Why are multi-turn hollow encoders an ideal partner for position feedback in frameless motors or direct-drive systems?
Release Time : 2025-09-23
With the rapid development of high-end manufacturing, precision automation, and robotics, frameless motors and direct-drive systems are gradually replacing traditional servo-and-reducer transmission solutions due to their advantages, such as high dynamic response, zero backlash, and high torque density. They are widely used in semiconductor equipment, medical robotics, high-precision turntables, aerospace actuators, and other fields. However, these systems pose unprecedented challenges for position feedback components: they must be extremely compact, highly accurate, and highly reliable, all without compromising the mechanical integrity. Multi-turn hollow encoders, with their unique structural and performance advantages, are an ideal partner for position feedback in frameless motor and direct-drive systems.
1. Highly Compatible Structure: Through-hole Design Enables Non-Intrusive Integration
Frameless motors typically consist of a rotor and stator, embedded directly into mechanical equipment, eliminating the need for a housing and bearings, significantly improving power density and installation flexibility. However, this also means that external sensors must share the same rotating axis as the motor and cannot occupy additional axial or radial space. Traditional solid-shaft encoders require couplings, which not only takes up space but can also introduce eccentricity, vibration, and mechanical errors. Multi-turn hollow encoders, on the other hand, feature a central through-hole design that allows them to be directly threaded onto the motor shaft or load shaft without disassembling the shaft end structure or requiring additional couplings. Their hollow shaft structure perfectly matches the hollow center layout of frameless motors, enabling non-intrusive integration and preserving the inherent simplicity and compactness of the direct-drive system.
2. Ultra-thin and concentric locking: Meeting the demands of tight installation spaces and high-precision alignment
Frameless motors are often used in space-constrained applications such as joint modules and rotary platforms, where the axial clearance for the encoder is often limited to just a few millimeters to a dozen millimeters. The multi-turn hollow encoder's ultra-thin, integrated design allows for an overall thickness of less than 10 mm, or even thinner, making it easily integrated into compact mechanical structures. Crucially, its concentric locking mechanism, using expansion rings or conical compression, ensures a rigid connection between the encoder body and the rotating shaft. This connection method not only facilitates installation but, more importantly, ensures that the encoder's rotation center is highly concentric with the motor shaft, preventing angular errors and signal fluctuations caused by eccentricity and guaranteeing feedback accuracy. Compared to traditional side-pressure or clamping mounting methods, concentric locking significantly improves long-term stability and vibration resistance.
3. Multi-turn absolute positioning: No rotation loss during power outages, meeting complex motion control requirements
Direct drive systems are often used in scenarios requiring precise trajectory control, such as multi-turn continuous rotation of robots, CNC rotary table indexing, and automated assembly. These applications require encoders to not only provide high-resolution single-turn angle information but also record the number of rotations to achieve absolute position memory. Multi-turn hollow encoders feature built-in mechanical or multi-turn electronic memory technology, which retains rotation count information even when powered off, allowing the current position to be determined upon power-up without returning to zero. This feature is crucial for direct drive systems—it eliminates the need for a home position return at every startup, improving startup efficiency and operational continuity. It is particularly suitable for unmanned or high-speed automated production equipment.
4. High Integration and Interference Resistance: Adaptable to Complex Electromagnetic Environments
Frameless motors generate strong electromagnetic fields during operation, while encoder signals are extremely weak and susceptible to interference. Multi-turn hollow encoders typically utilize a fully shielded design and differential signal output, offering excellent immunity to electromagnetic interference, ensuring stable and accurate position data output even in highly dynamic and noisy environments. Furthermore, their highly integrated design integrates the encoder, readhead, signal processing circuitry, and power management module, reducing the number of external wiring and interfaces. This not only improves reliability but also facilitates wiring and maintenance in confined spaces.
