How it works

Your head tilt travels through four small pieces of hardware to the piano pedal.

1
Head tilt
ARKit / TrueDepth face tracking on iPhone or iPad measures your head angle.
2
iOS app
Maps the angle to a pedal value and paces the radio over Bluetooth (BLE).
3
BLE board (nRF52)
Receives the value and bridges it over UART to the controller.
4
Pico (RP2040)
Drives the motor (Pro) or closes the switch (Switch) — the pedal moves.

System architecture: head tilt → iOS app → BLE board → Pico → piano pedal

The “airback” — a coined term, not “airbag”

The Pro’s “airback” is bFaaaP’s inflatable, air-braced anchor — not an “airbag”. An air cushion (a WINBAG air jack, inflated by a small electric pump inside the device through an air tube) inflates under a neighbouring pedal and absorbs the actuator’s reaction force, so the device stays firmly in place on an unmodified acoustic piano: no bolts, non-destructive, and quick to set up and remove. The name joins air + back (to brace / support), emphasising anchoring rather than the safety meaning of “airbag”.

Schematic: a single wide “airback” cushion under the two left pedals anchors the Pro device against the reaction force of pressing the right sustain pedal; the drive unit sits on that pedal; no bolts — The airback reaction-force anchoring (schematic). © Shishido & Associates (CC BY 4.0).

A neat design point: ARKit produces head angles much faster than Bluetooth should send them, so the app paces the radio (a 100 ms timer plus a throttle) to keep the link rock-solid.

What is bFaaaP?

Your threshold and multiplier: Calibrate the tilt angle and multiplier; together they set how fast the pedal follows you, so it feels like yours.
On-device AI: ARKit / TrueDepth face tracking runs on the iPhone or iPad — no cloud, low latency.
For everyone: Built with and for players who can’t use a foot pedal — and open to all.

A small head tilt is the key that unlocks the player’s own intended, natural pedalling — The control law is the key: a small head tilt — shaped by the offset and multiplier you preset — unlocks your own intended, natural pedalling, and this specific, tunable law is what made bFaaaP patentable. Illustration: AI illustration by Harmonia in Saki Shiokawa’s style © Shishido & Associates.

The control law, precisely (paper Figures 3 & 4)

Figure 3: (a) head angle above the offset maps linearly to the pedal value, clamped at 99; (b) engage/release hysteresis with a dead-band — Figure 3 — the control law. (a) Above your neutral offset the head angle maps linearly to the pedal value (0–99), scaled by your multiplier and clamped at full; (b) engage and release use a small hysteresis dead-band, so the pedal never chatters. (Figure in English.) © Shishido & Associates (CC BY 4.0).

Figure 4: bFaaaP’s proportional, user-tunable command (two slopes) versus binary prior-art on/off at a single threshold — Figure 4 — why it is patentable. Prior art was a binary on/off head switch (dashed step); bFaaaP sends a continuous, proportional command whose dead-zone (offset 3–10°) and slope (multiplier 10–50) each player presets — the quantitative, user-tunable law the patents were granted on. (Figure in English.) © Shishido & Associates (CC BY 4.0).

Read the architecture on GitHub ↗

Does it really work? The APEE study

We ran a human-subject study — the Auxiliary Pedal Effect Evaluation (APEE) — with 15 participants: adults, children whose feet don’t reach the pedals, and people with disabilities.

Children and a player in a wheelchair taking the friendly APEE piano test, with a smartphone on the music stand and the pedal device on the floor — An APEE session (illustration). AI illustration by Harmonia in Saki Shiokawa’s style © Shishido & Associates.

How we measured it

Each participant played the same short motif three ways — no pedal, bFaaaP pattern 1 (re-pedal each three-note group) and pattern 2 (held across groups) — and we recorded each take. We measured the tone-vibration area (TVA), the shaded area of the waveform, and normalized every recording to its own no-pedal take (TVA₀ ≡ 1.00). Sustain score = TVAₙ / TVA₀.

The APEE pipeline: score with two pedalling patterns, record three takes, measure tone-vibration area, normalize, relative sustain score — The APEE method end to end (paper figure). © Shishido & Associates (CC BY 4.0). (Figure in English.)

The APEE test score: a short three-note motif, played with pattern 1 (re-pedal each three-note group) and pattern 2 (one pedal held across the groups), with the pedal marks shown under the staff — The test score and the two pedalling patterns each participant played — pattern 1 re-pedals every three-note group; pattern 2 holds one pedal across the groups (paper figure). © Shishido & Associates (CC BY 4.0). (Figure in English.)

Three waveforms — no pedal (area 1.00), pattern 1 (1.59), pattern 2 (1.80) — more tone-vibration area with more pedal — Measuring sustain from the tone-vibration area; study means 1.00 / 1.59 / 1.80 (paper figure). © Shishido & Associates (CC BY 4.0).

What we found

bFaaaP significantly increases sustained-tone energy — both patterns beat no pedal (p < 0.01).
It is statistically indistinguishable from the player’s own foot (p > 0.05, “n.s.”).
No significant difference across participant classes. One participant with a leg disability and a tracheostomy performed successfully.

APEE results: (a) both bFaaaP patterns significantly increase sustain (p<0.01); (b) bFaaaP vs. own foot shows no significant difference — APEE clinical results (paper figure). © Shishido & Associates (CC BY 4.0).

