Although moons servo motor is widely used in industrial automation, robotics and other fields, it still has some limitations of its own, and these shortcomings may affect its applicability in specific scenarios, mainly reflected in the following aspects:
I. Higher cost, limited economy
moons servo motor has a complex manufacturing process (requiring high-precision rotors, encoders, servo drives, and other core components) and strict requirements for materials (such as high-performance permanent magnets, precision bearings) and assembly accuracy, resulting in its cost is much higher than that of ordinary asynchronous motors or stepper motors.
The procurement cost of a single small to medium power moons servo motor (e.g. below 1kW) is usually 3-5 times higher than that of an asynchronous motor of the same power, and the overall cost is even higher when paired with a servo drive;
High-precision servo system (such as equipped with more than 23-bit encoder, support for bus control models) costs can reach more than 2 times the ordinary models, for the low-precision requirements of simple transmission scenarios (such as ordinary conveyor belt drive), the economy is poor.
Second, sensitive to the use of the environment, high maintenance requirements
Weak environmental adaptability
moons servo motor internal permanent magnets (such as neodymium iron boron magnets) is sensitive to high temperatures, long-term operating temperature of more than 80 ° C may lead to demagnetization of the magnets, reducing the output torque; if the temperature changes (such as from - 10 ° C environment suddenly start), but also due to the internal components of the thermal expansion and contraction of the stress generated by the impact of the accuracy of the encoder.
Humid, dusty or corrosive environments can lead to corrosion of the motor bearings and encoder signal interference, so additional protective measures (such as IP65 protected enclosures and sealed interfaces) are required, which increases the cost of the equipment and the difficulty of maintenance.
High maintenance complexity
Fault troubleshooting of servo system relies on professional knowledge, for example, encoder signal loss, drive alarm (overcurrent, overvoltage) and other problems, which need to read fault codes and analyze parameter curves through special software, which is difficult to be solved independently by ordinary operators;
Replacement of bearings, carbon brushes (some brush servo motors) and other wear parts requires strict control of the installation accuracy (such as rotor concentricity error ≤ 0.02mm), otherwise it will aggravate the wear and shorten the life of the motor.
Third, the load capacity is limited, and the adaptability of heavy load scenes is insufficient.
Although the power density (output power per unit volume) of servo motors is higher than that of conventional motors, the continuous output torque is limited by the magnetic saturation characteristics of the permanent magnet material and heat dissipation capacity, and there is an upper limit to the continuous output torque:
The continuous torque of conventional servo motors (diameter ≤ 100mm) is usually below 50Nm, and if it is used to drive heavy-duty equipment (such as the waist joint of a large robotic arm, load ≥ 500kg), it needs to be equipped with a multi-stage reducer, which introduces a transmission gap and energy loss, affecting the control accuracy;
Even if it is a high-power servo motor (more than 5kW), its volume and weight will increase significantly (such as 10kW motor weight can be more than 30kg), is not suitable for the lightweight requirements of the high demand for the scene (such as collaborative robots, mobile robots).
Fourth, strong dependence on the control system
servo motor can not work independently, must rely on the servo drive and the upper controller (such as PLC, robot controller) of the cooperative control:
The driver needs to receive real-time position / speed instructions, and through the current loop, speed loop, position loop closed-loop adjustment (response cycle is usually ≤ 1ms) to ensure output accuracy, if the control system delays or interference (such as electromagnetic interference resulting in loss of signals), the generator may be induced "out of step," "oscillation " and other problems;
Different brands of servo motors and drives there are differences in compatibility, replacement models need to be re-tuned parameters (such as PID gain, inertia matching), increasing the complexity of system integration.
Summary
The disadvantages of servo motors are essentially tied to their core characteristics of "high precision and high response" -- in order to achieve precise control, complex structures and precision components have to be used, resulting in higher costs and increased maintenance difficulties. However, in scenarios requiring high precision and dynamic performance (e.g., robotics, CNC machine tools), these drawbacks can be compensated for by technical optimization (e.g., integrated design, intelligent algorithms); while in scenarios with low precision, low cost, and heavy loads, their applicability needs to be evaluated carefully.
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