Glossary · Motion control and drives
Trapezoidal profile
Also known as: Trapezoidal velocity profile
German: Trapezprofil
In motion control, a trapezoidal profile is a motion profile with constant acceleration, constant velocity and constant deceleration phases, so the velocity curve over time forms a trapezoid, or a triangle for short moves.
- Motion control
In one sentence
A trapezoidal profile accelerates, cruises and decelerates at constant rates, giving a trapezoid-shaped velocity curve.
Example
A simple indexing conveyor uses a trapezoidal profile with 2 m/s² acceleration and 0.5 m/s travel speed.
How it applies
- Engineering: Trapezoidal profiles are simple to calculate and give the shortest move time for given velocity and acceleration limits.
- Commissioning: The abrupt changes in acceleration can excite vibrations; if that's a problem, a jerk limit is added.
- Operation: Deceleration values also define how fast a normal stop brakes.
- Documentation: When parameters for velocity, acceleration and deceleration are adjustable, list units and ranges, and explain that reducing deceleration lengthens stopping distance.
Trapezoidal vs. S-curve profile
The trapezoidal profile changes acceleration abruptly. The S-curve profile ramps acceleration smoothly using a jerk limit.
For short moves, the axis never reaches the set velocity and the profile becomes a triangle; mention this when users wonder why the displayed speed stays below the setpoint.