How Does a DC Servo Motor Work?
DC servo motor is used in medical imaging devices like MRI & CT scanners to control the movement of imaging components to acquire accurate & detailed images. It is also used in drone navigation systems & weapon targeting systems to facilitate highly precise control over positioning.
A sensor (like a potentiometer or a push button) measures the position, speed, or torque of the output shaft and sends feedback signals to the controller. Then, the controller generates control signals based on this feedback signal for closed-loop operation.
Power
Powerful and efficient, a servo motor offers a high level of flexibility and precision. It can actuate and hold positions, torques and speeds precisely and reliably, even in complex machine actions and demanding production processes.
A servo motor is made up of four essential components: a DC motor, a position sensor, a gear assembly and a control circuit. The position sensor provides feedback of the current position and compares it with the desired position. Based on the feedback signal, a pulse width voltage converter generates control signals that power the motor for accurate positioning. The length of the pulse determines how far the motor turns, with shorter pulses resulting in a move toward the 0 degree position and longer pulses causing it to turn closer to 90 degrees.
Unlike brush-based motors, servo motors do not require any brushes or commutator. Servo motors also operate at higher temperatures and have a lower weight, making them a better option for a variety of applications. Additionally, they feature improved heat dissipation traits and advanced cooling systems that prevent overheating.
Moreover, they are also highly durable and long-lasting. The use of premium materials and meticulous manufacturing processes prevents wear and tear, allowing them to deliver consistent performance for extended periods. These characteristics make them a popular choice for modern automation systems.
Speed
DC servo motors are designed to respond to pulses of voltage from a controller and move accordingly. The resulting motion is smooth and precise, making them perfect for applications where high speed and accurate positioning are essential. Whether you’re a hobbyist building robots or an engineer designing industrial systems, you need to understand how a servo motor works to use it effectively.
The basic set-up of a servo is composed of four major components: a DC DC servo motor motor, a position sensor, a gear assembly, and a control circuit. A potentiometer produces a voltage that is fed to the error amplifier, which then controls the motor. The feedback system constantly monitors the actual rotational position of the servo, sending information back to the motor driver. The driver then calculates the difference between the input electric signal and the feedback signal, causing the servo to rotate into the desired position.
Servos work based on pulse signals that come from the controller, which sends a PWM voltage signal with different widths of time to control the motor’s speed and torque. Servos are lightweight and compact, with good commutation performance, low cogging, a large starting torque, and low operating temperature. They can be used in high-precision automatic control systems, measurement devices, TV cameras, X-Y function recorders, and machine tool control systems. They are also popular in robotics and CNC machines.
Accuracy
A DC servo motor is an electrical device that facilitates precise control of angular (or linear) position. Servos are commonly used in closed loop systems that require strict accuracy, such as robots, antenna positioning, and metal cutting and forming machines.
To operate, a servo motor requires a power amplifier and feedback sensor. The amplifier converts a digital or analog signal into the required voltage or current. The sensor, often a potentiometer, encoder, or resolver, measures the actual speed and position of the motor shaft. This information is sent to a controller, which then adjusts the motor’s movement to closely align with the desired setpoint.
The accuracy of a servo motor is determined by the magnitude of change in the armature current, which is proportional to the position error signal. For example, at saturation of the field current, a small change in armature current will result in a prominent change in motor torque.
Compared to standard DC motors, servos can handle a greater range of speeds and torques, and can respond to commands at high rates. However, they may not be ideal for all applications, due to their higher cost and complex circuitry. The best way to select a servo motor is to study your application’s speed and torque requirements and then match it with the appropriate model.
Efficiency
Power losses in a DC servo motor are caused by the power loss that occurs as electrical energy is converted to mechanical energy. This includes the servo drive’s logic brushless motor 250w system and power stage as well as motor windings, power cables, and other components that are part of the energy transformation process. These power losses result in heat dissipation.
To minimize these losses, the servo drive should be operated at or below its minimum power supply voltage, which is calculated by taking into account switching and conduction losses of the power stage. In addition, reducing the number of communication ports used will help improve efficiency by lowering the drive’s logic consumption.
The servo motor’s position is determined by the length of the control pulse sent through the control wire. Pulses longer than 1.5ms cause the motor to turn counter-clockwise toward the 0deg position and pulses shorter than that move the motor clockwise. This means that the servo only uses the amount of energy needed to get to or hold its position, making it highly efficient.
DC servo motors are a versatile and economical solution for industrial, commercial, and consumer applications that require precise motion control. They are also used in a wide range of medical devices, such as surgical pumps and prosthetic limbs, to provide accurate movement control.
