Abstract: An apparatus may include a ferromagnetic housing defining a housing cavity, an electrically-conductive coil disposed in the housing cavity and defining a coil cavity, a ferromagnetic core piece disposed in the coil cavity, a ferromagnetic pole piece comprising a first face in contact with the core piece and a projection extending from a second face of the pole piece opposite the first face, a flexible element defining an opening, where the projection is disposed within the opening and the flexible element is disposed between a portion of the projection and the first face of the pole piece, and a ferromagnetic armature coupled to the flexible element, where the flexible element is disposed between at least a portion of the armature and the first face of the pole piece.

Abstract: An apparatus may include a ferromagnetic housing defining a housing cavity, an electrically-conductive coil disposed in the housing cavity and defining a coil cavity, a ferromagnetic core piece disposed in the coil cavity, a ferromagnetic pole piece comprising a first face in contact with the core piece and a projection extending from a second face of the pole piece opposite the first face, a flexible element defining an opening, where the projection is disposed within the opening and the flexible element is disposed between a portion of the projection and the first face of the pole piece, and a ferromagnetic armature coupled to the flexible element, where the flexible element is disposed between at least a portion of the armature and the first face of the pole piece.

Abstract: An apparatus may include a ferromagnetic housing defining a housing cavity, an electrically-conductive coil disposed in the housing cavity and defining a coil cavity, a ferromagnetic core piece disposed in the coil cavity, a ferromagnetic pole piece comprising a first face in contact with the core piece and a projection extending from a second face of the pole piece opposite the first face, a flexible element defining an opening, where the projection is disposed within the opening and the flexible element is disposed between a portion of the projection and the first face of the pole piece, and a ferromagnetic armature coupled to the flexible element, where the flexible element is disposed between at least a portion of the armature and the first face of the pole piece.

Abstract: An apparatus may include a ferromagnetic housing defining a housing cavity, an electrically-conductive coil disposed in the housing cavity and defining a coil cavity, a ferromagnetic core piece disposed in the coil cavity, a ferromagnetic pole piece comprising a first face in contact with the core piece and a projection extending from a second face of the pole piece opposite the first face, a flexible element defining an opening, where the projection is disposed within the opening and the flexible element is disposed between a portion of the projection and the first face of the pole piece, and a ferromagnetic armature coupled to the flexible element, where the flexible element is disposed between at least a portion of the armature and the first face of the pole piece.

Abstract: A method and apparatus for controlling a two-stage valve using a closed-loop control system, the system including a variable gain element, the method involving continually performing the steps of estimating the flow gain of the pilot stage of the valve; comparing the estimated flow gain with a reference flow gain; and in response to said comparison step, adjusting the gain of the variable gain element to maintain a substantially constant closed-loop gain.

Abstract: Control method and apparatus for a moveable control member with n>3 observed states. The apparatus incorporates a sliding mode control system operable to maintain the state point of the moveable member on a predetermined non-linear hyperplane having n-1 dimensions. The hyperplane is such that, if the state point is maintained thereon, the maximum rate of change of the highest order observed state does not exceed that of which the control apparatus is capable. The sliding mode control system include sa digital processor operable to reference n-1 low order observed states to the predetermined hyperplane to establish a desired value of the highest order observed state. The control system compares such desired value with the observed highest order state, and implements the control action necessary to maintain the state point on the predetermined hyperplane.

Abstract: Control method and apparatus for a moveable control member with n observed states, the apparatus incorporating a sliding mode control system, operable to maintain the state point of the moveable member on a predetermined hyperplane having n-1 dimensions, and comprising digital processor means operable to reference, at a first frequency, n-1 low order observed states to the predetermined hyperplane to establish a desired value of the highest order observed state, the control system further comprising comparator means operable to compare, at a second frequency, said desired value with the observed highest order state, the first frequency being less than the second frequency, and means responsive to the comparator means and operable to implement the control action necessary to maintain the state point on the predetermined hyperplane.