The unstructured characteristics of skin tissue need to be faced in robotic ultrasound scanning applications.Aiming at the problem that traditional admittance control cannot achieve high-precision force control

an integral adaptive variable admittance control strategy is proposed.Firstly

by establishing a model for the contact force between the robot and the skin

the force control requirements in ideal state are analyzed.Then

an indirect adaptive update strategy is proposed to adapt to the unknown environmental stiffness and position

which is used to generate the reference trajectory required for tracking force.On this basis

an integral controller is introduced to reduce the steady-state error

and the stability of the proposed control strategy is proved.Finally

through comparative experimental results in different unknown environments show that the proposed strategy has better force tracking performance than traditional admittance control.