difference is sensed and an error signal is then amplified and then converted to reduce or completely erase the error. Other than electric force some servos also use magnetic, pneumatics or hydraulic force to correct position. They are widely used in military and marine navigation systems, satellite tracking.

Controlling a mechanical speed with servo amplifier –

The use of servo in controlling speed has seen many earlier applications like the steam engine. Today the application of servo motor control is found in trains, airplanes as well as ships. But that’s not all. These are also integral part of machine which run huge industrial functions and run the complex industrial motions. The applications of speed control can be seen from complex airplane navigation, to the cruise control function of a car, to a hard disk drive in the laptop, in both cases focusing in error free and precise performance.

Servo motor control is one of the key components of robotic functioning. Constant error sensing feedback keeps all parts of a robotic function in check. They also need very little power to run on and are ideal of machine like robots which run on batteries. They are also essential parts of any remote controlled device. These range from remotes for a child’s toy to a complex one to manage a submarine or an aircraft. Basically they are keys to any application which needs precise mechanical functioning and where error would mean malfunction with serious ramifications. This is why it is so important for the defense industry. Servo mechanism can make smooth functioning through unfriendly terrains as well as hard weather conditions.

The use of servo mechanism is the basis for mechanical accuracy.

AC Servo Drives

AC servo drives use alternating current to match and meet the varying industrial status and rise up to any occasion to meet machine deviations. AC motors have an outside stationary stator which has coils to produce a rotating magnetic field with the alternating current and an interior rotor which attached to this external shaft creating the precise torque for the machine function.

AC servo drives are widely used in industrial settings. They can be single phased or poly-phased (two-phased, three-phased or hysteresis synchronous). The single phase induction AC servo motor is connected to a single voltage line while the others take up more than one as their nomenclatures suggest. Of all these, the two phase ones most common as servo systems.

The two phase AC motors are more sensitive to voltage fluctuations and changes in the control system. They successfully create a rotating magnetic field. AC servo drives therefore offers better control with high torque, high speed and better application of velocity control.  Their high ability to start power allows lower levels of overall power to be transmitted. The alternating power function determines how much power is needed by the system and gives off only that amount thus managing power efficiency and industrial automation control superbly.

AC servo drives are intrinsic to electronic assembly because they can fill in gaps with alternating current and thereby ensure smooth uninterrupted flow of industrial performance. They come with interactive magnetic fields – the wound and the electrified which are used to synchronize with the frequency of the alternating current. An integrated feedback device that continuously monitors the shaft motion, and in combination with a servo drive regulates the commanded motion very precisely.

Benefits of the AC servo drives –

·         Lower maintenance

·         High starting power potential

·         Less wastage of power

·         Accurate performance for machines

·         Cost effective

·         Provides better industrial automation control for better turnover

Applications of AC servo drives –

·         Electric clocks and timer motors in appliances.

·         Home usage in appliances refrigerator, air conditioners, washing machines, dryers and fans.

·         Industrial usage is manifested in CNC machining, in electronic assembly, in factory automation and very widely in robotics industry.

More and more industries are switching to AC servo drives so that they can perform better, save assembly line costs, create a more economical process all the while making sure that there is optimum energy saving without compromising the level of performance and industrial automation control.

Servo Motor Control & Its Uses. Part 2

Servo controls are widely used as wind turbine pitch control too. The wind turbine pitch control system are used for changing the frequency of the rotor blades in a wind power system or a wind mill that works with the real wind speed in order to adjust the output power attaining the highest utilization efficiency of the wind power and thus providing a protection for the rotor blades. The servomotors are used as the pitch control for the wind turbines.  

There are three different types of servo motors that are normally used in the modern servo systems. These are:

• AC servo motors – These motors are based on the induction motor designs
• DC servo motors – These are based on the DC motor design
• AC brushless servo motors – These are based on the synchronous motor designs

  

The servo motors provide a motion profile that is a set of commands programmed in a controller which defines the operation of the servo motors in regards to velocity, position and time. Servo motion control makes the robotic devices and other such devices work with utmost precision.  





            

Servo Motor Control & Its Uses. Part 1

The Servo motor is in use for quite some time now. Because of its diverse functionality, the servo motor has gained popularity. The easy to use applications mostly in RC electronics and other devices make it a popular and widely used thing.   The Servo motor control refers to the error sensing the feedback control that is used for correcting the performance of a particular system. The RC servo motors are actually DC motors that are fitted with a servo mechanism in order to have accurate control of angular position. The RC servo motor control generally has a 90° to 180° rotation limit. But there other servo motors that come with 360° rotation limit. However, the servo motors do not need to rotate on a continuous basis. It will only rotate between its defined angles. 

The servo motors are majorly used for their precision positioning. These motors are widely used in robotic legs and arms, RC toys, sensor scanners, RC helicopters, cars and airplanes too.  The servo motors that are manufactured nowadays offer cost effective solutions for the users. These servo controls have efficient power saving technology and they can take up high inertial loads too. The servo motion control is exceptionally useful for robotics and thus they are made in small sizes but are very powerful and efficient.   

Mechanics of a Servo Control System

A servomotor is an essential component of a servo control system or servomechanism. It is usually paired with an encoding device to accurately provide the speed or position feedback detail. However, not all servomechanisms require a servomotor. A domestic furnace is a good example of a servo control device that does not use a servomotor. The thermostat in a domestic furnace acts as a servomechanism in the sense that it depends on feedback and error-control; however, no motor is directly controlled by it for performing this task.  

Classification of Servos

Servo amplifiers can be further classified based on the type of their performances and their feedback control:

·         Type 0- This type of servos typically generate a constant output value when the error signal remains constant under steady state

·         Type 1- These produce a constant output value when the error signal is null under steady state conditions. However, a constant change of reference would imply a constant error in reference tracking

·         Type 2 – These are capable of providing a steady output value with a null error signal under a steady state. Here a constant change in the reference provides zero error in reference tracking but a steady rate of acceleration of the reference would mean there is a constant error in reference tracking

Here, the bandwidth of the servo control systems, indicate their ability to respond to the rapidly changing input commands.

Servo Control System - What You Should Know

A servomechanism also commonly referred to as servo is a high-end device that works by using feedback and error sensing to automatically correct the performance of any mechanism. Typically, a servo control system is used to help control the speed, or the position but it may also be used in error correction of other parameters. For instance, the cruise control device in your automobile is a good example of a servomechanism. On the other hand, the automatic windows in your vehicle are not. This is because there is no error-correction or negative feedback involved in this process.

Uses of Servo Control Systems

Servomechanism has been commonly used in speed control for a very long time. Some of the early examples include the use of servomotors in steam engines, in the mechanism that governed the speed of the water wheels, in gas turbines for efficient fuel control, and in the aircraft speed propellers used during World War II for steady maneuvering. Servo controlsystems for positioning were first used in military navigation equipment and in fire-control devices.

Today, servo control devices are used in almost every field. Starting from satellite tracking devices, aircraft gun control, automatic machines, to remote controlled boats and airplanes all contain some kind of servo amplifiers. In addition, many cameras using auto-focus also make use of servomotors to simultaneously focus as well as accurately move the lens. It is also found in modern computer hard-disk-drives, and used commonly in industrial devices that require complex motion.