Industrial Electronics
The Issus, the strainwave and the cameraman
Graham Mackrell explains how precision gears enable camera systems used by broadcast engineers help create programmes. Surprisingly, the technology on which they are based has a relative in nature in the shape of an insect called the Issus
I
t's smaller than a five pence coin, green all over and sports a utilitarian look. It lives in your back garden and inconspicuously hops from plant to plant. In that very motion it carries within itself a secret as old as time. You see, the hind legs of an Issus consist of two 180 degree helix-shaped strips, each with twelve fully interlocking spur type gear teeth. Looking almost machine tooled, the fully formed gear system enables the humble Issus to perfectly synchronise the movement of its legs, to perform a
hopping manoeuvre, at speeds of 30 microseconds - where one microsecond is equal to a millionth of a second. Launching itself forward at an acceleration equivalent to 0-60mph in just 5.5 seconds, this supercar-shaming speed exerts over 500 units of G-force on the little critter. The gear system is essential to make such powerful jumps so quickly and accurately. "This precise synchronisation would be impossible to achieve through a nervous system, as even neural impulses would take far too long for the extraordinarily tight coordination required," explained Professor Malcolm Burrows, of Cambridge University, an expert on the subject. "Even a slight discrepancy in the synchronisation of its legs would cause the Issus to spin hopelessly out of control." The discovery discredits the widely held belief that, up until now, humans invented the gear. It is evident that gears play a vital role in both the natural and human world. While for the Issus using its super abilities for plant hopping may be enough, gears play a much more pivotal role for humans. From the gearbox in your car, and the clock on your wall, to the oil and gas used to make the plastics in your everyday electronics, gears are ubiquitous. One of the least apparent, but most widely used applications of advanced gears is in the film and broadcast industry. Traditionally, this has been a manually intensive process, with camera operators having to use fine movement to create controlled camera movements, which can then be replicated for multiple takes. The rise of artistic filmmaking, the increased use of computer generated imagery (CGI) and the popularity of high definition (HD) and 3D movies as well as many other special effects used in modern cinema would simply not be possible using traditional filming techniques. This is where motion control takes over.
Having developed over the last forty
36 September 2014 Components in Electronics
years, motion control in the broadcast industry has been used to create some of our best known films. From the epic deep space battle scenes in Star Wars and the sweeping shots of Hogwart's castle in Harry Potter to the larger than life characters in The Lord of the Rings, motion control has been the invisible enabler of cinema for decades. Typically consisting of a camera rig mounted on a motorised robotic arm, motion control allows pre- programmed moves to be entered into the camera control software. The resultant benefit of such a setup is two-fold. Firstly, highly accurate movements can be made, which would otherwise be impossible even with a cameraman's steady hands. Secondly, these moves can be repeated again and again with 'pixel-perfect' precision. Post production then allows multiple clips to be composited together to create a final scene, which is greater, in cinematic value, than the sum of its parts. With this new found accuracy and
repeatability, filmmakers could clone characters, replicate crowds of people and mix camera array setups with motion control footage to create scenes such as the iconic frozen-moment bullets scene from The Matrix. Scaled moves are another technique achieved with motion control. By filming a highly detailed model of a prop or set, and then magnifying the movement by a given ratio, filmmakers have been able to realise the tall spires of Hogwarts' fictitious castle in Harry Potter and the diminutive height of hobbits and dwarves in The Lord of the Rings trilogy.
CGI has been taken to a whole new level with motion control. Because the camera rig's X, Y and Z axis can be pre- programmed, data can be imported to and from the CGI software, allowing pre- production control over camera angles and specific controlled moves. A further benefit is improved budget management - as more actions can be accurately pre planned.
This rapid innovation and lowered cost helps to alleviate one of the key barriers that has traditionally impeded the transition of motion control to the TV and broadcast industry. With ever shrinking funds, producers are under pressure to make fiscal cuts, whilst being required to make even more compelling content. Diminishing advertising revenues
however, can be attributed to more than just an economic recession. A wider cultural shift in our viewing habits is the result of the increased competition from digital and online content. Viewers, more
connected to the tablet than the TV, have begun to demand more interactive content, preferring to tweet and comment whilst watching.
The advent of services like YouTube Live have catalysed this growth, with viewers able to simultaneously post questions to live shows, whilst actively commenting on, and discussing, their thoughts with millions of likeminded individuals. The combined effect on the broadcast industry is a demand for more and better content, produced on lower and lower budgets. Here at Harmonic Drive, we have sought to support filmmakers in the challenges they face by developing reliable equipment with the ability to take a beating in the, often harsh, conditions in which it is used. A good example of this is in the BBC's recent Frozen Planet series. Our compact servo actuators provided the gearing for a pan and tilt camera, which was used to film a six month time-lapse in the Arctic. With rugged Viton seals, maintenance
free lubrication and improved corrosion protection, the equipment was able to withstand the ferocious winds and bitterly cold, sub-zero temperatures. As TV programmers seek to commission content with a higher production quality, on a lower budget, the demand for portable equipment has increased. We have adapted our products to maintain performance in a smaller package. Our hollow shaft actuators are lightweight and compact, with smooth torque and high torsional stiffness. Backlash free gearing offers precision motion control, resulting in excellent accuracy and repeatability. Digital controllers complete the package, allowing setup software to run in Windows. It seems the Issus is not the only one with a few tricks up its sleeve. The use of gears in the broadcast industry may at first seem inconspicuous, but there is a lot more going on behind the lens than first meets the eye. Just as nature has used an elegant solution for the Issus, broadcasters must face the digital challenges ahead. Who will be around long enough to tell the story? Only time will tell, but it seems certain that those businesses able to deliver the advanced cinematography that is now demanded by both the movie industry and television will be best placed to achieve their objectives.
Harmonic Drive UK |
www.harmonicdriveuk.com
Graham Mackrell is managing director of Harmonic Drive UK
www.cieonline.co.uk
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