La conception du moteur de roue AGV expliquée: Comment est conçue une roue motrice intégrée
An AGV wheel motor is far more than a motor with a wheel bolted on. This guide disassembles the integrated drive wheel—motor, boîte de vitesses, frein, encoder and bearing—and explains the engineering trade-offs that decide torque density, efficacité, precision and service life.
Réponse rapide
Un AGV wheel motor (also called a wheel drive motor or integrated drive wheel) combines a BLDC or servo motor, a planetary gearbox, an electromagnetic brake, an encoder and a polyurethane-tread wheel into a single sealed module. The dominant AGV design is a BLDC + planetary gearbox integrated into the wheel hub, because it delivers 75–88% battery-to-floor efficiency and the highest torque density for the available envelope. UN direct-drive wheel (coreless torque motor in the rim) is chosen only when backlash-free motion is mandatory; un steering-wheel assembly adds a second motor on a vertical axis for full omnidirectional control. Selection hinges on payload, cycle de service (IEC S1–S4), required positioning accuracy, and IP/sealing for the floor environment.
What Is an AGV Wheel Motor?
An AGV wheel motor is the electromechanical traction unit at the bottom of an automated guided vehicle. Unlike an industrial motor bolted to mains power, it runs from a 24/48 V battery bus, survives thousands of start-stop cycles per day, and must provide closed-loop position feedback for navigation. Le terme wheel drive motor is used interchangeably, but it technically refers to the complete assembly—not just the motor element.
A modern integrated drive wheel is built from six subsystems, each with its own engineering specification:
| Subsystem | Fonction | AGV design requirement |
|---|---|---|
| Motor element | Converts DC battery power → mechanical torque | BLDC preferred; 85–92% efficiency at 24/48 V; high continuous & couple maximal |
| Boîte de vitesses | Multiplies torque, reduces speed to wheel RPM | Planétaire, 92–97% per stage, 5–15 arc-min backlash, coaxial |
| Frein | Holds position on slope / e-stop | Electromagnetic, 24 V, power-off engaged |
| Encodeur / Salle | Vitesse & position feedback for dead-reckoning | 500–4096 PPR (incrémentiel) or 17–24 bit absolute |
| Palier & logement | Carries radial/axial wheel load, seals contaminants | ≥IP54 (IP65 for wet/dusty); radial load rating > dynamic cornering load |
| Wheel tread | Transmits torque to floor | Polyurethane 90–95 Shore A; profile matched to floor & charger |
See Components of an AGV Vehicle for the full subsystem map, et How AGV Drive Systems Work for the power-chain context.
How an AGV Wheel Motor Is Designed — Step by Step
The engineering of a wheel motor proceeds from the outside in. Each step constrains the next, which is why off-the-shelf modules are usually specified rather than fully custom-built.
Étape 1 — Define the load envelope
The wheel diameter, tread width and maximum installed height are fixed first by the AGV chassis. A 150–250 mm wheel is typical; the motor-gearbox stack must fit inside or behind it. This envelope dictates the maximum motor outer diameter and gearbox stage count.
Étape 2 — Select the motor magnetic design
For battery AGVs, un BLDC with surface-mounted magnets and a slotted stator is the default. The speed constant n₀ = kₙ × U links battery voltage to no-load speed: un 48 V motor reaches roughly double the no-load speed of a 24 V unit of the same winding. Low-voltage, high-torque designs use a longer stator stack and more pole pairs to raise torque density without exceeding the voltage bus.
Étape 3 — Choose the gearbox topology
UN planetary reduction is almost universal inside AGV wheels. It gives the highest torque density for a given outer diameter, keeps input and output coaxial (inline motor → gearbox → wheel), and reaches 92–97% efficiency per stage. Engrenages à vis sans fin (50–85%) are avoided because a 70% gearbox wastes 30% of motor energy as heat—unacceptable for a battery vehicle.
