Design and analysis of Hermite curves

Hermite curve is one of the basic curves that is defined by control points and tangents. A GUI for simulating this curve is developed within NX using C++ and Ufuncs. This tool is used in the course for demonstrating the impact of change in parameters on the shape of hermite curve. Students are assigned problems to create Hermite curves with various parameters and this tool helps them in visualizing and validating their work. 

Installation Manual

  1. Download and extract the contents of the .zip file named Design & Analysis of Hermite Curves.zip.
  2. Open the extracted folder named Design & Analysis of Hermite Curves.
  3. Open the folder named ug_customization. Right click on the Windows Batch File named nx and open with Notepad/Notepad++.
  4. Find the current file path of the nx file in your computer (Right click >> Properties). Copy the file path and paste it in the first line (the highlighted portion in the notepad as shown below).
  5. Change the version of Siemens NX to the one you are using (module works for Siemens NX 10.0, 11.0, and 12.0) in the third line of the notepad file (as highlighted below)
  6. Once these steps are carried out, you have completed the installation procedures before launching the application.
Support Accessibility Output Window
Support Accessibility Output Window

Instruction Manual

  1. Now, double-click nx to launch the Windows Batch File. This will launch the Siemens NX window and a terminal window (you can minimize it or close it – it contains the information you input in steps 4 and 5). You may notice the UC Geometric Modeling Modules tab in the top toolbar. Click on it. The Design & Analysis of Hermite Curves module will be visible.
  2. To create the hermite curve the user is supposed to specify the control points and tangents. For illustration purposes, two text files with the hermite curve parameters are saved in the folder named Examples
  3. Once you can click on the Design & Analysis of Hermite Curves button on the Command Ribbon.  
  4. The Design & Analysis of Hermite Curves GUI is shown in the figure below. The detailed explanation of each option in the GUI is given below. 
NX API based GUI

NX API based GUI

a) Start Point
The control point at the start of hermite curve.

b) End Point
The Control point at the end of the hermite curve

c) Start Tangent
The tangent at the start of the hermite curve.

d) End Tangent
The tangent at the end of the hermite curve.

 

e) File Browse
Browse the text file with the parameters of the hermite curve to be generated.

f) Read values
Used only when getting the curve parameters from a file. Reads the parameters of the hermite curve (control points, tangents) in to the GUI.    

g) Update
Generates or updates the hermite curve along with the tangents according to the parameters specified manually or read using the appropriate text file.

h) Clear tangents
Clears all the tangents plotted on the NX interface.

i) Clear all
Clears curves as well tangent to the curves plotted on the NX interface

j) Tangent at U
The parametric value U on the hermite curve at which the tangent is to be determined.

k) Tangent
Plots the tangent at the specified U value and outputs the value of tangent, unit tangent in the information window.

To save the generated curve use ‘OK’ or ‘Apply’, else use ‘cancel’.

5. The output window of the Design & Analysis of Hermite Curves module is as shown below. The results consist all the curve along with the tangents.

Plot of two Hermite Curves with the same control points and the reversed tangents

Plot of two Hermite Curves with the same control points and the reversed tangents

Please watch the video tutorial of the module for an example included with the zip file of the module.

Example Problem

Try out the following to learn the impact of change in parameters (control points, tangents) on shape of curve.

Generate and plot the hermite cubic curve with the following parameters:

a. Start point (20, 5, 5), End point (5, 20, 5), start tangent (5, 5, 20), end tangent (5, 5, 20).

Calculate the tangent vector and unit tangent vector for the curve at u=0.5.

b. Reverse the direction of start and end tangent vectors while doubling the magnitude of the tangent vectors. Calculate the tangent vector and unit tangent vector for the curve at u= 0.7. 

Download Design & Analysis of Hermite Curves