Polynomial 3-4-5 Motion-Law

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Polynomial 3-4-5 Motion-Law

Polynomial 3-4-5 Cam-Law, Motion-Law

Motion Description

A Traditional Motion-Law.  Its name is often reduced to Poly-345.

A motion with continuous Velocity and Acceleration, from start to end. The Jerk is finite at its start and end. It has finite Jerk throughout.

It gives a relatively low nominal peak velocity, but a relatively high peak nominal Acceleration. It has a relatively low Jerk value at the crossover point (the mid-point). It is commonly used in high-speed mechanisms.


You CAN control the:

Start Position

The Start-Position usually flows from the End-Position of the Previous-Segment.

End Position

You CANNOT control the:

Start Velocity and End Velocity

Start Acceleration and End Acceleration

Start Jerk and End Jerk

Segment Parameters




See also : MD-Globe-www-24 Tutorial 5: Edit the Start of a Traditional Motion-Law

See also : MD-Globe-www-24 Tutorial 9: Asymmetrical Motions

Polynomial 3-4-5 Motion-Law / Cam-Law

Polynomial 3-4-5 Motion-Law / Cam-Law

Motion-Law Coefficients

Velocity Coefficient :

Acceleration Coefficient :

Jerk Coefficient :

Jerk at Crossover :

Application Notes

Dynamic Performance:

This Motion-Law is recommended for applications where the period ratio is less than 10, particularly where the input drive is stiff and the shaft speed does not fluctuate significantly under load.

It has good acceleration characteristics and is suitable for applications that need low levels of residual vibration.

Pressure Angle Considerations

This is a Traditional Motion-Law that produces a relatively large pressure angle - and so might need a larger cam for a given lift and pre-prescribed maximum pressure angle.

Drive Torques

The torque characteristics of this motion law are good compared to other traditional motion-laws, when the period ratio is less than 10. IT is recommended when no sudden change in torque is allowed.