Étape 4 — Size the bearing and shaft
The bearing assembly carries the entire radial wheel load plus cornering and braking thrust. In a forklift-class drive wheel a single bearing can see >7,000 N under dynamic cornering. Durée de vie des roulements, not motor torque, is frequently the limiting design parameter for heavy AGVs.
Étape 5 — Place the feedback device
Motor-shaft Hall sensors handle commutation; a higher-resolution encoder (incremental or absolute) on the motor or wheel shaft feeds odometry. For sub-degree or ±0.1 mm docking, a 17–24 bit absolute encoder is required.
Étape 6 — Seal and thermally manage
The module is sealed to IP54 (IP65 for wet/dusty floors) against floor-level dust and moisture. Heat is generated mainly in the stator windings, which sit against the housing for efficient conduction—one reason BLDC runs cooler than brushed DC.
Wheel Motor Architecture Comparison
Four integration topologies compete for the AGV traction role. The table contrasts them on the parameters that matter for design.
| Paramètre | Integrated hub (BLDC + planétaire) | Modular (moteur + separate gearbox) | Direct-drive wheel (coreless torque motor) | Steering-wheel assembly |
|---|---|---|---|---|
| Typical payload | 50–1,000 kg | 500 kg – 3,000+ kg | <500 kg (à basse vitesse) | 1,000–3 000kg |
| Contrecoup | 5–15 minutes d'arc | 5–15 minutes d'arc | ~0 (back-drivable) | 5–15 minutes d'arc |
| End-to-end efficiency | 75–88% | 75–88% | 88–93% (no gear loss) | 73–86% |
| Conditionnement / rigidité | Haut (few interfaces) | Moyen | Haut | Haut (horizontal motor) |
| Précision | ±0.5–2 mm | ±0.5–2 mm | ±0.1 mm | ±0.5–2 mm |
| Coût (relative) | Moyen | Moyen à élevé | Haut | Haut |
| Idéal pour | Entrepôt AMR, towing | Heavy forklift AGV | Précision, human-near | Palette, omnidirectional |
Coaxial vs right-angle gearbox is a secondary choice: coaxial keeps the motor inline with the wheel for the lowest profile; angle droit (bevel or worm) turns the motor axis to save width where chassis height is available. For AGV wheels, coaxial planetary is dominant.
Données d'ingénierie & Formules
Efficiency chain — from battery to floor
For a geared BLDC wheel motor, end-to-end efficiency is the product of each stage:
| Stage | Efficacité typique | Loss mechanism |
|---|---|---|
| Manette (FOC) | ~97% | Switching & conduction I²R |
| Moteur BLDC | 85–92% | Copper + iron + friction |
| Réducteur planétaire | 92–97% / organiser | Gear mesh & churn |
| Wheel-to-floor | ~96% | Tread slip & hysteresis |
| Battery-to-floor | 75–88% | — |
Core design formulas
| Quantité | Formule | Remarques |
|---|---|---|
| Wheel output torque | T_wheel = T_motor × i × η_g | i = rapport de démultiplication, η_g = gearbox efficiency |
| Required motor torque | T_motor = T_wheel / (i × η_g) | Derated from wheel torque |
| Traction force | F = T_wheel / r_wheel | r_wheel in metres |
| Total drive force (y compris. accel) | F_total = W·μ_r + W·sinθ + m·a | W=weight, μ_r=roll coeff., θ=grade, a=accel |
| Puissance du moteur | P = (T × n) / 9550 | P in kW, T in N·m, n in rpm |
| End-to-end efficiency | η_e2e = η_ctrl × η_motor × η_gear × η_wheel | Multiply stage efficiencies |
Worked example — 500 kg warehouse AMR
Given: total loaded mass 500 kg, 200 mm wheel (r = 0.1 m), 3% grade, 25:1 planetary gearbox at η_g = 0.95, 48 V bus.
