An open-source, battery-powered, compact sonic vibro-corer for undisturbed soil sampling (bulk density / core probes) — compatible with Geoprobe DT325 core tubes.

Company: Ground UP GmbH · Vienna, Austria License: CERN-OHL-S-2.0 (Hardware) / MIT (Software) Status: Active Development (2026)

Vibrocore is a field-deployable soil sampling machine that uses high-frequency axial vibration (sonic drilling principle) to drive core tubes into the ground with minimal sample disturbance. Unlike conventional percussion/hammer systems, the sonic method liquefies the thin boundary layer around the tube — reducing friction dramatically and preserving soil structure.

┌─────────────────────────────────────────────────────┐
│                    VIBROCORE SYSTEM                   │
├─────────────────────────────────────────────────────┤
│                                                       │
│  ┌──────────┐   ┌──────────────┐   ┌──────────────┐ │
│  │  CONTROL │   │  SONIC HEAD  │   │  HUB SYSTEM  │ │
│  │  (PLC)   │──▶│  (Vibration) │   │  (Lift/Push) │ │
│  └────┬─────┘   └──────┬───────┘   └──────┬───────┘ │
│       │                │                   │         │
│       │         ┌──────┴───────┐   ┌──────┴───────┐ │
│       │         │  2× OLI MVE │   │  NEMA 42     │ │
│       │         │  400/6-HF   │   │  + Gearbox   │ │
│       │         │  counter-   │   │  + Chain     │ │
│       │         │  rotating   │   │  + Carriage  │ │
│       │         └──────────────┘   └──────────────┘ │
│       │                                              │
│  ┌────┴──────────────────────────────────────────┐  │
│  │              POWER SYSTEM                      │  │
│  │  48V LiFePO4 / Instagrid ONE (230V AC)        │  │
│  │  + VFD (sonic) + DC PSU (hub) + DC/DC (ctrl)  │  │
│  └───────────────────────────────────────────────┘  │
│                                                       │
│  ┌───────────────────────────────────────────────┐  │
│  │              FRAME & MOBILITY                  │  │
│  │  mk 2004 Al-profiles · steel end plates        │  │
│  │  linear guides · tilt mechanism · UTV mount     │  │
│  └───────────────────────────────────────────────┘  │
│                                                       │
│  ┌───────────────────────────────────────────────┐  │
│  │              POSITIONING                       │  │
│  │  viDoc RTK (cm accuracy) · AR waypoint nav     │  │
│  │  GPS antenna on sonic head · WLAN relay        │  │
│  └───────────────────────────────────────────────┘  │
└─────────────────────────────────────────────────────┘

The sonic head uses two counter-rotating OLI MVE 400/6-HF industrial vibration motors mounted on a common rigid vibrating plate (Schwingplatte). This follows the principle described in Šporin & Vukelić (2017) and OLI's own application guide for linear vibration:

• Two OLI high-frequency vibration motors, counter-rotating
• Motor shafts perpendicular to the rod axis → pure axial force
• Horizontal forces cancel; vertical (axial) forces add up to ~8 kN
• Self-synchronising via shared rigid mass (no timing belts needed)
• VFD-controlled frequency for adaptive force tuning (0.9 – 9.7 kN range)
• OLI internal adjustable eccentric weights for secondary tuning

    FRONT VIEW (schematic)

    ┌──────────────────────────────────┐   ISOLATION
    │         CARRIAGE (slider)        │   PLATE
    └──┬──────────────────────────┬────┘
       │ rubber                   │ rubber
       │ isolator                 │ isolator
    ┌──┴──────────────────────────┴────┐
    │                                   │
    │  ┌──────────┐   ┌──────────┐    │   VIBRATING
    │  │ OLI MVE  │   │ OLI MVE  │    │   PLATE
    │  │ 400/6-HF │   │ 400/6-HF │    │   (Schwingplatte)
    │  │  ↻ CW    │   │  CCW ↺   │    │
    │  └──────────┘   └──────────┘    │
    │                                   │
    │          ┌───────────┐           │
    │          │  CENTER   │           │
    │          │  COLUMN   │           │
    │          │   Ø 50    │           │
    └──────────┼───────────┼───────────┘
               │           │
               └─────┬─────┘
                     │
              ┌──────┴──────┐
              │  DT325 Rod  │
              │  (82.55 mm) │
              └─────────────┘

No custom shafts, discs, timing belts, or external bearings needed. ~60% less power draw. Proven industrial reliability. 1–2 weeks to assemble vs. 4–8 weeks for custom fabrication. ~1,000 € cheaper.

