Each segment is assigned a Motion-Law by the user.
A Motion-Law specifies, with a mathematical expression, how an output variable changes as a function of an input variable.
The mathematical expression calculates displacement, velocity, acceleration, and jerk values. All motion-derivatives are exact, evaluated motion-values. The user does not need to know any mathematics. We plot the motion-laws.
The user needs to specify various parameters that may relate to the Motion-Law.
In the Motion-Law Selector, we list the Motion-Laws alphabetically (English Language).
In this topic, we can separate the motion-laws into three groups.
Traditional Motion-Laws (also named Standard Motion-Laws) have been used for many years in cam mechanisms for motions that have Rise and Return segments separated with Dwell segments.
The Traditional Motion-Laws are based on:
1.Constant-Acceleration & Deceleration - Polynomial Function
2.Constant-Velocity - Polynomial Function
3.Cubic - Polynomial Function
4.Cycloidal - Trigonometric Function
5.Cycloidal Constant-Velocity 50% -Trigonometric Function
6.Dwell - Polynomial Function
7.Modified-Sinusoid - Trigonometric Functions
8.Modified-Trapezoidal - Trigonometric Functions
9.Polynomial 2-3 - Polynomial Function
10.Polynomial 3-4-5 - Polynomial Function
11.Polynomial 4-5-6-7 - Polynomial Function
12.Polynomial Low Impact Crossover - construct with two Flexible-Polynomial segments
13.Quadratic - Polynomial Function
14.Ramp - Trigonometric Function
15.Simple-Harmonic - Trigonometric Functions
16.Sine-Constant-Cosine + SCCA with Constant-Velocity 20%, 33%, 50%, 66%.... - Trigonometric Functions
17.Sine-Squared - Trigonometric Functions
18.Sinusoidal - Trigonometric Functions
19.Triple-Harmonic (also called Three Harmonic) - Trigonometric Functions
Also, use the 'Triple Harmonic' Controls in the Segment-Editor to give:
a.Triple Harmonic - Modified Trapezoidal - Trigonometric Functions
b.Triple Harmonic - Modified Sine - Trigonometric Functions
c.Triple Harmonic - Zero Jerk at Crossover - Trigonometric Functions
Throw Motion-Laws (Symmetrical & Asymmetrical)
A Throw motion-law is a rise segment followed immediately with a return segment.
We call it a Throw because the motion is similar to a ball that is thrown up in the air. The transition of the ball from its Rise to Return (at its maximum-displacement) has zero-velocity, but has finite deceleration.
In general, the shape of the Throw motion from Rise to Return is defined by the acceleration and jerk values at the transition.
We design the Rise and Return parts of the Throw motion-law with two Flexible Polynomial segments. Thus, we can also edit the Segment-Width of the two segments that will also influence the shape of the Throw segments.
The 'Crossover Jerk' of 25 is greater than other motion-laws. This means that any backlash is traversed quickly to give a large velocity impact.
These meet the needs of specific applications.
26.Y–Inverse-Sinusoid : when applied to the motion of a crank, it gives a constant linear velocity at the tip of a crank. Limited to one segment per crank rotation.
27.Crank-Constant-Velocity : an enhancement of Y-Inverse-Sinusoid, this motion-law can be applied to more than one segment in a motion.
28.Flexible-Polynomial - a VERY important and useful motion-law.
29.Ramp - a useful motion-law.
You can import your own motion-values to a List Segment-Type:
The Flexible Polynomial is the default motion-law. It is very powerful. We recommend that you learn how to use it effectively and efficiently.
Traditional Motion-Laws have advantages in some circumstances.
We recommend that the segments are:
•All Flexible-Polynomials - most powerful and flexible motion-design possibilities
- or -
•All Traditional Motion-Laws - easiest motion-design
- or -
•A mixture of Flexible-Polynomial and Traditional Motion-Laws - most difficult motion-design but may offer advantages
The Motion-Laws available in MotionDesigner exceed the German Technical VDI-guidelines 2143 Papers (Part) 1 and 2. Also bear in mind, that the motion at a cam-follower or servomotor is usually found by MechDesigner with Inverse-Kinematics. In this case, the motion at the cam-follower or servomotor will not be the same as the motion of the Motion-Part.