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RobotLocomotion / drake

Model-based design and verification for robotics.
https://drake.mit.edu
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Add a constructor to `DirectCollocation` and `DirectTranscription` that does not call `System<double>::ToAutoDiffXd(.)` #21725

Open samzapo opened 4 months ago

samzapo commented 4 months ago

Is your feature request related to a problem? Please describe. The following code accepts a System<double> and Context<double> then immediate converts them to use AutoDiffXd. https://github.com/RobotLocomotion/drake/blob/84f4fc58557043bb73bb3ae2d2748c62b054ec4f/planning/trajectory_optimization/direct_collocation.cc#L236-L257

Implementing the various requirements necessary to call System::ToAutoDiffXd() is significantly more difficult than the caller simply constructing an AutoDiffXd system and its context themselves and passing it to the constructor.

Describe the solution you'd like Add a constructor to DirectCollocation and DirectTranscription that accepts double and AutoDiffXd instantiations of the System and Context.

hongkai-dai commented 3 months ago

Sorry for my belated reply. I was travelling last week without my programming computer.

I don't see a problem to add a constructor in DirectCollocation and DirectTranscription that accepts AutoDiffXd version System<AutoDiffXd> and Context<AutoDiffXd>. @RussTedrake as the original author of DirectCollocation class, are you OK with the additional constructors?

RussTedrake commented 3 months ago

Sorry for my delay. Yes, we discussed this during the drake developers meeting. I think it seems very reasonable.