Sök

AGV Motor Speed and RPM Selection Guide: Formler, Standards & Arbetade exempel

AGV Motor Speed and RPM Selection Guide

AGV Motor Speed and RPM Selection Guide: Formler, Standards & Arbetade exempel

Selecting the right motor speed for an Automated Guided Vehicle (AGV) is not a single-parameter decision. It sits at the intersection of vehicle dynamics, gearbox design, battery constraints, and control-loop bandwidth. Get it wrong and you face either a sluggish robot that cannot meet throughput targets, or an over-speeding motor that overheats, wastes battery, and dies prematurely. This guide walks through the full engineering chain—from the fundamental speed-to-velocity formula through IEC 60034-1 duty cycle classification, NEMA MG1 design types, and manufacturer datasheet interpretation—to give you a repeatable workflow for matching motor RPM to any AGV platform.

Why Motor Speed Defines AGV Performance

Motor rated speed (RPM) directly governs three AGV performance pillars:

Performance PillarHow Motor Speed Affects ItConsequence of Mismatch
Travel VelocityWheel speed = motor RPM ÷ gear ratio; vehicle speed = wheel RPM × wheel circumferenceMotor too slow → AGV cannot meet cycle-time targets; motor too fast → excessive gear ratio needed, efficiency drops
VridmomentdensitetFor a given power, higher-speed motors are smaller and lighter but produce less torque per ampUndersized torque → stall on ramps, sluggish acceleration; oversized motor → wasted payload capacity and cost
Battery RuntimeBLDC motors peak in efficiency at 70–90% of rated RPM; operating far below this wastes energy as heatPoor efficiency zone → 15–30% shorter battery life per charge cycle, more charging stops, lower fleet OEE

Industry data from AGV fleet operators shows that motors consistently running below 50% of rated RPM—common in over-geared designs—experience 20–35% higher energy consumption and 40% shorter bearing life compared to motors operating in their optimal efficiency band [1].

Quick Answer: Motor RPM Ranges by AGV Payload Class

For engineering teams that need a fast reference before diving into calculations, the table below consolidates field-proven motor RPM ranges across six AGV payload categories. These values assume BLDC or BLDC servo motors paired with single-stage planetary gearboxes (efficiency ≥ 90%) and polyurethane wheels on epoxy floors.

Payload ClassTypical AGV TypeMotor Rated RPMGear Ratio RangeWheel RPM (output)Vehicle SpeedMotorkraftSpänning
≤. 100 kgAGC / Light AMR3,000–5,0005:1–10:1300–6000.8–2.0 m/s50–100 W24V
100–300 kgWarehouse AMR3,000–4,00010:1–15:1200–4000.8–1.5 m/s100–200 W24V / 48V
300–600 kgUnder-Riding AGV2,500–3,5008:1–15:1150–3500.5–1.5 m/s200–400 W48V
600–1,200 kgTowing / Pallet AGV2,500–4,0006:1–15:1100–3000.5–1.5 m/s400–750 W48V
1,200–3,000 kgForklift AGV2,000–3,00012:1–25:180–2000.3–1.0 m/s750–1,500 W48V / 72V
3,000–20,000 kgHeavy-Duty AGV1,500–2,50015:1–30:150–1200.2–0.5 m/s1.5–5 kW+72V / 80V

Source: Consolidated from AGV manufacturer specifications [2][3], gear motor supplier data [4], and GreenSky Power’s AGV motor application guide [5].

The Speed–Torque–Gear Ratio Triangle

Every AGV drive design lives within a three-variable trade space. You cannot optimize one without affecting the other two. Understanding this triangle prevents the most common error in motor speed selection: choosing a motor based on speed alone and discovering the torque is inadequate only during prototype testing.

Variabel 1: Motorns nominella varvtal (nN)

The rated speed is the RPM at which the motor delivers its rated torque continuously without exceeding its thermal class limit. For BLDC motors used in AGVs, this typically falls between 1,500 och 5,000 RPM. The rated speed is not the no-load speed (n0)—the no-load speed is typically 10–20% higher than the rated speed under load [6].

Variabel 2: Gearbox Reduction Ratio (i)

The ratio converts motor shaft speed to wheel shaft speed. A higher ratio reduces output speed but multiplies output torque (minus gearbox efficiency losses). For AGV applications, ratios typically range from 5:1 (light AMR) till 50:1 (heavy-duty), med 15:1–25:1 being the most common range for warehouse AMRs [5].

Variabel 3: Output Torque at Wheel (Twheel)

This is the torque that actually reaches the drive wheel after gearbox reduction: Twheel = Tmotor × i × η, where η is gearbox efficiency (0.90–0.95 for planetary, 0.60–0.70 for worm gear). The wheel torque must exceed the sum of rolling resistance, gradient resistance, and acceleration inertia torque with a safety margin of 1.3–1.5× [7].

