Nonlinear Control of Two-Link Planar Manipulator Using Unstable Property of Zerodynamics

In this paper, a control method for an underactuated two-link planar manipulator using a partial linearization method, which is a one of the nonlinear control method based on structure theory, is proposed. In proposed method, for controlling of 2nd link, sliding-mode type partial linearization method is used, and for 1st link, the unstable property of Zerodynamics(it is dynamics of 1st link) is used, respectively. By analyzing a relationship between behavior of Zerodynamics and desired value of 2nd link, we find the property of Zerodynamics is changing by desired value of 2nd link. Therefore, the control of both links is able to achieve by single control input by deciding the desired value of 2nd link based on behavior of Zerodynamics. Finally, numerical simulations are performed to show the effectiveness of the proposed method.