RobotLocomotion/drake — pull request #129 by blandry (2014-05-28 02:34:30+00:00)
Title: Wing cleanup and perching with user gradients

I wanted to get some opinions on the result of trying the perching task in 3D and with user gradients. The test testWingForceGradients runs a few comparisons between the numerical and user gradients for the wing, and accumulating the error over a few test states it becomes clear that the only error comes from the acceleration of the roll, pitch, yaw with respect to the roll, pitch and yaw positions.
![forcegradienterror](https://cloud.githubusercontent.com/assets/2207326/3100096/44f5bb5c-e60f-11e3-888d-622dcd870a96.png)
That being said running trajectory optimization in 3D for perching gives the same resulting trajectories whether we use numerical or user gradients (which is great!). I am therefore not really worried about the gradients, but the resulting trajectories do not look right to me and I am starting to question the validity of modelling control surfaces with RigidBodyWings.

The file

examples/Glider/runDircolPerchingURDF.m

is what you would want to look at to get a trajectory.