Design ChoiceSpeed EffectEfficiency EffectWhen to Choose
High motor RPM + high ratioNormal–High vehicle speedHigh wheel torque (ratio multiplies motor torque)Good if motor stays in 70–90% rated RPM bandStandard warehouse AGV/AMR (recommended)
Low motor RPM + low ratioLower vehicle speedModerate wheel torqueRisk: motor may operate below optimal efficiency zonePrecision positioning AGV, cleanroom robots
High motor RPM + low ratioVery high vehicle speedLow wheel torqueRisk: insufficient acceleration torque, wheel slipLong-distance towing AGV on flat floors
Low motor RPM + high ratioVery low vehicle speedVery high wheel torqueRisk: motor overheating at low RPM, poor coolingHeavy-duty AGV (5+ massor) with multi-motor drive

Kärnformel: Motor RPM to Vehicle Speed

The fundamental equation linking motor speed to AGV linear velocity is:

v = (2 × π × r × nmotor) ÷ (60 × i)

Där:

  • v = AGV travel speed (m/s)
  • r = drive wheel radius (m)
  • nmotor = motor rotational speed (RPM)
  • i = gearbox reduction ratio (dimensionless)

Reverse Calculation: Deriving Gear Ratio from Target Speed

In practice, engineers usually know the desired vehicle speed and wheel diameter, then solve for the required gear ratio given a motor’s rated RPM:

i = (2 × π × r × nmotor) ÷ (60 × v)

For quick estimates, the wheel RPM can be calculated independently:

nwheel = (v × 60) ÷ (π × D) where D = wheel diameter (m)

Then: i = nmotor ÷ nwheel

Numerical Example

Target: 1.2 m/s travel speed, 200 mm wheel diameter (r = 0.1 m), motor rated at 3,000 RPM.

  1. Wheel RPM = (1.2 × 60) ÷ (π × 0.2) = 72 ÷ 0.628 114.6 RPM
  2. Gear ratio = 3,000 ÷ 114.6 26.2
  3. Select standard ratio 25:1 eller 30:1 (nearest available)
  4. Verify actual speed at 25:1: v = (2π × 0.1 × 3000) ÷ (60 × 25) = 1.256 m/s ✓
  5. Verify actual speed at 30:1: v = (2π × 0.1 × 3000) ÷ (60 × 30) = 1.047 m/s (slightly below target)

This example illustrates why motor speed selection and gear ratio selection must be performed iteratively—you rarely get an exact match with standard ratios [3][7].

Reading the Speed-Torque Curve: Maxon and Faulhaber Methodology

Motor datasheets from leading manufacturers like Maxon och Faulhaber present speed-torque characteristics as a linear graph. Understanding how to read this graph is essential for verifying that your selected motor speed will deliver the required torque under actual AGV load conditions.

The Speed-Torque Line (Maxon Methodology)

Maxon’s motor selection methodology defines the speed-torque relationship as a straight line from no-load speed (n0) at zero torque to stall torque (MH) at zero speed [6]:

n = n0 − (Δn/ΔM) × M

Där:

  • n0 = kn × UMot (no-load speed = speed constant × applied voltage)
  • Δn/ΔM = speed-torque gradient (slope of the line, in RPM per mNm)
  • M = instantaneous motor torque

Key insight from Maxon: the slope Δn/ΔM is a mechanical constant determined by the motor’s winding geometry and magnetic circuit—it does not change with voltage. Changing the applied voltage shifts the line up or down (parallel translation) but does not change the slope. This means a motor’spowerfulness” (how much speed it retains under load) is fixed by design, not by the supply voltage [6].

Operating Range Rules (Faulhaber Methodology)

Faulhaber’s DC motor technical documentation recommends that for optimal motor life and efficiency, the operating point should satisfy [8]:

  • Required speed n ≥ n0 / 2 (operate above half the no-load speed)
  • Required load torque M ≤ MH / 2 (operate below half the stall torque)
  • For continuous duty: stay within the continuous operation zone defined by the thermal limit curve

For AGV applications, this translates to a practical rule: select a motor whose rated speed is 1.5–2× the speed you actually need at the motor shaft, then use the gearbox ratio to reduce to the target wheel speed. This keeps the motor in its efficient upper-speed zone and leaves torque headroom for acceleration transients [6][8].

Maxon’s 20% Tolerance Rule

When selecting a motor winding for a specific AGV application, Maxon recommends adding a 20% margin to the calculated speed constant to account for tolerances in winding resistance, magnet strength, and load variability [6]:

kn 1.2 × (nmax,required + (Δn/ΔM)avg × Mmax) ÷ UMot

This ensures that even with manufacturing tolerances (Maxon publishes ±10% on no-load speed and ±50% on no-load current), the motor will still meet the AGV’s speed requirement under worst-case conditions [9].

Gearbox Ratio Selection by AGV Type

Different AGV architectures demand different speed-torque trade-offs. The table below maps six common AGV types to their recommended motor RPM, utväxlingsförhållande, and output characteristics, based on consolidated data from AGV motor manufacturers and system integrators [2][3][5].

