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Robovations
Robovations™
Robot Autonomy, Classified
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Comparison · 2 robots

HOBOT 388 Ultrasonic · Hobot R3

All robot window cleaners. Every measure below is plotted against the full class, so a difference can be read against how much the class itself varies.

  1. HOBOT 388 Ultrasonic
  2. Hobot R3
HOBOT

HOBOT 388 Ultrasonic

Autonomy
II Assisted Autonomy
Score
70/100 Strong
Readiness
Ready Now
Price
$299list
HOBOT

Hobot R3

Autonomy
II Assisted Autonomy
Score
55/100 Capable
Readiness
Ready Now
Price
$400list

Up to three

01 Classification

What each one does on its own.

The Autonomy Ladder is the same five rungs for every robot on the site. A rung describes the conditions a robot handles without you, not how good it is.

V
Generalized
Any task, any setting
IV
Environmental
Handles new obstacles without help
III
Conditional
Finishes familiar jobs on its own
II
Assisted
Runs preset routines, needs rescue
HOBOT 388 UltrasonicHobot R3
I
Manual
One action, on command
02 Assessment

Where they actually differ.

The Robovations Score is nine inputs across three pillars, each weighted as shown and each scored so that more is better. A robot can lead on one and trail on another, which is the point of showing them apart. Cost of ownership and data handling are reported on each robot's own page and are never averaged into the score.

Capability

Task completion16% of score
Does it finish the job it is sold to do, unattended
  • HOBOT 388 Ultrasonic75
  • Hobot R368
18median 72 across 354 scored robots100
Coverage and navigation10% of score
Does it work the whole area, and hold that between runs
  • HOBOT 388 Ultrasonic70
  • Hobot R370
15median 70 across 344 scored robots100
Edge-case recovery10% of score
Does it recover from the failures its category presents
  • HOBOT 388 Ultrasonic50
  • Hobot R345
18median 50 across 261 scored robots100
Operating envelope4% of score
How far conditions can vary before performance drops
  • HOBOT 388 Ultrasonic65
  • Hobot R360
25median 70 across 320 scored robots100

Dependability

Field failure rate16% of score
Documented hardware failures per owner-year
  • HOBOT 388 Ultrasonic85
  • Hobot R356
6median 70 across 344 scored robots100
Software stability14% of score
Whether updates fix more than they break
  • HOBOT 388 Ultrasonic33
  • Hobot R365
15median 65 across 275 scored robots100
Support longevity10% of score
Committed parts, service and updates, with dates
  • HOBOT 388 Ultrasonic73
  • Hobot R352
0median 63 across 354 scored robots100

Ownership burden

Routine maintenance12% of score
Hands-on time it asks for in normal operation
  • HOBOT 388 Ultrasonic34
  • Hobot R324
22median 68 across 355 scored robots100
Consumables8% of score
Parts that must be bought to keep it working
  • HOBOT 388 Ultrasonic91
  • Hobot R357
30median 69 across 354 scored robots100
03 Measured against the class

How far apart is a long way?

A number only means something next to the spread it sits in. Each track below is the real range across every classified robot in the class, with the median marked.

Price19 with a published figure
  • HOBOT 388 Ultrasonic$299
  • Hobot R3$400
$150median $365.80$850
Weight16 with a published figure
  • HOBOT 388 Ultrasonic2 lbs
  • Hobot R32.1 lbs
1.3 lbsmedian 2.9 lbs4.8 lbs
Height15 with a published figure
  • HOBOT 388 Ultrasonic3.7 in
  • Hobot R33.7 in
2.2 inmedian 3.5 in9.4 in

Not compared, because fewer than two of these robots carry a published figure: Suction, Runtime, Charge time, Noise.

04 Ownership

What the numbers leave out.

The trade-off

What each design gives up to be good at what it is good at.

HOBOT 388 Ultrasonic

Applying water as a mist rather than a soak keeps run-off off the sill, but a saturated pad on consecutive heavily-soiled panes still requires a mid-session swap that interrupts the automated workflow.