- W = 500 × 9.81 = 4,905 N; F_roll = 4,905 × 0.015 = 73.6 N; F_grade = 4,905 × 0.03 = 147.2 N
- F_total per motor (two driven wheels) = (220.8 / 2) = 110.4 N
- T_wheel = 110.4 × 0.1 = 11.0 N·m; T_motor = 11.0 / (25 × 0.95) = 0.46 N·m continuous
- Apply 2× safety factor → ~0.92 N·m peak motor torque. A BLDC planetary wheel motor ≥ 1 N·m peak at 48 V with 25:1 meets this.
CEI 60034-1 duty types for AGV wheels
| Devoir | Thermal behaviour | AGV relevance |
|---|---|---|
| S1 | Continu, reaches thermal equilibrium | 24/7 fleets, convoyeurs |
| S3 | Périodique intermittent (starting ignored) | Single-shift, stop-and-go AMR |
| S4 | Intermittent with frequent starting | Frequent start/stop towing AGV |
| S5 | Intermittent with braking | Rapid positioning, regenerative stop |
| S6 | Continuous with load/unload cycles | Mixed-load transport |
Efficiency classes — IEC 60034-30-1 vs NEMA MG 1
| IEC class | NEMA equivalent | Efficacité typique | AGV note |
|---|---|---|---|
| IE1 | Standard | Phase-out | Not acceptable for new AGV |
| IE2 | Haute efficacité | ≥88.7% | Minimum for <0.75 kW |
| IE3 | NEMA Premium® | ≥90.4% | Baseline for AGV drive motors |
| IE4 | Super prime | ≥92.6% | Specified for energy-critical fleets |
| IE5 | — | Emerging | Commercial, not yet mandated |
PAS DE MG 1 defines minimum nominal efficiency in Tableau 12-12 for general-purpose AC motors (1–500 hp) and permits a ±20% (§12.58) tolerance on efficiency test results—use nameplate IE3/IE4 and verify with a dynamometer test report. Under the U.S. DOE/EISA framework, PAS de prime (IE3) is the federally enforced minimum, with IE4 expanding from 2027.
Manufacturer benchmark data
| Source | Produit | Key figures |
|---|---|---|
| Maxon | Wheel Drive MW500 | ≤500 kg/wheel; 11.4–23.7 N·m cont.; 30–60 V; IP54; 1024 cpt encoder; integrated brake |
| FAULHABER | DualGear (BX4 + GPT) | Ø32 mm; 1.1 N·m cont. / 7 N·m peak; ≤0.6° backlash; −30…+120 °C; 4-pôle |
| Yaskawa | Sigma-7 SGM7D | 1.3–240 N·m; 30–360 rpm; 24-bit encoder; 3.1 kHz bandwidth; 350% overload 3–5 s; STO SIL3 |
| SKF | E2 Energy Efficient bearing | 30–50% lower friction vs standard; up to 3× life (Explorer class); drop-in for IEC frames to 355 |
Best Applications for Each Wheel Motor Design
| AGV type | Recommended wheel motor | Pourquoi |
|---|---|---|
| Light shelf AMR (50–300 kg) | Integrated BLDC hub, 24 V | Compact, faible coût, sufficient torque |
| Warehouse towing / pallet (300–1,000 kg) | Integrated BLDC hub, 48 V, 25:1 | Balanced torque, efficacité, emballage |
| Forklift / heavy AGV (1–3 t) | Horizontal steering-wheel assembly, 48–72 V | High radial load rating, pilotage + traction |
| Précision / human-near AMR | Direct-drive or QDD wheel | Backlash-free, smooth low-speed |
| Omnidirectional (mecanum) | 4× integrated BLDC hub + mecanum tread | Lateral/diagonal motion, 4-axis control |
For platform-level guidance, voir Types d'AGV utilisés dans les entrepôts modernes et Meilleurs types de moteurs pour les AGV et les robots mobiles.
Step-by-Step Wheel Motor Selection
- Fix the envelope. Diamètre de roue, tread width and installed height from chassis drawings.
