How Self-Balancing Vehicles Warn Users Before They Tip Over
A safety system for self-balancing vehicles that monitors how much 'room' the machine has left to accelerate before it loses its ability to stay upright.
Original patent title: “Personal mobility vehicles and methods”
A safety system for self-balancing vehicles that monitors how much 'room' the machine has left to accelerate before it loses its ability to stay upright. Granted to Deka Products LP in 2001 with 9 claims and 172 forward citations, and it is now in the public domain.
Key facts
Coverage
What does this patent actually cover?
This patent describes a safety mechanism for vehicles that are inherently unstable, like a Segway. Because these machines rely on active motors to stay upright, they have a physical limit to how fast they can accelerate to compensate for a lean. The system calculates a 'balancing margin'—the gap between the vehicle's current speed and the maximum speed it can reach while still maintaining balance. If that gap gets too small, the system triggers an alarm, such as a beeping sound or a physical 'ripple' vibration in the motors, to warn the rider to slow down.
The gap
What does this patent NOT cover?
- Does not cover vehicles that are inherently stable, such as four-wheeled cars or bicycles with kickstands.
- Does not cover systems that automatically stop the vehicle without providing a warning to the user.
- Does not cover non-motorized balancing devices like a standard unicycle or tightrope walker.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
What made this novel
The system treats 'acceleration potential' as a finite resource, effectively quantifying the safety buffer of a dynamic system that would otherwise be invisible to the rider.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Segway Personal Transporter (PT)
Self-balancing hoverboards
Electric unicycles
Why it matters
The bigger picture
This technology was essential for the commercial viability of the Segway PT. Without this safety 'headroom' monitor, a rider could unknowingly push the machine to its physical limit, causing the motors to lose their ability to balance and leading to a sudden fall. It established the standard for how active-balancing personal transport devices manage user safety.
Filed
June 4, 1999
Granted
October 16, 2001
Market context
Who's building on this
Companies in this space
Deka Products, founded by Dean Kamen, pioneered this technology. Today, companies producing electric unicycles and various personal mobility devices continue to rely on the fundamental principles of active balancing and safety monitoring established in this patent familypatent familyA group of related patents covering the same invention in different countries or as continuations.Read more →.
Market impact
This patent helped define the safety standards for the personal mobility market. It forced manufacturers to implement active feedback loops between the machine's internal sensors and the rider, effectively creating a new category of 'smart' vehicles that communicate their physical limitations to the operator.
Claim 1 — Plain English
What this patent covers
This patent describes a safety mechanism for vehicles that are inherently unstable, like a Segway. Because these machines rely on active motors to stay upright, they have a physical limit to how fast they can accelerate to compensate for a lean. The system calculates a 'balancing margin'—the gap between the vehicle's current speed and the maximum speed it can reach while still maintaining balance. If that gap gets too small, the system triggers an alarm, such as a beeping sound or a physical 'ripple' vibration in the motors, to warn the rider to slow down.
The clever bit
The system treats 'acceleration potential' as a finite resource, effectively quantifying the safety buffer of a dynamic system that would otherwise be invisible to the rider.
What it does not cover
- Does not cover vehicles that are inherently stable, such as four-wheeled cars or bicycles with kickstands.
- Does not cover systems that automatically stop the vehicle without providing a warning to the user.
- Does not cover non-motorized balancing devices like a standard unicycle or tightrope walker.
Patent Journey
From filing to expiry
PatentBrief Score
Impact Score
Moderate
Citation count
40/40
Highly cited
Claim breadth
6/20
Moderate scope
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$51K – $162K
Midpoint $101K · expired or expiring · industry ×0.9
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
The original legal language
Original claims
9 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Kamen, D. L., Ambrogi, R. R., Duggan, R. J., Field, J. D., Heinzmann, R. K., Amesbury, B., & Langenfeld, C. C. (2001). How Self-Balancing Vehicles Warn Users Before They Tip Over (U.S. Patent No. 6,302,230). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/6302230/segway-personal-transporter
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
Embed
Add this patent to your site
Drop this plain-English patent card into any blog post or article — free, no signup. It always links back to the full breakdown here.