Coverage within a single pane is systematic and unattended; the unit cannot advance to the next pane without the owner relocating it and re-anchoring the rope.

Hobot R3

Dual rotating pads improve corner coverage but complicate maintenance: two separate pad holders, motor couplings, and rotation mechanisms add weekly inspection points compared to single-pad competitors.

Who each one is wrong for

Stated by the record itself. A robot being wrong for a household is a fact about fit, not a fault.

HOBOT 388 Ultrasonic
Users expecting hands-free multi-window automation
Every pane requires manual placement, pad attachment, and safety rope anchoring. The unit automates the scrubbing path within a pane but does not eliminate per-window setup effort.
Homes with textured, frosted, or divided-pane glass
Surface irregularities break the suction seal. Owner reports confirm the unit detaches or loses path on patterned or divided glass, which is a safety risk in addition to a cleaning failure.
Buyers seeking a fully autonomous set-and-forget appliance
Window cleaners in this category require active supervision per session. The 388 automates path coverage within a pane, not the overall cleaning workflow across a home.
Owners with small standard windows cleaned rarely
Manual squeegee effort on small panes is often faster than the 388 setup cycle. The time-savings case is strongest on large or difficult-to-reach glass.
Hobot R3
Windows with no mains socket within about 4 meters
The cord is 4 meters and the robot draws mains power for the whole run, so the reachable set is the windows around one socket. HOBOT's own 2S and S6 Pro ship 5 meter cords.
Owners who want cordless operation
The wired design is not optional. The cell the R3 carries is an embedded UPS that keeps it in position on the glass with an alarm for 20 minutes after a power cut; it is a fall-protection measure, not a duty-cycle battery, and the robot does not clean without the cord.
Frameless or curved tempered glass surfaces
Vacuum edge detection struggles with reflections and lack of visual boundaries. Optical sensors cause frequent incorrect repositioning; manual path planning becomes tedious.

What stays your job

The upkeep ownership hands back to you, whatever the autonomy level says.

HOBOT 388 Ultrasonic
  • After every use: Remove microfiber pad, rinse with water, and hang to dry before storage.
  • After every use: Wipe suction ring with a clean damp cloth to remove glass cleaner residue that degrades the seal over time.
  • Monthly: Inspect safety rope for fraying; replace if any strand damage is visible before next use.
  • Every 3-6 months: Clean suction motor intake port with a dry brush to remove dust accumulation that reduces grip force.
  • Every 3-6 months: Check pad contact surface on the cleaning head for mineral buildup; rinse with diluted white vinegar if present.
  • Annually: Inspect power cable and connector for sheath cracking; manufacturer recommends replacement if outer jacket is compromised.
Hobot R3
  • Weekly: Rinse both pads under tap water; test pad rotation manually to ensure smooth motion; inspect nozzle spray pattern.
  • Monthly: Clean vacuum intake and motor filter; check pad-rotation bearings for smooth spin; soak nozzle in distilled vinegar if spray weakens.
  • Every 3-4 months: Replace cleaning pads (~$25-30 per pair); inspect power cable for insulation damage or fraying.
  • Every 6 months: Lubricate pad-rotation bearings with light machine oil (~$0, 5 min maintenance); test rotation force to detect bearing wear.
  • Annually: Replace motor intake filter (~$15); deep-clean nozzle assembly and pad-holder fasteners.
05 Evidence

How much each of these is standing on.

Classifications rest on different depths of evidence. A pre-release assessment and a verified one are not the same kind of claim.

Evidence behind each classification
Robot Evidence status Sources reviewed Last assessed
HOBOT 388 Ultrasonic Verified 9 Aug 2026
Hobot R3 Pending 1 Aug 2026

Robovations classifies robots; it does not rank them. Nothing on this page is a recommendation, and no manufacturer influences a classification or its placement here.