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Start with your drivetrain inputs to test whether a 100 rpm output class can actually meet speed, torque, traction, and current boundaries. Then use the report layer to understand limitations, alternatives, and the minimum validation gates before purchase.
100 rpm class quick benchmark
Published same-family data confirms tradeoff, not a single fixed truth: moving from 150 rpm (70:1) to 76 rpm (131:1) raises stall torque from 27 to 45 kg-cm but reduces max output power from 10 to 6 W. Use 100 rpm as a midpoint anchor, then validate against your mission profile.
Reference RPM
100 rpm
Continuous-load cue
25% stall current
Decision output
Pass / Watch / Fail
This layer translates tool output into decisions: what the numbers mean, who should use this 100 rpm class, and where the boundary is.
Need a reviewed shortlist before RFQ?
Send your assumptions now, then we align motor options and risk gates around this 100 rpm fit result.
Run the tool to quantify speed at fixed 100 rpm and compare against target speed.
If speed gap is strongly negative, 100 rpm is likely too slow for your wheel and mission profile.
Startup torque margin is unresolved until mass, grade, and torque inputs are provided.
Negative startup margin indicates immediate drivetrain resize or target adjustment.
Traction feasibility remains unknown until mu, Crr, and grade are entered.
Above 95% utilization indicates slip risk and unstable path tracking under disturbances.
Current margin is unresolved until rated current, startup multiplier, and motor peak multiplier are entered.
Use this as pre-check only; confirm with controller logs and thermal tests.
| Audience | Fit | Why | Next step |
|---|---|---|---|
| 2WD indoor AMR (8-20 kg), speed target <= 1.2 m/s | Applicable | The 100 rpm baseline often aligns with controlled indoor navigation when wheel diameter is moderate. | Use tool output to shortlist 2-3 torque/current-safe variants and validate thermal margin. |
| Service robot with frequent ramp starts | Applicable | Tool explicitly checks startup multiplier and current headroom, which dominate stop-start duty. | Focus on startup-current margin and driver foldback before locking controller. |
| Slope-heavy outdoor rover (>15% grade) | Not recommended | Fixed 100 rpm class can miss required torque unless wheel size and speed demand are reduced. | Consider lower output rpm + higher torque package or move to larger frame/voltage. |
| High-speed platform (>1.8 m/s on 130 mm wheel) | Not recommended | A 100 rpm output is usually speed-limited for this wheel band unless gearing/diameter changes. | Recompute with smaller wheel or select higher output rpm motor family. |
| Education prototype with uncertain terrain data | Applicable | Calculator provides quick boundary screening with transparent assumptions and recovery path. | Use conservative mu and Crr first, then update with measured values. |
| Scenario | Assumptions | Expected outcome | Risk signal | Decision action |
|---|---|---|---|---|
| Indoor patrol robot baseline | 12 kg, 130 mm wheel, 2WD, 0.9 m/s target, 8% grade, mu 0.65, Crr 0.03 | 100 rpm often lands in watch/pass band if torque and current margins are positive. | Startup current spikes near controller current limit. | Keep 100 rpm candidate and validate with 3-run startup trace before RFQ. |
| Heavy payload run with same motor class | 20 kg payload state, same wheel and speed target, service factor >=1.5 | Required startup torque can exceed 100 rpm motor continuous envelope. | Torque margin turns negative, fit shifts to fail. | Lower speed target or move to higher-torque motor/gear stage. |
| High-speed request on large wheel | 130-150 mm wheel, >1.8 m/s target speed, fixed 100 rpm output | Speed gap becomes strongly negative (motor too slow). | Large speed gap despite acceptable torque value. | Use smaller wheel or adopt faster output rpm family for mobility target. |
| Low-grip floor after contamination | mu drops from 0.65 to 0.35, same force demand | Traction utilization rises sharply; slip risk dominates. | Utilization approaches/exceeds 100%. | Reduce acceleration demand and upgrade tire/surface management. |
The tool layer gives immediate fit output. This report layer explains the formulas, source boundaries, alternative paths, and what must be validated before deployment.
Equation block A
Wheel RPM needed = speed / wheel circumference x 60.
Speed at 100 rpm = 100 x wheel circumference / 60.
Equation block B
Force = m x (accel + g sin(theta) + Crr g cos(theta)).
Per-motor startup torque = wheel torque/driven wheels x SF x startup factor.
Equation block C
Traction limit = mu x m x g x cos(theta).
Utilization = required traction / limit traction.
Equation block D
Current estimate scales with torque-load fraction.
