WAM Arm – User’s Manual
www.barrett.com
© 2008 Barrett Technology®, Inc.
Document: D1001, Version: AH.00
18 of 80
exceeded, the safety system automatically idles all motors (puts the WAM in the IDLE safety
state). See Section 6.3 for more information about how to set the torque limits.
Sometimes, when you exit a WAM control program, the torque warning light will stay on. That
just means that the last torque that the safety system saw go by was beyond the warning level for
the present state ( > 0 for E-STOP or IDLE, or > TL1 for ACTIVATED). As long as you send one
or more zero-torque commands to the pucks, the warning light should extinguish.
Voltage:
The voltage status lights indicate the state of the WAM Arm’s motor bus voltage. When
the system is first powered up, the bus is off (there is no motor power), and the safety system
registers a voltage fault. This fault is cleared by pressing Shift-Idle on the control pendant. Placing
the WAM Arm into the IDLE state applies a DC voltage on the motor bus and clears the fault. If
the voltage approaches the limits, the voltage warning light is lit. If the voltage exceeds the limits,
the voltage fault light is lit.
Heartbeat:
The heartbeat status lights indicate the state of the communication between the PC and
each motor controller in the WAM Arm. If the WAM is in the IDLE state and no control loop is
active between the PC and the motor controllers, the pendants will display a heartbeat warning. If
the WAM is in the ACTIVATED state, the computer must request encoder values in a constant
loop until you press Shift-Idle again. If PC or any motor controller fails to issue any
communication for longer than 16ms, the safety system will register a heartbeat fault and shut
down the WAM.
Other:
The “Other” status lights presently only indicate whether an E-STOP has occurred. If this
is the case, the fault light will be lit and the single-character display will show “E”.
2.3 Handling Safety Faults
If the safety system registers a fault during WAM operation, the fault must be cleared before
continuing to use the WAM. The most common safety faults (over velocity, over torque) leave the
WAM safety system in the IDLE state (yellow button is lit). To reset the fault from this state
(when using the btdiag example application):
1)
Stop any running Teach & Play playback (press ‘/’)
2)
Set the position controller to IDLE mode (press ‘p’ to toggle mode)
3)
Turn off gravity compensation (press ‘g’ and enter 0)
4)
Reset the safety fault (press <Shift+Reset/Idle> on the control pendant)
5)
Re-activate the WAM (press <Shift+Activate> on the control pendant)
6)
Turn on gravity compensation (press ‘g’)
If the safety system encountered a critical fault that resulted in an E-STOP of the WAM (no
pendant buttons are lit), follow these steps to recover from the fault:
1)
Exit the application (press ‘x’)
2)
Reset the safety fault (press <Shift+Reset/Idle> on the control pendant)
3)
Grab the WAM and move it back to the home position (the joint positions are lost after
an E-STOP)
4)
Re-launch the control program and follow the on-screen instructions
