2.3 Manipulation control
Figure 2.2: Manipulation control scheme proposed in [43] with a detector of events
and a module for smooth transitions.
information coming from the upper level.
2.3.3
Hybrid position/force control
Grasping and manipulation tasks require both a force and a position controller
to accomplish the desired object's motion, avoiding slippage and satisfying fric-
tion constraints. This type of controller can be feasible only if an appropriate
decoupling between position and force spaces is performed.
In [92], the position is the main variable to control, while the force is supplied
by parallel controllers. The position control algorithm is outlined for both joint
space and Cartesian space applications. The robustness of the position controller
is guaranteed, while the parallel force control is based upon the requirements for
the particular task. Moreover, in the work just mentioned, a final discussion about
errors due to the static friction of tendons is presented.
A simple method for a dynamic manipulation/grasping controller of multi-
fingered robot hands is proposed in [68]. Starting from the consideration that the
force on a finger can be seen as the sum of two orthogonal components, namely
manipulation forces necessary for the manipulation/grasp of the object and
internal forces necessary to satisfy the constraints about friction cones , an
on-line linearization of the dynamics of the whole system is introduced in order
to design a simple controller for manipulation purposes. A PID plus feedforward
is used for the position control part, while a PI is employed for the control of the
force.
For the rejection of noises in force sensors data, a fuzzy controller has been
used in [27]. In particular, the output of the fuzzy controller can perform a correc-
13
Summary :
Starting from the consideration that the force on a finger can be seen as the sum of two orthogonal components, namely manipulation forces necessary for the manipulation/grasp of the object and internal forces necessary to satisfy the constraints about friction cones , an on-line linearization of the dynamics of the whole system is introduced in order to design a simple controller for manipulation purposes.
Tags :
control,controller,force,position,manipulation,while,parallel,particular,space,used,forces,fuzzy,proposed