  With the goal of increasing the speed and efficiency in robotic dual arm
manipulation, a novel control approach is presented that utilizes intentional
simultaneous impacts to rapidly grasp objects. This approach uses the
time-invariant reference spreading framework, in which partly-overlapping ante-
and post-impact reference vector fields are used. These vector fields are
coupled via the impact dynamics in proximity of the expected impact area,
minimizing the otherwise large velocity errors after the impact and the
corresponding large control efforts. A purely spatial task is introduced to
strongly encourage the synchronization of impact times of the two arms. An
interim-impact control phase provides robustness in the execution against the
inevitable lack of exact impact simultaneity and the corresponding unreliable
velocity error. In this interim phase, a position feedback signal is derived
from the ante-impact velocity reference, which is used to enforce sustained
contact in all contact points without using velocity error feedback. With an
eye towards real-life implementation, the approach is formulated using a QP
control framework, and is validated using numerical simulations on a realistic
robot model with flexible joints and low-level torque control.
