2018/04/23
AGV
Application Cases of Magnetic Ring Encoders
In today’s rapidly advancing smart era, AGVs are increasingly used in logistics, warehousing, automation, new retail, and outdoor transportation.
“As smart technology advances, AGVs require better power control and stability. High-precision control algorithms rely on accurate motion feedback to function effectively.
Conventional solution
As shown in the right figure, the conventional Hall control scheme inserts three Hall switches into the motor stator slots to detect the N and S pole changes of the rotor magnets, generating motion waveforms that provide position feedback to the controller.
Advantages
- To obtain absolute angle data, the encoder principle needs to be improved. The main methods are as follows:
- Low cost: A circuit module composed of three Hall switches and a simple PCB.
- Simple control: The coil magnetic flux is directly controlled by the Hall switch signals, allowing for a low-cost controller.
Disadvantages
- Low accuracy: Only up to N pulses per revolution (N = number of magnet pole pairs), insufficient for precise angle feedback.
- Damage risk: Halls placed inside the motor slots are close to heat sources (coils), making them prone to damage. High operating temperatures prevent sealed protection, so water ingress can cause short circuits and failure.
- Poor startup performance: Due to angular gaps between magnets, starting from zero speed can cause varying degrees of vibration.
To obtain absolute angle data, the encoder principle needs to be improved. The main methods are as follows:
Application analysis
“AGVs have autonomous navigation and complex control needs. Conventional control methods often can’t meet many application demands. Better algorithms and high-precision feedback are essential. Examples include:
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A single-drive setup typically has one powered wheel (front or rear). Precise control of the steering wheel’s deflection angle is required during turning. |
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“A dual-drive setup typically has two powered wheels. During turning, precise control of each wheel’s speed enables differential steering. |
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Precise speed control during cruise |
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Controlling the speed change curve during acceleration and deceleration enables smoother speed transitions and more balanced motion. |
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“A dual-drive setup typically has two powered wheels. During turning, precise control of each wheel’s speed enables differential steering. |
KingKong Technology, as a professional magnetic encoder custom manufacturer, offers the best solutions and support for AGV high-precision feedback needs. Our high-precision magnetic ring encoders boast excellent performance and are widely used in motor control applications. They also provide better cost efficiency and high customization, capable of adapting to all types of driver interfaces for our clients.
Magnetic Ring Encoder
A magnetic ring encoder consists of the encoder body and a magnetic ring. The chip inside the encoder body non-contactly detects the magnetic field generated by the rotating magnetic ring to measure the current position and outputs data according to the customer’s required interface format. The following figure illustrates an example of an internal hub mounting method:
The encoder body is mounted on the stator shaft.
“The encoder magnetic ring is mounted on the rotor end cap.
The encoder is mounted at the shaft center, away from heat sources, allowing for full waterproofing and further reducing the failure rate.
Internal circuitry of the magnetic ring encoder
(Each model has different internal circuitry)
The magnetic ring encoder contains three pairs of magnetic sensors to measure changes in the magnetic field of the ring. Through data processing, issues like temperature drift and harmonic interference are addressed. Its unique symmetrical design helps partially cancel installation-induced eccentricity errors, reducing assembly complexity.
Features
- Ring structure:This allows it to be mounted on the shaft or shaft end of an AGV motor
- High precision with multiple output interfaces; it supports the following interfaces and can be configured with several simultaneously:
- 16-bit absolute type: provides absolute position within one rotation, mapping 360° to 0–65,535, transmitted via bus
- 64 to 5000-line incremental type: outputs N pulses per revolution, dividing 360° into N×4 parts, transmitted via pulses
- Sine and cosine type: outputs the current angle as analog signals
- Hall type: the number of Hall pulses is configured based on the pole pairs, consistent with standard three-phase Hall outputs
- High speed:Maximum measurable speed up to 20,000 rpm
- Oil and dust resistant:Capable of operating in harsh environments
- Vibration resistant:Can withstand significant axial vibration and some degree of tangential jitter
- Compact size:Minimum thickness of 8mm, easily embedded into various product designs
- Low damage rate:In applications like AGVs, it operates away from heat sources and offers waterproof protection
- Low Cost:Among high-precision products of the same type, magnetic ring encoders offer better cost control
Most AGVs use incremental type, incremental + Hall type, absolute type, or absolute + Hall type encoders
This encoder’s high-precision output meets the stringent position control requirements of AGVs and offers enhanced robustness, delivering a superior and reliable user experience.
Features
You can choose the best solution based on your product design, working environment, and accuracy requirements—such as encoder line count, output interface, inner and outer diameters, vibration resistance, and impact durability—to achieve better cost control.
As a professional custom magnetic encoder provider, KingKong Technology welcomes you to contact us with any questions about the solutions above. We offer excellent technical support and tailored options to accelerate your product development, including rapid prototyping to shorten your R&D cycle.
Welcome to contact us to request free samples.
