Extendidng Hamilton's Principle to Non-Holonomic sytems

AI Thread Summary
Extending Hamilton's principle to non-holonomic systems through Lagrange undetermined multipliers is complex, as a true "Nonholonomic Constrained Action Principle" does not exist unless the constraints are integrable. Nonholonomic constraints often disguise holonomic constraints, leading to inconsistencies in variational principles found in some literature. The Hamilton-Jacobi-Bellman Principle, applicable to optimal control problems with non-holonomic constraints, differs from Hamilton's Principle and can result in non-unique solutions. Dirac's Theory of Constrained Hamiltonian Systems also requires integrable constraints for derivation from a variational principle. Overall, the discussion emphasizes the challenges and limitations in applying Hamilton's principle to non-holonomic systems.
pardesi
Messages
337
Reaction score
0
Can someone explain me how to extend Hamilton's principle to non-holonomic system's thru the lagrange undetermined multipliers?
PS:Assume the system is Semi-Holonomic that is f_{\alpha}(q_{i},q_{2} \cdots q_{n} ,\dot{q_{1}}, \dot{q_{2}}, \cdots \dot{q_{n}})=0 such a equation exists for \alpha=1,2,3 \cdots m
 
Last edited:
Physics news on Phys.org
If by "Hamilton's Principle," you mean "the Variational Principle that Hamilton's Action is Extremized," strictly speaking, no such "Nonholonomic Constrained Action Principle" exists, except in the special case that the "nonholonomic constraints" are "integrable" --- i.e., that they are really just "disguised" holonomic constraints that have been written in an apparently non-holonomic form. (One will find a few contrary claims in a few textbooks and papers, but on careful examination, these so-called "nonholonomic variational principles" are all either ill-posed or not self-consistent unless the constraints are integrable.)

IIRC, a mathematically rigorous treatment of constrained variational problems may be found in Rund and Lovelock's https://www.amazon.com/dp/0486658406/?tag=pfamazon01-20 but it's fairly heavy going. (Or perhaps I may be thinking of Rund's "Hamilton-Jacobi Theory of the Calculus of Variations," which is sadly now out of print...)

There is a modification of Hamilton's Principle called the "Hamilton-Jacobi-Bellman Principle" (or just the "Bellman Principle" for short), that is used to formulate "Optimal Control Problems" --- including problems with non-holonomic constraints. However, the Bellman Principle is not in general equivalent to Hamilton Principle, and it does in general lead to equations of motion that are "mathematically degenerate" --- i.e., they have a nontrivial "nullspace," implying that their solutions are non-unique.

There is also Dirac's Theory of Constrained Hamilitonian Systems, but Dirac's formalism cannot be derived from a variational principle except in the special case that the constraints are integrable --- i.e., the constraints are equivalent to holonomic constraints.
 
Last edited by a moderator:
Thread 'Question about pressure of a liquid'
I am looking at pressure in liquids and I am testing my idea. The vertical tube is 100m, the contraption is filled with water. The vertical tube is very thin(maybe 1mm^2 cross section). The area of the base is ~100m^2. Will he top half be launched in the air if suddenly it cracked?- assuming its light enough. I want to test my idea that if I had a thin long ruber tube that I lifted up, then the pressure at "red lines" will be high and that the $force = pressure * area$ would be massive...
I feel it should be solvable we just need to find a perfect pattern, and there will be a general pattern since the forces acting are based on a single function, so..... you can't actually say it is unsolvable right? Cause imaging 3 bodies actually existed somwhere in this universe then nature isn't gonna wait till we predict it! And yea I have checked in many places that tiny changes cause large changes so it becomes chaos........ but still I just can't accept that it is impossible to solve...
Back
Top