Technology

Specified in full. Not yet built.

MurA is at the digital-twin stage, with the bench rig to follow from March 2027; there is no working prototype yet. The values below are the figures the machine is designed to, taken from the engineering specifications written before any metal was cut. Performance figures are design targets until a bench rig and then a prototype prove them, and every figure names the document section it comes from.

Source documents dated July to October 2026. Hover or focus any value for its full reference.

Form factor

A compact rover sized for UK housing plots and the gaps between scaffold.

Layout: Battery-electric rover with a rotating overhead gantry carrying the gripper and mortar nozzle assembly design Hardware spec 2.1
Length: 2.0 m design Hardware spec 2.2
Width: 1.0 m design Drives standard UK housing plots and scaffold gaps. Hardware spec 2.2
Mass, dry: 1,200 kg design maximum The battery doubles as ballast; no heavy-lift transport is needed. Hardware spec 2.2
Horizontal reach: 1.4 m design minimum Clears the 1.0 m rover width plus a 0.2 m wall, with margin to spare. Hardware spec 2.2
Vertical reach: 2.2 m design minimum Covers most of a standard 2.4 m UK storey from ground level. Hardware spec 2.2
Ground clearance: 200 mm design minimum Hardware spec 2.2

Performance targets

What the machine is designed to do, and how each figure is to be verified before it is claimed.

Placement rate: 1,200 bricks an hour design target Acceptance test: timed continuous operation over 4 hours or more. The Phase 3 gate checks 2 hours. Hardware spec 2.3
Placement accuracy: ±1.0 mm design target Relative to the previous course; laser tracker over 100 consecutive bricks. Hardware spec 2.3
Course level: ±3.0 mm per metre design target Digital inclinometer. Hardware spec 2.3
Plumb: ±5.0 mm per 2.0 m design target Total station or plumb-bob. Hardware spec 2.3
Failure rate: under 0.1 % design target One brick in 1,000; field logging over 10,000 or more bricks. Hardware spec 2.3
Statistical proof: about 3,000 consecutive bricks design target Zero failures over that run shows the rate is under 0.1% at 95% confidence; one failure extends the run to about 4,750 bricks. Safety assurance 8.2
Continuous operation: 8 hours per shift design target Battery state-of-charge telemetry. Hardware spec 2.3

Mobile platform

Four driven wheels on independent suspension, with outriggers that level the chassis before a brick is laid.

Chassis: Welded S355 steel space frame design Torsional stiffness 15,000 Nm per degree minimum between the arm flange and the wheel centres. Hardware spec 3.1
Drive: Four brushless DC hub motors, 48 V design 8:1 planetary reduction inside each wheel. Hardware spec 3.2
Continuous power: 1.5 kW per motor design Hardware spec 3.2
Peak wheel torque: 450 Nm per motor for 10 s design To climb out of ruts. Hardware spec 3.2
Top speed: 6 km/h design Walking pace. Hardware spec 3.2
Suspension: Double wishbone, independent, all four corners design 150 mm bump and 80 mm rebound; damping switches between transport and laying. Hardware spec 3.3
Outriggers: Four telescopic legs, 500 mm travel design 5,000 kg static load per leg on 200 mm swivel footpads. Hardware spec 3.4
Auto-levelling: ±0.3 ° in roll and pitch design target Levelled before any brick is laid; the safety PLC holds the arm until all four legs confirm ground contact. Hardware spec 3.4
Parking brakes: Spring-applied, hold on a 15° slope design Hardware spec 3.2
Slope limits: 10° longitudinal, 5° lateral design Hard-coded in the safety PLC; the rover refuses to move beyond them. Hardware spec 3.5Safety assurance 4.2
Emergency stops: Two hardwired buttons and a wireless pendant design Any of them opens the main contactor and applies the parking brakes. Hardware spec 3.5

Power

One battery pack, charged overnight from site three-phase power and topped up at lunch for a full shift.