AGV TypeMotor RPMUtväxlingsförhållandeOutput CharacteristicRecommended GearboxKey Design Constraint
Under-Riding AGV2,500–3,5008:1–12:1Low speed, högt vridmoment, precise positioningPlanetarisk (low backlash ≤ 5 arc-min)Top-lift torque must exceed full-load gravity torque
Forklift AGV2,000–3,00012:1–20:1Ultra-high starting torque, strong brakingPlanetarisk (2-skede) or worm gear (self-locking)Torque priority over speed; electromagnetic brake required
Towing AGV2,500–4,0006:1–10:1Medium speed, long continuous runPlanetarisk (spiralformad, hög effektivitet)Thermal management for extended duty cycles
Load-Carrying AGV3,000–4,0005:1–8:1Fast response, agile steeringCompact planetary or integrated drive wheelBalance speed and acceleration performance
Differential Drive AGV3,000–4,5005:1–8:1Fast response, sensitive steering controlLow-backlash planetary (≤. 3 arc-min)Left/right wheel torque matching for straight-line tracking
Heavy-Duty AGV (5–20t)1,500–2,50015:1–25:1Extreme torque, low-speed stabilityMulti-stage planetary (2–3 stage)Multi-motor synchronized drive; redundant cooling

Gearbox Efficiency Impact on Effective Speed

The gearbox efficiency directly reduces the output torque (and thus the effective tractive force), but it does not change the output speed. dock, because the motor must produce more torque to compensate for gearbox losses, the motor’s actual operating speed drops along the speed-torque line. This means a worm gearbox (h = 0.65) causes the motor to run 10–15% slower than a planetary gearbox (h = 0.92) at the same load, because the motor must deliver more torque to achieve the same wheel output [7].

Gearbox TypeEffektivitetMax Single-Stage RatioGlappBullernivåAGV Suitability
Planetarisk90–95 %3:1–10:1 (upp till 100:1 multi-stage)3–15 arc-minLågStandard for all AGV types
Worm Gear60–75%5:1–60:115–30 arc-minLågForklift AGV (self-locking benefit)
Parallel Shaft90–94%3:1–30:115–30 arc-minMåttligLight-load AGV, cost-sensitive
Harmonic Drive85–90%50:1–200:1≤. 1 arc-minVery LowPrecision positioning, robotic joints

IEC 60034-1: Duty Cycle Classifications for AGV Speed Selection

Motor speed selection cannot be separated from thermal considerations. IEC 60034-1:2022 (Edition 15) defines ten duty cycle classifications (S1–S10) that determine how long a motor can sustain its rated speed and torque without exceeding thermal limits. For AGV applications, three classifications are most relevant [10][11].

S1 — Continuous Duty

The motor runs at constant rated load long enough to reach thermal steady state. This applies to towing AGVs on long-distance transport loops. The rated speed and torque on the motor nameplate are S1 values—selecting a motor based on nameplate ratings is safe only if your AGV operates in S1 mode.

S3 — Intermittent Periodic Duty

The motor cycles between run and stop periods without significant thermal equilibrium. This is the most common AGV duty cycle: pick-up → travel → drop-off → idle → repeat. S3 is expressed as a percentage (TILL EXEMPEL., S3-40% means the motor is energized 40% of the cycle time). A motor rated for S3-40% can deliver 1.6× its S1 torque during the on-period, but only if the off-period provides sufficient cooling.

S4 — Intermittent Periodic Duty with Starting

Similar to S3 but includes a significant starting (acceleration) phase that contributes to heating. This applies to AGVs with frequent start-stop cycles (TILL EXEMPEL., warehouse AMRs navigating through aisles with obstacle avoidance).

IEC 60034-1 KlassAGV ApplicationThermal Impact on SpeedDerating Factor vs. S1Insulation Class Recommendation
S1 (Continuous)Towing AGV, long-distance transportFull thermal load; rated speed = max continuous speed1.0 (baseline)Klass F (155°C) minimum
S3-40% (Intermittent)Warehouse AMR, pallet moverMotor can run at higher torque between rests; speed maintained during on-period1.6× torque during on-periodKlass F (155°C) or Class B (130°C)
S4 (Intermittent + Starting)High-frequency pick-and-place AGVStarting current adds thermal load; effective continuous speed reduced1.3–1.5× torque, shorter dutyKlass F (155°C) recommended
S2 (Short-Time)AGV steering motor (intermittent rotation)Rated for short burst; must cool before next cycle2.0× torque for ≤ 30 minKlass B (130°C) acceptable

For AGV motor selection, the practical implication is: if your AGV operates in S3 or S4 mode, you can select a motor with a lower S1-rated speed than a pure S1 calculation would suggest, because the intermittent duty allows the motor to run harder during active periods. dock, you must verify that the RMS (root-mean-square) torque over the full cycle does not exceed the motor’s S1 rated torque [11].

NEMA MG 1: Standard Speed Ratings and Design Types

While AGV motors are typically DC-powered (BLDC or brushed), many AGV systems in North American facilities also integrate AC induction motors for auxiliary functions (pumps, lifts, transportörer). NEMA MG 1-2021 defines standard speed ratings that engineers should recognize when specifying complete AGV systems [12].

