Overview

The purpose of this tutorial is to introduce you to the competition interface that is used to interact with GEAR, the software used by teams participating in the Agile Robotics for Industrial Automation Competition (ARIAC).

Running GEAR

After setting up a system, you should have GEAR installed. To set up your terminal for running GEAR you will have to run:

source /opt/ros/melodic/setup.bash

If you built gear from SOURCE, you will also have to source the setup file from your catkin workspace.

# Path is where you built and installed gear
source ~/ariac_ws/install/setup.bash

To launch GEAR with a sample work cell that has some sensors and parts in various locations, run:

roslaunch osrf_gear sample_environment.launch

Starting and Stopping the Competition

Starting

When gear is started, various competition elements will be in an inactive state. A service must be called to activate these components. Run the following command to manually start the competition:

rosservice call /ariac/start_competition

Trial End

When all orders have been filled, or the time limit for the trial has been exhausted, the competition state published on /ariac/competition_state will change to done.

To check the competition state, run:

rostopic echo /ariac/competition_state -n 1

If you wish to end the trial early (e.g. you detected a fault in your system and wish to terminate), run:

rosservice call /ariac/end_competition

Fulfilling Orders

Orders for kits will be published during the competitions. An order is composed of products to place onto a tray. Teams earn points by completing orders quickly.

Receiving Orders

Teams must subscribe to this topic to receive the initial order, as well as any future order updates. To see the last order that was published, run:

rostopic echo /ariac/orders

Note the competition must be started before an order will be published. You must add your sensors to detect and classify products in the storage bins or conveyor belt.

The most recently received order is the highest priority.

Delivering Orders

There are two AGVs carrying trays that kits can be assembled on. When a kit has been completed, the AGV must be commanded to deliver the kit so it can be scored.

The service /ariac/agv[N} where N is 1 or 2 is used for this purpose. The type of kit that is on the tray must be specified. This is included in the original order. Call this service to submit a tray for evaluation:

rosservice call /ariac/agv1 "kit_type: order_0_kit_0"

If multiple trays need to be submitted, the AGV will return an empty tray after the submitted tray has been evaluated.

During the final competition the order may indicate that it must be delivered to a particular AGV. Orders delivered on the wrong AGV will be counted as a zero score.

Faulty Products

There are quality control sensors above each AGV that publish the pose of faulty parts that they see on the tray. The quality control sensors:

have an equivalent interface to logical camera sensors
publish tf frames of faulty parts
are positioned above each AGV in pre-defined locations
users cannot specify the locations of these sensors
report faulty parts only once they are in the tray of an AGV
do not report any information about non-faulty parts

As an example (this command will not work during the qualifier or finals), spawn a known faulty part on AGV 1's tray:

rosrun gazebo_ros spawn_model -sdf -x 0.1 -y 0.1 -z 0.05 -R 0 -P 0 -Y 0 -file `catkin_find osrf_gear --share --first-only`/models/piston_rod_part_ariac/model.sdf -reference_frame agv1::kit_tray_1::kit_tray_1::tray -model piston_rod_part_5

Then run this command to see the quality control sensor's output.

rostopic echo /ariac/quality_control_sensor_1

You should see that the part spawned has been detected as faulty.

models: 
  - 
    type: "model"
    pose: 
      position: 
        x: 0.743197471473
        y: -0.100148694292
        z: 0.453218022501
      orientation: 
        x: -0.496443448488
        y: 0.50485071322
        z: 0.496120280969
        w: -0.502527936164
pose: 
  position: 
    x: 0.3
    y: 3.5
    z: 1.5
  orientation: 
    x: 0.501601833862
    y: 0.499997434122
    z: -0.499997434122
    w: 0.498398166138

Controlling the Arms

There are two UR10 arms in the simulation. The UR10 simulation and control code is provided by ROS Industrial's universal_robot ROS packages. The control parameters have been modified for use in the ARIAC simulation.

