Feetech STS3215 servos has around 1 degree real backlash #134
Description
| Parameter / Test Method / Condition | Measured Result | Specification / Datasheet Value | Remarks / Comments |
|---|---|---|---|
| Operating Voltage | 12 V | 12 V | Operating range: 4–14 V |
| Static (Stall) Torque Lever arm 10 cm at 45° angle on scale | ~3.5 kg (35 kg·cm) | 30 kg·cm | Slightly higher than rated; enters protection at extended load |
| Dynamic Torque Lifting 1.5 kg on 10 cm lever | Supports load with +15 °C rise | — | Temperature increased by +15 °C after 10 min; overload triggered at 2 kg load |
| No-Load Speed (RPM) Measured at 100% and 50% speed | Max ~46 RPM; ±2% accuracy; ~7% fluctuation | 45 RPM (0.22 s/60°) | Standard settings; slightly unsmooth operation but acceptable |
| Encoder Resolution UART register read | 4096 steps per turn (12-bit) | 12-bit magnetic encoder (4096) | 0.088° per step |
| Encoder Backlash (Free Play) Measurement of free hand rotation | ~ 1° | ≤ 0.5° | — |
| Positional Error Under Load 1.5 kg load, 10 cm lever, 45° angle | 20–30 encoder values (1.8–2.6°) | — | Error increases significantly under load |
| Repeatability (Dial Indicator) 10 cm lever vertical; 20-step increments; 3 cycles each direction; 3 iterations | ±0.3 mm deviation at measurement points | — | Spring probe compensates mechanical slack; test could be refined or conducted under load |
| Temperature Rise (Static Load Test) – 1 kg load at 15 cm lever arm (≈15 kg·cm torque); arm positioned sideways | Temperature rose to 48 °C after 10 min and remained stable for >1 h with no further increase | Operating temperature range: –10 °C – 60 °C | Stable thermal behavior under static load; well within rated operating limits |
| Temperature Rise (Oscillation Test) – ±90° range; continuous motion; initial temperature 48 °C | Reached 60 °C after 50 min, stabilized for 20 min, then increased to 71 °C after ~110 min, resulting in overheating | Overheat protection threshold: 70 °C | No active thermal shutdown observed — manual cutoff required near 70 °C. Reducing acceleration increased heating rate (accel = 2 → overheat; accel = 5 → stable ~ 60 °C). |
| Communication Interface | UART TTL, half-duplex | Functional | 38400 bps – 1 Mbps (default 1 Mbps); Chainable multi-servo connection |
| Closed-Loop Control | Position and speed feedback works reliably | — | Supports position holding and speed control |
| Telemetry / Feedback | UART readout: position, speed, current, voltage, load, temperature | — | Full telemetry available |
| Protection Systems | Overload, overcurrent, overvoltage, undervoltage, overtemperature | Functional | Configurable timeout and safe limits via registers |
| Firmware Dead Zone | Command input < 10 encoder steps | No motion observed | Built-in 10-count deadband |
| Price / Accessories | — | ~$15 (servo) + ~$5 (UART adapter) | Excellent cost-to-performance ratio |
Detailed testing for of the servo Feetech STS3215 motors: https://robonine.com/testing-of-feetech-sts3215-servomotor-backlash-repeatability-and-torque/