RELEASED 2020.05REASSESSED 2026.08.07

Yard Force

Yard Force Compact 400Ri

Name: Yard Force Compact 400Ri
Brand: Yard Force

Wire-guided baseline with an added ultrasonic collision-sensing layer. The iRadar system reduces dock-impact and obstacle-contact frequency but does not enable independent navigation or escape wire dependency. Owners pay for safety redundancy, not autonomy advancement.

PriceNot listedNot tracked yet

Autonomy Ladder

Why Level II.

One five-rung scale, every category, from acting only on command to working unsupervised anywhere.

VGeneralized AutonomyAny task, any setting. No consumer robot has reached it.
IVEnvironmental AutonomyHandles new obstacles and re-plans in real time; rare in consumer products.
IIIConditional AutonomyFinishes whole jobs in familiar spaces; struggles at the edges.
To reach Level IIIMost sessions finish without intervention. Rescue is occasional, not routine.
IIAssisted AutonomyThis robot

Yard Force Compact 400Ri runs preset routines on its own, and the owner is its recovery system.

Navigation and control
Perimeter-wire guided with randomized path; iRadar ultrasonic obstacle detection for collision avoidance.
Why this level
- Wire-guided operation with randomized path execution within perimeter boundary. iRadar ultrasonic obstacle detection is a safety addition.
- It does not enable navigation or end-to-end task planning.
- Meets Level II (Assisted Autonomy) criteria, requiring boundary-wire setup and maintenance but enabling scheduled autonomous operation within defined zones.
Autonomy dimension 45 / 100 · 2 sources reviewed
IManual AutomationOne action on command; no independent operation.

How we assign a level →

Behind the classification

Sources we reviewed.

Provisional2 sources reviewed

Enough has been reviewed to classify, but gaps remain across source types.

Sources reviewed

Specification sources2 sourcesReviewed

Pages the published specifications were read from.

Also monitored, nothing listed yet

Manufacturer documentationReviewed

Yard Force Compact 400Ri product page and manual: charging station and boundary-wire contents, 16 cm cutting width, iRadar detection range, 30 percent maximum incline, disc blade set.

Owner reportsReviewed

European forums (Yard Force community, Amazon EU reviews) documenting iRadar collision-detection performance, wire durability, battery runtime consistency.

Press & video reviewsReviewed

European robotics and consumer tech publications covering the Compact 400Ri positioning and iRadar differentiation.

Firmware release notesOngoing

Yard Force app changelog documenting iRadar sensitivity tuning and boundary-detection refinements across firmware updates.

How we evaluate evidence →

Human Readiness

Ready Now.

Available through European retailers and selective North American channels. Six-year consumer history with modest but documented owner base. Requires boundary-wire installation and manual charging. iRadar ultrasonic detection system is functional but does not upgrade autonomy classification (Level II infrastructure limit); ultrasonic is a safety addition, not a navigation system.

Where this sits on the readiness scale

Ready NowThis robotProven autonomous performance, reliable, and available for purchase.
Promising ProgressReal advancement, but the ownership experience is still maturing.
OverhypedMarketing is outpacing actual capability.
WaitTechnology exists but better options are coming soon.
Falls ShortFails core autonomy or reliability standards.

How we assess readiness →

Robovations Score

How this number was reached

64of 100

CapableAt or above 37% of the 355 robots we scoreand 22% of the 79 scored robot lawn mowers

DeficientLimitedCapableStrongExemplary

Measured on 8 of the 9 inputs4% not counted

Our assessment did not establish an independent source for operating envelope on this machine, so that input is left out of the score rather than guessed at, and the rest re-weighted to fill the space. A gap in what we have been able to verify is not evidence against the robot. Where it reaches 30% of the rubric we publish no number at all.

What moved itpoints gained or lost against a typical robot

Carried by

Field failure rate85+2.4
Software stability82+2.4
Edge-case recovery58+0.8

Held back by

Routine maintenance40−3.4
Coverage and navigation42−2.8
Support longevity48−1.5

Capability40% of the score59What it does without you.

Task completion16% of the score70

Evidence

Expert Reviews set it running for a chosen number of hours per day and found "no patch of lawn left unmowed" in their tests, with the mower docking and recharging itself; the perimeter cable must sit 30 cm in from most edges and 50 cm on the dock side, which "will leave a strip of about 22cm of uncut grass around the edge of your lawn that you'll need to decide how to deal with separately".

Coverage and navigation10% of the score42

Evidence

Expert Reviews reports it "moves around the lawn randomly", setting off in one direction and turning at the boundary wire, which "runs the risk of missing bits of your lawn"; the fix is run time, and in their test that produced complete coverage but with the mower travelling "repeatedly over the same areas". Random bump-and-turn on a wired boundary is class-normal for a mower at this price, so this is complete but inefficient, re-established every run.

