How do I prove that the given system is globally asymptotically stable, using Lyapunov analysis?











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How do I prove that the given system is globally asymptotically stable, using Lyapunov analysis?



begin{equation}
left.begin{aligned}
dot{x_1} &= x_2 \
dot{x_2} &= -frac{x_1}{1 + x_2^2} label{eq:q2}
end{aligned}qquadright}
end{equation}










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  • Are you familiar with Lyapunov functions? And what have you tried yourself?
    – Kwin van der Veen
    Nov 12 at 16:58










  • I have tried general quadratic functions, such as (x1^2 + x2^2), but a term xy remains and I can't conclude properly.
    – Abhinav Sinha
    Nov 12 at 17:25















up vote
0
down vote

favorite












How do I prove that the given system is globally asymptotically stable, using Lyapunov analysis?



begin{equation}
left.begin{aligned}
dot{x_1} &= x_2 \
dot{x_2} &= -frac{x_1}{1 + x_2^2} label{eq:q2}
end{aligned}qquadright}
end{equation}










share|cite|improve this question







New contributor




Abhinav Sinha is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.




















  • Are you familiar with Lyapunov functions? And what have you tried yourself?
    – Kwin van der Veen
    Nov 12 at 16:58










  • I have tried general quadratic functions, such as (x1^2 + x2^2), but a term xy remains and I can't conclude properly.
    – Abhinav Sinha
    Nov 12 at 17:25













up vote
0
down vote

favorite









up vote
0
down vote

favorite











How do I prove that the given system is globally asymptotically stable, using Lyapunov analysis?



begin{equation}
left.begin{aligned}
dot{x_1} &= x_2 \
dot{x_2} &= -frac{x_1}{1 + x_2^2} label{eq:q2}
end{aligned}qquadright}
end{equation}










share|cite|improve this question







New contributor




Abhinav Sinha is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











How do I prove that the given system is globally asymptotically stable, using Lyapunov analysis?



begin{equation}
left.begin{aligned}
dot{x_1} &= x_2 \
dot{x_2} &= -frac{x_1}{1 + x_2^2} label{eq:q2}
end{aligned}qquadright}
end{equation}







dynamical-systems control-theory nonlinear-system lyapunov-functions






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Abhinav Sinha is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.











share|cite|improve this question







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Abhinav Sinha is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.









share|cite|improve this question




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asked Nov 12 at 16:48









Abhinav Sinha

31




31




New contributor




Abhinav Sinha is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.





New contributor





Abhinav Sinha is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.






Abhinav Sinha is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.












  • Are you familiar with Lyapunov functions? And what have you tried yourself?
    – Kwin van der Veen
    Nov 12 at 16:58










  • I have tried general quadratic functions, such as (x1^2 + x2^2), but a term xy remains and I can't conclude properly.
    – Abhinav Sinha
    Nov 12 at 17:25


















  • Are you familiar with Lyapunov functions? And what have you tried yourself?
    – Kwin van der Veen
    Nov 12 at 16:58










  • I have tried general quadratic functions, such as (x1^2 + x2^2), but a term xy remains and I can't conclude properly.
    – Abhinav Sinha
    Nov 12 at 17:25
















Are you familiar with Lyapunov functions? And what have you tried yourself?
– Kwin van der Veen
Nov 12 at 16:58




Are you familiar with Lyapunov functions? And what have you tried yourself?
– Kwin van der Veen
Nov 12 at 16:58












I have tried general quadratic functions, such as (x1^2 + x2^2), but a term xy remains and I can't conclude properly.
– Abhinav Sinha
Nov 12 at 17:25




I have tried general quadratic functions, such as (x1^2 + x2^2), but a term xy remains and I can't conclude properly.
– Abhinav Sinha
Nov 12 at 17:25










1 Answer
1






active

oldest

votes

















up vote
1
down vote



accepted










You could try to get the Lyapunov function in the form
$$
V=frac12x_1^2+g(x_2)
$$

so that
$$
dot V=x_1x_2+g'(x_2)frac{-x_1}{1+x_2^2}
$$

so that one would get a usable result with $g'(x_2)=x_2(1+x_2^2)$, integrating to,for example, $g(x_2)=frac14(1+x_2^2)^2$.






share|cite|improve this answer





















  • Thank you so much. I was taking something similar to g(x2) but it was constant and I was stuck. Thanks for your help :)
    – Abhinav Sinha
    Nov 12 at 18:55






  • 1




    @SampleTime : Then consider $V-V(0)$ to get the normalized value. I prefer the completed square for its simplicity.
    – LutzL
    Nov 12 at 21:18






  • 1




    @SampleTime : Could you elaborate? How to get a negative value from $V-V(0)=frac12x_1^2+frac12x_2^2+frac14x_2^4$?
    – LutzL
    Nov 12 at 21:27










  • @LutzL You are correct, nice! I made an error when writing down the equation, sorry for the confusion.
    – SampleTime
    Nov 12 at 21:40











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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

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active

oldest

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active

oldest

votes








up vote
1
down vote



accepted










You could try to get the Lyapunov function in the form
$$
V=frac12x_1^2+g(x_2)
$$

so that
$$
dot V=x_1x_2+g'(x_2)frac{-x_1}{1+x_2^2}
$$

so that one would get a usable result with $g'(x_2)=x_2(1+x_2^2)$, integrating to,for example, $g(x_2)=frac14(1+x_2^2)^2$.






share|cite|improve this answer





















  • Thank you so much. I was taking something similar to g(x2) but it was constant and I was stuck. Thanks for your help :)
    – Abhinav Sinha
    Nov 12 at 18:55






