FEETECH HL-3955 Servo Motor, 12V Coreless, 55kg.cm Stall Torque, Double Shaft, PID Control, 360°/Multi‑turn UART

Overview

The FEETECH HL-3955 Servo Motor is a 12V coreless, double-shaft constant force servo for robotics and motion applications. It features steel gears, ball bearings, and an aluminium case, with PID control via half duplex asynchronous serial communication. The servo delivers a peak stall torque of 55kg.cm@12V and a no-load speed of 0.182sec/60° (55RPM)@12V. Supported modes include angle servo control (0–360°), motor constant speed, motor constant current, and multi-loop operation.

Key Features

Mechanical and performance

• Coreless Motor; steel gear train; ball bearings; aluminium case
• Double shaft constant force servo; horn gear spline: 25T/OD5.9mm
• Gear Ratio: 1/378; limit angle: NO limit
• Peak stall torque: 55kg.cm@12V; rated load: 13.5kg. cm@12V
• No-load performance: 0.182sec/60° (55RPM)@12V; running current (at no load): 150mA@12V

Operating Modes

• Mode 0: Angle servo mode (default mode, absolute position controllable from 0-360 degrees)
• Mode 1: Motor constant speed mode (maintains speed without deceleration as the load increases)
• Mode 2: Motor constant current mode (maintains current without decreasing with increasing load) and can achieve absolute position

Multi-Loop Mode

Control of positive and negative 7 turns at the highest accuracy; the number of turns during power failure is not saved. Resolution can be expanded, and the number of turns can be doubled.

Constant force output

Set the output torque value; the servo can maintain this torque (input the target torque value corresponding to address 44, the servo can maintain this torque).

Control and feedback

• Command signal: Digital Packet; protocol type: Half Duplex Asynchronous Serial Communication
• ID range: 0-253; communication speed: 38400bps ~ 1 Mbps
• PID control algorithm; neutral position: 180°（2048）
• Running degree: 360° (when 0~4096); resolution: 0.088°(360°/4096)
• Rotating direction: Clockwise(0→4096）
• Feedback: Load, Position, Speed, Input Voltage，Current, Temperature

Specifications

Applications

• Humanoid Robots
• Robotic Arms
• Exoskeletons
• Quadruped Robots
• AGV Vehicles
• ARU Robots

Manuals

• HL3955-PRODUCT_SPECIFICATION.pdf
• HL3955_Product_structure_diagram.pdf
• SC-0090-C001Serial_Communication_Specification.pdf

Details