…Kokotovic for more on this. Compared to linear control theory, nonlinear controls is much more fractured and domain-specific. No concept is as widely applicable as ones from linear controls. Khalil's Nonlinear Systems book is generally considered a top reference, but it does start to get into the PhD-level stuff and I don't recommend it to a non-specialist unless you are really into this stuff. I can give more specific…
Hassan K. Khalil 写的《非线性系统》（ISBN 978-0130673893）也很值得一读，能帮你巩固底层数学基础！
Nonlinear systems by Hassan K. Khalil (ISBN 978-0130673893) is also worth it to solidify the underlying maths!
……想了解更多可以看看 Kokotovic。与线性控制理论相比，非线性控制要零碎得多，而且高度依赖特定领域。没有任何概念能像线性控制里的那样具有广泛适用性。Khalil 的《非线性系统》（Nonlinear Systems）通常被奉为顶级参考书，但它确实开始涉及到博士层面的内容了，除非你真对这块超级感兴趣，否则我不推荐非专业人士去读。我可以给出更具体的……
…Kokotovic for more on this. Compared to linear control theory, nonlinear controls is much more fractured and domain-specific. No concept is as widely applicable as ones from linear controls. Khalil's Nonlinear Systems book is generally considered a top reference, but it does start to get into the PhD-level stuff and I don't recommend it to a non-specialist unless you are really into this stuff. I can give more specific…