欠驱动形状自适应气动夹具夹持稳定性

Underactuated fixture has the features of enveloping and powerful grip. On the other hand, underactuated mechanism is more easily to be disturbed by external interference. The contribution of gripped configuration and underactuated elements’ parameters for gripped stability has not been revealed. The dynamic equations of an underactuated fixture are established by analysing the relationship between the gripping state and the small displacement. The equivalent stiffness of the underactuated gripped contact object is obtained, and the dynamic equation is established for gripped object. The dynamic contact stiffness matrix of the underactuated fixture is obtained by constructing the energy function. An example is used to analyse a planar two joints and symmetry gripped underactuated fixture. The asymptotically stable condition for gripped system can be described by two items: the contact point is symmetrical distribution, the equivalent contact damping C and contact stiffness K at each contact point is equal respectively. Furthermore, the asymptotic stability of the fixture can be satisfied when the stiffness and damping parameters meet the relative relation with the gripped configuration. The proposed method can be used to predicate the stability of the underactuated fixture. It can also guide the underactuated fixture design for gripped configuration and underactuated elements’ parameters. The approach is significant to improve gripping safety and reliability of underactuated mechanical fixture.