Hongkai Dai

> But whether or not this constraint also adds a cost, I would like to be able to add a cost based on the minimum distance to an obstacle. @cohnt...

@cohnt could you try this code snippet? ```py min_distance_constraint = multibody.MinimumDistanceLowerBoundConstraint(plant, plant_context, bound=0) # min_distance_constraint.Eval() computes ϕ(d/d_influence − 1)/ϕ(−1), where d is the minimal distance, and ϕ() is the penalty...

@cohnt does the code snippet in the previous comment work? Do you think we still need to add any new features, or we can close this issue?

Sorry for the late reply. I will write the optimization program in CLP native API, not through Drake, and then reproduce the error so that we can report on CLP...

I can reproduce the problem using CLP native code without using Drake's code. I filed the issue in CLP upstream https://github.com/coin-or/Clp/issues/316

BTW, we do have a warning inside ClpSolver when the user attempts to solve a QP with CLP https://github.com/RobotLocomotion/drake/blob/23c696b59ea3739dbfc21e5b9701735781b71165/solvers/clp_solver.cc#L37C1-L41C47

> Yes, I added that warning in https://github.com/RobotLocomotion/drake/pull/23199. Ah I see, thank you very much for adding the warning, very helpful!

As suggested by the CLP author https://github.com/coin-or/Clp/issues/316#issuecomment-3096258927, we could switch to the most up-to-date CLP.

I am less familiar with `GcsTrajectoryOptimization`. I think @cohnt and @wrangelvid know that code better than I do. Re-assigned to @cohnt

I should have been more clear, I mean ∂²f(i) / ∂q², namely the second order derivative of the i'th entry of `f` w.r.t `q`.