Abstract: A method/system for achieving force control in externally driven hydraulic/gas-filled cylinders estimates effective flow parameters based on sensor measurements, and predicts desired flow parameters for force control objectives and determines required control actuation signals. The system selectively uses pressure sensors to measure the pressure of fluid in each (hydraulic) cylinder, displacement sensors to measure the displacement of the piston in each (hydraulic) cylinder, piston velocity sensors or piston velocity estimators, manifold pressure sensors or manifold pressure estimators, converters that digitize analog signals from the sensors, a microprocessor capable of storing data from the converters and producing actuator signals, and flow regulating actuators responsive to the actuator signals for regulating the flow of (hydraulic) fluid out of each cylinder by changing the effective flow-area of flow ports.

Abstract: A method/system for achieving force control in externally driven hydraulic/gas-filled cylinders estimates effective flow parameters based on sensor measurements, and predicts desired flow parameters for force control objectives and determines required control actuation signals. The system selectively uses pressure sensors to measure the pressure of fluid in each (hydraulic) cylinder, displacement sensors to measure the displacement of the piston in each (hydraulic) cylinder, piston velocity sensors or piston velocity estimators, manifold pressure sensors or manifold pressure estimators, converters that digitize analog signals from the sensors, a microprocessor capable of storing data from the converters and producing actuator signals, and flow regulating actuators responsive to the actuator signals for regulating the flow of (hydraulic) fluid out of each cylinder by changing the effective flow-area of flow ports.

Abstract: A reconfigurable variable blank-holder force system (and method) for producing sheet metal stampings comprises a portable hydraulic unit, controlled by a digital control system and a knowledge-based expert system to enable reconfigurability and an easy transition from the try-out stage to production. The knowledge-base has a hierarchical structure and includes stored information about part geometry, material properties and press parameters. The expert system enables an operator to determine optimal blank-holder forces, and to fine-tune through a graphical interface unit. The optimal blank-holder forces are generated by hydraulic force actuators, using a controller running a nonlinear algorithm that accounts for valve nonlinearities, variable flow-rate and numbers of operational cylinders. The portable hydraulic unit preferably comprises hydraulic cylinders with quick disconnect hoses, a manifold, servo-valves and a pump unit.

Abstract: A reconfigurable variable blank-holder force system (and method) for producing sheet metal stampings comprises a portable hydraulic unit, controlled by a digital control system and a knowledge-based expert system to enable reconfigurability and an easy transition from the try-out stage to production. The knowledge-base has a hierarchical structure and includes stored information about part geometry, material properties and press parameters. The expert system enables an operator to determine optimal blank-holder forces, and to fine-tune through a graphical interface unit. The optimal blank-holder forces are generated by hydraulic force actuators, using a controller running a nonlinear algorithm that accounts for valve nonlinearities, variable flow-rate and numbers of operational cylinders. The portable hydraulic unit preferably comprises hydraulic cylinders with quick disconnect hoses, a manifold, servo-valves and a pump unit.

Abstract: A method and system for attenuating the effects of unknown, unmeasurable and time-varying exogenous disturbances on multiple-input multiple-output dynamical systems are described. The disturbance rejection system is characterized in terms of an ARMARKOV or predictive model controller. The parameters of this controller are revised in real time at discrete time steps so as to generate an input to the dynamical system that attenuates the effect of the exogenous disturbance on any chosen set of measured outputs of the dynamical system. The method for revising the controller parameters involves the steps of defining a novel retrospective cost function based on windows of past data, calculating a gradient that is based on this cost function, and using an implementable adaptive step size that brings the controller parameters closer to optimal controller parameters after each revision.