  In various interaction tasks using Underwater Vehicle Manipulator Systems
(UVMSs) (e.g. sampling of the sea organisms, underwater welding), important
factors such as: i) uncertainties and complexity of UVMS dynamic model ii)
external disturbances (e.g. sea currents and waves) iii) imperfection and
noises of measuring sensors iv) steady state performance as well as v) inferior
overshoot of interaction force error, should be addressed during the force
control design. Motivated by the above factors, this paper presents a
model-free control protocol for force controlling of an Underwater Vehicle
Manipulator System which is in contact with a compliant environment, without
incorporating any knowledge of the UVMS's dynamic model, exogenous disturbances
and sensor's noise model. Moreover, the transient and steady state response as
well as reduction of overshooting force error are solely determined by certain
designer-specified performance functions and are fully decoupled by the UVMS's
dynamic model, the control gain selection, as well as the initial conditions.
Finally, a simulation study clarifies the proposed method and verifies its
efficiency.
