Rethink Robotics Intera SDK

Cartesian trajectories for Rethink robots

Vendor specifics
Teach pendant Integrated into the robot
Programming / simulation software Intera 5
Software Intera SDK
Programming language Python
Relevant hardware Robots Sawyer and Baxxter

Rethink robots support a native ROS interface. The ROS master runs on the robot.

Further reading

Feature list

  • Contains accelerations
  • For Cartesian segments, the joint positions are used as nullspace biases
  • Joint interpolation or cartesian interpolation
  • Hybrid Trajectories not possible
  • All trajectory points take an optional WaypointOptions
  • Contains path and goal tolerances in joint space
  • Contains for each waypoint: * Max joint speed ratio * Max joint acceleration * Max linear speed * Max linear acceleration * Max rotational speed * Max rotational acceleration * Corner distance
  • Allows to specify active endpoint

Features required from hardware / driver

Message definition

Trajectories have some global options and a list of waypoint. Each waypoint itself can also have some local options.

[Waypoint]
# Representation of a waypoint used by the motion controller

# Desired joint positions
# For Cartesian segments, the joint positions are used as nullspace biases
float64[] joint_positions

# Name of the endpoint that is currently active
string active_endpoint

# Cartesian pose
# This is not used in trajectories using joint interpolation
geometry_msgs/PoseStamped pose

# Waypoint specific options
# Default values will be used if not set
# All waypoint options are applied to the segment moving to that waypoint
WaypointOptions options

[WaypointOptions]
# Optional waypoint label
string label

# Ratio of max allowed joint speed : max planned joint speed (from 0.0 to 1.0)
float64 max_joint_speed_ratio

# Slowdown heuristic is triggered if tracking error exceeds tolerances - radians
float64[] joint_tolerances

# Maximum accelerations for each joint (only for joint paths) - rad/s^2.
float64[] max_joint_accel

###########################################################
# The remaining parameters only apply to Cartesian paths

# Maximum linear speed of endpoint - m/s
float64 max_linear_speed

# Maximum linear acceleration of endpoint - m/s^2
float64 max_linear_accel

# Maximum rotational speed of endpoint - rad/s
float64 max_rotational_speed

# Maximum rotational acceleration of endpoint - rad/s^2
float64 max_rotational_accel

# Used for smoothing corners for continuous motion - m
# The distance from the waypoint to where the curve starts while blending from
# one straight line segment to the next.
# Larger distance:  trajectory passes farther from the waypoint at a higher speed
# Smaller distance:  trajectory passes closer to the waypoint at a lower speed
# Zero distance:  trajectory passes through the waypoint at zero speed
float64 corner_distance

[Trajectory]
# Representation of a trajectory used by the engine and motion controller.

# optional label
string label

# Array of joint names that correspond to the waypoint joint_positions
string[] joint_names

# Array of waypoints that comprise the trajectory
Waypoint[] waypoints

# Trajectory level options
TrajectoryOptions trajectory_options

[TrajectoryOptions]
# Trajectory interpolation type
string CARTESIAN=CARTESIAN
string JOINT=JOINT
string interpolation_type

# True if the trajectory uses interaction control, false for position control.
bool interaction_control

# Interaction control parameters
intera_core_msgs/InteractionControlCommand interaction_params

# Allow small joint adjustments at the beginning of Cartesian trajectories.
# Set to false for 'small' motions.
bool nso_start_offset_allowed

# Check the offset at the end of a Cartesian trajectory from the final waypoint nullspace goal.
bool nso_check_end_offset

# Options for the tracking controller:
TrackingOptions tracking_options

# Desired trajectory end time, ROS timestamp
time end_time

# The rate in seconds that the path is interpolated and returned back to the user
# No interpolation will happen if set to zero
float64 path_interpolation_step

[TrackingOptions]
# Minimum trajectory tracking time rate:  (default = less than one)
bool     use_min_time_rate
float64  min_time_rate

# Maximum trajectory tracking time rate:  (1.0 = real-time = default)
bool     use_max_time_rate
float64  max_time_rate

# Angular error tolerance at final point on trajectory (rad)
float64[] goal_joint_tolerance

# Time for the controller to settle within joint tolerances at the goal (sec)
bool     use_settling_time_at_goal
float64  settling_time_at_goal