Crab-M Assembly

TL;DR

Purpose: Logistics robot, material transport

Mass: ~1000 kg

Battery: NaS 20 kWh

Power: 10 kW

Assembly time: 48 hours per station

Overview

Crab-M is a Gen-2 logistics robot for transporting materials between factory facilities. The six-wheeled platform with a 2x3 m cargo bed can carry up to 5 tonnes of regolith or finished products.

Crab-M Material Balance

Component	Material	Mass	Source
Frame + chassis	Steel Fe-6%Mn	350 kg	Frame Manufacturing
Body, radiators, sensor housings	Aluminum	470 kg	Aluminum
NaS Battery	Na + S + beta-Al2O3	150 kg	Battery Production
Actuators (6 wheels + manipulator)	Fe + Al + NaK	40 kg	Actuators
Electronics (chips)	-	0.5 kg	Import from Earth
TOTAL	-	~1000 kg	>99% local

Material distribution: - Iron (Fe): 350 kg = 35% - Aluminum (Al): 470 kg = 47% - Sodium + Sulfur: 150 kg = 15% - Actuators: 40 kg = 4% - Import (chips): 0.5 kg = <0.1%

Electronics 20 kg = chips 0.5 kg (import) + camera/lidar housings, cables ~19.5 kg (Al, local)

Design

Dimensions

Parameter	Value
Length	4.5 m
Width	2.5 m
Height	2.0 m
Ground clearance	0.5 m
Payload capacity	5 t

Wheel Base

flowchart LR
    subgraph CHASSIS["CHASSIS"]
        W1["Wheel 1"]
        W2["Wheel 2"]
        W3["Wheel 3"]
        W4["Wheel 4"]
        W5["Wheel 5"]
        W6["Wheel 6"]
    end

    W1 -.-> W2
    W2 -.-> W3
    W4 -.-> W5
    W5 -.-> W6

    style CHASSIS fill:#d4edda

6 wheels: 3 on each side, independent suspension on each wheel.

Wheel diameter: Ø1.2 m (to traverse regolith up to 0.5 m deep)

Assembly Process

Assembly Line (10 stations, 48 hours per station)

Station	Stage	Time	Robots
1	Frame installation on assembly fixture	2 hours	2 Centaur-M
2	Chassis mounting (6 wheels)	6 hours	4 Centaur-M
3	Al body and radiator installation	8 hours	3 Centaur-M
4	NaS battery installation (20 kWh)	4 hours	2 Centaur-M
5	Actuator mounting (6 wheel drives + 2 manipulators)	6 hours	3 Centaur-M
6	Power cable routing	4 hours	2 Centaur-M
7	Electronics installation (processor, sensors)	6 hours	2 Centaur-M
8	NaK cooling circuit filling	2 hours	1 Centaur-M
9	Sensor calibration and testing	6 hours	Automated
10	Initial battery charging	4 hours	Charging station
TOTAL		48 hours

Stage 1: Frame Installation

Crab-M Frame: - Mass: ~800 kg (350 kg Fe + 450 kg Al) - Design: Hybrid Fe/Al (modular, bolted assembly) - Production: WAAM 3D printing

Process: 1. Crane lifts frame from conveyor 2. Frame placed on assembly fixture 3. Secured on 4 supports 4. Geometry check (laser scanner)

Stage 2: Chassis Mounting

6 wheels: - Diameter: Ø1.2 m - Material: Al rim + Fe-6%Mn band (local) - Drive: Electric motors 5 kW × 6 = 30 kW + cycloidal gearbox 1:20 (100% local)

Suspension: - Independent on each wheel - Hydraulic dampers (NaK) - Suspension travel: +/-200 mm

Process: 1. Install 6 hubs on frame (M20 bolts) 2. Mount wheel drive motors 3. Install wheels 4. Alignment adjustment

Stage 3: Body and Radiator Installation

Aluminum body: - Mass: 450 kg - Design: Panels from 3 mm Al sheets - Function: Dust protection, cooling radiators

