A method for controlling a control surface multirod actuator arrangement and the arrangement including: a first and a second multirod actuator configured to move or clamp around a first set of piston rods; a third multirod actuator configured to move or clamp around a second set of piston rods; a control unit configured to control motion of the first set of piston rods in a first motion mode and to control motion of the second set of piston rods in a second motion mode. Steps are moving at least one piston rod of first set of piston rods and/or clamping in parked position at least one piston rod of the second set of piston rods.

A method for controlling a control surface multirod actuator arrangement and the arrangement including: a first and a second multirod actuator configured to move or clamp around a first set of piston rods; a third multirod actuator configured to move or clamp around a second set of piston rods; a control unit configured to control motion of the first set of piston rods in a first motion mode and to control motion of the second set of piston rods in a second motion mode. Steps are moving at least one piston rod of first set of piston rods and/or clamping in parked position at least one piston rod of the second set of piston rods.

Provided is an actuator apparatus including a positioning actuator device configured to position a first carrier member of the actuator apparatus. The positioning actuator device includes a first hydraulic fluid actuator having a first clamping means and a second hydraulic fluid actuator having a second clamping means, wherein the first and second hydraulic fluid actuator are configured to alternately clamp around a guide arrangement for moving the positioning actuator device along the guide arrangement. The first carrier member is provided with a first coupling member configured to be releasable coupled to the positioning actuator device. A method of positioning a first carrier member by means of the positioning actuator device is provided.

Stepper motor with a housing 1,2,4,6,16, in which a cylindrical rotor 11,15 fixed on a central shaft 12 can rotate but not translate along an axial direction. There are cylindrical translators 9, 14 on both sides of the rotors 11, 15, where the translators 9, 14 are sealed fit in a cylindrical space within the housing 6 and around the central shaft 12 and where the translators 9, 14 can only translate in an axial direction, where in one axial position of a translator 9, 14 a set of triangular asymmetric teeth 20 located on the translator 9, 14 can interact and fit into a set of triangular asymmetric teeth 21 on the rotor 11, 15, where the shape of the teeth 21 on both sides of the rotor 11, 15 is symmetric and where one of the sets of teeth 20, 21 between one translator 9 (14) and the rotor 11 (15) and a set of teeth 20, 21 between the other translator 9 (14) and the rotor 11 (15) are tangentially shifted, i.e. offset over a length equal to half the width of a tooth 20, 21 and where the translators 9, 14 can be moved by a pressure difference between the part of the cylindrical space between the housing 6 and a translator 9, 14 and the part of the cylindrical space between the translator 9, 14 and the rotor 11, 15.

Stepper motor with a housing 1,2,4,6,16, in which a cylindrical rotor 11,15 fixed on a central shaft 12 can rotate but not translate along an axial direction. There are cylindrical translators 9, 14 on both sides of the rotors 11, 15, where the translators 9, 14 are sealed fit in a cylindrical space within the housing 6 and around the central shaft 12 and where the translators 9, 14 can only translate in an axial direction, where in one axial position of a translator 9, 14 a set of triangular asymmetric teeth 20 located on the translator 9, 14 can interact and fit into a set of triangular asymmetric teeth 21 on the rotor 11, 15, where the shape of the teeth 21 on both sides of the rotor 11, 15 is symmetric and where one of the sets of teeth 20, 21 between one translator 9 (14) and the rotor 11 (15) and a set of teeth 20, 21 between the other translator 9 (14) and the rotor 11 (15) are tangentially shifted, i.e. offset over a length equal to half the width of a tooth 20, 21 and where the translators 9, 14 can be moved by a pressure difference between the part of the cylindrical space between the housing 6 and a translator 9, 14 and the part of the cylindrical space between the translator 9, 14 and the rotor 11, 15.

A fluid actuator arrangement comprises a first cylinder housing including a first head member and a second head member; a first piston body is slidable arranged in said first cylinder housing; the first piston body divides the first cylinder housing interior into a first cylinder chamber and a second cylinder chamber, at least the first cylinder chamber is coupled to a fluid supply. The first piston body exhibits a first through-bore and a second through-bore that extend through the first piston body in an axial direction; a first piston rod is arranged slidable in the first through-bore and a second piston rod is arranged slidable in the second through-bore; and the first through-bore comprises a first engagement and disengagement device and the second through-bore comprises a second engagement and disengagement device, which are arranged for providing individual engagement or disengagement to or from the respective first and second piston rod.

A pneumatic stepper motor includes a housing, said housing accommodating at least part of: a rack or geared axle comprising a plurality of gear elements; and two pistons, each comprising at least two teeth, said pistons being arranged to cooperate with said rack or geared axle. The racks may either be straight or curved. The pistons are preferably double-acting pistons. A device includes at least one, and preferably a plurality of, such pneumatic stepper motor(s). The device may in particular be an MRI-compatible robotic system, more in particular for example an MRI-guided breast biopsy device.

A pneumatic stepper motor includes a housing, said housing accommodating at least part of: a rack or geared axle comprising a plurality of gear elements; and two pistons, each comprising at least two teeth, said pistons being arranged to cooperate with said rack or geared axle. The racks may either be straight or curved. The pistons are preferably double-acting pistons. A device includes at least one, and preferably a plurality of, such pneumatic stepper motor(s). The device may in particular be an MRI-compatible robotic system, more in particular for example an MRI-guided breast biopsy device.

A fluid actuator arrangement comprises a first cylinder housing including a first head member and a second head member; a first piston body is slidable arranged in said first cylinder housing; the first piston body divides the first cylinder housing interior into a first cylinder chamber and a second cylinder chamber, at least the first cylinder chamber is coupled to a fluid supply. The first piston body exhibits a first through-bore and a second through-bore that extend through the first piston body in an axial direction; a first piston rod is arranged slidable in the first through-bore and a second piston rod is arranged slidable in the second through-bore; and the first through-bore comprises a first engagement and disengagement device and the second through-bore comprises a second engagement and disengagement device, which are arranged for providing individual engagement or disengagement to or from the respective first and second piston rod.

A pneumatic stepper motor includes a housing, said housing accommodating at least part of: a rack or geared axle comprising a plurality of gear elements; and two pistons, each comprising at least two teeth, said pistons being arranged to cooperate with said rack or geared axle. The racks may either be straight or curved. The pistons are preferably double-acting pistons. A device includes at least one, and preferably a plurality of, such pneumatic stepper motor(s). The device may in particular be an MRI-compatible robotic system, more in particular for example an MRI-guided breast biopsy device.