NEMA Standard Speeds at 60 Hz

The synchronous speed of an AC motor is determined by the formula: Ns = 120 × f ÷ P, where f = frequency (Hz) and P = number of poles.

polackerSynkron hastighet (60 Hz)Typical Full-Load SpeedAGV Application
23,600 RPM3,450–3,540 RPMHigh-speed auxiliary pump (rare in AGV)
41,800 RPM1,725–1,780 RPMHydraulic lift pump motor
61,200 RPM1,140–1,175 RPMConveyor drive (on-board AGV belt)
8900 RPM850–870 RPMLow-speed high-torque auxiliary

NEMA Design Types and IEC Equivalents

NEMA MG 1 classifies motor designs by their torque-speed characteristics. For AGV auxiliary AC motors, the design type determines starting behavior under load [12][13].

NEMA DesignIEC EquivalentStartmomentBreakdown TorqueSlip at Full LoadAGV Suitability
Design ANormalHög (>200%)< 5%Not recommended (high starting current)
Design BDesign NNormal (150–280%)200–250%3–5%Standard AGV auxiliary motors (most common)
Design CDesign HHög (200–250%)190–225%3–5%AGV hydraulic lift (högt startmoment)
Design DMycket hög (275%+)5–13%AGV traction (high slip, högt startmoment)

For the primary AGV drive motor (BLDC), NEMA MG 1 design types do not directly apply, but the thermal class and insulation rating standards are shared. Most AGV-grade BLDC motors use Klass F (155°C) insulation per IEC 60034-1 / NEMA MG 1, with Class H (180°C) for high-ambient or heavy-duty applications [10][12].

Motor Speed Constants: kn, Kt, and Speed-Torque Gradient

Three constants define a motor’s speed behavior. Understanding them is essential for interpreting manufacturer datasheets and performing speed calculations that go beyond simple ratio division.

Speed Constant (kn)

Expressed in RPM per volt (RPM/V). Defines the no-load speed at a given voltage: n0 = kn × U. A higher kn means the motor spins faster at the same voltage but produces less torque per amp. For AGV BLDC motors, kn values typically range from 50–300 RPM/V (at 24V: 1,200–7,200 RPM no-load) [6].

Momentkonstant (Kt or kM)

Expressed in Nm/A (or mNm/A for small motors). Defines the torque produced per amp of current: M = Kt × I. Maxon notes that for their motors, torque and current are directly proportional, meaning the current axis on a speed-torque graph can be read as a parallel torque axis. Typical AGV BLDC motor Kt values range from 0.02–0.5 Nm/A [6].

Speed-Torque Gradient (Δn/ΔM)

Expressed in RPM per Nm (or RPM per mNm for small motors). Defines how much speed drops per unit of load torque increase: Δn/ΔM = n0 ÷ MH (no-load speed divided by stall torque). A flatter gradient (smaller value) means a more powerful motor that maintains speed under load. Maxon considers this the most meaningful single number for motor comparison, as it is a mechanical constant independent of winding choice [6].

Motorstorlek (AGV Class)Typical kn (RPM/V)Typical Kt (Nm/A)Typical Δn/ΔM (RPM/mNm)No-Load Speed at 24VRated Speed at 24V
57mm ram (≤100W)150–3000.02–0.055–153,600–7,2003,000–5,000
80mm ram (200–400W)80–1500.05–0.153–81,920–3,6002,500–3,500
100mm ram (500–750W)50–1000.10–0.302–51,200–2,4002,000–3,000
120mm+ frame (1kW+)30–600.20–0.501–3720–1,4401,500–2,500

Notera: Maxon publishes ±10% tolerance on no-load speed and ±50% tolerance on no-load current. Always include this tolerance in speed calculations, especially for AGV fleets where multiple motors must track the same speed [9].

Closed-Loop Speed Control: Encoder Resolution and PWM

Selecting the motor’s rated RPM is only half the equation—maintaining that speed precisely under varying load requires closed-loop control. AGV systems use encoder feedback to achieve speed regulation accuracy of ±0.5% to ±1.0% for standard industrial AGVs, and ±0.1% for high-precision positioning AGVs [3].

Encoder Resolution Impact on Speed Control

The encoder’s pulses per revolution (PPR) determines the minimum speed increment the controller can resolve:

Speed resolution = 60 ÷ (PPR × Tsample) (RPM)

Where Tsample is the control loop sampling period in seconds. På 5 ms loop time (200 Hz update rate, typical for AGV motor controllers):

Encoder PPRSpeed Resolution at 5ms LoopMin Detectable Speed ChangeTypical AGV Application
1,000 PPR12 RPM±0.4% at 3,000 RPMLow-cost AMR, AGC
2,500 PPR4.8 RPM±0.16% at 3,000 RPMStandard warehouse AGV
5,000 PPR2.4 RPM±0.08% at 3,000 RPMPrecision positioning AGV
17-bit absolute (131,072)0.09 RPM±0.003% at 3,000 RPMForklift AGV, high-precision docking

PWM Frequency and Speed Ripple

The servo drive’s PWM switching frequency affects speed smoothness at the motor shaft. Typical AGV BLDC controllers use 16–20 kHz PWM, which is above the audible threshold and provides smooth current regulation. At lower PWM frequencies (8–10 kHz), speed ripple increases, causing visible wheel jitter at low speeds—an issue for AGVs performing precision docking [3].