Controlling a Vacuum Gripper

Each arm has a simulated pneumatic gripper attached to the arm's end effector. Teams can enable or disable the suction of the gripper. When the suction is enabled and the gripper is making contact with a product, the contacting product will be attached to the gripper. At any point, teams will also be able to disable the suction, causing the detachment of the object if it was previously attached. To enable arm1's gripper suction from the command line, run:

rosservice call /ariac/arm1/gripper/control "enable: true"

The gripper periodically publishes its internal state on topic /ariac/armN/gripper/state. Subscribe to this topic to introspect the gripper's status. You can check whether the suction is enabled/disabled or whether there is an object attached to the gripper. Execute the following command to display arm1's gripper state:

rostopic echo /ariac/arm1/gripper/state -n 1

Disable the suction again for now with

rosservice call /ariac/arm1/gripper/control "enable: false"

Controlling Arm Joints

Each arm has its own command topic for controlling the joints of the arm on /ariac/armN/arm/command where N is 1 or 2. The topic uses trajectory_msgs/JointTrajectory messages. The arm's controller will try to match the commanded states. The arm is controlled by an instance of ros_controllers/joint_trajectory_controller.

Command Line

Run this command to move arm1 over a gasket part in the sample environment.

rostopic pub /ariac/arm1/arm/command trajectory_msgs/JointTrajectory    "{joint_names: \
        ['linear_arm_actuator_joint',  'shoulder_pan_joint', 'shoulder_lift_joint', 'elbow_joint', 'wrist_1_joint', 'wrist_2_joint', 'wrist_3_joint'], \
     points: [ \
{time_from_start: {secs: 2}, \
        positions: [0.15, 3.14,  -1.570,  2.14, 3.1, -1.59, 0.126]}, \
{time_from_start: {secs: 4}, \
        positions: [-0.35, 3.14,  -0.6,  2.3, 3.0, -1.59, 0.126]}, \
{time_from_start: {secs: 6}, \
        positions: [-0.35, 3.14,  -0.5,  2.3, 3.05, -1.59, 0.126]}, \
]}" -1

You should see the arm move to the specified joint positions. To get the current joint positions of the arm, run:

rostopic echo /ariac/arm1/joint_states -n 1

The /ariac/armN/joint_states topic uses the sensor_msgs/JointState message which contains joint positions, velocities, efforts, and the name of the joints.

Now, enable the gripper on arm1.

rosservice call /ariac/arm1/gripper/control "enable: true"

The gripper state should now show it has attached to an object.

$ rostopic echo -n 1 /ariac/arm1/gripper/state 
enabled: True
attached: True
---

Note, you could have enabled the gripper at the beginning. It will attach to the first product it contacts.

Move the part over AGV1's tray

rostopic pub /ariac/arm1/arm/command trajectory_msgs/JointTrajectory    "{joint_names: \
        ['linear_arm_actuator_joint',  'shoulder_pan_joint', 'shoulder_lift_joint', 'elbow_joint', 'wrist_1_joint', 'wrist_2_joint', 'wrist_3_joint'], \
     points: [ \
{time_from_start: {secs: 2}, \
        positions: [0.0, 3.14,  -1.570,  2.14, 3.27, -1.51, 0.0]}, \
{time_from_start: {secs: 5}, \
        positions: [1.0, 1.85,  0,  -0.38, 1.57, -1.51, 0.00]}, \
{time_from_start: {secs: 7}, \
        positions: [1.0, 1.507,  0,  -0.38, 0.38, -1.51, 0.00]}, \
{time_from_start: {secs: 10}, \
        positions: [1.18, 1.507,  0.38,  -0.38, 1.55, 1.75, 0.127]}, \
]}" -1

Disable the gripper to drop the object

rosservice call /ariac/arm1/gripper/control "enable: false"

Return the arm to the starting position.