Startup current margin = rated current - estimated startup current.
| Option | Speed control | Torque headroom | Wiring complexity | Lifecycle risk | Best for |
|---|---|---|---|---|---|
| 100 rpm brushed DC gearmotor (open loop PWM) | Basic, depends on load and supply stability | Moderate if current limit is set correctly | Low | Brush wear and heat risk under high duty | Cost-sensitive prototypes and simple indoor robots |
| 100 rpm brushed DC gearmotor + encoder closed loop | Good speed consistency under varying load | Moderate to high with tuned current loop | Medium | Better controllability; still brush-limited lifetime | Service robots needing repeatable navigation speed |
| BLDC + gearbox tuned to ~100 rpm output | High with FOC/closed loop | High for same thermal envelope in many duty profiles | High | Lower brush-maintenance risk but higher integration effort | Long-duty deployments and lower maintenance plans |
| Higher-rpm motor + external reduction stage | Flexible but requires ratio/system integration work | Can be high if reduction is robust | Medium to high | Added backlash/noise interfaces if reducer quality is low | Platforms with custom wheelbase and packaging constraints |
| Variant | No-load speed | Stall torque | Stall current | Max output power | Decision signal | Source |
|---|---|---|---|---|---|---|
| 37D 12V, 70:1 (item 4744) | 150 rpm | 27 kg-cm | 5.5 A | 10 W | Faster, but lower stall torque. Useful when speed gap is negative at 100 rpm. | Pololu 4744 |
| 37D 12V, 100:1 (item 4745) | 100 rpm | 34 kg-cm | 5.5 A | 8 W | Middle ground benchmark for speed/torque around this page target. | Pololu 4745 |
| 37D 12V, 131:1 (item 4746) | 76 rpm | 45 kg-cm | 5.5 A | 6 W | Higher torque but slower output and lower max power than 100 rpm class. | Pololu 4746 |
| 37D 24V, 100:1 (item 4685) | 100 rpm | 39 kg-cm | 3.0 A | 8 W | Lower stall current at 24 V, but requires full 24 V electrical architecture. | Pololu 4685 |
Checked on 2026-05-22. In this published 12 V family, speed drops 49.3% from 150 rpm to 76 rpm while stall torque rises 66.7% from 27 to 45 kg-cm. The 12 V variants share 5.5 A stall current, so ratio change alone may not resolve startup-current risk.
For teams that can migrate architecture to 24 V, one published 100 rpm reference shows lower stall current (3.0 A), but wiring, controller, and battery compatibility must be re-validated.
| Standard / source | Applies when | Out of scope | Decision impact |
|---|---|---|---|
| ISO 3691-4:2023 | Driverless industrial trucks and their systems are in project scope. | Does not by itself certify personal-care or consumer-service robot deployments. | A pass in this tool does not replace formal safety verification for industrial AMRs. |
| ISO 13482:2014 | Personal care robot functions are in scope (mobile servant, physical assistant, person carrier). | Industrial automation and mobile servant robots above 20 km/h are excluded in the scope statement. | Confirms that speed and use-case class can change which safety standard set applies. |
| OSHA (US) robotics guidance | Workplace robots are deployed in the US under employer safety obligations. | OSHA notes there is no robot-specific OSHA standard; consensus standards still required. | Sizing output is only one input. You still need documented hazard controls and compliance review. |
| Failure case | Why model can mislead | Minimum action | Evidence status |
|---|---|---|---|
| 100 rpm catalog speed looks valid, but loaded speed drops under sustained torque. | Catalog rpm values are usually no-load references; real speed shifts with torque, current, and thermal state. | Log loaded speed at duty cycle, not only no-load bench speed, before RFQ freeze. | Confirmed |
| Switching from 100:1 to 131:1 solves torque, but mission time fails due to lower speed. | Same-family data shows torque rise comes with large speed drop and lower max output power. | Run mission-time simulation for both ratios before selecting higher reduction by default. | Confirmed |
| Current-margin estimate passes, but controller foldback still causes launch lag. | Public pages rarely disclose foldback vs undervoltage/thermal interaction for your exact controller+battery stack. | Capture startup voltage-current-speed traces and compare against controller protection behavior. | Pending |
| Risk | Trigger | Impact | Mitigation |
|---|---|---|---|
| Speed mismatch risk | Speed gap beyond +/-35% from target | Navigation timing drift and mission-cycle miss | Adjust wheel diameter or move to a different output-rpm family before software tuning. |
| Startup overcurrent risk | Estimated startup current near or above driver peak limit | Controller foldback, sluggish starts, or thermal shutdown | Apply acceleration ramp, check current limit policy, and validate with real telemetry. |
| Traction mismatch risk | Traction utilization > 95% | Wheel slip, odometry drift, and unstable stopping distance | Reduce accel/grade target or improve tire-ground friction condition. |
| Duty-cycle overheating risk | Continuous current close to rated current for long cycles | Brush wear acceleration and winding temperature rise | Add thermal test gate and size controller/motor with reserve margin. |
| Source | Checked | Use | Scope | Confidence | Caveat |
|---|---|---|---|---|---|
| DFRobot: How to Calculate the Motor Torque for a Mobile Robot | 2026-05-22 | Anchors force->torque workflow for first-pass mobile-robot sizing. | Reference tutorial for first-pass force/torque decomposition. | Secondary | Engineering tutorial, not a normative standard; use with primary motor curves and validation tests. |