Yaskawa Servo Speed Control Architecture

Yaskawa’s Sigma-5 and Sigma-X servo systems, widely used in industrial automation, illustrate best-in-class speed control architecture for AGV-class applications. The Sigma-5 series supports maximum speeds of 6,000 RPM (low-inertia) och 3,000 RPM (medium-inertia) with 20-bit (1,044,576 counts/rev) encoder resolution. The speed control loop typically operates at 62.5 μs (16 kHz), enabling ±0.01% speed regulation—well beyond AGV requirements but illustrative of what closed-loop servo architecture achieves [14][15].

ParameterStandard BLDC ControllerBLDC Servo (mid-range)Yaskawa Sigma-5/X
Speed loop bandwidth200–500 Hz500–1,000 Hz1,000–2,500 Hz
Encoder resolution1,000–2,500 PPR2,500–5,000 PPR20-bit / 26-bit absolute
Hastighetsreglering±0.5–1.0%±0.1–0.5%±0.01%
Max motor speed3,000–5,000 RPM3,000–6,000 RPM3,000–7,000 RPM
Peak torque150–200% rated200–300% rated300–350% rated

Voltage Platform and Its Impact on Speed Range

AGV battery voltage directly constrains the motor’s achievable speed through the speed constant relationship (n0 = kn × U). Lower-voltage systems limit the maximum no-load speed, which in turn limits the available speed headroom for gear ratio optimization.

Battery VoltageTypical AGV PayloadMax Practical Motor RPMCurrent at Rated PowerWire/Connector Loss ImpactRecommended Motor Type
24V≤. 300 kg3,000–5,000Hög (8–20A per 100W)Significant at >15A; use short runsBLDC (small frame)
48V300–1,500 kg2,500–4,000Måttlig (4–10A per 100W)Manageable; standard in warehouse AGVBLDC servo (mainstream)
72V1,500–3,000 kg2,000–3,500Lägre (3–7A per 100W)Minimal; allows longer cable runsBLDC servo (high-power)
80V+3,000+ kg1,500–3,000Låg (2–5A per 100W)Minimal; heavy-duty cablingBLDC servo / AC servo (with inverter)

A critical design note: never operate a motor significantly below its rated voltage. A 48V-rated motor running on a 24V bus will only reach half its rated no-load speed, pushing the operating point into the low-efficiency zone and potentially causing thermal issues due to high current draw [3].

Worked Example 1: 500 kg Warehouse AMR

Design Requirements

  • Total mass (vehicle + payload): 500 kg
  • Target travel speed: 1.5 m/s
  • Hjuldiameter: 200 mm (r = 0.1 m)
  • Maximum gradient: 3% (1.7°)
  • Acceleration target: 0.5 m/s²
  • Batteri: 48I likvida
  • Arbetscykel: S3-40% (warehouse pick-and-place)

Step-by-Step Speed Selection

StegActionCalculationResultat
1Calculate required wheel RPMnwheel = (1.5 × 60) ÷ (π × 0.2)143.2 RPM
2Select motor rated RPM (1.5–2× headroom)Target motor RPM = 143.2 × 20 (initial ratio guess)~2,864 RPM → select 3,000 RPM motor
3Calculate gear ratioi = 3,000 ÷ 143.220.9 → select standard 20:1
4Verify actual speed at 20:1v = (2π × 0.1 × 3000) ÷ (60 × 20)1.57 m/s ✓ (exceeds 1.5 target)
5Calculate rolling resistance forceFf = 0.015 × 500 × 9.8173.6 N
6Calculate gradient resistance forceFθ = 0.03 × 500 × 9.81147.2 N
7Calculate acceleration resistance forceFa = 500 × 0.5250 N
8Calculate total resistance (peak)Ftotal = 73.6 + 147.2 + 250470.8 N
9Calculate required wheel torqueTwheel = 470.8 × 0.147.1 Nm
10Calculate required motor torque (at 20:1, η=0.92)Tmotor = 47.1 ÷ (20 × 0.92)2.56 Nm
11Apply safety factor (1.3×)Tmotor,rated = 2.56 × 1.33.33 Nm
12Select motor: 48V, 3,000 RPM, ≥3.3 Nm rated torqueCheck datasheet speed-torque curve at 3,000 RPMConfirm rated torque ≥ 3.3 Nm at 3,000 RPM
13Verify RMS torque for S3-40% dutyTrms = √[(Tpeak² × 0.4 + Tidle² × 0.6)]Verify Trms ≤ motor S1 rated torque

Resultat: Select a 48V BLDC servo motor rated at 3,000 RPM with ≥ 3.3 Nm continuous rated torque, paired with a 20:1 single-stage planetary gearbox (η ≥ 92%, backlash ≤ 10 arc-min). This configuration delivers 1.57 m/s top speed with adequate torque margin for 3% gradients and 0.5 m/s² acceleration under 500 kg total mass [5][7].

