Motion supplier's supporting role in animated film production

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HepcoMotion has supplied a PDU profile driven unit with a SmartDrive stepper motor and controller for use in a rig for creating stop motion animated films.

Thanks to some clever design work based on a HepcoMotion linear actuation system, production of the Glendogie Bogey was a slick operation. Funded by BBC Scotland, this stop/motion animated film was the sequel to the BAFTA-nominated Haunted Hogmanay and sees two friends go in search of the fearsome monster, the Glendogie Bogey, that lurks in caves under a golf course. Former S Clubber, Rachel Stevens, and actor Peter Capaldi provided two of the voices.

The film was conceived by Edinburgh-based Ko Lik Films. The company specialises in stop frame animation, a method that involves clay models being moved, frame by frame, to create a sequence. This is time-consuming work as typically 25 camera shots are required to complete one second of film.

Historically Ko Lik used a rig wherein the camera was mounted on a hand-wound helical screw that enabled it to be moved along the scene set. However, this technique was neither accurate nor flexible, resulting in increased production hours and compromised cost-efficiency. The company therefore sought the help of engineering designer and model maker David Campbell and his colleague Michael Gormley.

Designed from scratch

Gormley says: "We explored proprietary motion systems for Ko Lik but they were too costly and over-specified for its needs. So we set about designing a system ourselves. And although what we came up with was a fairly straightforward two-axis system carrying a small load, there were several factors that made it a nifty bit of kit."

The resultant system comprises two HepcoMotion PDU profile driven units and a SmartDrive stepper motor and controller. Designed to straddle the set, it was a fairly long-winded development, as Gormley explains: "We had to translate exacting production needs into design engineering and both HepcoMotion and its motion control partner SmartDrive contributed a great deal in this regard."

Rigidity was an important criteria for the linear motion. As the system is cantilevered, the vertical axis had to provide solid support for the motorised X-axis on which the camera is mounted. Gormley and Campbell also had to contend with an element of bounce within the system, but the stiffness of the beams and use of the motor to counterbalance the camera and camera head at extremes of travel ensured that this effect does not compromise the camera's positioning accuracy.

Control and accuracy

Key to the success of this rig is its controllability; it is able to move the camera a set distance to within 0.1mm accuracy and, most importantly, provide a datum. This is critical from a production cost standpoint. When a sequence has been shot it is naturally reviewed for quality. If part of it needs to be re-taken, it is now easy for the production team to re-shoot, for example from frame 10–20 in a 100-frame sequence. This is because the exact camera position is now known.

The SmartDrive controller also provides other valuable automation features. Knowing what distances to move the camera to achieve the required visual effect is a complex task. Historically it needed a combination of mathematical calculation and intelligent guesswork on the part of the production team. Gormley states: "On the new system we have fed these algorithms into the controller so it has executable routines that the camera operators can just run. It is completely transparent to them."

In conclusion, Gormley praises both HepcoMotion and SmartDrive for their ongoing advice on this project: "In the greater scheme of things this was a fairly small job but both companies were only too pleased to give us the benefit of their knowledge."

Follow the link for more information about HepcoMotion's PDU profile driven units.

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