Optimal initialization of manipulation dynamics by vorticity model of robot hand preshaping. Part I: Vorticity model

The manipulation phase of a multifingered robot hand is initialized, upon c ontact, by the impact force patterns imparted to the object at contact poin ts, in the final state of a preshaped hand closure. The object then inherit s from contacts different helix motion tendencies (translation, rotation) a s the initial conditions of manipulation. These motion tendencies are cause d by the forces/torques imparted to the object upon impact, and are generat ed by changes of momenta of the closing hand preshape at the contact locati ons. The generalized impact force patterns vary for different hand preshape s, since each preshape closes upon an object with different momenta types. Consequently, the purposive closing of a preshaped hand should be kinematic ally modeled in such a way that impact force patterns can be naturally dedu ced from the model and compared to the desired ones so that this preshaped dosing can be optimized according to the impact force pattern it applies to the object at contact. This would generate the optimal initial conditions of manipulation. Our work in this two part article focuses on developing me thods of determining, optimally, the preshape of a robot hand closing onto an object, in order to achieve at contact a certain stability and manipulab ility degree based on kinematic considerations. Toward this objective, in P art I of the manuscript we define the stability and manipulability criteria of a robot hand preshape based on vortex theory, dealing with the analysis of vorticities in the robot hand workspace. (C) 2000 John Wiley & Sons, In c.