- Compute required wheel torque. Utiliser
T_wheel = F_total × r / n_drivenwith rolling, grade and acceleration resistance; add 2× peak factor. - Pick the gear ratio. Back-calculate
i = T_wheel / (T_motor × η_g)from a candidate motor’s continuous torque. - Select voltage & duty. 24 V for ≤300 kg, 48 V for 300–1,500 kg, 72 V+ above. Match IEC S1/S3/S4 to the duty profile.
- Vérifier la marge thermique. Confirm continuous torque at ambient + derating; check insulation class F (155 °C) hauteur sous plafond.
- Specify feedback & frein. 500–1000 PPR for navigation; 17–24 bit absolute for ±0.1 mm docking; power-off brake for slopes.
- Confirm IP & bearing rating. IP54 minimum, IP65 for wet/dusty; radial load rating > dynamic cornering load.
Start the calculation from Comment choisir un moteur pour les applications AGV, then validate with Guide de calcul du couple du moteur AGV et Guide de sélection de la vitesse et du régime du moteur AGV.
Erreurs d'ingénierie courantes
| Erreur | Conséquence | Correct approach |
|---|---|---|
| Sizing on peak torque only | Thermal overload in continuous S1 duty | Verify continuous torque > RMS over the duty cycle |
| Choosing worm-gear reduction | 30% gearbox loss, short battery life | Specify planetary (92–97%/stage) |
| Ignoring bearing radial load | Premature bearing failure on heavy AGV | Rate bearing above dynamic cornering load |
| Under-specifying encoder | Poor odometry, positioning drift | ≥500 PPR; 17–24 bit for precision docking |
| Running 48 V motor on 24 V bus | Half no-load speed, low-efficiency zone | Match motor rated voltage to battery bus |
| Skipping IP sealing | Dust/moisture ingress, early failure | IP54 min, IP65 for wet/dusty floors |
| No power-off brake on slopes | Roll-away on e-stop / grade | Specify electromagnetic 24 V brake |
| Overlooking gearbox efficiency in torque math | Undersized motor by 5–8% | Include η_g in T_motor = T_wheel/(i·η_g) |
Tableau de dépannage
| Problème | Cause | Solution | Subsystem |
|---|---|---|---|
| Overheating in continuous run | Duty S3 motor in S1 service | Reselect for S1 or add duty margin | Moteur |
| Défaillance prématurée des roulements | Radial load > bearing rating | Up-size bearing or add 2nd driven wheel | Palier |
| Positioning drift | Low encoder resolution | Increase PPR / use absolute encoder | Encodeur |
| Autonomie courte de la batterie | Worm/low-efficiency gearbox | Switch to planetary, raise IE class | Boîte de vitesses |
| Wheel slip on start | Traction < required force / low μ | Verify F = T_wheel/r; add preload | Wheel/tread |
| Excess noise | Worm or spur gear whine | Use helical planetary; check backlash | Boîte de vitesses |
| No holding on slope | Brake not specified | Add power-off electromagnetic brake | Frein |
| Pénétration d'humidité | IP below environment | Upgrade to IP65, reseal housing | Logement |
| Overcurrent trip on accel | Peak torque exceeds controller | Match controller I²t to motor peak | Manette |
| Commutation jitter | Hall misaligned / degraded | Recalibrate or replace Hall/encoder | Feedback |
Foire aux questions
An AGV wheel motor (integrated drive wheel) packages a BLDC or servo motor, a planetary gearbox, an electromagnetic brake, a Hall/encoder feedback device, and a polyurethane-tread wheel into one sealed module. In a steering-wheel assembly a separate steering motor rotates the whole unit about a vertical axis.
For most AGVs below 1 ton, the integrated hub motor wins on packaging, stiffness and reduced wiring. Separate motor-plus-gearbox designs remain useful for very high torque applications where a single integrated module would be mechanically oversized, or where the motor must be mounted away from floor contamination.
Planetary gearboxes give the highest torque density for a given outer diameter (critical because the motor-gearbox-wheel stack must fit in a tight wheel envelope), provide coaxial input/output for an inline assembly, and reach 92–97% efficiency per stage versus 50–85% for worm drives.
