Nuno, If you re using KanesMethod it supports two types of constraints: holonomic and non-holonomic. You can supply these constraints to the initializer and then the equations of motion will be formed that take the nonholonomic constraints into account. Note that if you have holonomic kinematic constraints, you'll have to ensure that any of your numerical analyses code properly deals with that constraint, for example you may need to numerically solve for your dependent coordinates when setting initial conditions for simulation.
Jason moorepants.info +01 530-601-9791 On Tue, Aug 9, 2016 at 10:28 PM, Nuno <nmi...@gmail.com> wrote: > Since I think I was not clear with the first question, I'm going to try > and explain it better now. > > What I'm trying to achieve is a simple example similar to a 3D pendulum. > At the time I talked about 2 masses, but one of those was the anchor point, > so in fact everything can be done with only one mass. > > The twist here (in comparison with the simple 3D pendulum) is that besides > the gravitational force, the mass is under the effect of: > - A force in the x-axis of the mass > - A torque about the z-axis of the mass > > Futhermore, since I'm choosing to describe the system using the (x,y,z) > coordinates of the mass (and 3 euler angles) I was trying to add a distance > constraint: > (r_anchor - r_mass) - L = 0 > > Here is the jupyter notebook I created in order to define this system: > https://nbviewer.jupyter.org/github/ndevelop/sympy_3D_ > pendulum/blob/master/3D%20pendulum.ipynb > > Could someone help me understand any mistake I'm making and point me in > the right direction? > > Thanks in advance, > Nuno > > sexta-feira, 5 de Agosto de 2016 às 18:01:39 UTC+1, Nuno escreveu: >> >> I'm trying to get familiar with the sympy and its uses in obtaining the >> equations of motion of multi-body systems. >> >> In order to test things out I decided to use an example similar to a 3D >> pendulum where I have two masses. However the mass that is not fixed has a >> force and torque applied to it. So I wanted to have a distance constraint >> between the two masses: (r_a - r_b)^2 - L = 0 >> >> However I'm not sure how I should set this constrain in python/sympy in >> order to input it to KanesMethod() >> >> I'm sorry if this is question is a mess and thanks in advance for any help >> > -- > You received this message because you are subscribed to the Google Groups > "sympy" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to sympy+unsubscr...@googlegroups.com. > To post to this group, send email to sympy@googlegroups.com. > Visit this group at https://groups.google.com/group/sympy. > To view this discussion on the web visit https://groups.google.com/d/ > msgid/sympy/fd9a076b-8aad-4aeb-9765-6fc765d4119a%40googlegroups.com > <https://groups.google.com/d/msgid/sympy/fd9a076b-8aad-4aeb-9765-6fc765d4119a%40googlegroups.com?utm_medium=email&utm_source=footer> > . > > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "sympy" group. To unsubscribe from this group and stop receiving emails from it, send an email to sympy+unsubscr...@googlegroups.com. To post to this group, send email to sympy@googlegroups.com. Visit this group at https://groups.google.com/group/sympy. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAP7f1AgvPLPaXVsi7ycfp5bF44xCsk%3Dr8w%2Bj-6oQK_QTW2ezug%40mail.gmail.com. For more options, visit https://groups.google.com/d/optout.
