The subject matter of this specification can be embodied in, among other things, a fluid actuator including a housing defining a first chamber having a first cavity and a first open end, a first piston assembly including a tubular first piston defining a second chamber having a second cavity and a second open end, disposed in said first housing for reciprocal movement in the first chamber through the first open end, wherein a first seal, the first cavity, and the first piston define a first pressure chamber, and a second piston assembly having an second piston disposed in said first piston assembly for reciprocal movement in the second chamber through the second open end, wherein a second seal, the second cavity, and the second piston define a second pressure chamber, and a first portion of the second piston contacts a first end effector.

There is provided a mechanical avatar assembly for use in a confined space in a structure. The mechanical avatar assembly includes a rail assembly for attachment to an access opening to the confined space. The rail assembly includes two or more rail segments coupled together to form an elongated base having a rail and a gear rack extending along a length of the elongated base. The rail assembly further includes a carriage portion coupled to the rail, and movable relative to the rail, and a drive assembly coupled to the carriage portion and to the gear rack, to move the carriage portion along the rail. The mechanical avatar assembly further includes an articulating avatar arm coupled to, and movable via, the carriage portion. The mechanical avatar assembly further includes an image capturing device.

A rotary actuator may include a first holder in which a fluid injecting portion is formed, a second holder rotatably coupled to the first holder, a flexible body fixed to the first holder and the second holder and configured to expand as a fluid is injected through the first holder, and a plurality of fibers radially disposed in a spiral shape at the flexible body and configured to rotate the flexible body when the flexible body expands.

The subject matter of this specification can be embodied in, among other things, a rotary actuator that includes a housing defining an arcuate chamber comprising a cavity, a rotor arm configured for rotary movement, an arcuate-shaped first piston disposed in said housing for reciprocal movement in the arcuate chamber, where a seal, the cavity, and the piston define a pressure chamber that includes part or all of the arcuate chamber, and a portion of the piston contacts the rotor arm, and a rotor assembly rotatably surrounding said housing and having a rotary output tube about the axis, wherein the rotor arm extends radially outward to the rotary output tube and the rotor arm is coupled to the rotary output tube.

For tightening screwed connections by a multi-screwing device with first and second screwing tools, each with rotary drive for screwing an exchangeable bushing on and off, a device for longitudinally straining a threaded bolt, and a tool for retightening the nut, the screwing tools are moved at right angles relative to tool axes by an actuating drive. When the bushings of the screwing tools are both screwed onto a threaded bolt, these steps are performed: a) bushing of first screwing tool is unscrewed from threaded bolt and raised; b) first screwing tool is moved relative to the second into a position in which tool axis of first screwing tool is aligned with screw axis of a further threaded bolt; c) first screwing tool is lowered and screwed onto further threaded bolt; d) threaded bolt is longitudinally strained, and e) steps a) to d) are repeated for second tool.

An in-pipe robot is provided with a rotary actuator 30 that rotates the drilling blade 21 in the circumferential direction of an existing pipe. A wheel body 50 provided with a traveling wheel 52 on both sides and a wheel body 70 provided with a traveling wheel 72 on both sides are supported between side frames 43 of a chassis via pins 54 and 74. The other ends of both the wheel bodies are rotatably coupled around an axle 63 of an intermediate wheel 65 as a pivot. When both the wheel bodies rotate, the intermediate wheels and the rotary actuator move above a horizontal line passing through the pin center. Each pin is disposed at the midpoint of a line connecting the center of the traveling wheel and the center of the intermediate wheel so that the rotation axis vi of the rotary actuator coincides with the pipe center axis of the existing pipe.

A rotary joint, including: a hydraulic follow-up mechanism and a rotary transmission mechanism. The hydraulic follow-up mechanism includes a cylinder body, a valve sleeve, a valve core, a valve body, a left end cover and a right end cover. The rotary transmission mechanism includes a tray, a stabilizing ring, a follow-up disk, a torque transfer disk and a stable supporting wheel mechanism. The left end cover and the right end cover are arranged at the left and right ends of the cylinder body, respectively. The valve body is concentrically mounted in a cylindrical hollow chamber of the cylinder body. The output shaft at the right end of the valve body projects out of the right end cover. The right end of the valve core is provided with a valve core torque transfer shaft extending rightwards through the right end of the valve body.

An actuator includes first and second ends defining an axis there between, and at least four inflatable chambers. Each inflatable chamber is resiliently deformable, elongate, and extends axially between the first and second ends and circumferentially about a central core defined between the ends and by the inflatable chambers. A first pair of the four inflatable chambers is contra rotatory about the core to a second pair of the four inflatable chambers. A pressure change in one or more of the inflatable chambers causes motion of the first end relative to the second end. The actuators can be employed in robots or robotic arms.

For tightening screwed connections by a multi-screwing device with first and second screwing tools, each with rotary drive for screwing an exchangeable bushing on and off, a device for longitudinally straining a threaded bolt, and a tool for retightening the nut, the screwing tools are moved at right angles relative to tool axes by an actuating drive. When the bushings of the screwing tools are both screwed onto a threaded bolt, these steps are performed: a) bushing of first screwing tool is unscrewed from threaded bolt and raised; b) first screwing tool is moved relative to the second into a position in which tool axis of first screwing tool is aligned with screw axis of a further threaded bolt; c) first screwing tool is lowered and screwed onto further threaded bolt; d) threaded bolt is longitudinally strained, and e) steps a) to d) are repeated for second tool.

The subject matter of this specification can be embodied in, among other things, a fluid actuator including a housing defining a first chamber having a first cavity and a first open end, a first piston assembly including a tubular first piston defining a second chamber having a second cavity and a second open end, disposed in said first housing for reciprocal movement in the first chamber through the first open end, wherein a first seal, the first cavity, and the first piston define a first pressure chamber, and a second piston assembly having an second piston disposed in said first piston assembly for reciprocal movement in the second chamber through the second open end, wherein a second seal, the second cavity, and the second piston define a second pressure chamber, and a first portion of the second piston contacts a first end effector.