The full anonymized data (Appendix A)

All 46 recordings, participants anonymized as No. 1–15, with each player’s chosen offset and multiplier and the relative sustain of patterns 1 and 2.

Appendix A — full anonymized APEE per-recording data: 46 recordings across adults, children and people with disabilities — Appendix A — full anonymized APEE data (No. 1–15, 46 recordings). © Shishido & Associates (CC BY 4.0).

Ethics & consent

Participation was voluntary, and written informed consent was obtained for every participant: adults consented themselves; the children signed after a parent or guardian confirmed consent through their piano teacher; and participants with disabilities took part with a parent or guardian’s consent, who also accompanied them. No formal ethics-board (IRB) approval was available, but the study followed the ACM policy on research with human participants, and all data are anonymized.

Ethics & consent on GitHub ↗

Read the full APEE study on GitHub ↗

The controller as a reusable accessibility input

bFaaaP’s smartphone controller — a quantitative, user-tunable head-angle channel on commodity hardware — is the most reusable part. The same controller already drives two actuators (a motor on the Pro, an electronic switch on the Switch), and the device-controller method is patented independently of the pedal, covering “any device.”

Foot-free — it doesn’t need the lower limbs that wheelchair users often can’t use.
Nothing on the face or head — the phone sits on a stand (important with a tracheostomy).
Tunable to a restricted range of motion — a small offset with a large multiplier lets a few degrees of head movement span the full output.

Because the head-angle signal is a continuous, proportional value (not a single on/off switch), it is a general accessibility-control primitive: the same channel could meter other graded controls (environmental control, a communication-aid scan rate, a powered-device level). We present this as future work — bFaaaP is validated for piano pedalling; broader assistive control is not yet validated.

These populations are large and worldwide. The figures below come from heterogeneous surveys with different definitions/metrics and are not strictly comparable — they convey scale, not a ranking. (WHO gives only a single global wheelchair estimate, not a country-by-country table.)

Wheelchair users (or people who need a wheelchair), by region

Region	Estimate	Source
World	~80 million (~1%) need a wheelchair	WHO
USA	3.6 million users (1.5%, 15+), 2010	US Census
UK (England)	~1.2 million users (est.), 2017	NHS England
Canada	288,800 wheelchair/scooter users (~1%), 2012	Smith et al.
Japan	~818,000 manual wheelchairs in use (~0.6%), 2019	Shirogane et al.
Australia	~119,000 manual users (65+); 679,000 mobility-aid users, 2018	AIHW/ABS

Home mechanical ventilation (HMV) & invasive subset, by country

Country	HMV	Invasive	/100k	Source
Japan	~21,000	7,700 (TPPV)	—	MHLW 2020
Europe (16)	21,526	varies	6.6	Eurovent 2005
Canada	4,334	~18%	12.9	Rose 2015
Poland	12,616	—	2.8→20	JCM 2022
Hungary	384	40 (10.4%)	3.9	BMC 2018
South Korea	—	62.8% trach.	9.3	Resp. Care 2019
Germany	~17,000/yr*	~6%	—	Dtsch. Ärztebl. 2021
USA	no registry	—	—	Mehta 2015

Metrics differ and are not strictly comparable. *inpatient episodes/year; USA has no national home-ventilation registry.

Cited works

Verified June 2026. Full list and saved copies are in the open-source repository.

WHO. WHO releases new wheelchair provision guidelines. 2023. link
WHO & UNICEF. Global Report on Assistive Technology. 2022. link
Brault M. Americans With Disabilities: 2010. US Census Bureau P70-131, 2012. link
NHS England. Wheelchair services. link
Smith EM, et al. Prevalence of Wheelchair and Scooter Use Among Community-Dwelling Canadians. Phys Ther 96(8):1135, 2016. link
Shirogane S, et al. Provision of public funding for wheelchairs… in Japan. J Phys Ther Sci 31(2):122, 2019. link
AIHW. People with disability in Australia (ABS SDAC 2018). link
MHLW (Japan). Nationwide home mechanical-ventilation survey (2020). link
Lloyd-Owen SJ, et al. Patterns of home mechanical ventilation use in Europe (Eurovent). Eur Respir J 25(6):1025, 2005. link
Rose L, et al. Home Mechanical Ventilation in Canada: A National Survey. Respir Care 60(5):695, 2015. link
Czajkowska-Malinowska M, et al. Home Mechanical Ventilation in Poland 2009–2019. J Clin Med 11(8):2098, 2022. link
Valkó L, et al. National survey: home mechanical ventilation in Hungary. BMC Pulm Med 18:190, 2018. link
Kim H-I, et al. Home Mechanical Ventilation Use in South Korea. Respir Care 64(5):528, 2019. link
Schwarz SB, et al. Inpatient Initiation and Follow-up of Home Mechanical Ventilation in Germany. Dtsch Arztebl Int 118(23):403, 2021. link
Mehta AB, et al. Trends in Tracheostomy for Ventilated Patients in the US, 1993–2012. Am J Respir Crit Care Med 192(4):446, 2015. link
bFaaaP device-controller patent JP 7004771 B2 (covers “any device”). link

References & archived copies on GitHub ↗