| Pololu 100:1 Metal Gearmotor 37D 12V (item 4745) specs | 2026-05-22 | Provides published 12 V, 100 rpm, 5.5 A stall-current reference. | Reference point for 100 rpm brushed DC motor benchmark data. | Primary | N/A |
| Pololu 37D Metal Gearmotor datasheet (Rev 1.2) | 2026-05-22 | Adds torque-speed-current curve context and max-efficiency operating point. | Used for risk messaging around overload and sustained duty. | Primary | Vendor data is model-specific and must be replaced with your shortlisted motor curves. |
| Engineering ToolBox: Rolling resistance coefficients | 2026-05-22 | Supports first-pass rolling-resistance coefficient ranges. | Boundary guidance when measured route data is unavailable. | Secondary | Crr varies with tire pressure, material, and terrain; field measurements should override defaults. |
| OpenStax / LibreTexts friction model | 2026-05-22 | Anchors static friction boundary fs(max)=mu*N. | Traction-feasibility guardrail for wheel-slip checks. | Secondary | N/A |
| FAULHABER DC-Motors Technical Information | 2026-05-22 | Supports linear relationship reasoning between torque, speed, and current for brushed DC motors. | Interpretation layer for current-margin and speed-drop behavior. | Primary | Motor constants differ across families; this is a trend reference, not a universal constant set. |
| ISO 3691-4:2023 abstract page Published: 2023-06 edition | 2026-05-22 | Defines safety-verification scope for driverless industrial trucks/AMRs. | Clarifies that drivetrain sizing is necessary but insufficient for deployment approval. | Primary | Abstract-only source; project sign-off requires licensed full text and safety review. |
| NIST Handbook 44 (2026), Appendix C Published: 2026 edition | 2026-05-22 | Anchors inch/mm conversion for wheel and hub communication across teams. | Dimensional consistency in RFQ and integration notes. | Primary | N/A |
| Pololu gearmotor operation guidance (continuous vs stall) | 2026-05-22 | Includes stall damage caveat and common recommendation for sustained load below stall fraction. | Used for current safety and duty-cycle warning near results. | Primary | General recommendation; always apply model-specific thermal limits and controller limits. |
| Pololu 70:1 Metal Gearmotor 37D 12V (item 4744) specs | 2026-05-22 | Provides same-family 150 rpm / 27 kg-cm / 5.5 A comparison point. | Quantitative tradeoff anchor versus 100 rpm and 76 rpm variants. | Primary | N/A |
| Pololu 131:1 Metal Gearmotor 37D 12V (item 4746) specs | 2026-05-22 | Provides same-family 76 rpm / 45 kg-cm / 5.5 A comparison point. | Counterexample for torque-up vs speed-down tradeoff around 100 rpm. | Primary | N/A |
| Pololu 100:1 Metal Gearmotor 37D 24V (item 4685) specs | 2026-05-22 | Adds 24 V reference (100 rpm, 39 kg-cm, 3.0 A stall current). | Current-reduction option when architecture can move from 12 V to 24 V. | Primary | N/A |
| ISO 13482:2014 scope page Published: 2014-02 edition | 2026-05-22 | Defines safety requirement scope for personal care robots. | Boundary check for projects outside industrial driverless-truck scope. | Primary | Scope page only; clause-level compliance still requires licensed full text and safety review. |
| OSHA Robotics overview | 2026-05-22 | Confirms OSHA has no robot-specific standard and points to general obligations plus consensus standards. | US deployment governance boundary for interpreting motor-sizing output. | Primary | Regulatory interpretation varies by application; validate with qualified EHS and legal teams. |
| Topic | Status | Reason | Action |
|---|---|---|---|
| Controller current foldback curve vs battery sag | Pending | Public product pages rarely disclose dynamic foldback under undervoltage and thermal throttling. | Capture startup telemetry (voltage/current/speed) with final battery and controller settings. |
| Wheel-ground friction coefficient for the exact route surface | Pending | Published mu ranges are generic and cannot reflect dust, moisture, or tire wear in your site. | Run slip-threshold tests on target surface and replace default mu with measured value. |
| Thermal rise at mission duty profile | Pending | Catalog current values do not capture enclosure heat soak, stop-start frequency, and ambient extremes. | Run 30-60 min duty-cycle endurance test with winding and controller temperature logging. |
| Gearbox backlash growth under bidirectional loads | Pending | Public datasheets provide initial backlash but often omit wear growth under reversal-heavy workloads. | Request durability data and execute reversal-cycle bench test before procurement freeze. |
| Safety clause mapping from ISO abstract to site SOP | Pending | Public abstract confirms scope but cannot replace clause-level verification planning. | Map project use case to full standard text with safety engineering review. |
| Public numeric thresholds for startup current by robot category | Pending | No reliable public cross-industry threshold dataset was found; limits are controller-, battery-, and safety-case-specific. | Define project-specific thresholds in hazard analysis and verify with logged startup traces. |
Treat calculator output as stage-1 screening. Release readiness starts only after bench current traces, duty thermal data, and integration checks are complete.
Grouped answers for execution decisions, not glossary filler.
Continue with adjacent tools and guides to complete supplier shortlisting and validation planning.
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