At the forefront of frameless motor and direct-drive systems, which strive for ultimate performance and compact design, position feedback components are no longer just "add-ons" but rather core components that determine system accuracy and reliability. With its hollow through-hole, ultra-thin structure, concentric locking, multi-turn memory, and high interference resistance, multi-turn hollow encoders perfectly meet the mechanical and electrical requirements of direct-drive systems, truly achieving "seamless integration, precise feedback, and ready-to-use" performance. It is not only a tool for position measurement, but also a key enabler for the evolution of high-end motion control systems towards smaller size, higher intelligence and higher performance.
1. Highly Compatible Structure: Through-hole Design Enables Non-Intrusive Integration
Frameless motors typically consist of a rotor and stator, embedded directly into mechanical equipment, eliminating the need for a housing and bearings, significantly improving power density and installation flexibility. However, this also means that external sensors must share the same rotating axis as the motor and cannot occupy additional axial or radial space. Traditional solid-shaft encoders require couplings, which not only takes up space but can also introduce eccentricity, vibration, and mechanical errors. Multi-turn hollow encoders, on the other hand, feature a central through-hole design that allows them to be directly threaded onto the motor shaft or load shaft without disassembling the shaft end structure or requiring additional couplings. Their hollow shaft structure perfectly matches the hollow center layout of frameless motors, enabling non-intrusive integration and preserving the inherent simplicity and compactness of the direct-drive system.
2. Ultra-thin and concentric locking: Meeting the demands of tight installation spaces and high-precision alignment
Frameless motors are often used in space-constrained applications such as joint modules and rotary platforms, where the axial clearance for the encoder is often limited to just a few millimeters to a dozen millimeters. The multi-turn hollow encoder's ultra-thin, integrated design allows for an overall thickness of less than 10 mm, or even thinner, making it easily integrated into compact mechanical structures. Crucially, its concentric locking mechanism, using expansion rings or conical compression, ensures a rigid connection between the encoder body and the rotating shaft. This connection method not only facilitates installation but, more importantly, ensures that the encoder's rotation center is highly concentric with the motor shaft, preventing angular errors and signal fluctuations caused by eccentricity and guaranteeing feedback accuracy. Compared to traditional side-pressure or clamping mounting methods, concentric locking significantly improves long-term stability and vibration resistance.
3. Multi-turn absolute positioning: No rotation loss during power outages, meeting complex motion control requirements
Direct drive systems are often used in scenarios requiring precise trajectory control, such as multi-turn continuous rotation of robots, CNC rotary table indexing, and automated assembly. These applications require encoders to not only provide high-resolution single-turn angle information but also record the number of rotations to achieve absolute position memory. Multi-turn hollow encoders feature built-in mechanical or multi-turn electronic memory technology, which retains rotation count information even when powered off, allowing the current position to be determined upon power-up without returning to zero. This feature is crucial for direct drive systems—it eliminates the need for a home position return at every startup, improving startup efficiency and operational continuity. It is particularly suitable for unmanned or high-speed automated production equipment.
4. High Integration and Interference Resistance: Adaptable to Complex Electromagnetic Environments
Frameless motors generate strong electromagnetic fields during operation, while encoder signals are extremely weak and susceptible to interference. Multi-turn hollow encoders typically utilize a fully shielded design and differential signal output, offering excellent immunity to electromagnetic interference, ensuring stable and accurate position data output even in highly dynamic and noisy environments. Furthermore, their highly integrated design integrates the encoder, readhead, signal processing circuitry, and power management module, reducing the number of external wiring and interfaces. This not only improves reliability but also facilitates wiring and maintenance in confined spaces.
At the forefront of frameless motor and direct-drive systems, which strive for ultimate performance and compact design, position feedback components are no longer just "add-ons" but rather core components that determine system accuracy and reliability. With its hollow through-hole, ultra-thin structure, concentric locking, multi-turn memory, and high interference resistance, multi-turn hollow encoders perfectly meet the mechanical and electrical requirements of direct-drive systems, truly achieving "seamless integration, precise feedback, and ready-to-use" performance. It is not only a tool for position measurement, but also a key enabler for the evolution of high-end motion control systems towards smaller size, higher intelligence and higher performance.