Thanks Jason for the reply. As I have mentioned before, my actual system is a bit more complex with the manipulator attached to a floating base. There are several non-holonomic constraints as well. I am not sure if these could be addressed by pydy or may be it will but still I need to go through examples and learn and develop again. Could you please let me know how to replace the functions of time with ordinary symbols. I am expecting something like q1(t) to be q[0] and d q1(t) /dt to be dq[0]?
Ash On Mon, Oct 28, 2019 at 12:39 PM Jason Moore <[email protected]> wrote: > https://github.com/pydy/pydy will do all this for you with just a few > commands. > > If you want to use the code generation tools in sympy directly, it may > help to replace the functions of time with ordinary symbols. > > Jason > moorepants.info > +01 530-601-9791 > > > On Mon, Oct 28, 2019 at 4:04 AM Ash <[email protected]> wrote: > >> Hello >> I am trying to develop equations of motion using sympy of a complex >> system. It takes 4-5 minutes to get the mass matrix (M) and coriolis vector >> (C). Hence I decided to use sympy's codegen and try to make it fast. >> I can write my equations as >> >> d^2 *q*/ dt^2 = M_inverse (Tau - C - G) >> but M, C, Tau (torque) and G(gravity) are defined with respect to state >> variables and its derivatives. And I cant figure out how to do it. >> >> I am attaching a simple two degree of freedom planar robot's code for >> easy understanding of my problem. My state variables are the angles q1(t) >> and q2(t) (dynamic symbols). There are other variables like lengths, mass, >> inertia of the links which are defined as symbols. M(q(t)), C(q(t), dq(t)), >> G(q(t)) matrices are derived symbolically (line 14). My doubt is if I want >> to play around with the numerical values of the variables in M, C, and G, >> how can I efficiently generate code and cythonize and build wrapper? >> >> Any help would be really appreciated >> >> Thanks >> >> -- >> 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 [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/sympy/eb589af0-2dca-4b8d-bfff-290a4767e20a%40googlegroups.com >> <https://groups.google.com/d/msgid/sympy/eb589af0-2dca-4b8d-bfff-290a4767e20a%40googlegroups.com?utm_medium=email&utm_source=footer> >> . >> > -- > 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 [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/sympy/CAP7f1AjbK%2BKTZJV9z8XO3Y7x_S0%2B7xR969%2BK8GcptG-tgwue%2BQ%40mail.gmail.com > <https://groups.google.com/d/msgid/sympy/CAP7f1AjbK%2BKTZJV9z8XO3Y7x_S0%2B7xR969%2BK8GcptG-tgwue%2BQ%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- R.B. Ashith Shyam <https://sites.google.com/site/rbashithshyam/> +44 7459909812 -- 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 [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/sympy/CAGassLARFMmfZ5uWfiN0y8KLWxfR19A2WtjJ%2Bjf-6OCyzfzDAQ%40mail.gmail.com.
