# RLS AksIM-4 Dual Concentric Off-Axis Absolute Encoder

![RLS AksIM-4 Dual Concentric Off-Axis Absolute Encoder](https://parts.trymaglev.com/img/ac-rls-aksim-4-dual-concentric.webp)

Two 19-bit absolute off-axis encoders in one ultra-thin ring (motor + reducer output), launched 2026 for humanoid and cobot joints.

- Maglev ID: ac-rls-aksim-4-dual-concentric
- Brand: RLS
- MPN: AksIM-4 Dual Concentric
- Category: actuators / Magnetic Encoders
- Origin: SI (maker HQ, factory not confirmed)
- Maker: RLS d.o.o. (brand, SI)
- NDAA: unknown · Blue UAS: unknown · FCC: n/a
- HTS: 9031.80.80.85 (typical)
- MOQ: unknown · Lead time: unknown
- Confidence: VERIFIED

## Price
- No public price. Request a quote via POST /api/rfq or the order pad.

## Specifications
- Resolution: 19 bit per revolution on each ring (inner and outer)
- Accuracy: System accuracy ±0.015° (inner MRA039) / ±0.010° (outer MRA053) after self-calibration; typical installed calibrated ±0.020° / ±0.015°; uncalibrated ±0.050° / ±0.040°
- Max speed: 7,500 rpm (both rings)
- Interface: BiSS C over RS422 (12-pin connector, separate channel per ring); SPI EncoLink for Dual Encoder (board-to-board)
- Form: off-axis ring kit, dual (MD053 readhead, 180° arc, + MRA039 inner ring + MRA053 outer ring)
- Sensing: unknown
- Supply: 4.5-5.5 V at connector
- Bore: 20 mm inner ring ID (MRA039); outer ring ID 40 mm, readhead ID 25 mm
- Outer diameter: 53 mm outer ring OD; readhead OD 62 mm
- Multi-turn: yes, 16-bit multiturn counter option (inner ring interface only)
- Operating temp: -40 to 105 °C

## Links
- Product: https://www.rls.si/eng/aksim-dual
- Datasheet: none
- CAD: none

## Equivalents
- RLS AksIM-2 Off-Axis Absolute Rotary Encoder (ac-rls-aksim-2)
- KingKong DPT Series Robot Joint Dual Magnetic Encoder, 24-bit (ac-kingkong-dpt)
- KingKong DPB Series Robot Joint Dual Magnetic Encoder, 20-bit (DPB-10B-15B-25 to DPB-30B-35B-45) (ac-kingkong-dpb)

## Works with
- RLS AksIM-2 Redundant Off-Axis Absolute Encoder (two readheads) (ac-rls-aksim-2-redundant)

## Sources
- https://www.rls.si/eng/aksim-dual (specs: 19+19 bit, up to ±0.006°, 4.5-5.5 V, -40 to +105 °C)
- https://www.rls.si/cn/news/aksim4-dual-concentric-launch (launch news 2026-02-11, samples available)
- https://cdn.rls.si/media/documents/MDD01.pdf (AksIM-4 Dual Concentric datasheet MDD01: 19+19 bit, accuracy, 7,500 rpm, 4.5-5.5 V, ring sizes, interfaces, temperature)