- 上一篇：PHP安全英文文献和中文翻译
- 下一篇：注射成型模具英文文献和中文翻译
In applications like polishing and deburring the manipulator may have to work on very stiff materials. The force control algorithm should be robust with respect to high values of environment stiffness, and possibly should not require knowledge of the stiffness parameters. On the other hand, it should take account of the high torsional flexibility that commonly affects the joints of industrial manipulators.
4.2 ,Selection of control algorithms for the RUB action
The execution of the RUB action involves the modelling of contact, the planning of trajectories and contact forces, and their actuation through a proper hybrid position/force controller.
Contact modelling and action planning. It is assumed that the contact between the working tool and the working surface extends to a given plane contact area, and a compliant frame is chosen with its origin in the center point or at a convenient point of the contact area, with the z c axis directed along the nornml to the area. This is sketched in Fig. 3.
If the working surface and the tool are rigid, virtual displacements of the origin of the compliant frame along the normal z c, and virtual rotations of the compliant frame about axes x C and Yc are inhibited, while reaction force along z c and torques about x c and Yc can be generated. To ensure the proper contact between the working tool and the workpiece it may be necessary to control both the force and the torques.
The user plans the action by defining the contact frame on the end effector, assigning the path of the origin O c on the working surface, the orientation of axis z c (parallel to the surface normal) and of axes x c and Yc (conveniently), and the set points of the contact force and torques. An off-line programming environment might help the introduction of such values in cases of working surfaces of complex shapes.
Hybrid position[force control algorithm In the scientific literature, several force-control algorithms have been proposed that comply with the presence of position control loops (see for instance (De Schutter, et aL, 1988; Duelen, et al., 1992)). The rigid contact task and the joint elasticity, however, are never explicity considered. To fully comply with the requirements stated above, the hybrid position/force control algorithin described in (Ferretti, et al., 1995b), and sketched in Fig.4, is adopted.