Worked Example 2: 2,000 kg Forklift AGV

Design Requirements

  • Total mass: 2,000 kg
  • Target travel speed: 0.8 m/s
  • Hjuldiameter: 300 mm (r = 0.15 m)
  • Maximum gradient: 5% (2.9°)
  • Acceleration target: 0.3 m/s²
  • Batteri: 72I likvida
  • Arbetscykel: S4 (frequent start-stop with lifting)

Step-by-Step Speed Selection

StegActionCalculationResultat
1Calculate required wheel RPMnwheel = (0.8 × 60) ÷ (π × 0.3)50.9 RPM
2Select motor rated RPM (heavy-duty, lower speed)Target: 2,500 RPM (per payload class table)2,500 RPM
3Calculate gear ratioi = 2,500 ÷ 50.949.1 → select 50:1 (2-stage planetary)
4Verify actual speed at 50:1v = (2π × 0.15 × 2500) ÷ (60 × 50)0.785 m/s (slightly below 0.8; acceptable with 2% margin)
5Calculate rolling resistance forceFf = 0.015 × 2000 × 9.81294.3 N
6Calculate gradient resistance force (5%)Fθ = 0.05 × 2000 × 9.81981.0 N
7Calculate acceleration resistance forceFa = 2000 × 0.3600 N
8Calculate total resistance (peak)Ftotal = 294.3 + 981.0 + 6001,875.3 N
9Calculate required wheel torque (dual drive)Twheel,per = (1875.3 ÷ 2) × 0.15140.6 Nm per wheel
10Calculate required motor torque (50:1, η=0.88 for 2-stage)Tmotor = 140.6 ÷ (50 × 0.88)3.20 Nm
11Apply safety factor (1.5× for S4 duty)Tmotor,rated = 3.20 × 1.54.80 Nm
12Select motor: 72V, 2,500 RPM, ≥4.8 Nm rated torqueCheck datasheet; verify thermal class F or HConfirm; add temperature sensor for S4 monitoring

Resultat: Dual 72V BLDC servo motors, 2,500 RPM, 4.8 Nm rated torque each, med 50:1 2-steg planetväxellådor (η ≥ 88%), delivering 0.79 m/s top speed and 1,875 N peak tractive force for 2,000 kg forklift AGV on 5% gradients. The S4 duty cycle requires Class F insulation and integrated thermal sensors [7][10].

Common Speed Selection Mistakes

#MistakeWhat HappensHow to Avoid
1Using no-load speed instead of rated speed for ratio calculationDC motor no-load speed is 10–20% higher than loaded speed; using it produces a ratio that delivers 10–20% less output speed than intendedAlways use the speed at rated torque (from the speed-torque curve) for ratio calculations [4]
2Selecting ratio based on speed only, ignoring torque verificationRatio delivers correct speed but output torque is insufficient; motor stalls on ramps or during accelerationComplete both speed calculation and torque verification before finalizing [4]
3Choosing excessively high ratiofor extra torqueMotor operates at very low speed, outside efficient zone; överhettning, poor cooling, wasted speed rangeMatch ratio to required speed with appropriate torque margin (1.3–1.5×), not maximum ratio [4]
4Ignoring gearbox efficiency in motor speed calculationMotor must produce more torque than calculated, pushing operating point down the speed-torque line; actual speed 5–15% lower than expectedInclude gearbox η in torque calculation; verify resulting motor speed on speed-torque curve [7]
5Selecting motor voltage below battery bus voltageMotor reaches only fraction of rated speed; high current draw, thermal issues, minskad effektivitetMatch motor rated voltage to battery nominal voltage; never undervolt significantly [3]
6Not verifying RMS torque for intermittent dutyMotor passes peak torque check but fails thermal check over full cycle; overheating during multi-shift operationCalculate RMS torque over full duty cycle; verify ≤ S1 rated torque per IEC 60034-1 [11]
7Ignoring motor speed tolerances (Maxon ±10% on n0)Fleet motors run at different speeds; straight-line tracking fails, differential AGV veers off courseApply 20% margin per Maxon methodology; use closed-loop speed synchronization [6][9]

7-Step Motor Speed Selection Workflow

Based on the engineering principles, standarder, and manufacturer methodologies covered above, the following workflow provides a repeatable process for AGV motor speed selection:

StegActionInputProduktionStandard / Reference
1Define vehicle parametersTotal mass, target speed, max gradient, acceleration, wheel diameter, batterivoltDesign requirement sheet
2Calculate required wheel RPMnwheel = (v × 60) ÷ (π × D)Wheel RPM at target speedBasic kinematics
3Select motor rated RPM from payload class tablePayload class → motor RPM range (see Quick Answer table)Candidate motor RPM[2][5]
4Calculate gear ratio and verify speedi = nmotor ÷ nwheel; verify v = (2π × r × nmotor) ÷ (60 × i)Candidate ratio; verified speed[3][7]
5Verify torque on speed-torque curveCalculate Tmotor = Twheel ÷ (i × η); apply 1.3–1.5× safety; check on datasheet curve at rated RPMConfirmed motor torque ratingMaxon methodology [6]; Faulhaber rules [8]
6Verify thermal duty cycleDetermine IEC 60034-1 duty class (S1/S3/S4); calculate RMS torque; verify ≤ S1 rated torqueThermal pass/fail; insulation classIEC 60034-1:2022 [10][11]
7Apply tolerance margin and finalizeAdd 20% speed margin (Maxon rule); select standard ratio; specify encoder PPR and IP ratingFinal motor + gearbox specificationMaxon tolerance [9]; NEMA MG 1 [12]

