As the "power heart" of industrial robots, moons servo motor has become the core component of joint drive and trajectory control by virtue of its high precision, high responsiveness and strong load capacity. Its application scenarios and technical characteristics can be developed from the following aspects:
I. Core Application Scenarios
The motion control of industrial robots relies on the precise drive of servo motors, and the differences in the demands of different joints and functional modules determine the selection and configuration of moons servo motor:
Joint drive
Heavy-duty joints such as waist and big arm: need to drive the robot body to rotate or swing in a wide range, usually with RV reducer, using medium to high power moons servo motor (1.5-5kW), emphasizing high torque output (peak torque can reach hundreds of Nm) and overload resistance (need to withstand the composite force of the robot's own weight and load).
Small arm, wrist and other precision joints: responsible for the fine movements of the end-effector (e.g. gripper, welding torch), requires small power and high speed servo motors (500-1500W) with harmonic reducer, focusing on ensuring the positional control accuracy (repetitive positioning error ≤ ± 0.02mm) and dynamic response speed (acceleration time ≤ 0.1s), to meet the needs of assembly, welding and other high-precision operations.
End-effector drive: such as gripper opening and closing, rotation, most of the micro servo motors (50-200W), compact size and support for low-speed and smooth operation (speed can be as low as 5rpm), to avoid pinching the workpiece.
Trajectory Planning and Synchronized Control
Complex movements (e.g. arc motion, spatial trajectory tracking) of multi-jointed robots (e.g. 6-axis robots) require real-time synchronized control of multiple servo motors via bus communication (e.g. EtherCAT, PROFINET). For example, the welding robot's torch path requires each joint motor to adjust the rotation speed and angle according to the preset timing, and the servo system's position loop and speed loop control cycle needs to be within 1ms in order to ensure the trajectory accuracy (deviation ≤ ± 0.5mm).
Technical adaptation requirements
Power and inertia matching
The output torque of the servo motor should cover the rated load of the robot joints + dynamic inertia load (such as additional torque when accelerating), and 20%-30% of torque margin should be reserved to prevent overload. At the same time, the ratio of motor rotor inertia to load inertia (e.g., inertia of the joint arm, speed reducer) should be controlled within 1:5, otherwise it will lead to response hysteresis, which will affect the smoothness of movement.
Feedback Accuracy
In order to realize high-precision positioning, servo motors need to be equipped with high-resolution feedback devices:
Ordinary handling robots: 17-bit encoder (resolution 131072 pulses/turns) to meet ±0.1mm positioning accuracy;
Precision assembly robot: 23-bit absolute encoder (resolution 8388608 pulses/turn), which can achieve ±0.01mm accuracy when combined with a gearbox.
Environmental adaptability
Dusty environments (e.g., machine shops): IP65 protection is required for motors to prevent dust from penetrating the interior and causing bearing wear;
Humid or corrosive environments (e.g. food, chemical industry): stainless steel motors and encoder interfaces should be sealed;
High-temperature environments (such as welding workstations): the motor needs to be equipped with forced air-cooling device to ensure that the operating temperature does not exceed 85 ℃ (to avoid demagnetization of the magnet).
Third, the technology trend
integrated design
servo motor and reducer, brake integration (such as "motor + harmonic reducer + absolute value encoder" module), can reduce the volume of joints (than the traditional split type to save 30% of the space), and at the same time reduce the impact of the assembly error on the accuracy of the collaborative robots have been widely used.
Frameless motors and direct-drive technology
Frameless servo motors (removing the housing and bearings and embedding them directly into the robot joints) can further reduce weight, making them suitable for lightweight robots; while direct-drive motors (which do not require a gearbox and drive the joints directly) can eliminate transmission gaps and improve response speed, but due to the limitation of torque density, they are only used in high-precision scenarios with small loads (≤50kg) (e.g., semiconductor wafer handling robots).
Intelligent Drive Algorithm
The new servo system, equipped with an adaptive control algorithm, can recognize the load changes of the robot joints in real time (e.g., differences in the weight of the gripped workpiece) and automatically adjust the PID parameters to avoid vibration or overshooting during the movement, so that the robot can still maintain stable operation under complex working conditions.
The application of servo motors in industrial robots is essentially a "synergy of power and precision", and its performance directly determines the robot's operational capability and applicable scenarios, as well as one of the core supports for the development of industrial automation to high precision and high flexibility.
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