Custom built positioners

Linear positioning tables for camera tracking and rotary stages for mirror positioning are built to customers specification for 3D stop-motion animation applications

Aardman Animation is about to release a new feature length stop motion movie called The Pirates! In an Adventure with Scientists! During the making of the film the Bristol based studio commissioned several custom-built linear and rotary positioning stages from LG Motion to enable synchronised 3D camera tracking and special set lighting effects.

The Pirates! In an Adventure with Scientists! is a swashbuckling adventure with a rich vein of surreal and broad comedy, based on best selling series of The Pirates! books by Gideon Defoe. The story follows the fortunes of a cheerful but hapless pirate band as they cross the seven seas in search of adventure. From the Caribbean, their journey takes them to Victorian London, where they encounter Charles Darwin, an articulate ‘man-panzee’ named Mister Bobo, and an all-powerful enemy determined to wipe out pirates forever. The pirates find that their quest is a victory for good-natured optimism over the boring forces of common sense.

The movie has been created with the same beautiful hand-crafted technique that Aardman brought to its Wallace and Gromit feature films but with the added ingredient of 3D for an even more fantastic experience. Filming involves capturing tiny incremental movements of modelling clay figures and objects which are individually photographed on single frames. Whilst a great deal of this intricate work is carried out by skilled animators, precision positioning and motion control can help speed the process, particularly where pin-point camera synchronisation is required for 3D animation to guarantee repeatable results and ensure precise continuity.

The camera tracker positioning system in particular brings a high technology element to the process by locking the cameras to a target in conjunction with a vision system and following its horizontal and vertical movements with micron level precision during a shooting sequence.

LG Motion Limited were asked to submit design outlines for generally more compact camera tracker positioning stages than those offered by traditional film industry manufacturers - with the additional challenge of further rigidity and improved load carrying capacity. The linear stages have a nominal travel range of 600mm with a 150mm square moving carriage plate machined to directly mount Aardman’s camera system. The base of the stage provides the inherent stiffness for free mounting as well as accommodating X-Y mounting if required. Furthermore, the design specification called for the flexibility to accommodate various travel ranges to suit potentially different types of filming. A simple spirit level is also built into each stage to aid levelling the assembly at set-up.

To accommodate the cantilever loading specification of up to 30kg at one metre from the moving carriage for the camera and mounting arrangement, LG Motion chose dual linear motion guide bearings from its distribution partner Schneeberger. The design also includes a 10mm diameter precision ballscrew with a 2mm pitch and a standard NEMA 23 frame motor mount which can be used with a wide selection of stepper or servo motors to suit the performance dynamics required for each particular set-up. In addition, the ballscrew may be replaced with a higher friction leadscrew system that suits vertical mounting and removes the tendency for back driving the stage when power is removed.

The rotary stages were designed for positioning large mirrors for special set lighting effects and are based upon standard LGR1000 series. The 90:1 worm-wheel stages provide a similar motor selection flexibility to the linear stages, with servo or stepper motor drives available via a NEMA 17 size motor mount. The design also includes a 12.5 mm diameter through-hole which may be used to carry wiring and other services through the stage. A wide range of stepper and servo motors with associated drives and motion controls were also part of the scope of supply.