Presented is a method, apparatus and computer-readable medium for reducing error. The apparatus includes a rotatable element having a plurality of spaced light modifying ports located at set positions in the rotatable element, the rotatable element rotatable about an axis. The apparatus further includes a drive engagedly coupled to the rotatable element to rotate the rotatable element, wherein one periodic cycle of the rotatable element is an integer number of periodic cycles of the drive.

A transmission assembly for a rotary piston and cylinder device, comprising a rotor including a piston, a stator, a shutter including a slot to receive the piston, and a first gear and a gear sub-assembly, the first gear connectable to a rotatably mounted shutter of the device, and the first gear extending from a side of the shutter, and the first gear connected to the gear sub-assembly which converts rotation to an axis of rotation different to that of the shutter.

A curvilinear gear system and method for transferring force and speed through a wide range of angles is disclosed. The system can optionally incorporate curvilinear U joints to increase effective range of angles to tailor the system to specific applications. The system includes complimentary gear heads, one of which is a curvilinear gear such as a hemispherical gear. A method of using the gear systems in a transmission apparatus is also disclosed.

A transmission assembly for a rotary piston and cylinder device, comprising a first gear (120) and a gear sub-assembly (15, 16, 17, 18, 19), the first gear connectable to a rotatably mounted shutter (12) of the device, and the first gear extending from a side of the shutter, and the first gear connected to the gear sub-assembly which converts rotation to an axis of rotation different to that of the shutter.

A transmission assembly for a rotary piston and cylinder device, comprising a first gear (120) and a gear sub-assembly (15, 16, 17, 18, 19), the first gear connectable to a rotatably mounted shutter (12) of the device, and the first gear extending from a side of the shutter, and the first gear connected to the gear sub-assembly which converts rotation to an axis of rotation different to that of the shutter.

An actuator system having a controlled element configured for rotary movement about a first axis relative to a reference structure; a linkage system between the element and reference structure; a first actuator and a second actuator configured to power a first degree of freedom and an independent second degree of freedom of the linkage system, respectively; the linkage system having a first link configured for rotary movement about a second axis not coincident to the first axis and second link configured for rotary movement about a third axis; the linkage system configured such that a first angle of rotation may be driven independently of a second angle of rotation between said first link and said reference structure; wherein one of the first or second actuators is configured and arranged to drive rotation of the element about the first axis when the other is operatively locked.

A camshaft unit (1), having a first camshaft (2) which is phase-adjustable with respect to a crankshaft, having a second camshaft (3) which is arranged concentrically with respect to the first camshaft (2), and having a camshaft adjuster (5) by which both camshafts (2, 3) are phase-adjusted with respect to the crankshaft.

A spring drive system includes a housing, an extendible window cover coupled with the housing, and at least one lift cord coupled to the cover for raising and lowering the window cover. A spring drive system comprises a first spring drive spool spaced apart from a second spring drive spool and at least one spring having a storage end coupled to one of the spring drive spools and an output end coupled to the other of the spring drive spools. A first cord spool has a first cord spool axis. The lift cord extends from the first cord spool to the window cover for assisting in raising and lowering of the cover, and the spring drive system affects rotation of the first cord spool about the first cord spool axis and has no external hand-operated control cord input to raise and lower the window cover.

In at least one illustrative embodiment, a rotary impact tool may include an anvil and at least one hammer configured to impact the anvil to cause the anvil to rotate. The anvil may include an output shaft, a first lug extending outward in a radial direction from the output shaft and extending a first distance around the output shaft in a circumferential direction, and a second lug extending outward in the radial direction from the output shaft and extending a second distance, different from the first distance, around the output shaft in the circumferential direction.