ROBOT JOINT DESIGN REVIEW
An angular headline cannot describe a whole joint.
Choose a harmonic, or strain-wave, reducer around the joint's load history, error budget and mechanical package. Cup geometry, input coupling, output support and life assumptions belong in the specification alongside the reduction ratio.
Keep the precision quantities in separate columns
Leaderdrive publishes backlash, hysteresis loss, torsional rigidity and angular transmission accuracy separately. For its LCS14 at ratio 50, maximum backlash is ≤10 arcsec, while angular transmission accuracy is 90 arcsec. The two numbers describe different properties. [1]
10 arcsec is about 0.167 arcmin; 90 arcsec is 1.5 arcmin. A unit conversion does not make backlash an accuracy guarantee. Specify the measurement load, direction, temperature and output reference for the required test.
- Backlash
- Ask how reversal play is measured, with what test load and at which output reference.
- Hysteresis & rigidity
- Request the torque–angle loop and stiffness regions relevant to the joint's working load.
- Transmission accuracy
- Ask for the angular error measurement over rotation for the selected assembly.
- Joint repeatability
- Define the repeated task, payload and measurement location; test the complete joint or robot against that requirement.
Freeze the flexspline drawing and the supply boundary
Laifual identifies the FSS mechanism as a cup-shaped flexspline, circular spline and wave generator. [2] Record the maker, family, frame and ratio together. A nominal size code such as “20” is not a complete dimensional specification or a cross-brand interchangeability approval.
On the flexspline / mating drawing
- Cup or other specified geometry, body length and required clearance.
- Locating diameters, flange thickness, bolt pattern and reference faces.
- Selected ratio and matched flexspline, circular spline and wave-generator identifiers.
- Drawing tolerances, material/process requirements where specified, and the supplier's assembly procedure.
No unverified cup dimensions are inferred from the frame number here. Request the current drawing for the exact variant before cutting the surrounding housing.
On the purchased assembly
State whether the quote covers components, an assembled reducer with output bearing, or an integrated joint with motor and encoder. Identify which party supplies and aligns the bearing, housing, seals and coupling.
Leaderdrive's LCS-I uses a keyed shaft connection to the wave generator; LCS-II uses an Oldham coupling. [1] These variants require different input-interface reviews. The coupling choice does not eliminate the supplier's alignment and fitting requirements.
Read a life figure with its load history
Laifual's FSS size-20 table puts several torque limits and a design-life entry on each ratio row. Keep the input-speed condition attached to rated torque. [2]
| Ratio | Rated at 2,000 rpm input | Start/stop peak | Average-load allowance | Momentary maximum | Listed design life |
|---|---|---|---|---|---|
| 50 | 25 | 56 | 34 | 98 | 10,000 h |
| 100 | 40 | 82 | 49 | 147 | 15,000 h |
Do not use the momentary maximum as running torque, or carry the longer life entry to another ratio. Ask Laifual to identify the load/speed spectrum, lubrication, failure criterion and life-calculation basis for the proposed assembly; the public row is not a joint-life warranty.
Review the joint at its hardest operating points
Laifual lists robot applications including industrial, collaborative and humanoid systems. [4] This is application context, not a declaration that one reducer suits every axis or establishes a robot's payload or safety rating.
Example brief: a reversing wrist with an offset tool
This is a procurement scenario, not a reported customer installation. Supply tool mass and centre of gravity, arm/tool geometry, orientation, acceleration/deceleration, travel range, external process forces and operating time. Identify gravity load, drive torque and overturning moment separately.
- At reversal: confirm start/stop torque, settling requirement, encoder location and measurement under load.
- During repeated motion: submit time-stamped torque and speed segments, cycle count, dwell, lubricant and temperature assumptions for a life assessment.
- At the output flange: check the selected support bearing and its radial, axial and moment ratings, housing stiffness and bolt/locating arrangement.
- During an exceptional stop: identify collision or overload events, duration, permitted event count and inspection/replacement rules. A peak-torque allowance is not a holding or safety function.
Request a signed selection covering the complete reducer code, flexspline/assembly drawing revision, precision test, life basis and supply responsibilities. Then qualify the actual quoting/manufacturing entity; the directory source trail does not replace an order-specific review.
Prepare a joint specification →Browse strain-wave manufacturers ↓
PICEA Motion
Laifual
KOFON
Finemotion
Leaderdrive
WANSHSIN
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