Chemistry: Lithium iron phosphate (LiFePO4) design Chosen for thermal stability and cycle life on a construction site. Hardware spec 4.1
Nominal voltage: 48 V DC design Hardware spec 4.1
Capacity: 40 kWh design minimum Four 200 Ah or five 160 Ah LiFePO4 modules at 51.2 V nominal on the 48 V bus: about 41 kWh. Hardware spec 4.1
Battery mass: 340 to 425 kg design Mounted low and rearward as ballast against tipping. Hardware spec 4.1
On-board charger: 6.6 kW design Hardware spec 4.2
Charging inlet: 3-phase 400 V AC, 32 A design IEC 60309 socket; charges from site generators or temporary supplies. Hardware spec 4.2Hardware spec 12.2
Charge time: 0 to 80% in about 5 hours design Hardware spec 4.2
Average load: 5.78 kW design model The mortar pump takes about half of it. Hardware spec 4.4
Modelled runtime: 6.9 hours on 40 kWh design model 5.5 to 6.0 hours in winter with battery heating. Hardware spec 4.4
Shift: 8 hours design target Needs about 46 kWh at the 5.78 kW average: met with an hour of charging at lunch (6.6 kWh) or a 48 to 50 kWh pack. Hardware spec 2.3Hardware spec 4.4
Main bus: 48 V DC, 400 A continuous design A 500 A pyro-fuse on the main battery, fired by the safety PLC. Hardware spec 4.3
Battery protection: IP65 steel pack enclosure inside an IP66 battery bay, with a flame-arrested vent design Smoke or CO detection isolates the pack by pyro-fuse and fires an aerosol suppressor. Hardware spec 4.1Hardware spec 11.1Safety assurance 4.2

Arm and gantry

A side-mounted cantilever with a 1.4 m design reach over the wall.

Column: 200 × 200 × 8 mm S355 steel box section, 1.2 m tall design Hardware spec 5.1
Beam: Hybrid: 0.6 m steel box inboard, 0.8 m 6082-T6 aluminium outboard design Steel where the bending moment is highest; a ribbed aluminium extrusion at the tip. Hardware spec 5.1
Distal payload: about 60 kg design The gripper head and the nozzle, with the mortar in the hose. Hardware spec 5.1
Static deflection: under 0.5 mm at full load design target Hardware spec 5.1
Dynamic deflection: under 1.0 mm at 2 m/s² design target Hardware spec 5.1
Camber: 2.0 mm upward at the tip design Settles to about 0.5 mm under static load. Hardware spec 5.1
Truss: 8 mm stainless tension rod, pre-tensioned to 5 kN design 30 to 40% more stiffness for little added mass. Hardware spec 5.1
Slewing ring: 500 mm diameter, ±180° rotation design 22-bit absolute encoder; no homing cycle on power-up. Hardware spec 5.3
Rotation drive: 1.5 kW servo through a 60:1 worm gearbox design Non-backdrivable, so no holding brake. Hardware spec 5.3
Linear guides: C5-grade recirculating ball guides on 35 mm rail design Running parallelism 0.015 mm over 1.5 m. Hardware spec 5.4
Gripper drive: C5 ball screw, 32 mm diameter, 10 mm pitch, 1 kW servo design Ball screws over belts: belt stretch adds backlash. Hardware spec 5.4
Rail acceleration: 2.5 m/s² design target Hardware spec 5.4

Grippers

Pneumatic jaws grip each brick and check its mass before it is set into the mortar bed.

Jaws: Pneumatic 40 mm cylinders closing urethane-coated aluminium jaws design The urethane takes ±3 mm of brick variation without crushing. Hardware spec 6.2
Grip force: 200 to 400 N per jaw design Verified by pressure transducer; a drop aborts the cycle. Hardware spec 6.2
Mass check: 10 kgf load cell, alarm above 0.5 kg deviation design Hardware spec 6.2
Brick rotation: ±2° about the vertical design A harmonic-drive servo corrects perpend alignment. Hardware spec 6.2
Placement vibration: 120 to 150 Hz design 0.1 to 0.3 mm amplitude for 0.5 to 1.0 s per brick, to de-air the bed. Hardware spec 6.4
Vibration isolation: under 10 % transmitted to the arm design target Hardware spec 6.4
Frame: Machined 6082-T6 aluminium, hard-anodised 25 µm design Hardware spec 6.2
Brick: 215 × 102.5 × 65 mm UK modular brick design 440 × 215 × 100 mm block with a jaw change. Hardware spec 13, item 1

Mortar system

A pump rated above the full demand at the 1,200 bricks an hour design target, under closed-loop mass flow control.