Edge-case recovery10% of the score58

Evidence

Two genuine mechanisms and one gap. iRadar detects obstacles by ultrasonic sonar at a barrier defaulting to 30 cm and extendable to 60 cm in the app, then pauses and backs away, so the commonest interruption is handled before contact and the run continues rather than needing a rescue; owner reports cite fewer dock impacts. WiFi means a fault reaches the owner's phone rather than sitting in the yard, which is what separates this from the Flymo. The gap is the category's signature failure: a wire break still stops the machine, and no entrapment or escape behavior is documented.

Operating envelopenot countedno source verified64

Evidence

Rated to a 30 percent maximum incline, which is lower than the Flymo's 35 percent, on a rated 400 m2. Sonar rather than a camera means obstacle sensing works in any light, which is real width. Against that, the record states dense obstacles limit it and that iRadar does not enable efficient multi-zone operation or layout-change adaptability, wire installation is a precondition of any operation, and no wet-grass or weather behavior is documented in either direction.

Dependability40% of the score75Whether it keeps doing it.

Field failure rate16% of the score85

Evidence

Six years on sale since May 2020 with no recall and no documented systemic defect, and unlike the Flymo there is an owner base behind that: 45 or more European forum and Amazon EU reports specifically covering wire durability and battery runtime consistency, marked complete. Held below the isolated-failures anchor and said plainly: that base is retail and forum text, it is unlinked, and part of it is the Yard Force community, which is vendor-hosted material.

Software stability14% of the score82

Evidence

Above the floor because a changelog exists with named content rather than a bare update channel: the record cites a Yard Force app changelog documenting iRadar sensitivity tuning and boundary-detection refinements across firmware updates, marked ongoing. That names what updates changed. It stays well below stability because the changelog is vendor-published and unlinked, and nothing independent establishes whether any update broke anything; owner reports are cited for iRadar performance but not for update behavior.

Support longevity10% of the score48

Evidence

Scored as commitments. A six-year-old model with an EU dealer and parts ecosystem, shipping with the charging station, a 9 m station cable, 100 m of wire and 120 pegs, and spare disc blades in the box. Against that, Yard Force publishes no blade interval and no spare price, no parts-availability window and no end-of-support date, and the record is explicit that North American repair and part sourcing faces long lead times and high costs with sparse regional authorization.

Ownership burden20% of the score54What it asks of you.

Routine maintenance12% of the score40

Evidence

The after-every-use step is what sets this apart: with the mower switched off, brush clippings from the underside and cutting disc and dry the exterior if it is wet. On top of that, weekly cleaning and drying of the station contacts and mower charging strips, monthly perimeter-wire inspection and wiping the iRadar sensor faces, a seasonal wire condition audit and repair, and winter storage of both mower and charging station. Blades are replaced as a full set of three so the disc stays balanced, and are replaced rather than sharpened.

Consumables8% of the score76

Evidence

Three razor blades on a rotating disc replaced as a set, with spares shipped in the box and no published interval or price, so cadence is judged on condition. Wire and pegs are occasional spares against the 100 m and 120 pegs supplied. That is a small annual figure against a $599 machine, and boundary wire installation itself is a one-time cost rather than a recurring burden. A battery replacement is the one larger item likely inside five years.

middle half of the databaseits medianthis robot

Reported, not scoredneither measures how well the robot works

Five-year cost$1,040

Lower middle for robot mowers. $599 at purchase plus roughly $60 a year in disc blade sets, occasional wire and peg spares beyond the 100 m and 120 pegs supplied, and one battery replacement likely inside five years. No subscription. Yard Force publishes neither a blade interval nor a spare-blade price, so the annual consumable figure is the least certain part of this number, and North American buyers should expect part sourcing to cost more than the EU-based figures imply.

Data postureCloud-linked

Account required. Maps and telemetry leave the home; core function survives an outage.

What leaves the homeNot documented

Read the full methodology →

FIT CHECK

Will the Yard Force Compact 400Ri work on your yard?

Describe your yard using the controls. Each choice reads the spec sheet for you, flagging where the Yard Force Compact 400Ri is built for your space and where it isn’t.

Yard size

Terrain

Grass type

Boundary setup

A classification of fit for the conditions you set, not a recommendation. Verdicts describe engineering design intent, not test results.

SPECIFICATION

The full spec sheet.

Manufacturer-published figures, measured against every robot lawn mowers we track.

