Custom Robot Joint Actuator Development¶

Start From the Joint Requirement, Not From an Existing Actuator Model¶

A robotics project does not need to fit an existing SigGear actuator exactly.

You may already know the joint torque, speed and installation envelope. You may also have only a robot mechanism, link geometry, motor preference, CAD concept or early prototype.

SigGear develops and manufactures robot joint actuators, planetary actuator platforms and cycloidal joint modules for robotics and compact motion systems.

SigGear can review the joint as a system and evaluate the actuator gearbox or reducer, motor, sensing, driver and mechanical interfaces together.

Depending on the project, the engineering path may start from:

an existing SigGear planetary actuator
an existing SigGear cycloidal joint module
a gearbox-centered solution for the customer's own motor and controller
a motor + gearbox combination
a modified mechanical interface
a new compact actuator configuration based on the application requirements

Send Your Joint Requirement Humanoid and Bipedal Robot Joint Engineering Request Engineering Review

What Can SigGear Supply?¶

Depending on the project and engineering feasibility, the supply scope may include:

gearbox / reducer only
motor + gearbox assembly
planetary robot joint actuator
cycloidal joint module
actuator with encoder
actuator with driver where applicable
modified mechanical interface
project-specific joint configuration

The exact configuration depends on torque, speed, packaging, motor, sensing, controller and mechanical-interface requirements.

Project-Specific and OEM Development¶

For OEM or project-specific robot joint programs, the engineering review can begin from an existing SigGear actuator platform, the customer's motor/controller architecture, or a new mechanical requirement. Final feasibility depends on the complete torque-speed requirement, packaging, interfaces, electronics configuration and production plan.

What the Engineering Review Starts With¶

A meaningful robot-joint review normally needs the axis requirement rather than one isolated torque number.

Useful inputs include:

robot type and joint position
payload and moving-link mass
link length and center-of-gravity location
continuous torque
peak torque and peak duration
output speed and motion cycle
maximum diameter, thickness, length and weight
radial / axial load and overturning load where relevant
operating voltage and controller current limits
encoder and feedback requirement
driver and control mode
communication interface
power-off behavior and brake requirement
prototype quantity and expected production volume

If some of these are not known yet, send the mechanism, CAD, sketch or the information already available. The engineering review can identify what needs to be calculated, measured or tested before the actuator architecture is fixed.

Planetary, Cycloidal or Another Joint Architecture?¶

SigGear publishes both planetary robot joint actuators and cycloidal joint modules.

Neither structure should be selected from a general rule alone.

The choice needs to consider:

torque-speed requirement
installation diameter and axial thickness
motor speed and motor size
ratio
efficiency
backlash
external loads
thermal condition
noise target
backdrivability or holding requirement
encoder / driver architecture
prototype and production constraints

For a project where the transmission structure has not been decided, send the operating requirement first.

Custom Planetary Gearbox Engineering Custom Cycloidal Transmission Engineering

Existing Planetary Joint Reference Platforms¶

SigGear currently publishes three integrated planetary robot joint actuator reference models:

Reference model	Transmission	Published rated torque	Published peak torque	Published rated output speed
SG-6010C	Planetary	6 Nm	18 Nm	310 rpm
SG-6010D	Planetary	16 Nm	50 Nm	100 rpm
SG-8021	Planetary	10 Nm	30 Nm	160 rpm

These products are reference platforms, not the only joint configurations SigGear can evaluate.

A new project may require a different:

reduction ratio
torque-speed balance
motor
outer diameter or axial thickness
output interface
housing or mounting structure
encoder
driver
communication arrangement
cable or connector configuration

Any change must be reviewed as a complete configuration.

Existing Cycloidal Joint Reference Platforms¶

SigGear also publishes cycloidal joint-module references:

Reference model	Transmission	Published rated torque	Published peak torque	Published rated output speed
CPM-80-25	Cycloidal pinwheel	10 Nm	50 Nm	120 rpm
CPM-100-25	Cycloidal pinwheel	25 Nm	75 Nm	60 rpm
CPM-78-39	Cycloidal pinwheel	20 Nm	52 Nm	48 rpm

The published values belong to the listed products only and must not be transferred to a different motor, ratio, diameter or custom configuration without engineering confirmation.

SG-6010C as a Public Engineering Reference¶

SG-6010C currently has the most complete public Engineering Pack among the planetary joint actuators.

Public resources include:

technical datasheet
mechanical-interface reference
simplified STEP model

View SG-6010C View SG-6010C Datasheet View SG-6010C Mechanical Interface

Its public product documentation also describes driver-equipped configurations with CAN, USB Type-C, position / velocity / torque control and encoder support. These functions are configuration-dependent and must be confirmed for the quoted hardware and firmware.