  • 1




    @SampleTime : Then consider $V-V(0)$ to get the normalized value. I prefer the completed square for its simplicity.
    – LutzL
    Nov 12 at 21:18






  • 1




    @SampleTime : Could you elaborate? How to get a negative value from $V-V(0)=frac12x_1^2+frac12x_2^2+frac14x_2^4$?
    – LutzL
    Nov 12 at 21:27










  • @LutzL You are correct, nice! I made an error when writing down the equation, sorry for the confusion.
    – SampleTime
    Nov 12 at 21:40















up vote
1
down vote



accepted










You could try to get the Lyapunov function in the form
$$
V=frac12x_1^2+g(x_2)
$$

so that
$$
dot V=x_1x_2+g'(x_2)frac{-x_1}{1+x_2^2}
$$

so that one would get a usable result with $g'(x_2)=x_2(1+x_2^2)$, integrating to,for example, $g(x_2)=frac14(1+x_2^2)^2$.






share|cite|improve this answer





















  • Thank you so much. I was taking something similar to g(x2) but it was constant and I was stuck. Thanks for your help :)
    – Abhinav Sinha
    Nov 12 at 18:55






  • 1




    @SampleTime : Then consider $V-V(0)$ to get the normalized value. I prefer the completed square for its simplicity.
    – LutzL
    Nov 12 at 21:18






  • 1




    @SampleTime : Could you elaborate? How to get a negative value from $V-V(0)=frac12x_1^2+frac12x_2^2+frac14x_2^4$?
    – LutzL
    Nov 12 at 21:27










  • @LutzL You are correct, nice! I made an error when writing down the equation, sorry for the confusion.
    – SampleTime
    Nov 12 at 21:40













up vote
1
down vote



accepted







up vote
1
down vote



accepted






You could try to get the Lyapunov function in the form
$$
V=frac12x_1^2+g(x_2)
$$

so that
$$
dot V=x_1x_2+g'(x_2)frac{-x_1}{1+x_2^2}
$$

so that one would get a usable result with $g'(x_2)=x_2(1+x_2^2)$, integrating to,for example, $g(x_2)=frac14(1+x_2^2)^2$.






share|cite|improve this answer












You could try to get the Lyapunov function in the form
$$
V=frac12x_1^2+g(x_2)
$$

so that
$$
dot V=x_1x_2+g'(x_2)frac{-x_1}{1+x_2^2}
$$

so that one would get a usable result with $g'(x_2)=x_2(1+x_2^2)$, integrating to,for example, $g(x_2)=frac14(1+x_2^2)^2$.







share|cite|improve this answer












share|cite|improve this answer



share|cite|improve this answer










answered Nov 12 at 17:43









LutzL

53.4k41953




53.4k41953












  • Thank you so much. I was taking something similar to g(x2) but it was constant and I was stuck. Thanks for your help :)
    – Abhinav Sinha
    Nov 12 at 18:55






  • 1




    @SampleTime : Then consider $V-V(0)$ to get the normalized value. I prefer the completed square for its simplicity.
    – LutzL
    Nov 12 at 21:18






  • 1




    @SampleTime : Could you elaborate? How to get a negative value from $V-V(0)=frac12x_1^2+frac12x_2^2+frac14x_2^4$?
    – LutzL
    Nov 12 at 21:27










  • @LutzL You are correct, nice! I made an error when writing down the equation, sorry for the confusion.
    – SampleTime
    Nov 12 at 21:40


















  • Thank you so much. I was taking something similar to g(x2) but it was constant and I was stuck. Thanks for your help :)
    – Abhinav Sinha
    Nov 12 at 18:55






  • 1




    @SampleTime : Then consider $V-V(0)$ to get the normalized value. I prefer the completed square for its simplicity.
    – LutzL
    Nov 12 at 21:18






  • 1




    @SampleTime : Could you elaborate? How to get a negative value from $V-V(0)=frac12x_1^2+frac12x_2^2+frac14x_2^4$?
    – LutzL
    Nov 12 at 21:27










  • @LutzL You are correct, nice! I made an error when writing down the equation, sorry for the confusion.
    – SampleTime
    Nov 12 at 21:40
















Thank you so much. I was taking something similar to g(x2) but it was constant and I was stuck. Thanks for your help :)
– Abhinav Sinha
Nov 12 at 18:55




Thank you so much. I was taking something similar to g(x2) but it was constant and I was stuck. Thanks for your help :)
– Abhinav Sinha
Nov 12 at 18:55




1




1




@SampleTime : Then consider $V-V(0)$ to get the normalized value. I prefer the completed square for its simplicity.
– LutzL
Nov 12 at 21:18




@SampleTime : Then consider $V-V(0)$ to get the normalized value. I prefer the completed square for its simplicity.
– LutzL
Nov 12 at 21:18




1




1




@SampleTime : Could you elaborate? How to get a negative value from $V-V(0)=frac12x_1^2+frac12x_2^2+frac14x_2^4$?
– LutzL
Nov 12 at 21:27




@SampleTime : Could you elaborate? How to get a negative value from $V-V(0)=frac12x_1^2+frac12x_2^2+frac14x_2^4$?
– LutzL
Nov 12 at 21:27












@LutzL You are correct, nice! I made an error when writing down the equation, sorry for the confusion.
– SampleTime
Nov 12 at 21:40




@LutzL You are correct, nice! I made an error when writing down the equation, sorry for the confusion.
– SampleTime
Nov 12 at 21:40










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