Pump: Progressive cavity, driven by a 3 kW servo at 0 to 1,000 rpm design Continuous, pulsation-free flow; the stator is a 200 to 400 hour consumable. Hardware spec 7.2
Rated flow: above 60 kg per minute design target To be verified over five 10-minute runs. Hardware spec 7.1Safety assurance 8.2
Demand at the 1,200 bricks an hour design target: 40 to 60 kg per minute design 2.0 to 3.0 kg of mortar per brick. Hardware spec 7.1
Pressure: 30 bar continuous, 50 bar peak design The safety PLC disables the pump at 50 bar; software reverse-purges above 35 bar. Hardware spec 7.2Safety assurance 4.2Software spec 7.2
Flow control: Coriolis mass flow meter on the pump outlet design Closed-loop PI control at 500 Hz. Hardware spec 7.2Software spec 7.1
Hopper: 250 L, 304 stainless steel design 45° conical bottom; a 30 rpm paddle agitator against segregation and crusting. Hardware spec 7.3
Hopper endurance: 6 to 9 minutes at full flow design Fed by umbilical from a ground mixer through a 50 mm hose. Hardware spec 7.3Hardware spec 12.2
Nozzle: Slot nozzle laying a 20 mm mortar bed design Hardened skids hold a 20 mm standoff from the course below. Hardware spec 7.4
Purge: 2 L of water and compressed air design At the end of each course or every 10 minutes. Hardware spec 7.4Software spec 7.4
Mortar temperature: 5 to 30 °C design Outside this window the system alarms and refuses to start; the hose is heated below 10 °C. Software spec 7.3Hardware spec 7.5
Mortar: Cementitious, slump 100 to 150 mm design Hardware spec 13, item 2
Hose: 3 m of 40 mm bore hose, working pressure at least 50 bar design Hardware spec 7.5

Sensing

Satellite positioning gets the rover to the wall; relative sensors on the gripper place the brick.

Global position: RTK-GNSS, dual-band, multi-constellation, ±10 mm horizontal design Places the rover within ±20 mm of the wall design; never used to place a brick. Hardware spec 8.2
Inertial: Tactical-grade MEMS IMU at 500 Hz design Gyro bias stability under 5° per hour; watches for chassis movement during placement. Hardware spec 8.4Software spec 5.2
Fusion: Extended Kalman filter, navigation only design 200 Hz prediction with 10 Hz GNSS correction; kept out of the placement loop. Software spec 5.1Software spec 5.2
Forward LiDAR: Solid-state, 40 m range at 0.25° resolution design Terrain mapping and obstacle detection; a hole deeper than 50 mm counts as an obstacle. Hardware spec 8.5Hardware spec 3.5
Downward sensing: Eight-sensor ultrasonic array with 2 m range design Negative obstacles against a stored ground map. Hardware spec 8.5
Vertical datum: Two laser time-of-flight sensors on the gripper, ±0.5 mm design 50 to 300 mm range. Hardware spec 8.3
Vertical datum sampling: 1 kHz design A 10-sample median filter rejects dust outliers. Software spec 5.3
Horizontal alignment: Laser line projector and position-sensitive detector, ±0.5 mm design Hardware spec 8.3
Post-placement check: Stationary laser time-of-flight sensor on the arm design Height or alignment out by more than 1.5 mm flags the brick. Hardware spec 8.3Software spec 4.3
Arm safety scanner: 270° safety-rated laser scanner on the arm column design 1.5 m zone; an intrusion decelerates the arm to standstill. Hardware spec 8.5Safety assurance 4.2
Course correction: Wall profile scan every 5 courses design A mean deviation above ±2 mm applies one additive offset to the rest of the wall. Software spec 5.4

Control

Deterministic control on an industrial PC and FPGA, with an electrically independent safety PLC.

