Changing reference frame in Cartesian trajectories

[pouyan-asg]

Description

I send Cartesian waypoint trajectories to Gen3 robot. By default (based on api_python example "02-send_cartesian_waypoint_trajectory") the reference frame is BASE. See below code:

 def cartesian_pose(waypointInformation):
            waypoint = Base_pb2.CartesianWaypoint()  
            waypoint.maximum_linear_velocity = 0.5
            waypoint.maximum_angular_velocity = 99
            waypoint.reference_frame = Base_pb2.CARTESIAN_REFERENCE_FRAME_BASE
            waypoint.pose.x = waypointInformation[0]
            waypoint.pose.y = waypointInformation[1]
            waypoint.pose.z = waypointInformation[2]
            waypoint.blending_radius = waypointInformation[3]
            waypoint.pose.theta_x = waypointInformation[4]
            waypoint.pose.theta_y = waypointInformation[5]
            waypoint.pose.theta_z = waypointInformation[6]
            return waypoint

I need to change reference frame to CARTESIAN_REFERENCE_FRAME_MIXED. However, I see this error when I change waypoint.reference_frame = Base_pb2.CARTESIAN_REFERENCE_FRAME_BASE with waypoint.reference_frame = Base_pb2.CARTESIAN_REFERENCE_FRAME_MIXED. The error is shown below:

Error found in Stroke trajectory
trajectory_error_elements {
  error_type: TRAJECTORY_ERROR_TYPE_INVALID_REFERENCE_FRAME
  min_value: 1.0
  max_value: 2.0
  message: "Requested reference frame is not supported"
  waypoint_index: 1
}

My question is, do you know how can I change reference frame to Mixed one? I should mention that I added below code in my Main file but it does not work.

with utilities.DeviceConnection.createTcpConnection(args) as router:
      base = BaseClient(router)
      vari = ControlConfigClient(router)
      ref_f = CartesianReferenceFrameInfo()
      ref_f.reference_frame = 1
      vari.SetCartesianReferenceFrame(ref_f)

Thanks for time and consideration

regards,
Pouyan

[felixmaisonneuve]

Hi @pouyan-asg,

I have looked into this issue, I found that the first CartesianWaypoint needs to be in a Base Reference Frame. Following waypoints can be in Mixed Reference Frame.

According to the documentation, using SetCartesianReferenceFrame will only work for twist and wrench commands

Defines the reference frame to use with twist and wrench commands

Best,
Felix