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Design Optimization

Tutorial Developers: Robert Salati, B.J. Fregly, Rice Computational Neuromechanics Lab, Rice University

Last Updated: 3/10/2026

For the last step in the soccer kicking example, you will use the Design Optimization (DO) tool to design a better soccer kicking motion. This will be done in multiple ways:

  1. Using a constraint on the toe marker velocity
  2. Using a user defined cost term to increase toe marker velocity
  3. Allowing the DO problem to change the final time of the problem

Setting up a DO settings file​

  1. Copy and paste your settings file VOSettings.xml and name it DOSettings.xml
  2. Open DOSettings.xml in a text editor and change the XML headings at the top and bottom of the file from <VerificationOptimizationTool> to <DesignOptimizationTool>
  3. Change <initial_guess_directory> and <tracked_quantities_directory> to VOResults
  4. In the Final_Toe_Marker_Velocity_Value constraint, change the max error to 14.4 and the min error to 14.3
  5. Save this settings file.

Running DO​

Open runDOTool.m in Matlab and click run

Runtime

This DO run takes 36 iterations to finish.

Exploration Opportunities​

Modification #1: Add free final time​

In a text editor, copy and paste the following into your settings file:

<final_time_range>0.26 0.36</final_time_range>

Modification #2: Add a user defined cost term:​

In a text editor, copy and paste the following cost term into your RCNL Cost Term set:

<RCNLCostTerm name="User_Defined_Cost_Term" >
    <!--Indicate whether the term is enabled or not. Default is false.-->
    <is_enabled>true</is_enabled>
    <!--Type of cost term.-->
    <type>user_defined</type>
    <!--Name of Matlab function containing cost term implementation.-->
    <function_name>footSpeedCost</function_name>
    <!--Type of cost term (discrete or continuous).-->
    <cost_term_type>discrete</cost_term_type>
    <!--Required cost term input.-->
    <marker_name>R_Toe</marker_name>
    <!--Required cost term input.-->
    <target_speed>14.35</target_speed>
</RCNLCostTerm>

Disable the Final_Toe_Marker_Velocity_Value constraint term

Modificiation #3: Add a user defined constraint term:​

In a text editor, copy and paste the following constraint term into your RCNL Constraint Term set:

<RCNLConstraintTerm name="User_Defined_Constraint_Term">
    <!--Flag (true, false) indicating whether this contraint term is enabled. Default is false.-->
    <is_enabled>true</is_enabled>
    <!--Type of constraint term.-->
    <type>user_defined</type>
    <!--Type of constraint term (path or terminal).-->
    <constraint_term_type>terminal</constraint_term_type>
    <!--Name of Matlab function defining constraint term.-->
    <function_name>footSpeedConstraint</function_name>
    <!--Space separated list containing markers to be included in this cost term.-->
    <marker_name>R_Toe</marker_name>
    <!--Maximum error allowed by this constraint term.-->
    <max_error>14.4</max_error>
    <!--Minimum error allowed by this constraint term.-->
    <min_error>14.3</min_error>
</RCNLConstraintTerm>

Make sure both the other user defined cost term and toe velocity constraint term are disabled.