Tyto Sensory Labs

Engineering basis

From vehicle dynamics to a tactile carrier.

MCP4SH does not choose one frequency and call it physics. It sits between three different systems: what the vehicle is doing, what our sense of touch can read, and what the rig can physically reproduce.

This page collects some of the public research and engineering context behind that way of thinking, including the driving-coaching "String Theory" analogy that inspired the name. It is supporting context, not a claim that one driving analogy or one published frequency maps directly to one haptic effect.

The short version

Interpret the event first; then choose a tactile expression that can actually work.

The natural motion of a car, the vibration that reaches a seat or steering wheel, the sensitivity of touch, and the useful range of a tactile transducer are not the same thing.

MCP4SH therefore does not try to copy every real-world frequency one-to-one. It uses vehicle state and relationships to identify useful events, then renders those events within a tactile range that can be perceived and reproduced.

Vehicle state

Tyres, suspension, chassis, drivetrain and road input evolve on their own physical time scales.

Perception

Frequency, amplitude, timing and body location all change what a vibration feels like.

Rig response

Shakers, mounts, seats, frames and pedal plates reshape the signal again.

String Theory in driving

The name starts with a driving-coaching technique: blend the inputs instead of treating them as separate switches.

In track-driving instruction, "string theory" or the "string analogy" imagines an invisible string connecting the steering wheel to the brake and/or throttle pedal. The simple lesson is that as steering demand rises, the driver generally releases some longitudinal input; as the wheel opens, more braking or acceleration capability becomes available. It is closely related to the traction-circle idea and to teaching smooth trail-brake release.

That is the inspiration behind the MCP4SH name. It is not used as a literal linear formula inside the plugin. Real cars, tyres and drivers are more complicated than the beginner analogy; advanced coaching sources explicitly account for rotation, feedback, line, timing and vehicle behaviour. MCP4SH carries forward the useful part of the idea: interpret related inputs and states as a coupled system rather than treating every signal as an isolated effect.

Why this matters to MCP4SH: the product name is about relationships. Steering and pedal inputs compete and cooperate through the tyre; MCP4SH similarly tries to make tyre, suspension, drivetrain, road and chassis cues coexist as parts of one readable vehicle state.
Teaching Trail Braking
Ross Bentley / Speed Secrets; 2021
Instructor-focused trail-braking material that explicitly introduces the "string theory" analogy alongside the friction-circle / 100% tyre concept: add steering as brake pressure is released rather than asking the tyre for peak braking and peak cornering at once.
Open PDF
Track Technique: String Theory - Blending Steering with Pedal Inputs
Greg Troester; Utah Motor News; 2023
A practical driving-instruction version using imagined strings from the steering wheel to both pedals, with examples for throttle application, trail-brake release and smooth transitions.
Read article
String Theory / Advanced String Theory
Suellio Almeida Racing Academy
Modern racing and sim-racing coaching that uses the basic steering/brake relationship as an entry point, then explicitly warns that the simple linear version is incomplete and must give way to vehicle rotation, steering feedback and the intended line.
Read lesson
String Theory - motorsport glossary
Motorsports Calendar
A concise definition of the technique as coordinated steering, braking and throttle input using the imaginary-string visualization and a shared tyre-grip budget.
Read glossary
Trail Braking; The String Theory
BoxThisLap; 2023
Sim-racing-oriented explanation connecting progressive brake release, steering input, trail braking and the imaginary string analogy.
Read article
Big Lies #5: the string analogy
Ian Korf; You Suck at Racing; 2020
Useful counterpoint: accepts the value of coordinating steering and pedal input, but argues that a fixed linear string model is too simple for real corner timing, rotation and corrections. Included because the limitation matters as much as the analogy.
Read critique
Driving the Traction Circle
Mitchell, Schroer & Grisez; SAE 2004-01-3545
Technical motorsport context for the underlying idea: longitudinal acceleration/deceleration and lateral cornering capability are combined rather than independent, and trail braking is one way a driver operates within that combined capability.
SAE paper
String Theory driving-technique video
YouTube; additional visual reference
A visual explanation of the same steering/pedal coordination idea, included as an accessible companion to the written sources.
Watch video

Frequency context

Different parts of the problem live in different bands.

Low-frequency vehicle body motion, wheel and suspension behaviour, steering-wheel vibration and tactile rendering overlap in places, but they are not interchangeable.

Body bounce / ride modes
Wheel-hop region
MCP4SH calibration window
Measured sim-wheel vibrotactile bands

This is an explanatory map, not a universal tuning chart. Hardware, mounting, body location, amplitude and individual perception all matter.

What the receiver changes

The same signal does not feel the same everywhere.

Tactile perception is frequency-dependent.

