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.

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.   

AC Servo Drives – The Present Industrial Requirement

Servo drives are specially made electronic amplifier that is used to boost or run electric servo mechanisms. All the feedback signals that come from the servo mechanisms are actually monitored by the servo drives. A servo drive continuously adjusts even the smallest deviation from the normal behavior.

It should be known that the main function of a servo drive is to receive the command signals from the control system and then amplify it so as to transmit the electric current to the servo motor. This is done to produce motion that is proportional to command signal. In general, the command signal signifies a preferred velocity but it can also signify a desired torque if and when required. 

The servo drive gets the feedback of the actual status of servo motor control from the servo motor’s attached sensor. The actual status of the motor is then compared with the commanded motor status by the servo drive. The servo drive alters the voltage frequency of the motor in order to correct any small deviation from the desired commanded status. 

The servo motor control rotates at a speed which closely matches the velocity signal that is being received from the control system by the servo drive. There are several parameters like derivative gain, proportional gain and feedback requires proper adjustment so as to achieve the desired performance. This process of adjusting of the parameters is known as performance tuning.   
     

With the advancement in the technology of the microprocessor units there has been a constant growth of cost effective solution and development of a permanent magnet manufacturing technology for the servo motors. There has been a great improvement in the technological development of the high performance and high power semi conductor power devices. Thus, AC servo drives, AC servo motor has now become the basic technology for achieving automation control system in the present industrial scenario. 

AC servo drivers bring in the newest high speed DSP in order to meet the varied requirements of your high speed and high precision control system. The latest AC servo drives have a lot better dynamic feature and stability that the convention PI controls systems of yester years.  

Today’s AC Servo drives includes analogue apparatus within the control loop of a servo motor that helps to minimize the energy consumption and ensures maximum output. They assist in changing frequency of the AC voltage which is received by the motor with the use of electronic devices.

AC Servo Drives

Mechanisms belonging to the range of motion electronic products, AC servo drives operate on alternate voltage patterns. As electronic amplifiers, they serve to power electric servo motors that similarly operate on alternate voltage pattern.

As special electronic amplifiers they A) monitor control feedback signals received from motors. B) According to feedback signals received they make necessary adjustments. C) They form a part of a dynamical system.

The function of AC servo drives is guided by the ‘control theory’, which is a sub part of Physics and Mathematics. According to this theory, A) A controller, manipulates the input to a system. B) This manipulation is geared to achieving the desired effect on the output. C) Output variables follow a reference of time. A.C servo drives act as controllers or A.C electrical amplifiers.


"Motion theory" also controls the functioning of servo drives. As special electronic mechanisms, they control the velocity of mechanisms. After receiving a command signal from a control system geared to A.C voltage, they amplify such signals and after due amplification, they transmit electric current to a system. Automatically, the electric current transmitted will be proportionate to the received command signal.

The servo motor with an attached velocity sensor does the needful work of reporting the motor’s actual velocity back to servo drive. After a due comparison of motor’s actual velocity with the command velocity, AC servo drives contribute to altering the due voltage frequency. Thus any error in voltage frequency is corrected by A.C servo drives. Usually servo motors rotate at a velocity matching the control signal. Servo motor control ensures the due matching leading to the establishment with proper configuration and tuning- which is a combination of proportional and derivative gain.

A.C servo drives are not only easily available, but they are also compatible with different variety of motors. Use of A.C servo drives has manifold advantages. Forming an integral part of the servo system their additional feedback serves to detect unwanted motion. They usually accurately assess the commanded motion. Moreover they are better adjusted to changing speed, with a better life span; giving effective durability to a system.

Servo drives are generally of two types. 1) Digital servo deals with discreet tracking of signals. 2) Analog deals with continuous tracking of signals.  Servo drives which form an integral part of the servo system have an enormous role to play in industries involved with robotics, automation and any other kind reliant on motion theory.