# About the use of the Curve

**URL:** <https://forum.deltamotion.com/t/about-the-use-of-the-curve/475>\
**Category:** RMCTools\
**Created:** [December 10, 2018, 4:05pm UTC](https://forum.deltamotion.com/t/about-the-use-of-the-curve/475 "2018-12-10T16:05:11Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![mars\_bruce\_lee](https://forum.deltamotion.com/letter_avatar_proxy/v4/letter/m/a587f6/32.png) [@mars\_bruce\_lee](https://forum.deltamotion.com/u/mars_bruce_lee)\
**Post date:** [December 10, 2018, 4:05pm UTC](https://forum.deltamotion.com/t/about-the-use-of-the-curve/475/1 "2018-12-10T16:05:11Z")

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The following functions need to be implemented in the project.

At different points in time, it is necessary to accurately reach the required speed and position.  
Currently using the curve function，The current problem is  
When using mode Interpolation Linear , the command speed when reaching the target position can reach the required speed. Because the collection points used are not much, the theoretical speed is constant in a certain interval, but the actual situation is that it needs to be at the target point. The position reaches this speed, and the rest cannot reach this speed.  
When using mode Interpolation Cubic , although the speed corresponding to different position points is different, but the command speed reached by the target position is slightly different from the calculated speed, and the project  
requirements are not met.

At present, I am using Interpolation Linear. By increasing the sampling points to achieve better results, is there any better way?、

 ![截图09.png](https://forum.deltamotion.com/uploads/default/original/1X/017e186d81dae6a822d8c3e2c0ae93b3549e9575.png)

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**Author:** ![Jacob\_Paso](https://forum.deltamotion.com/letter_avatar_proxy/v4/letter/j/439d5e/32.png) [@Jacob\_Paso](https://forum.deltamotion.com/u/Jacob_Paso)\
**Post date:** [December 10, 2018, 5:19pm UTC](https://forum.deltamotion.com/t/about-the-use-of-the-curve/475/2 "2018-12-10T17:19:06Z")

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I am not sure I understand what you mean. Are you trying to create a velocity versus position profile?

Maybe if you include some plots or drawings of how you want the position and speed to behave, then maybe I will understand better.

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**Author:** ![mars\_bruce\_lee](https://forum.deltamotion.com/letter_avatar_proxy/v4/letter/m/a587f6/32.png) [@mars\_bruce\_lee](https://forum.deltamotion.com/u/mars_bruce_lee)\
**Post date:** [December 11, 2018, 2:44am UTC](https://forum.deltamotion.com/t/about-the-use-of-the-curve/475/3 "2018-12-11T02:44:14Z")

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the core requirement is the curve of speed and time.  
see the attachment

 ![Function reques.jpg](https://forum.deltamotion.com/uploads/default/original/1X/ee21fe7ed7eeed4e7e0f5461d3e17d214ec6832c.jpeg)

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<div class="post-metadata">

**Author:** ![Jacob\_Paso](https://forum.deltamotion.com/letter_avatar_proxy/v4/letter/j/439d5e/32.png) [@Jacob\_Paso](https://forum.deltamotion.com/u/Jacob_Paso)\
**Post date:** [December 12, 2018, 1:33am UTC](https://forum.deltamotion.com/t/about-the-use-of-the-curve/475/4 "2018-12-12T01:33:56Z")

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Here is a method of making and running a velocity curve:

1. Create a curve so that the y-axis is the velocity and the x-axis is time.
2. Run the curve on a virtual axis (it will do it on the position, but we will just know we mean it to be velocity).
3. Use the Gear Velocity command on your position control axis to gear to the Target Position (we know it is velocity) of the virtual axis.

See the attached project and plot.  
[VelCurve.rmcplots](https://forum.deltamotion.com/uploads/default/original/1X/d5845770dd4dcf8415d2044a4fef1023317a51f4.rmcplots) (3.82 MB)  
[VelocityCurve.rmcproj](https://forum.deltamotion.com/uploads/default/original/1X/08551ffdfe3c44ed58c4b88b227e5d77ec2e96b8.rmcproj) (23.2 KB)