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NPS-SRL / SPART

Open-source modeling and control toolkit for mobile-base robotic multibody systems
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Maybe I find a bug! #1

Open Mike1425217072 opened 3 years ago

Mike1425217072 commented 3 years ago

In function [t0dot,tLdot]=Accelerations(t0,tL,P0,pm,Bi0,Bij,u0,um,u0dot,umdot,robot)

line 49, %Base-link Omega0=[SkewSym(t0(1:3)), zeros(3,3); zeros(3,3), zeros(3,3)];

This should be:

Omega0=[SkewSym(t0(1:3)), zeros(3,3); zeros(3,3), SkewSym(t0(1:3))];

right?

YukiCR commented 6 months ago

Hi, as far as I'm concerned, the calculation of Omega0 is right. in line 63, we have

t0dot = Omega0*P0*u0+P0*u0dot;

which is $\dot{t}_0 = (\Omega_0 P_0 )u_0+ P_0 \dot{u}_0$. so Omega0*P0 should be $\frac{\mathrm{d}}{\mathrm{d}t}P_0$, since P0 is 

[R,           zeros(3);
 zeros(3),   eye(3)];

it's derivative will be the derivative of the top left part of P0, i.e, R_dot = SkewSym(t0(1:3))*R