Servo Motor Planetary Hall Sensing for Absolute Output Position
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Solution Overview
Problem
Existing servo motors used in footed robots lack accurate detection of absolute motor output positions, leading to low control accuracy due to reliance on position sensors and magnets for relative position detection.
Innovation Solution
A servo motor design incorporating a planetary reduction mechanism with Hall switches and magnets, allowing for precise detection of rotor position through Hall switch activation and position sensor measurement, improving detection accuracy and control precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If position sensors and magnets are used to detect relative position of stator and rotor, then the robot can move, but the absolute position of the motor output cannot be detected accurately
Solution Approach 1:
The patent employs a planetary reduction mechanism where the sun gear is connected to the rotor shaft, planetary gears are mounted on the planetary carrier, and the inner gear ring is fixed to the housing. This nested gear structure allows the motor output to be reduced while maintaining a compact design, enabling accurate position detection without excessive structural complexity
Solution Approach 2:
The patent introduces Hall magnets and Hall sensors as intermediary components to detect the position of the planetary carrier. The Hall magnet is fixed to the planetary carrier while the Hall sensor is mounted on the housing, creating an intermediary detection system that accurately measures the absolute position of the motor output without requiring direct measurement of the rotor
2Measurement precision
If planetary reduction mechanism is added with Hall magnets and sensors, then absolute position detection is achieved, but the device complexity increases
Solution Approach 1:
The planetary reduction mechanism serves multiple functions: it reduces the motor output speed, provides a mounting structure for the Hall magnet, and enables absolute position detection. The same mechanical structure that transmits power also facilitates position sensing, eliminating the need for separate detection mechanisms and reducing overall system complexity
Solution Approach 2:
The planetary carrier itself serves as the mounting base for the Hall magnet, and its rotational position directly indicates the motor output position. The mechanism uses its own moving parts (planetary carrier, sun gear, inner gear ring) to provide both power transmission and position reference, making the system self-sufficient for both drive and detection functions
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the detection accuracy and control precision of servo motors in robots by enabling the precise measurement of rotation angles and positions, thereby improving the overall movement accuracy of footed robots.
Implementation Method 1
a first Hall magnet arranged on the planetary carrier; a plurality of Hall switches corresponding to the first Hall magnet
Implementation Method 2
a second Hall magnet arranged on the rotor; and a position sensor arranged in the housing and opposite the second Hall magnet
Data Source
AI summary
A servo motor includes a housing, a rotor, a stator, a planetary reduction mechanism, a first Hall magnet, Hall switches, a second Hall magnet, and a position sensor; the rotor, stator, the planetary reduction mechanism, and the position senor are arranged in the housing. The rotor has a rotor support and a rotor shaft; the planetary reduction mechanism includes a sun gear, a planetary carrier, and planetary gears; a reduction ratio of the planetary reduction mechanism is N:1, where N is a positive integer; the first Hall magnet is arranged on the planetary carrier; the Hall switches correspond to the first Hall magnet and are arranged in the housing at even intervals around a rotation axis of the rotor shaft. The number of Hall switches is N; the second Hall magnet is arranged on the rotor; and the position sensor is opposite the second Hall magnet.