Servo Actuators in Robot Schematics: A Comparative Analysis
The servo actuators of a robot play a crucial role in converting electrical signals into precise mechanical movements. In this article, we will delve into the world of servo actuators, exploring the advantages and disadvantages of different types, including stepping motors, DC servo motors, and AC servo motors.
Stepping Motor: A Precise and Reliable Choice
A stepping motor is a type of servo actuator that converts electrical pulses into linear or angular displacement. When an electrical pulse is received, the stepping motor drives the robot’s joint axes to rotate by a corresponding angle. The accuracy of the output angle is directly proportional to the number of pulses received by the stepping motor. This characteristic makes stepping motors highly advantageous in various applications.
Advantages of Stepping Motors:
- High Accuracy: Stepping motors offer high accuracy in their output angle, with minimal accumulation of errors. When the motor rotation error is zero, the output is highly precise.
- Linear Relationship: The input and output of stepping motors have a strictly linear relationship. Factors affecting the output voltage, such as the angle and current waveform, depend solely on the number of input pulses.
- Easy Control: Stepping motors are easy to control in terms of position, speed, starting, stopping, and reversing. The position of the motor is determined by the input pulses, the speed by the frequency of the pulses, and the direction by the sequence of the pulses.
- Digital Signals: Stepping motors output digital signals, allowing for direct interface with computers.
- Simple Structure: Stepping motors have a simple structure, making them easy to use, reliable, and long-lasting.
Phase Reaction Stepping Motor Stator Winding Structure
The phase reaction stepping motor stator winding structure consists of:
- Stator Core (2-): The core of the motor that supports the stator winding.
- Rotor (3-): The moving part of the motor that converts electrical energy into mechanical energy.
- A-Phase Magnetic Flux (4-): The magnetic field generated by the stator winding.
DC Servo Motor: A High-Torque but Limited Choice
DC servo motors have a large starting torque, small size, light weight, and high efficiency. However, they require periodic replacement and maintenance of brushes, which shortens their service life and generates noise. Additionally, DC servo motors have limited capacity, with armature voltage being low and parameters varying with speed. They are not suitable for high-speed or large-capacity applications, especially in environments with flammable gases, where the brush-commutated process may cause sparking.
AC Servo Motor: A High-Power and Reliable Choice
AC servo motors offer high output power, small rotor inertia, good dynamic response, and simple structure. They are reliable and have a long service life. In general, the same volume, the output power of the AC motor is higher than the DC motor by 10 to 70%. The capacity flow of AC motors is larger than that of DC motors, allowing for higher speeds and voltages. In the present robot system, 90% of the AC servo motor is used.
Conclusion
In conclusion, the choice of servo actuator depends on the specific application and requirements. Stepping motors offer high accuracy and ease of control, while DC servo motors have high torque but limited capacity. AC servo motors provide high power and reliability, making them a popular choice in robot systems. By understanding the advantages and disadvantages of each type, engineers and developers can select the most suitable servo actuator for their specific needs.