Servo Motor Control
Inexpensive servo controllers are used in many different animatronic shows. There are a variety of servo controllers on the market today.
Scott Edwards Mini SSC II Servo Controller
The card that set the bar for low-cost servo control is Scott Edwards' Mini SSC II. The Mini SSC II is capable of controlling up to 8 servos per card. The cards can be daisy chained together to be able to control 256 servo motors, efficiently using a serial data protocol.
Gilderfluke Servo Controllers
The SER-DMX card is Gilderfluke's top of the line controller for servos. Each card controls up to 16 model airplane-style servo motors, using programming from PC-MACS and a DMX control signal. Using a Gilderfluke network, it is possible to control over 60 servo motors per DMX-512 signal. More servos could be added by adding additional DMX signals.
BR-MiniBrick 8 - This little card can control up to 8 digital switches, but also controls 2 servo motors. The BR-Minibrick 8 is set up right on the card or programmed with PC-MACS and downloaded to the card.
Pololu Servo Controllers
Pololu has a large family of servo control boards available. The best features of these boards is the small size and the price. They have both USB-based servo control boards and serial control boards. Their largest group of boards is the Mini Maestro USB boards. Pololu offers these boards which control 12, 18, or 24 servo motors. The USB boards are controlled not only by USB, but also TTL (serial) and internal scripting. Scripting is performed using a free program provided by Pololu. The script size is 8K, which gives space for different program options. The Mini Maestro boards also support analog or digital inputs for control from sensors, motors, and push buttons. They can also control digital outputs.
Pololu also produces the tiny Micro Maestro boards which control up to 6 servos in only a 0.91" x 0.91" form. The Micro Maestro boards have all the features of the Mini Maestro boards, except there is only 1K available for scripting.
Pololu also sells the Servo 16 serial controller, the Serial-8 servo controller, and the USB-16 servo controller. The USB servo controller is their most expensive board because it has a dual USB and UART interface.
All Pololu servo controller boards are compatable with Scott Edwards Mini SSC II. Most can also be daisy-chained together through the serial line to control additional servo motors.
Parallax Servo Controller
Parallax current servo controller is the Propeller Servo Controller USB. The built-in propeller microcontroller chip opens up many different possibilities for animatronics use. A built-in EEPROM chip also provides 32KB for custom control programming. The Propeller Servo Controller is controlled from USB or serial data. It can control up to 16 servo motors. Control of up to 32 servo motors is possible by using a second board.
The Picobotics PicoPIC 20 was one of the most popular servo control boards available when they were still selling. The PicoPIC is ideal for animatronics and robotics because it has 20 channels that control either servos or digital outputs. Each channel is 16 bits and operates at a very fast 57 frames per second thanks to the PIC16 processor. This gives the board plenty of capacity since servos only demand data at 30 frames per second.
PicoPIC can operate in a MiniSSC II compatability mode with output for 20 servo motors. The real strength of the board, however, is operating the board with a Basic Stamp processor. This opens up more possibilities with the built-in UART communication and the servo or digital output. PicoPIC boards are no longer available today, but when one pops up on eBay, it sells very well.
Arduino Servo Motor Shields
Adafruit Industries - Motor Shield: controls 2 servos + more
Creatron Inc. - Idea Shield: controls 2 servos + more
Critical Velocity - Accelerometer Shield : has 6 servo motor headers
Renbotics - Servo Shield: controls 16 servos
Ro-bot-X designs - Robot builder's shield: controls 6 servos + more
Solarbotics - SB Protoshield: controls 2 servos + more
LynxMotion Servo Controller
LynxMotion offers the SSC-32 Servo Controller which is the cheapest board available for controlling the most servo motors. It controls up to 32 servo motors and has a Mini SSC II mode, so it operates like 4 SSC II boards. The LynxMotion board also has a hexapod mode with sequencing built in. The board does not have other input other than the data port and does not have any digital outputs. For under $40, this board is a deal for controlling a lot of servo motors.
Different Size Servo Control Boards
Servo control boards come in many sizes. In the photo, clockwise, starting in the top left corner is the MIT Robot Controller (largest), LynxMotion SSC32, Arduino Duemilanove, Arduino Uno, Pololu SSC04 (smallest), Pololu Mini Maestro 12, Scott Edwards Mini SSC II, Picobotics PicoPIC-20, and KMK USB 10 Servo Controller