Pacinian corpuscles are one of several mechanoreceptive structures involved in vibration perception. The practical point is not that one receptor gives us a tuning table. It is that the receiving body has its own response to frequency, timing, amplitude and location.

CC0; commercial reuse permitted

Image source and licence

Histology image of a Pacinian corpuscle

The vehicle is a coupled system too.

Road input, wheel and axle motion, spring stiffness, damping and chassis movement are related. MCP4SH looks for useful relationships in the telemetry rather than treating every raw value as a separate vibration effect.

Public domain; commercial reuse permitted

Image source and public-domain notice

Public-domain vehicle suspension diagram

Vehicle movement

Movement is interpreted as a relationship, not a pile of isolated axes.

A vehicle can heave, pitch, roll, yaw, surge and sway. Those motions interact with suspension travel, load transfer, tyre state, acceleration and road input.

MCP4SH is not a replacement physics solver. It uses the state the simulator exposes, conditions it, compares related signals and translates the useful part into tactile semantics.

TelemetryConditioningSemantic eventTactile projectionRig + receiver

Earlier MCP4SH vibration research trail

Some of the sources cited while the early haptics rationale was being explained publicly.

These are part of the earlier public research trail around MCP4SH's haptic engineering rationale. They support the physical and perceptual context behind vehicle vibration, seating, steering-wheel vibration and transfer paths. They were never intended as a lookup table where one paper frequency becomes one MCP4SH effect.

Predicting discomfort from whole-body vertical vibration when sitting with an inclined backrest
Basri & Griffin; Applied Ergonomics; 2013
Experimental work across 1 to 20 Hz showing that perceived whole-body vibration depends on frequency and seating/backrest conditions.
PubMed
An Experimental Study of Vehicle 1st Order Vibration Improvement at Engine Idle
Shen et al.; International Journal of Acoustics and Vibration; 2020
Examines powertrain excitation, transfer paths, resonance and measured seat-rail vibration, including strong first and second engine-order components.
Open PDF
Micro-Doppler Signal Features of Idling Vehicle Vibrations
Signals; 2025; open access
Uses measured vehicle vibration signatures to show how mechanical state and operating conditions appear in spectral and time-frequency structure.
Open paper
A Survey Study of Steering Wheel Vibration and Sound in Automobiles at Idle
Ajovalasit & Giacomin; Engineering Integrity Society; 2008
Field measurements from 24 cars found important low-frequency harmonic content in steering-wheel vibration, with substantial energy in roughly the 20 to 40 Hz region and strong dependence on engine and vehicle structure.
Open PDF

Additional research

More context for perception, dynamics and sim-racing haptics.

Decoding the Feeling
Murphy, Campbell & Toth; Sensors; 2025; CC BY 4.0
Direct measurement of force and vibrotactile content from a sim-racing wheel; useful for separating low-frequency steering motion from higher vibrotactile bands.
Open paper
Audio-Tactile Rendering Review
Open-access review
Broad context for vibrotactile perception, body-site differences and why frequency, amplitude and placement cannot be considered independently.
Open review
Importance of Spike Timing in Touch
Neuroscience review
Useful support for treating temporal structure and tactile frequency selectivity as information rather than amplitude alone.
Open paper
Transmission of fore-aft vibration to a car seat
Qiu & Griffin; Journal of Sound and Vibration; 2003
Reports coupled seat/body resonance regions around 4 to 5 Hz, 25 to 30 Hz and 45 to 50 Hz; useful evidence that the receiver and seat system reshape vibration.
Research record
Quarter-car active suspension model
Machines; 2023; open access
A clear example of sprung and unsprung mass relationships between road input, wheel/axle and chassis response.
Open paper
Tire-road interaction review
Machines; 2024; open access
Background for why load, slip, road state and contact behaviour should be treated as a coupled problem rather than one raw scalar.
Open review

Research honesty

What these sources support; and what MCP4SH does not claim.

SupportedNot claimed
Tactile sensitivity depends on frequency, amplitude, timing and body location.One receptor curve gives a universal "correct" frequency for an effect.
Vehicle vibration contains identifiable modes, harmonics, resonances and transfer paths.MCP4SH reproduces every natural vehicle frequency one-to-one through a shaker.
Steering wheels, seats and sim-racing interfaces can carry useful information across multiple vibration bands.One published band is optimal for every device, body location, rig and effect.
Hardware and receiver response materially change what reaches us.Research papers remove the need for calibration, empirical testing or subjective validation.
The driving "string theory" analogy is a useful teaching model for coordinated steering and pedal input within a shared traction limit.Steering and pedal inputs follow one universal linear ratio, or MCP4SH uses that coaching analogy as a literal effect formula.
Preserve the event. Adapt the carrier. The research helps define the problem. MCP4SH's job is to make the resulting cues coherent, readable and useful on a real rig.