Dimensional drawing

Key specificationsManufacturer-published

Footprint: 16.3 × 10.8 in · 8.3 in tall
Weight: 26.5 lbs✓
Battery: 40 Wh · Li-ion
Wi-Fi: Supported

Where it lands · ranked across 91 robot lawn mowersThis robotMedianTypical range

Runtime60min

30 min240 min

Below median

Noise71dB

50 dB82 dB

Above median

Charge time100min

30 min300 min

Near median

Weight26.5lbs

11.9 lbs134 lbs

Near median

Position shows where the figure sits across the tracked category, not a quality judgment.

Official referencesManufacturer support Manufacturer site

RECORD

How the assessment has moved.

Every announcement, release and reassessment behind the current classification.

Coming soon

Just launched

Active updates

Settled

Discontinued

Sep 2024 · NewsRetail pricing settles across EU channels
Jul 2026 · AssessmentRobovations Score recorded at 55 of 100
Jul 2026 · AssessmentRobovations Score revised 55 → 62
Aug 2026 · AssessmentRobovations Score rescored under v4.0: 62 → 65
Aug 2026 · AssessmentRobovations Score rescored under v4.2: 65 → 67
Aug 2026 · AssessmentRobovations Score revised 67 → 64
Aug 2026 · AssessmentRecord status: Verified → Provisional

Editorial comparisons

How Yard Force Compact 400Ri compares.

All comparisons →

Goal-based

Small urban lawns: is a simple wired robot mower better than RTK?

Gardena Sileno City + 3 more

Read comparison

Common questions

What people actually ask.

5 answered

OperationHow does the iRadar ultrasonic detection system work?

iRadar uses ultrasonic sonar to detect obstacles ahead of the mower. If an object blocks the path, the system pauses autonomy and backs away. This reduces dock collisions and obstacle strikes compared to wire-guided mowers without sonar.

OwnershipDoes iRadar replace perimeter-wire setup or boundary maintenance?

No. The Yard Force Compact 400Ri requires perimeter wire for all navigation and zone definition. iRadar is an additional safety layer; boundary-wire installation and maintenance are mandatory.

OperationWhat is the battery runtime and can the Compact 400Ri handle a full yard on one charge?

Manufacturer specs list 60-minute runtime on a single 20V battery charge (about 100 minutes charging). A 3,500 sq ft yard typically needs one to two passes; larger properties need multiple charging sessions per week.

OperationHow is the battery charged, and is a docking station included?

A charging station is included. Yard Force ships the Compact 400Ri with the station, a 9 m station power cable, 100 m of perimeter wire and 120 pegs. The mower returns to the station on its own to recharge and then resumes, so the 60-minute runtime is a per-pass figure rather than a daily ceiling. The app sets a daily operating window of four, six, eight or ten hours. The battery is not pulled and charged separately between sessions.

OwnershipWhat is the cutting width and blade maintenance interval?

Cutting width is 16 cm. The mower cuts with three replaceable razor blades on a rotating disc, and spares ship in the box. Change all three together so the disc stays balanced, and replace rather than sharpen: sharpening thins a small pivoting blade and unbalances the disc on a machine that runs unattended. Yard Force does not publish a replacement interval or a spare-blade price, so neither is stated here.

Cite / Embed

Reference the Yard Force Compact 400Ri classification.

Embed the Autonomy Ladder™ mark or copy the citation. The mark is served from this record rather than saved as a file, so it always shows the level we currently hold. If we reassess, it updates on your page by itself.

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Citation

Robovations. "Yard Force Compact 400Ri: Autonomy Level II (Assisted Autonomy)." Autonomy Ladder™, assessed August 2026. https://robovations.com/robots/yard-force-compact-400ri/

Where to next

Three ways to keep going.

For evaluators

Compare with a peer.

See the Yard Force Compact 400Ri and McCulloch ROB R1000 side by side: autonomy level, Robovations Score, readiness, and price. Classification, not a verdict.

See the full comparison

Or compare with Ambrogio Twenty Elite, Gardena Sileno Life 750, Husqvarna Automower Aspire R4.

For browsers

See every Level II.

Every robot we’ve classified at assisted autonomy. Sorted by readiness, score, and price. Filter by category, manufacturer, or release date.

Browse the database

Updated weekly with new entries and reclassifications.

Yard Force Compact 400Ri

Will the Yard Force Compact 400Ri work on your yard?

The full spec sheet.

How the assessment has moved.

How Yard Force Compact 400Ri compares.

Small urban lawns: is a simple wired robot mower better than RTK?

What people actually ask.

Other robot lawn mowers we have classified.

McCulloch ROB R1000

Ambrogio Twenty Elite

Gardena Sileno Life 750

Husqvarna Automower Aspire R4

Reference the Yard Force Compact 400Ri classification.

Three ways to keep going.

Get the next reassessment.

Compare with a peer.

See every Level II.