Un BLDC + planetary wheel motor typically delivers 75–88% from battery to floor: controller FOC ~97%, motor 85–92%, planetary gearbox 92–97% per stage, wheel-to-floor ~96%. Worm-gear designs lose 30% in the gearbox alone and are not recommended for battery AGVs.
24/7 fleets run S1 continuous; single-shift or stop-and-go fleets are typically S3 (intermittent) ou S4 (intermittent with frequent starting). The thermal class and duty rating must match the actual load profile or the winding will overheat.
500–1000 PPR at the motor shaft is sufficient for standard planetary reduction. High-resolution 17–24 bit absolute encoders (par ex., Yaskawa 24-bit, FAULHABER 15-bit SSI) are used when ±0.1 mm docking or sub-degree positioning is required.
Why Choose GreenSky Power for Your AGV Wheel Motor?
GreenSky Power has designed and manufactured motion-control solutions for AGV and AMR builders since 2011, serving OEM customers in over 50 des pays. For wheel motor design and sourcing, we provide:
- Integrated or modular, your call — BLDC and servo wheel motors in hub-integrated or motor-plus-gearbox configurations, with planetary, right-angle and worm options where the application demands it.
- One supplier, both architectures — pair our BLDC/servo platforms with planetary gearboxes (voir Gear Motor vs Direct Drive for AGVs et Spur vs Planetary Gear Motor).
- AGV-specific engineering support — send mass, vitesse, accélération, slope and wheel diameter; our team returns a calculation sheet with recommended motor, gearbox and controller specs. Start at Moteur pour AGV et De combien de couple un AGV a-t-il besoin?.
- Conformité aux normes — all motors tested per IEC 60034 et GB/T 1032, with dynamometer test reports; insulation class F (155 °C) standard.
- Efficacité & battery focus — IE3/IE4-capable BLDC platforms and planetary drives for maximum battery runtime; voir Efficacité du moteur AGV et autonomie de la batterie.
- Global supply — experienced with EU CE/LVD/EMC and North-American compliance for AGV motor supply to Europe et au-delà.
Références & Authority Sources
- CEI 60034-1 motor duty types S1–S10 (AGV thermal/duty reference): industrialmonitordirect.com — IEC S1–S10 Motor Duty Ratings Explained
- PAS DE MG 1 motor efficiency classes & Tableau 12-12 (IE/NEMA mapping): electricneutron.com — Understanding Motor Efficiency (NEMA vs IEC)
- NOUS. BICHE / EISA NEMA Premium (IE3) enforcement & IE4 roadmap: fujielectric.com — Overseas High Efficiency Regulations Compliant Motors (USA/Canada)
- IEA Energy Efficiency 2025 (industrial motor systems, IE classes): iea.org — Energy Efficiency 2025 (PDF)
- SKF Energy Efficient (E2) deep-groove ball bearings for motors: skf.com — E2 Electric Motors Offer Sheet (PDF)
- Siemens digital factory for electric motor manufacturing (Digital Twin, qualité): siemens.com — Electric Motor Factory Bad Neustadt (Digital Enterprise)
- Maxon Wheel Drive MW500 (AGV/AMR integrated drive wheel): maxongroup.com — maxon Wheel Drive MW500 Flyer (PDF)
- FAULHABER DualGear (BX4 + planetary GPT for logistics wheels): faulhaber.com — FAULHABER DualGear for Logistics
- Yaskawa Sigma-7 servo & direct-drive motors (24-bit encoder, 3.1 kHz bandwidth): yaskawa.eu.com — Sigma-7 Series
- IEEE Transactions on Industrial Electronics — two-layer trajectory planning for AGV (drive/motion context): doi.org/10.1109/TIE.2023.3250847
Related: Qu'est-ce qu'un AGV et comment ça marche? · AGV à entraînement différentiel ou à double entraînement · Guide de fabrication de moteurs OEM AGV
