SlimeVR Butterfly Trackers: The Future of Affordable, Wireless Full-Body Tracking is Here
Rotterdam-based SlimeVR is poised to disrupt the virtual reality landscape with its new Butterfly Trackers. These ultra-slim, open-hardware trackers promise to deliver a comfortable and affordable full-body tracking (FBT) experience, eliminating the need for cumbersome base stations or complex setups. The trackers are designed for a wide range of applications, including VR gaming, VTubing, and motion capture.
Beyond Base Stations and Wires: How SlimeVR Butterfly Trackers Work
Unlike traditional FBT systems that rely on external base stations, SlimeVR Butterfly Trackers utilize Inertial Measurement Units (IMUs) to track absolute rotation. Each tracker transmits data wirelessly via a custom 2.4 GHz protocol to a dedicated USB dongle, supporting up to 10 trackers simultaneously. This innovative approach removes the limitations of space and setup complexity associated with older technologies. The system doesn’t require Wi-Fi or Bluetooth, addressing concerns about latency and interference.
Engineering Marvel: Comfort and Performance in a 7mm Package
SlimeVR has prioritized comfort with the Butterfly Tracker’s design. Weighing less than 10 grams and measuring under 7mm thick, these trackers are designed to be worn discreetly under clothing. The “butterfly” split design, with the PCB and 90 mAh battery positioned side-by-side and connected by a flexible bridge, contours to the body for a more natural and comfortable fit. Despite their little size, the trackers boast an impressive battery life of over 48 hours on a single charge, utilizing USB-C for convenient recharging.
Technical Specifications: A Deep Dive
The Butterfly Trackers are built around the Nordic nRF52833 wireless MCU, featuring an Arm Cortex-M4F microcontroller running at 64 MHz. They offer a 100-200 Hz refresh rate and latency of less than 15ms. Key specifications include:
- Wireless MCU: Nordic nRF52833
- Memory: 128 kB RAM, 512 kB flash
- Connectivity: 2.4 GHz proprietary wireless (ESB protocol)
- Sensor: 6-axis IMU (TDK ICM-45686)
- Battery: 90 mAh (48+ hours active use)
- Dimensions: 56 x 35 x 7 mm
Software Ecosystem: From Firmware to Full-Body Integration
SlimeVR’s ecosystem extends beyond the hardware. The trackers run on Smol Slime firmware, originally a community-led project designed to optimize power efficiency. The SlimeVR Server, available for Windows, macOS, Linux, and Android, acts as the central processing unit, combining data from the trackers and using forward kinematics to calculate body position based on user height and proportions. Integration with popular VR platforms is achieved through the OpenVR Driver, allowing seamless compatibility with SteamVR. Support for OSC protocol enables direct connection to standalone headsets.
From Gaming to Motion Capture: Versatile Applications
The SlimeVR Butterfly Trackers unlock a wide range of possibilities. They are compatible with VR games like VRChat, enabling full-body tracking for enhanced immersion. VTubers can leverage the trackers for more expressive and engaging streams, and motion capture artists can utilize them for recording BVH files for use in programs like Blender. The system’s ability to track movement without occlusion – meaning clothes or body parts won’t block the signal – further expands its potential applications.
Availability and Pricing
The SlimeVR Butterfly Trackers are currently available for pre-order on Crowd Supply, with shipping scheduled for August 31, 2026. Pricing starts at $279 for the Core Set (6 trackers + dongle), with options for larger sets and accessories, including a charging dock.
Frequently Asked Questions
- Do SlimeVR Trackers require base stations? No, they do not. They utilize IMUs for tracking and do not rely on external base stations.
- Can the trackers be used under clothing? Yes, their slim design and flexible interconnect make them comfortable to wear under clothing.
- What is the battery life of the trackers? The trackers offer over 48 hours of active use on a single charge.
- How many trackers can be connected? The system supports up to 10 trackers connected to a single dongle.
- What platforms are supported? The SlimeVR Server is available for Windows, macOS, Linux, and Android.
Explore more about SlimeVR and the Butterfly Trackers on the official website and GitHub repositories.