Tag engineering brief

1. Product

A personal and building carrying robot. It walks beside one person or runs a delivery alone, carries a full grocery order in a locked, covered bay, climbs stairs and kerbs, crosses trails, steps into a car boot and folds to a bench at the door. It rises to the working height of whoever is using it, rests on its own charging dock between jobs, and is set up and run from a phone app, with every daily task also possible without one. Sold to households and leased to buildings as fleets.

1. Never ask a person to lift it, bend to it, or chase it. A breach is a defect.
2. Predictable before clever. Anyone nearby can tell what it will do next.
3. One platform. Use cases are modules and software, never hardware variants.
4. Looks and behaves like a well-made object, not a lab robot or a medical aid.

2. Revision C changes

3. Architecture

Body. Lower chassis: 76 × 38 × 14 cm anodised aluminium unibody (bead-blasted warm titanium), carrying two battery packs, compute, safety controller and the module deck. Machined cooling ribs on both sides over the battery bay. Upper shell: chalk-white PC-ABS over a glass-fibre frame, forming the cargo bay with a hinged, gas-damped lid. A warm-white light line marks the seam.

Legs. Four legs, hip and knee, 28 + 28 cm, hips at the chassis corners (x = ±30 cm), knees bending outward. Both motors sit coaxially in the hip housing; a toothed belt in the thigh drives the knee. A coil-over air shock runs along each thigh. Every joint has a spring-applied brake.

Wheels. 305 mm cast polyurethane tyres on machined hubs with in-hub motors. Skid steering through four hubs; no steering actuators.

Handle. Fold-up brushed-aluminium push handle at the rear with a capacitive grip. Push assist when held.

4. Envelope

5. Cargo bay

Item	Value
Internal size	71 × 35 × 30 cm
Volume	75 L calculated
Rated load	60 kg flat, 40 kg stairs
Lining	Removable washable felt, wipe-clean base tray
Light	Warm LED strip under the lid lip, on when open
Lid	Gas-damped, soft-close actuator, latch with lock
Access	Household UWB key, phone, or one-time courier code
Weighing	Four hip load cells, ±0.2 kg
Weather	Gasketed lid, IP65 closed

Reference order used for packaging studies: water 24 × 500 ml (12.4 kg), rice 5 kg, milk 4 L (4.1 kg), two pantry bags (4.3 kg), eight cans (3.4 kg), detergent 3 L (3.3 kg), produce, bread and eggs (6.1 kg). Total 38.6 kg; the lid must close over it without force.

Load placement. The robot reads centre of mass from the load cells after loading. If the load is off-centre by more than 8 cm it says so and asks for a shuffle; it never refuses silently.

6. Wheels

7. Legs and actuation

Coil-over air shocks give 80 mm travel at the wheel; preload is set automatically from measured load. Knee gas springs carry about 60 % of nominal static load so the legs never sag on power loss.

8. Rise

R1 says nobody bends to it. Rise lifts the lid from walking height to a height set for each person, anywhere from 61 cm (kneel) to 110 cm, so the bay comes up to the hands instead of the back going down to the bay.

Geometry

The lid sits 56 cm above the chassis bottom, the hips 7 cm above it. Legs are 28 + 28 cm; wheel radius 15.25 cm. For lid height h: hip height H = h − 49, hip-to-axle d = H − 15.25, knee offset x = √(28² − (d/2)²). Centre of mass with a 60 kg load uses the robot (39 kg) at H + 4 and the load at h − 18; half-track 28 cm, half-wheelbase 30 cm.

calculated Knee torque is before the gas springs, which carry about 60 % of it. The knee is still bent 110° at full rise, so the shocks keep working. Lifting 99 kg at 4 cm/s needs about 39 W.

Suggested height

The app proposes h = 0.58 × stature + 5 cm, clamped to 61 to 110: 99 cm for a 162 cm adult, 106 cm for 175 cm. The rim lands near hip height and the bay floor, 30 cm lower, near knuckle height, so a full load comes out with a straight back. Each person can adjust it; the height follows their key or phone. estimate Confirmed by the trunk-flexion test in section 25.

