“…The equations describing the fluid flow rate q in an actuator can be linearized about the origin to obtain the following equations: where F a , , V, A a , K q , i, K c , x, and x 1 indicate actuator force, bulk modulus of the fluid, half the volume of the actuator, piston area, valve flow gain, valve input, leakage coefficient, and actuator displacement and velocity, respectively. 2,4,[11][12][13][14][15] By combining Equations (1) and (2), and solving for . F a , the following expression is obtained:…”