Radiators: - Area: ~10 m2 (oriented toward shadow) - Material: Aluminum - Circuit: NaK cooling for battery and motors

Process: 1. Install side panels (bolts + rivets) 2. Mount radiators on roof 3. Seal joints (TIG welding)

Stage 4: NaS Battery Installation

NaS Battery 20 kWh: - Mass: 150 kg (active materials Na + S + β-Al₂O₃ + case + insulation) - Voltage: 400 V (200 cells x 2 V) - Placement: Center of gravity (under platform)

Process: 1. Lift battery with crane 2. Install in battery compartment 3. Connect power cables (M10 bolts) 4. Connect battery management system (BMS)

Details: Battery Production

Stage 5: Actuator Mounting

8 actuators: - 6 wheel drives (electric, 5 kW each) - 2 cargo platform manipulators (hydraulic, 30 kN)

Process: 1. Install electric motors in wheel hubs 2. Route power cables to battery 3. Mount hydraulic cylinders for platform 4. Fill NaK into hydraulic circuit

Details: Actuators

Stage 6: Power Cable Routing

Cables: - Main power cable: 50 mm2 Al (400 V, 100 A) - Control cables: 20 wires (signals, sensors)

Process: 1. Route cables through cable trays 2. Connect to distribution panel 3. Insulation test (megohmmeter)

Stage 7: Electronics Installation

Crab-M Electronics: - Processor: ARM Cortex-A72 (4 cores, 1.5 GHz) - Sensors: 12 cameras, 6 LiDARs, GPS, IMU - Communication: Wi-Fi, 2.4 GHz radio - Mass: 20 kg

Process: 1. Install computer in shielded enclosure 2. Connect cameras and LiDARs 3. Calibrate sensors 4. Install communication antennas

Stage 8: NaK Cooling Circuit Filling

NaK Circuit: - Volume: ~50 liters - Temperature: +50-100C (operating) - Radiators: 10 m2 Al panels

Process: 1. Evacuate circuit (remove air) 2. Fill NaK through fill valve 3. Leak check (vacuum test) 4. Start NaK pump

Stage 9: Calibration and Testing

Test Program:

Test	Description	Specification
Motion	Check all 6 wheels	Speed 10 km/h
Manipulator	Lift 5 tonne load	Height 2 m
Battery	Full charge/discharge cycle	Capacity >18 kWh
Cooling	Radiator test	T <+100C
Autonomy	Autopilot, obstacle avoidance	100% success

Duration: 6 hours

Stage 10: Initial Charging

Charging Station: - Voltage: 400 V - Current: 25 A (gentle initial charge mode) - Full charge time: 2 hours (20 kWh / 10 kW)

Process: 1. Connect to charging station 2. Battery activation (first cycle at 350°C) 3. Full charge 4. Capacity check (must be >18 kWh)

Power Consumption

Mode	Power	Operating Time
Empty travel	5 kW	4 hours (20 km)
Loaded travel (5 t)	10 kW	2 hours (10 km)
Loading/unloading	3 kW	6 hours
Idle	0.5 kW	40 hours

Range: - Empty: 20 km - With 5 t load: 10 km

Maintenance

Operation	Frequency	Performed by
MoS₂ wheel bearing recoating	3-6 months	Magnetron station + Centaur-M
Sensor calibration	3 months	Automated
NaS battery replacement	5-7 years	Assembly line
Wheel replacement	1 year	Centaur-M

Service life: - Frame: 10-15 years - Battery: 5-7 years (4500 cycles) - Electronics: 5-10 years - Robot overall: 5-10 years

Applications

Main Crab-M Tasks:

Task	Description	% time
Regolith transport	Delivery of 100 t/day from Mole-M to factory	40%
JIT factory supply	Loading/unloading through airlock (coils, ingots, finished goods)	20%
Mass Driver buffer	Delivery of mirror containers from F-M to Mass Driver	15%
Inter-factory logistics	Domes, equipment, robots from F-R to sites	15%
Maintenance	Spare parts transport, external warehouse servicing	10%

Productivity: - 20 trips/day x 5 t = 100 t/day per Crab-M