Joint Angle Limits Calculator

Work out joint angle limits instantly with clear inputs, formula shown and shareable results.

About Joint Angle Limits Calculator

Joint limits are enforced in two layers: hard limits from the mechanics and soft limits set inside them so the controller can decelerate before hitting a stop. Checking the commanded angle against both, and reporting the margin, is what prevents a trajectory from being planned into an unreachable pose.

Formula

Joint limits

soft range = [lower + margin, upper - margin]; margin to limit = min(cmd - soft lower, soft upper - cmd)

Worked example

With the default values below, Joint Angle Limits Calculator returns Limit status of Within safe range. Change any input above and every figure here is recalculated in your browser.

Inputs used

Lower joint limit: -170 °
Upper joint limit: 170 °
Commanded angle: 165 °
Soft limit margin: 5 °

Results

Limit status: Within safe range
Usable range after margins: 330.00 °
Margin to the nearest limit: 0.00 °
Range used: 100.0% %

Step by step

1Values used
2Joint limits
3Limit status= Within safe range
4Usable range after margins= 330.00 °
5Margin to the nearest limit= 0.00 °
6Range used= 100.0 %

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax, fees or charges or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

Why have soft limits at all?

So the axis can stop under control. Hitting a hard stop at speed damages the transmission and usually needs a re-home and re-calibration.

How large should the margin be?

At least the stopping distance at maximum speed for that joint, which is deceleration-limited, plus an allowance for following error.