Academic Research on AGV Motor Speed Optimization

Several peer-reviewed IEEE papers have addressed motor speed optimization for AGV and mobile robot platforms:

  • Energy-optimal speed profiles — Jaramillo-Morales et al. (2020) demonstrated that optimized speed profiles for differential-drive mobile robots can achieve significant energy savings compared to trapezoidal profiles, by operating motors closer to their peak efficiency RPM during acceleration phases [16].
  • BLDC motor speed control for self-driving robots — Bae et al. (2020) presented sensorless speed estimation for in-wheel BLDC motors, showing improved low-speed control performance by compensating for Hall sensor lag—a relevant finding for AGVs operating at low wheel RPM [17].
  • Dual-PM motor design for AGV — Lin et al. (2020) proposed a novel direct-drive dual-PM motor specifically designed for electric AGVs, achieving high efficiency across a wide speed range by reducing torque ripple through split-tooth stator design [18].
  • Fuzzy speed control — Kodagoda et al. (2002, cited 250+ times) developed fuzzy PD-PI controllers for AGV speed and steering, demonstrating that intelligent control can decouple speed from steering and maintain stable speed under varying load—a foundational result for AGV speed regulation [19].
  • Intelligent speed controllers comparison — Khan et al. (2025) compared PID, FLC, ANFIS, and MPC controllers for DC motor speed regulation in wheeled autonomous robots, providing quantitative guidance on controller selection for different speed-regulation requirements [20].

These studies collectively reinforce the principle that motor speed selection is not just a mechanical ratio calculation but must be coupled with control architecture design to achieve the speed regulation precision that AGV navigation systems demand.

FAQ: AGV Motor Speed and RPM Selection

What is the typical RPM range for AGV motors?

AGV motors typically operate in the 1,500–5,000 RPM rated speed range, with 2,500–3,500 RPM being the most common for warehouse AMRs and logistics AGVs (500–1,200 kg payload). Light AMRs (≤100 kg) may use motors up to 5,000 RPM, while heavy-duty AGVs (3,000+ kg) typically use 1,500–2,500 RPM motors with high gear ratios (15:1–30:1) [2][5].

How do I calculate the gear ratio from motor RPM to wheel speed?

The formula is: utväxlingsförhållande (i) = motor RPM ÷ wheel RPM. Wheel RPM = (target speed in m/s × 60) ÷ (π × wheel diameter in meters). Till exempel, a 3,000 RPM motor with a 200 mm wheel at 1.5 m/s target speed: wheel RPM = (1.5 × 60) ÷ (π × 0.2) = 143 RPM; ratio = 3,000 ÷ 143 21:1 [3][7].

Should I use no-load speed or rated speed for gear ratio calculation?

Always use the nominell hastighet (speed at rated torque), not the no-load speed. DC and BLDC motors run 10–20% slower under load than at no load. Using no-load speed will produce a ratio that delivers 10–20% less output speed than intended under actual AGV load conditions [4][6].

What happens if my motor runs too slowly for the application?

If the motor operates far below its rated RPM (Nedan 50% of rated), it enters a low-efficiency zone where: (1) energy consumption increases 15–35%, (2) cooling fans (if shaft-mounted) provide insufficient airflow, (3) current draw increases to maintain torque, accelerating thermal aging, och (4) battery runtime decreases proportionally [1][6].

How does IEC 60034-1 duty cycle classification affect motor speed selection?

IEC 60034-1 defines duty cycles S1–S10. For AGVs operating in S3 (intermittent) or S4 (intermittent with starting) läge, the motor can deliver 1.3–1.6× its S1-rated torque during active periods. This means you can select a motor with a lower S1-rated speed than a pure continuous-duty calculation would suggest—provided the RMS torque over the full cycle does not exceed the motor’s S1 rating [10][11].

Can I use a 48V motor on a 24V AGV battery?

Not recommended. A 48V motor on 24V will only reach approximately half its rated no-load speed, pushing the operating point into the low-efficiency zone. The motor will draw higher current to produce the same torque, increasing thermal load and reducing bearing life. Always match the motor’s rated voltage to the battery bus voltage [3].

Need a Custom AGV Motor Solution?

Selecting the right motor speed for your AGV platform requires balancing kinematics, termisk hantering, gearbox efficiency, and control architecture. GreenSky Power manufactures BLDC-motorer, planetväxellådor, och custom electric motor solutions specifically optimized for AGV and AMR drive systems. Our engineering team can help you calculate the optimal motor RPM, utväxlingsförhållande, and voltage platform for your specific payload, fart, and duty cycle requirements. Kontakta oss for a technical consultation or request a product specification sheet for your AGV motor project.

