Point on Curve Constraint

Kinematic constraint between frame origin and curved path

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Libraries:
Simscape / Multibody / Constraints

Description

The Point on Curve Constraint block confines a point to a curve. The frame attached to the point is free to rotate depending on other constraints in the model. Use the Point on Curve Constraint block to model point-on-curve constraints, such as that between a roller coaster and a track or a cam follower and a cam.

The Point on Curve Constraint block has two ports: F and B. Port F is a frame port whose origin corresponds to the point. Port B is a geometry port that you connect to a curve. Avoid curves with sharp changes in slope, as these can cause simulation issues.

You can use this block to sense the constraint forces and torques between the point and curve. Based on the setting of the Resolution Frame parameter, the block resolves the forces and torques in either the base or follower frame.

Examples

Using the Point-On-Curve Block: Flapping Wing Mechanism

This model simulates a barrel cam based wing flapping mechanism. This is a one degree of freedom mechanism and the two wings flap in sync with each other. The Spline and Point On Curve blocks have been used to model the Barrel Cam mechanism that actuates the flapping motion of the wings.

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Ports

Geometry

B — Base frame

frame

Geometry port associated with the curve defined by the Spline block.

Frame

F — Follower frame

frame

Follower frame whose origin is confined to the curve connected to port B.

Output

f — Constraint force

vector

Constraint force that acts between the point and curve, returned as a vector. See Measure Joint Constraint Forces for more information. If you set the Resolution Frame parameter to Base, the sensed force is with respect to the reference frame of the curve connected to port B.

Dependencies

To enable this port, under Constraint Force/Torque Sensing, select Force Vector.

t — Constraint torque

vector

Constraint torque that acts between the point and curve, returned as a vector. See Force and Torque Sensing for more information. If you set the Resolution Frame parameter to Base, the sensed torque is with respect to the reference frame of the curve connected to the port B.

Dependencies

To enable this port, under Constraint Force/Torque Sensing, select Torque Vector.

Parameters

Direction — Measurement direction

Follower on Base (default) | Base on Follower

Direction in which to measure the constraint force and torque. Reversing this direction changes the sign of the measurements. See Force and Torque Measurement Direction for more information.

Resolution Frame — Frame to resolve measurements

Base (default) | Follower

Frame used to resolve the measured vector quantities. See Selecting a Measurement Frame for more information.

Force Vector — Whether to sense constraint force

off (default) | on

Select this parameter to expose port f, which outputs the constraint force vector between the B and F frames.

Torque Vector — Whether to sense constraint torque

off (default) | on

Select this parameter to expose port t, which outputs the constraint torque vector between the B and F frames.

Extended Capabilities

C/C++ Code Generation
Generate C and C++ code using Simulink® Coder™.

Version History

Introduced in R2015b