rostopic pub /ariac/arm1/arm/command trajectory_msgs/JointTrajectory    "{joint_names: \
        ['linear_arm_actuator_joint',  'shoulder_pan_joint', 'shoulder_lift_joint', 'elbow_joint', 'wrist_1_joint', 'wrist_2_joint', 'wrist_3_joint'], \
     points: [ \
{time_from_start: {secs: 5}, \
        positions: [0.0, 3.14,  -1.570,  2.14, 3.27, -1.51, 0.0]}, \
]}" -1

rqt GUI

To control an arm from a GUI, run:

rqt robot_description:=/ariac/arm1/robot_description

Open a joint controller plugin with Plugins -> Robot Tools -> Joint trajectory controller. Select /ariac/arm1/controller_manager and the arm controller. You should be able to adjust the arm by modifying the joint values.

Be aware that enabling the joint trajectory controller in rqt can conflict with other joint trajectories that the arm might be receiving from, for example, the command-line. Disable the controller in rqt if you wish to send trajectories from the command-line.

Repeat the procedure replacing arm1 with arm2 to control the second arm.

MoveIt

See the ARIAC 2019 MoveIt tutorial.

Visualization in RViz

TF frames

GEAR publishes various TF frames of various poses in the world. These frames may be useful when developing the robot control algorithm.

To view them, use the provided rviz config

rosrun rviz rviz -d `catkin_find osrf_gear --share --first-only`/rviz/ariac.rviz

Note that GEAR uses tf2_msgs and not the deprecated tf_msgs. Accordingly, you should use the tf2 package instead of tf.

Robot Model

Using the RobotModel display, one arm at a time can be visualized in rviz. It requires remapping the tf topics and robot_description parameter.

Arm 1

rosrun rviz rviz /tf:=/ariac/arm1/tf /tf_static:=/ariac/arm1/tf_static robot_description:=/ariac/arm1/robot_description

Arm 2

rosrun rviz rviz /tf:=/ariac/arm2/tf /tf_static:=/ariac/arm2/tf_static robot_description:=/ariac/arm2/robot_description

Troubleshooting Interfaces

There are a few interfaces that will not be available during the competition but can be useful during development. These interfaces will not be available during the competition.

Controlling the Conveyor belt

The service /ariac/conveyor/control can be used to modify the power of the conveyor belt or stop it. The power can be 0 or a value in the range of 50 to 100, with 100 representing full speed.

You can start the conveyor belt with

rosservice call /ariac/conveyor/control "power: 100"

Viewing Tray Contents

The /ariac/trays topic can be used during development for seeing the pose of products in the shipping boxes in the same frame as that which will be used for shipment evaluation.

$ rostopic echo /ariac/trays 
tray: "agv1::kit_tray_1::kit_tray_1::tray"
objects: []
---
tray: "agv2::kit_tray_2::kit_tray_2::tray"
objects: []
---

Submitting Trays without delivery

The /ariac/submit_tray service can be used during development for submitting kits for evaluation without them being ready for delivery.

$ rosservice call /ariac/submit_tray "tray_id: 'agv1::kit_tray_1::kit_tray_1::tray'
kit_type: 'order_0_shipment_0'"
success: True
inspection_result: 0.0

Querying Locations of Products

To determine where in the workcell products may be found, you can use the osrf_gear/GetMaterialLocations service. The bins where products are found will change between trials.

An example service call and response is:

$ rosservice call /ariac/material_locations "material_type: piston_rod_part"
storage_units: 
  - 
    unit_id: "bin2"
  - 
    unit_id: "belt"

which suggests that products of type piston_rod_part may be found in bin2 or on the conveyor belt. The TF frame bin2_frame can be used to know the location of bin2 with respect to the origin of the "world":

$ rosrun tf tf_echo /world /bin2_frame
At time 0.000
- Translation: [-0.300, -1.150, 0.720]
- Rotation: in Quaternion [0.000, 0.000, 1.000, 0.000]
            in RPY (radian) [0.000, -0.000, 3.142]
            in RPY (degree) [0.000, -0.000, 180.000]

Wiki

ariac / 2019 / tutorials / gear_interface