  This study proposes novel control methods that lower impact force by
preemptive movement and smoothly transition to conventional contact impedance
control. These suggested techniques are for force control-based robots and
position/velocity control-based robots, respectively. Strong impact forces have
a negative influence on multiple robotic tasks. Recently, preemptive impact
reduction techniques that expand conventional contact impedance control by
using proximity sensors have been examined. However, a seamless transition from
impact reduction to contact impedance control has not yet been accomplished.
The proposed methods utilize a serial combined impedance control framework to
solve this problem. The preemptive impact reduction feature can be added to the
already implemented impedance controller because the parameter design is
divided into impact reduction and contact impedance control. There is no
undesirable contact force during the transition. Furthermore, even though the
preemptive impact reduction employs a crude optical proximity sensor, the
influence of reflectance is minimized using a virtual viscous force. Analyses
and real-world experiments confirm these benefits.