Main controller: Fanless industrial PC, real-time Linux with PREEMPT_RT design Real-time cores isolated; non-essential interrupts masked. Hardware spec 9.1Software spec 4.1
Servo loop: 1 ms design target Jitter budget under 50 µs (design target), to be proven over 10,000 cycles. Software spec 4.2Software spec 13
FPGA co-processor: 8 axes at 10 kHz design Under 1 µs jitter; freezes every motor output in under 50 µs, independent of the CPU. Software spec 2.3
Drives: EtherCAT at 1 kHz with Safe Torque Off design STO hardwired to the safety PLC on every servo. Hardware spec 9.2Software spec 8.2
Software layers: Four, from planning to safety design L4 planning non-real-time; L3 coordination 50 ms; L2 control 1 ms; L1 safety 10 ms. Software spec 2.2
Real-time rule: No GPU inference, no dynamic allocation design Trajectories are computed before each placement, not during it; worst-case execution time is analysed for every task. Software spec 2.1
Placement data: Brick Placement File generated offline from the IFC model design A checksummed sequence of every brick and tie. Software spec 3.1Software spec 3.5
Trajectories: S-curve, 0.8 m/s and 2.5 m/s² on the rail design Jerk limited to 10 m/s³; played back from waypoints at 1 ms intervals. Software spec 6.2
Safety PLC: Independent, to Category 3 and Performance Level d target To EN ISO 13849-1; 10 ms cycle with its own sensors and its own contactor, electrically separate from the main controller. Safety assurance 3.1Safety assurance 3.2Hardware spec 9.1
Diagnostic coverage: 90% minimum, MTTFd 100 years per channel design target Safety assurance 3.2
Heartbeat: 100 Hz square wave design Lost for 200 ms, it opens the main contactor. Software spec 8.4Safety assurance 5.2
Safety stop: under 50 ms from e-stop to drive disable design target Brakes within 100 ms (design target); to be proven on 50 triggers with an oscilloscope on the STO line. Safety assurance 8.2Software spec 13
Coding standard: MISRA C:2012 for the control layer design Static analysis on every build; no dynamic allocation after boot. Safety assurance 9.1Safety assurance 9.2
Firmware updates: Signed (ED25519) with automatic rollback design The safety PLC is never updated over the air. Safety assurance 9.4

Environmental

Designed for a UK site in a UK winter: rain, mud, dust and cold.

Ingress protection: IP65 design Everything external, motors and connectors included; the battery bay and control enclosures to IP66. Hardware spec 11.1
Operating temperature: -5 to +40 °C design Hardware spec 11.1
Storage temperature: -20 to +50 °C design Hardware spec 11.1
Rain: Operates to 2.5 mm per hour design Above that the arm stows and the system pauses; a 1.5 × 2.0 m canopy covers the fresh bed in heavy rain. Hardware spec 11.1
Wind: Paused above 30 mph design Hardware spec 13, item 6
Cold-weather heating: Battery below 5 °C, electronics below 0 °C design Hardware spec 11.1
Shock mounting: 20 G half-sine design The controllers and the inertial unit sit on wire-rope or elastomer isolators. Hardware spec 11.2
Corrosion: Hot-dip galvanised or powder-coated steel design A2-70 stainless or zinc-plated fasteners; aluminium anodised to 25 µm. Hardware spec 11.1
EMC: EN 61000-4-3 radiated immunity at 10 V/m target Lab test targeted at Month 28 on the certification roadmap. Safety assurance 2Safety assurance 10.1
Connectors: Positive-locking only design Push-pull connectors without a secondary lock are prohibited. Hardware spec 11.2

Held back until filing

Some figures in this specification are held back until their patent applications are filed.

Sealed 1 of 3: Patent application 1 of 3, planned. Released here on filing.On filing
Sealed 2 of 3: Patent application 2 of 3, planned. Released here on filing.On filing
Sealed 3 of 3: Patent application 3 of 3, planned. Released here on filing.On filing