Servo Controllers: From MIT To The Mainstream
Servo controllers are essential to the operation of large assemblies of servo mechanisms or motors. They provide a user interface that allows a single technician to simultaneously oversee and alter the workings of any number of servo machines (as many as 256 ‘channels’ are allowed on the most sophisticated servo controllers), and provide very concise, close-looped position control, an effect provided by means of resolvers, encoders and Hall-Effect sensors.
Of course advanced controllers can be very pricy indeed – as with most proprietary software and hardware marketed to big industry, you can expect to pay as much as $2000 for a single chip. Thus it’s certainly in your interest to look for second hand or used servo controllers. Try browsing Craigslist of specialty forums online to find offers that’ll beat the prices of brand new servo controllers tenfold.
Servo controllers tend to interface best with brushless servo motors, as these offer completely electronic operating systems that allow for maximized efficiency. Such servos tend to be of the DC motor type, so it’s in your best interest, when shopping for a servo controller, to ensure that it’s DC, or, better yet, capable of using both AC and DC power sources.
Perhaps the biggest consumers in terms of servo controllers next to factories and heavy industry are far more unassuming than either. They’re the users of home RC toy cars, and the builders of makeshift robotic projects. Inspired by Make magazine and the explosion of free, sophisticated engineering and technological information made possible by the internet, these small-time consumers have grown to become the long tail of the motion control industry – and it’s a very, very long tail indeed, with annual revenues in the hundreds of millions. These consumers rely on the existence of relatively cheap, and very small servo mechanisms and controllers. The basic servos they purchase, which run up to about 32 channels, can go for as little as $20 a piece.
The availability of such small scale robotics components is vitally important to the health of the robotics industry, allowing for so-called ‘garage geniuses’ to develop products along different lines than might occur to the crème de la crème of technology experts trained at MIT or Stanford. It’s such people, many experts believe, that will be the first to build robots capable of cleaning our carpets or washing our cars without supervision. Indeed, it’s initiatives such as the Jasmine Project, operated by swarmrobot.com, which make software and hardware design open-source (rather than keeping knowledge jealously guarded, as it tends to be when developed under the funding and guidance of major corporations) that seem mostly likely to render up the potential inherent in nanotechnology, by, providing the basic principles by which to create a swarm of cooperative, albeit very limited, robotic entities.
For affordable home robotics components, including motor and servo controllers and electronics kits, check out Pololu Robotics and Electronics, which sells the components in various degrees of disassembly depending on whether you prefer to solder things together or not. Aside from being able to facilitate online, telephonics and postal orders, Pololu also has an online robotics forum, where enthusiasts can consult with company engineers while building their robots.
