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This is a very subjective problem. A good motion for one application may not always be a good motion for another.
An attempt to answer the question of “How to improve a motion?”
Assumptions:
•The motion is for a machine, and not for the animation of a cartoon character.
•The motion is intended for a machine where the machine elements reciprocate, oscillate, index, or the speed modulates in some way. Each machine element has mass, mass moment of inertia, stiffness, and backlash.
•The inertia forces are dominant - or at least 80% of the total load.
General Advice:
•Remove all Velocity motion-discontinuities.
•Remove all Acceleration motion-discontinuities.
•Use a minimum number of segments.
oAlways ask yourself: “Can I reduce the number of segments?”
oAlways ask yourself: “Can I delete a Dwell Segment?” - especially short dwells.
•Reduce the number of motion constraints. E.g. Do you need to control the position of a Blend-Point - possibly you only need to control its velocity.
•Try to make the maximum acceleration values of each segment similar to each other. This is not always possible or desirable. But consider balancing the motion to give similar motion durations or peak accelerations, or both.
•When different tools must interact in some way, consider moving a tool further than you need to, if you can also give it more time. This is often a very powerful way to reduce accelerations of tools.
For example, if you increase the displacement by 20% and increase the duration by 20%, the maximum velocity will not change, but the maximum acceleration will reduce by 20%.
A motion-law might:
•give more flexibility for you to control the motion-derivatives at the Blend-Points.
•suit the mechanical system. For example, the motion-law might have a “low peak maximum velocity”.
•give a good dynamic response to the mechanical system. For example, the motion-law might have a good response to system backlash, low drive stiffness.
•agree with a company preference(!) - for example Modified Sinusoid is often a company preference.
Note:
I nearly always design my motions with Flexible-Polynomial segments as they give me almost all of the flexibility I need.