Rules P1

1. Only when stopped, on floor sloped no more than 5° (IMU). It lowers to walking height before any motion and never drives with the lid above 92 cm.
2. It looks up first. Time-of-flight sensors on the lid edges need 10 cm clear above the lid and its opening arc. Under a shelf or counter lip it rises only as far as is clear, and says so.
3. Slow and soft. 4 cm/s; any unexpected contact (joint current, lid load cells) stops it within 5 mm and lowers 1 cm.
4. By hand. P2 Hold the lid grip and lift or press: admittance control follows the hand at up to 6 cm/s and holds where it is let go.
5. Leaning. If someone leans on the lid, brakes hold and it will not move until the extra load is gone. It is not sold as a mobility aid.
6. Locked out with the Nest fitted, on stairs, and in car entry.

9. Perception

What it recognises

Perception to motion latency ≤ 120 ms. All video is processed on the robot. A visible indicator shows whenever any camera feed leaves the robot (only when the owner shares it).

10. Behaviour

Following

Path replay: Tag retraces the line its person took, or walks alongside on wide ground. Losing the person for 3 s means stop, hold, amber state, buzz the key. It never drives off to search.

Stairs P6

Statically stable crawl. Before each wheel lifts, the load cells locate the centre of mass and the body shifts inside the triangle of the other three wheels. About 2.5 s per step at 40 kg. Square-on approach only.

Speeds

11. Buildings

A fleet of two to six Tags charges at a lobby dock. A courier scans the dock code; the nearest Tag rolls out, opens, and locks once loaded. It calls the lift through the lift maker's robot interface (fallback: stick-on button actuator), rides parked against the back wall, travels corridors at 3 km/h keeping to one side, and stops at the door. The resident gets one notification; the lid opens only for their household. If nobody answers within ten minutes it returns to the dock.

12. Car entry

Depth cameras map the opening, lip and floor first; the robot refuses if any clearance is under 5 cm. Front legs place both front wheels on the protective mat; the chassis pitches nose-up to clear the lip; rear legs push, then each rear wheel steps in. Inside, it folds to bench height. Boot floors up to 75 cm. Robot only, payload ≤ 10 kg. P3

1. No paint contact. Wheels lifted 5 cm clear of the bumper before moving forward.
2. Force-limited. Every joint halts at 15 N of unexpected contact.
3. Soft edges. Chassis nose, glass edges and leg plates covered in non-marking polymer.
4. Mat in the box. Thin magnetic boot-lip guard and mat included.

risk Tailgate clearance and boot-floor grip vary by model; test on the top 30 selling SUVs and hatchbacks.

13. Modules

Each module tells the safety controller what is fitted, and the controller enforces that module's limits. P5

14. Interaction

Light line states (four, no more): white following; slow amber waiting; green locked with a delivery; red needs help. At rest the line is off; a dot on the dock breathes while charging and holds steady when full. A soft tone and light precede every start or turn within 2 m of a person.

15. Mobile app

iOS 17 and Android 12 onward, one app for households; building managers use a web console. The app is a requester: every command goes to the safety controller, which owns all limits and can refuse. Nothing safety-critical needs the app, and nothing in the app can exceed a limit.

Setup, about ten minutes

1. Scan the code under the lid. Proves physical access; pairs over Bluetooth LE and joins Tag to the home Wi-Fi.
2. Height. Stature in, suggested lid height out (section 8). Repeated for each person added.
3. One lap of the home. Builds the map: rooms, doors, thresholds, stairs flagged, dock position chosen.
4. Household. Invite people; each gets a role, a key or phone, and a lid height.

16. Empathy requirements

Each is a release test.

1. It comes to you. No interaction needs a hand below 45 cm or above 90 cm.
2. It warns before it moves. Light and tone at least 0.5 s ahead within 2 m.
3. It never strands you. Stops safely and says so; reports "enough to get home" while true.
4. It gives way. Half the pavement at most; back of the lift; yields to wheelchairs, prams and canes.
5. It knows who is on board. Child profile within 1 s, not overridable.
6. It keeps your dignity. A well-made object, never a medical aid.
7. It respects privacy. On-device video; visible indicator when shared.
8. It fails gently. Brakes hold, springs carry, slow kneel; wheels freewheel for pushing.
9. It is kind to strangers. One sentence and a green line for couriers; no one else can call it.
10. It is calm. ≤ 45 dB(A) at 1 m walking, ≤ 55 running. No fake emotions.