CPM-80-25 as a Public Cycloidal Reference¶

For cycloidal joint evaluation, CPM-80-25 has a public Engineering Pack including:

technical datasheet
mechanical-interface reference
simplified STEP models
measured performance data

View CPM-80-25 View CPM-80-25 Measured Performance Data

Measured test points are engineering evidence for the released configuration and are not universal continuous ratings for a custom joint.

What Can Be Reviewed in a Custom Joint Project¶

Depending on the reference platform and project feasibility, the review may include:

Engineering area	Examples
Transmission	planetary or cycloidal structure, ratio and gearbox architecture
Motor	motor type, speed, power, torque constant and mechanical interface where applicable
Packaging	outer diameter, axial thickness, housing and total joint envelope
Output	flange, shaft, locating feature and robot-side mounting interface
Feedback	Hall / encoder arrangement supported by the selected configuration
Driver	integrated or external driver architecture
Control	position, velocity or torque control where supported by the selected driver
Communication	CAN, RS485 or other supported project-specific interface
Safety	brake, power-off behavior and mechanical stops where required
Mechanical load	radial, axial and overturning load review
Integration	cables, connectors, housing and assembly arrangement

Not every item can be changed independently. A change to motor, ratio, size, driver or interface may affect torque, speed, thermal behavior, weight, efficiency, life, control limits and cost.

If You Do Not Know the Required Joint Torque¶

A robot team can still start the discussion before the torque value is finalized.

Useful inputs include:

supported mass
link mass
payload
link length
center-of-gravity location
acceleration target
external force
joint angle range
motion cycle
whether the axis works against gravity

For a first single-axis screening, gravity, acceleration and external-force torque can be estimated before the actuator is shortlisted.

Open the Robot Joint Actuator Selection Guide

If You Have a Motor or Controller Already¶

Some robotics teams already have a preferred motor, driver or control stack.

In that case, send the available:

motor drawing and shaft details
motor speed / voltage / power data
controller current limits
encoder requirement
communication requirement
available installation space
required output torque and speed

SigGear can then evaluate whether the project should use a gearbox-centered joint solution, a motor + gearbox assembly or another integrated actuator approach.

Motor + Gearbox Integration Engineering Prototype → Design-In → Production Open the Engineering Center

Robot and AI Hardware Applications¶

Custom joint and compact actuator development may be relevant for:

humanoid robots
quadruped robots
robotic arms
exoskeletons
rehabilitation robots
service robots
compact rotary automation axes
AI-enabled hardware products that require compact controlled motion

For smaller mechanisms such as dexterous hands, grippers and compact end effectors, a micro planetary gearbox or gear-motor architecture may be more appropriate than the larger published joint modules.

Browse Micro Gear Motors Robot Gripper and Dexterous-Hand Applications

These are application areas where SigGear transmission products and engineering review may be relevant. They are not claims that SigGear has a public production case in every listed application.

Engineering Development Path¶

A custom robot-joint project may move through:

Joint Requirement / Robot CAD / Existing Prototype
→ Torque and Motion Review
→ Transmission Architecture Review
→ Motor / Encoder / Driver Review
→ Mechanical Interface and Packaging Review
→ Configuration Drawing
→ Prototype / Sample
→ Representative Joint Test
→ Parameter / Interface Refinement
→ Design Confirmation
→ Pilot Preparation
→ Production

The exact path depends on how much of the robot architecture is already fixed.

What to Send First¶

You do not need to prepare a complete joint specification before contacting SigGear.

For a first review, send what you already have:

robot type and joint position
link / load information
target torque if known
target speed
maximum joint diameter and thickness
operating voltage
motor / controller preference if already selected
encoder / communication requirement if already defined
drawing, CAD screenshot or mechanism sketch
prototype quantity and expected production volume if known

If several values are still unknown, the project can start from the robot mechanism and design intent.

Confidential Robotics Projects¶

Robot and AI-hardware development often involves unreleased mechanisms, customer CAD and project-specific actuator architecture.

Those projects may be covered by confidentiality agreements and cannot be shown publicly.

SigGear therefore uses public actuator platforms, gearbox platforms, CAD resources, mechanical interfaces and test data to demonstrate real engineering capability without exposing confidential customer designs.

Discuss Your Robot Joint Project¶

Send the joint requirement, robot CAD, mechanism, motor or the information you already have.

Wanrong Wang
International Sales / Sales Engineer, SigGear
wangwanrong@siggear.com

Request Engineering Review Send Your Joint Requirement