WAM Arm – User’s Manual
www.barrett.com
© 2008 Barrett Technology®, Inc.
Document: D1001, Version: AH.00
57 of 80
The external PC fulfills the same function as the internal computer, but it provides extra
processing power and hard drive space. The external PC uses CAN communication to connect to
the WAM. If the external PC is used, communications and commands bypass the internal PC.
The WAM safety system consists of the pendants and the safety board/module, and it monitors
joint torque and velocity, communication between the computer and the Pucks™ (heartbeats),
voltage levels to the WAM, and safety states (see Section 2 for details). The safety module will
shut down the WAM and cause the motors to resistively brake if it senses a dangerous situation
(see Section 2.2).
Barrett Technology has created specially designed motor controllers called “Pucks™”, which are
mounted directly to the motors they control. A Puck™ serves as a power source for the motors and
commands a smooth, continuous torque based on the digital torque command. It also serves as an
encoder for the motor angle, a power amplifier, and contains precision internal current and
temperature sensing as well as high-speed CANbus communications.
Figure 34 – WAM System Schematic
5 VDC
48 VDC
CA
Nb
us
SAFETY
MODULE
dynamic
braking
CONTROL
PENDANT
DISPLAY
PENDANT
M
PUCK™
M
PUCK™
PUCK™
…
POWER
SUPPLY
EXTERNAL
PC
optional
INTERNAL
PC 104
120 or
240 VAC
WAM
M