17. Twenty laws as product requirements

18. Power

19. Rest and dock

At rest

1. Still. Kneeling (centre of mass 32 cm, tip angle above 40°), brakes on, leg drives off. A child pulling the handle cannot tip or move it.
2. Private. Cameras, lidar and microphones are powered off, not just muted. A wake word is opt-in per household.
3. Dark. The light line is off; only the dock dot shows charge.
4. Wakes on an app call, the household key within 2 m plus a touch, a lid touch, a schedule or a building job.
5. Returns after every job, after 10 minutes idle at home, and at 15 % from anywhere, keeping enough range to get back. If the dock is blocked it waits beside it and says why.

20. Electronics

21. Safety and certification

22. Mass and cost

estimate Budgets to design to; the volume column is the cost ceiling of $1,500 that every group is held under. Target retail $4,900, or $129 a month; building fleets leased per unit. Hardware gross margin at target price: 59 % on the first run, 72 % at volume. Mass target remains 39 kg; current budget is 2 kg over. The dock ($45) and lid time-of-flight sensors ($6, inside the sensors line) are new in C.1.

23. Benchmarks

24. Intellectual property

Working assessment from a desk search on 4 October 2026. It is not legal advice: every item needs a professional search and a patent attorney before anything is filed.

Position

The concept as a whole is prior art and cannot be claimed: a wheel-legged stair-climbing carrier, a level cargo bay, person following, lobby-to-door delivery with lifts, self-docking, and raising a container toward the user all exist in patents or products. The protectable value is in the specific mechanisms and control methods below, in the industrial design, and in know-how kept secret.

Patent candidates

Not claimable

Other protection

Freedom to operate

Other people's patents are a bigger exposure than our own. A professional freedom-to-operate review covers legs and stairs (Amazon / Rivr), docks for legged robots (Boston Dynamics and others), person following (Piaggio Fast Forward), and delivery compartments with lift integration (Relay Robotics), and must finish before Prototype 2 tooling.

Rules

1. This brief is confidential. No public posting or shared links until US provisional applications for P1 to P3 are filed.
2. Disclosure clock. The US allows 12 months after our own disclosure; Europe and China generally require absolute novelty, so any public disclosure before filing loses rights there.
3. Enablement. Each candidate gets a written invention disclosure with drawings, control logic, and alternative versions, enough for an engineer to build it.
4. Ownership. Everyone who contributes signs an invention assignment before contributing.

Filing plan

1. Now. Invention disclosures for P1 to P3; patentability searches; US provisional applications (filing fees from about $65 to $325 depending on entity size, plus attorney time).
2. Within 12 months. Non-provisional and PCT applications for the candidates that survive search.
3. At design freeze. Design patents for robot, dock and app screens; trademark filing for the cleared name.
4. Before Prototype 2 tooling. Freedom-to-operate opinion.

25. Acceptance tests

26. Open risks

1. Car entry across boot geometries and floor materials.
2. Stair crawl transitions at 40 kg on worn, narrow treads.
3. Mass: budget 41 kg against a 39 kg target.
4. Perception at 16 km/h in dense forest (UWB multipath, latency).
5. Lift integration across older lift controllers.
6. Regulation of pavement robots and of carrying children.
7. Cost against the $1,500 bill-of-materials ceiling and the $4,900 target.
8. Rise near counters, shelves and leaning people: overhang sensing and lean behaviour.
9. App reliance for older owners: keep the no-app path complete; family-assisted setup.
10. Docking on deep carpet and in narrow hallways.
11. Intellectual property: name conflict, and freedom to operate against Rivr, legged-dock and following patents.

Build order

Prototype 1: leg-and-chassis mule proving K1 and K2. Prototype 1 also proves Rise (K8). Prototype 2: full platform with bay, perception, building software, dock and app alpha. Beta: Nest, flatbed, cooler, certification.

Competitor figures are public as of October 2026. Tag figures are targets or calculations from them; none is measured. Images are generated renders of the design.