How to quick stop a slave?

[qleonardolp]

Hello. I'm trying to implement the quick stop feature in a custom ros2_control controller. By now, we are able to manage the driver mode_of_operation through the respective interface, claimed by the controller, and command the slave when the controller is active, either through position or velocity.

We are considering set the quick stop bit in the controlword when deactiving the controller (ros2 control set_controller_state <controller_name> inactive). The controller does write on the controlword, since the interface is available and claimed, but the slave state machine will be at PRE-OP after that.

To do so, we write the desired controlword for the joints as:

  for (size_t joint = 0; joint < dof_; ++joint) {
    joint_command_interface_[4][joint].get().set_value(0b000000010);  // Quick-stop bit 1
  }

The first index, 4, is because the other indexes are reserved for other command interfaces.

When implementing the on_activate method, the controller fails to make the state machine transitions Faultless -> Ready -> Waiting to enable -> Running. For such transitions I'm writing 0b00000000, 0b00000110, 0b00000111, and 0b00001111, respectively in the controlword. What am I missing?

[pzanne]

Hello,

if the ethercat slave machine is in PRE-OP state, the drive state machine will remain stuck at : SWITCH_ON_DISABLED. this is why the conrolword has no effect.
What is important to understand is why the slave goes into PRE-OP mode?
Could you switch the ethercat stack to debug mode:
ethercat debug 1
test the quick stop and send the kernel messages?
dmesg | grep EtherCAT
Could you also check the status of the ethercat ros2 hardware before and after the quick stop ?
Best
Philippe