For more AGV motor engineering resources, see our related guides:

Referenser

  1. JKong Motor. “AGV无刷电机的转速和减速比应该如何匹配?” Available at: http://jkongmotor.cn/agvwushuadianjidezhuansuhejiansubiyinggairuhepipei.html
  2. JKong Motor. “直流无刷电机在自动引导车中的实际应用.Available at: https://www.jkongmotor.cn/zhiliuwushuadianjizaizidongyindaochezhongdeshijiyingyong.html
  3. HKT Robot (AGVMotor.com). “Brushless Servo Motor for AGV: Key Specs and Selection Guide.Available at: https://agvmotor.com/blogs/knowledge/brushless-servo-motor-for-agv
  4. SY Motor. “How to Select the Right Gear Reduction Ratio: A Practical Guide for Engineers and Procurement Teams.Available at: https://www.symotor-hz.com/news/industry-news/how-to-select-the-right-gear-reduction-ratio-a-practical.html
  5. GreenSky Power. “Hur man väljer en motor för AGV-applikationer: Complete Selection Guide.Available at: https://greensky-power.com/how-to-choose-a-motor-for-agv-applications/
  6. Maxon Precision Motors. “Motor Type Selection.Published via A3 Association for Advancing Automation. Available at: https://www.automate.org/tech-papers/motor-type-selection
  7. Bicontrols (YK-Control). “AGV行走系统动力学计算与驱动选型指南:从整车阻力到舵轮电机及驱动器匹配.Available at: https://www.bicontrols.com/news_detail/73.html
  8. Faulhaber Drive Systems. “Beräkningar & Formulas for Brush DC Motors” (White Paper). Available via Qmed at: https://qmed.com/when-selecting-a-brush-dc-motor-for-an-file104689.html
  9. Maxon Group. “Motor Data and Simulation — Standard Tolerances.Available at: https://support.maxongroup.com/hc/en-us/articles/360013761160-Motor-data-and-simulation
  10. Internationella elektrotekniska kommissionen. IEC 60034-1:2022 — Rotating electrical machines — Part 1: Rating and performance (Edition 15). Geneva: IEC.
  11. HYX Geological Equipment. “Low-Speed Motor Parameter Encyclopedia: Comprehensive Technical Guide for Industrial Selection.Available at: http://www.hyxgeo.com/article/179424572649472.html
  12. National Electrical Manufacturers Association. NEMA MG 1-2021 — Motors and Generators. Rosslyn, VA: NEJ.
  13. The Engineering Toolbox. “Electric Motors — IEC and NEMA Standard Torques.Available at: https://www.engineeringtoolbox.com/iec-nema-standards-torques-d_741.html
  14. Yaskawa Electric Corporation. “Sigma-5 Servo Family — Product Catalog.Available at: https://www.yaskawa.com/delegate/getAttachment?documentId=BL.Sigma-5.01
  15. Yaskawa Electric Corporation. “Sigma-X Rotary Servomotors — Product Specifications.Available at: https://yaskawa.co.uk/motion-control/sigma-x/sx-rotary-servomotors
  16. Jaramillo-Morales, M.F., Dogru, S., & Marques, L. (2020). “Generation of energy optimal speed profiles for a differential drive mobile robot with payload on straight trajectories.2020 IEEE International Symposium on Safety, Säkerhet, and Rescue Robotics (SSRR), 136–141. DOI: 10.1109/SSRR50563.2020
  17. Bae, J., Lee, D.-H., & Cho, K. (2020). “Speed and Direction Control of Two In-wheel BLDC Motors for the Self-Driving Surveillance Robot.2020 IEEE International Conference on Mechatronics and Robotics Engineering (ICMRE). DOI: 10.1109/icmre49073.2020.9065011
  18. Lin, Q., Niu, S., Cai, F., Fu, W., & Shang, L. (2020). “Design and Optimization of a Novel Dual-PM Machine for Electric Vehicle Applications.IEEE-transaktioner på fordonsteknik, 69(12), 14391–14400. DOI: 10.1109/TVT.2020.3034573
  19. Kodagoda, K.R.S., Wijesoma, W.S., & Teoh, E.K. (2002). “Fuzzy speed and steering control of an AGV.IEEE Transactions on Control Systems Technology, 10(1), 112–120. DOI: 10.1109/87.974981
  20. Khan, H., Namazi, H., & Lenort, R. (2025). “Advanced Intelligent Controllers Design and Simulation Analysis for Optimizing Speed Control of Autonomous Systems.IEEEX. Available at: https://ieeexplore.ieee.org/document/11370730

Du kanske också gillar

AGV Motor Speed and RPM Selection Guide: Formler, Standards & Arbetade exempel

Hur mycket vridmoment behöver en AGV? Ett nyttolastbaserat svar med tekniska standarder

Avsluta rutnätet

Skicka din förfrågan idag

Greensky power WeChat

Lämna din jobbmail.

Berätta för oss om dina behov