<div data-patentlens-widget data-patent-number="US6302230"></div> <script src="https://patentbrief.org/embed.js" async></script>
Stay in the loop
Get a weekly digest of new patents.
One email per week. No spam. Unsubscribe anytime.
Keep exploring
Related patents you should know
US 4683195 · 1987
How to Make Billions of Copies of a DNA Segment
This patent describes the Polymerase Chain Reaction (PCR), a method to rapidly create many copies of a specific piece of DNA or RNA, enabling its detection and analysis.
Cetus Corp
US 8697359 · 2014
How to Edit Genes in Human Cells Using an Engineered CRISPR System
This patent describes an engineered CRISPR-Cas9 system for precisely cutting DNA in eukaryotic cells to change how genes work, opening the door for gene editing in complex organisms.
Massachusetts Institute of Technology
US 7657849 · 2010
How the iPhone's Slide-to-Unlock Gesture Works
Apple's 2010 patent describes unlocking a device by dragging a specific graphical image across the touchscreen along a predefined path, a gesture that became iconic with the original iPhone.
Apple Inc
US 4733665 · 1988
How Doctors Implant a Permanent Stent Using a Balloon
This patent describes the method for placing a permanent, expandable wire mesh tube inside a blood vessel or other body tube using a balloon-tipped catheter to widen it and keep it open.
Expandable Grafts Partnership
US 4405829 · 1983
How RSA Public-Key Encryption Keeps Digital Messages Secret
This patent describes the foundational RSA algorithm, a method for securely sending messages where anyone can encrypt a message using a public key, but only the intended recipient can decrypt it using a secret private key.
Massachusetts Institute of Technology
US 4575330 · 1986
How 3D Printers Build Objects Layer by Layer from Liquid
This patent describes the foundational method for 3D printing, where a machine builds a three-dimensional object layer by layer by hardening a liquid material with light or other energy.
UVP Inc
Semantically similar
You might also find these interesting
US 3552770 · 1971 · Eaton Yale and Towne Inc
How Early Vehicle Airbag Safety Systems Work
US 6883201 · 2005 · iRobot Corp
How the iRobot Roomba Automatically Cleans Floors Without Falling Down Stairs
US 31128 · 1861 · Elisha G. Otis
How Elisha Otis Invented the Modern Safety Elevator
US 37305 · 1863 · James L. Plimpton
How James Plimpton Invented the Modern Roller Skate
More to explore
More in Consumer Electronics
US 7657849 · 2010 · Apple Inc
How the iPhone's Slide-to-Unlock Gesture Works
US 7479949 · 2009 · Apple Inc
How Touchscreens Understand Your Finger Swipes and Scrolls
US 4528643 · 1985 · FPDC Inc
How Stores Make Custom Products On-Demand with Remote Approval
US 7469381 · 2008 · Apple Inc
How Touchscreens Show and Snap Back When You Scroll Past an Edge
New to patents?
Common Questions
Frequently Asked Questions
What does How Self-Balancing Vehicles Warn Users Before They Tip Over cover?
A safety system for self-balancing vehicles that monitors how much 'room' the machine has left to accelerate before it loses its ability to stay upright.
Who owns patent US 6302230?
Deka Products LP owns this patent, granted in 2001.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 6302230 cited by?
This patent has been cited by 172 later patents that build on its ideas.
What problem does this patent solve?
This technology was essential for the commercial viability of the Segway PT. Without this safety 'headroom' monitor, a rider could unknowingly push the machine to its physical limit, causing the motors to lose their ability to balance and leading to a sudden fall. It established the standard for how active-balancing personal transport devices manage user safety.
What does this patent NOT cover?
Does not cover vehicles that are inherently stable, such as four-wheeled cars or bicycles with kickstands.
Patent monitoring