An incompressible fluid is used to adjust fit for a prosthetic device, the use of a closed loop control system and force, motion, and position measurement to aid with algorithms controlling the fit of the prosthetic device to a residual limb. Embodiments include automatic actuation, based on triggering of threshold values from sensors, a powered full release feature, use of hydraulic transducers to transfer fluid pressure to force on a limb, and customizable pressure distribution pads and embedded valves in transducers to prevent backflow and allow stabilization of the residual limb. A retrofit system may be used for existing prosthetic sockets. A triggering algorithm utilizes measured force exceeding a threshold or thresholds with a characteristic pulse signature and a triggering of release based on a combination of total motion and measured force below a threshold or thresholds.
