Build Your Own Combat Robot

Innovation First Isaac Robot Controller
and Other Radio Modems
Chapter 8: Remotely Controlling Your Robot 175
The IFI Robotics Isaac R/C system was originally developed for the FIRST (For Inspiration
and Recognition of Science and Technology) robotics competition.
FIRST robots are designed to participate in a competition requiring rather complex
mechanisms with jointed arms, telescoping grabbers, and complex omni-directional
movement, which makes their control needs a lot more involved than
that of a typical combat robot.
The FIRST system is built around a 900-MHz, bi-directional radio modem,
which transmits high-rate serial data between the control gear and the robot. The
transmitter gear is a modular design that is capable of using standard PC-compatible
game-type peripherals such as joysticks, steering wheels, foot pedals, or custom
user-built control gears. The receiver contains a user-programmable radio, which
can control complex functions on the robot in response to commands from the
transmitter. Digital and analog inputs to the receiver board can be used as feedback
to the control system, or they can gather telemetry data to send back to the
transmitter for driver displays or recording on a laptop computer.
The IFI Robotics system uses the 900-MHz band to transmit its control signals.
The data packets traveling between the transmitter and receiver are coded with a
team number to ensure that one IFI Robotics radio set does not interfere with another
IFI Robotics radio set, which is a tremendous advantage over hobby R/C
gear that has no way of distinguishing between one radio and another on the same
frequency. The coded team number is custom settable by the users and the event’s
organizers. The bi-directional data transmission also gives the operator a clear indication
of radio signal integrity, diagnostic lights on the operator interface tell
the operator the status of the receiver, and a button on the transmitter control
board can be used to reset forcibly the receiver’s user-programmed computer system.
IFI Robotics sells two types of robot controllers—the Isaac16 and the
Isaac32—that are similar except the Isaac32 has twice the number of output channels
and onboard sensor inputs, and the radio modem is a separate item and not built
into the system as is the Isaac16. Table 8-3 shows a list of the number of inputs and
outputs in the two robot controllers.
Feature Isaac16 Isaac32
Digital sensor inputs 8 16
Analog sensor inputs (0–5 volt, 8-bit A/D) 4 8
PWM outputs 8 16
Solid-state relay outputs 8 16
TABLE 8-3 IFI Robotics Isaac Robot Controller Input/Output Specifications �