• Closed-loop encoder prevents step loss under load
• Power-off brake holds carriage when de-energised
• Upper + lower limit switches
• Current monitoring for stone detection (auto-stop)
• Emergency stop circuit

• 2× mk 2004 aluminium profile 50×100×1500 mm (left + right)
• Steel end plates top and bottom (force introduction on tension)
• Front: linear guide rails for sonic head carriage
• Rear: tilt mechanism for transport / horizontal storage
• Bottom steel plate: rod guide hole + NEMA 42 mount + profile base
• All loads in tension along profile long axis
• UTV mounting points on bottom plate

• Instagrid ONE max (230V AC, 3.6 kW cont., 18 kW peak, 2.1 kWh)
• VFD for sonic motors (230V 1ph → 3ph variable frequency)
• DC PSU (230V AC → 48–60V DC) for hub stepper
• DC/DC converters for 24V (brake, relays) and 5V/12V (control)

• 48V LiFePO4 main battery (30–50 Ah)
• 100A+ BMS
• DC bus architecture with proper fusing and contactors
• Integrated charging from mains or generator

• PLC/Controller: CONTROLLINO or Arduino Opta (industrial, Arduino-compatible)
• Hub driver: Nanotec C5-E-2-09 or Leadshine CL86T-V4.1
• Sonic VFD: compact frequency inverter (230V class)
• Inputs: limit switches, current sensors, emergency stop, mode selector
• Outputs: motor enable, brake release, VFD start/stop/frequency
• Communication: WLAN to tablet (viDoc integration)

1. DT325 Mode — sonic at 90–100 Hz, full stroke, auto-depth-stop
2. Auger Mode — sonic at 110–120 Hz, rotation enabled, for 30 mm nut auger
3. Manual — joystick up/down, sonic on/off

• viDoc Light RTK rover on UTV (cm-level global position)
• GPS antenna on sonic head (exact bore point)
• WLAN bridge between head GPS and viDoc
• Auto-logging: GPS coordinates, depth, cycle time, VFD current (soil resistance)
• AR waypoint navigation to pre-calculated sampling points

vibrocore/
├── README.md                    # This file
├── LICENSE                      # CERN-OHL-S-2.0
├── docs/
│   ├── design/
│   │   ├── ARCHITECTURE.md      # System architecture
│   │   ├── SONIC_HEAD.md        # Sonic head design & kinematic analysis
│   │   ├── HUB_SYSTEM.md        # Hub/lift mechanism design
│   │   └── POWER_SYSTEM.md      # Electrical architecture
│   ├── engineering/
│   │   ├── DIMENSIONING.md      # Force/frequency/mass calculations
│   │   ├── BOM.md               # Bill of materials with EU suppliers
│   │   └── RESONANCE.md         # Resonance analysis & skip frequencies
│   └── references/
│       ├── REFERENCES.md        # Academic papers & patents
│       └── (PDFs — not in repo, linked)
├── hardware/
│   ├── sonic-head/              # CAD files, drawings
│   ├── hub-system/              # Hub mechanism drawings
│   ├── frame/                   # Frame assembly
│   └── bom/                     # Structured BOM files
├── firmware/
│   └── control/                 # Arduino/PLC control code
└── scripts/
    └── (calculation scripts, helpers)

1. Šporin, J. & Vukelić, Ž. (2017). Structural drilling using the high-frequency (sonic) rotary method. RMZ – M&G, Vol. 64, pp. 1–10. DOI: 10.1515/rmzmag-2017-0001

   • Key equations: resonance frequency f = c / 2l, power N = F²·t²·f / 2m
   • Sonic head diagram (Resodyn Corporation)
   • Comparison: sonic vs. classical core drilling (4× faster progression)

2. Wang, Y. et al. (2015). Design and model analysis of the sonic vibration head. Journal of Vibroengineering, Vol. 17(5), pp. 2121–2131. Link

   • 3D FEM analysis of dual-eccentric vibration head
   • Mathematical model: Lagrange equations for damped forced vibration
   • Natural frequencies, isolation design, experimental validation

3. Lucon, P.A. (2013). Resonance: The Science Behind the Art of Sonic Drilling. Dissertation, Montana State University.

• Open-Source Drilling Community — drillstring models
• ARTS Lab Smart Penetrometer — UAV-deployable smart penetrometer
• NASA USDC — Ultrasonic/Sonic Driller/Corer (piezoelectric, different principle)

• Geoprobe DT325 System — DT325 probe rods, cutting shoes, liners
• OLI Vibrators MVE-HF — high-frequency industrial vibration motors
• Neugart PLPE Gearboxes — precision planetary gearboxes
• Nanotec NEMA 42 Steppers — hybrid stepper motors
• mk Technology Group — aluminium profile systems
• Instagrid ONE — portable battery power station

This is an active development project by Ground UP GmbH. We welcome contributions:

• Mechanical engineers — CAD, FEA, manufacturing drawings
• Electrical engineers — power electronics, motor control
• Firmware developers — Arduino/PLC control logic
• Field testers — soil sampling validation data

Please open an issue before submitting PRs for major changes.

• Hardware: CERN Open Hardware Licence Version 2 — Strongly Reciprocal (CERN-OHL-S-2.0)
• Software/Firmware: MIT License
• Documentation: CC BY-SA 4.0

Ground UP GmbH · Iglasegasse 21-23, A-1190 Wien · FN 481220 b