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Building the Low Level API Example

The following instructions assume a Linux system (or the Windows Subsystem for Linux).

  1. Extract the source code from the archive linked at the top of the page

  2. Open a terminal in the folder created from the archive (lowlevelapi)

  3. Build the example by typing the command make in the terminal

  4. Run the example by typing ./lowlevelapi_example (You may need to first set execute permissions by typing chmod +x lowlevelapi_example)

  5. If the example is running properly, you should see the following in the terminal:

Sending commands to 127.0.0.1 on port 25500
Listening for data from 0.0.0.0 on port 25501

Running the Example in Simulation

  1. Run the simulator with both the lowlevelapi_example.toml and lowlevelapi_example_teststand.toml configuration files applied. Use the following command inside of the main folder ./ar-control-2021.02.11 'simulator.dynamic = true' ./lowlevelapi/examples/lowlevelapi_example.toml ./lowlevelapi/examples/lowlevelapi_example_teststand.toml The simulator should display the following message in the terminal:
Agility Robotics Control Stack
Listening for low-level action data at port 25500
JSON message API server started, connect to http://localhost:8080/

  1. Open a web browser and navigate to http://localhost:8080/gamepad

  2. You should see the robot fixed upright in place with its limbs relaxed

  3. Run the Low-level API example code as described in the previous section

  4. The terminal running the simulator should display the message Publishing low-level observation data to 127.0.0.1:25501

  5. Using the message-composer in another window, send an action-set-operation-mode to set the operation mode to low-level-api. ["action-set-operation-mode", {"mode": "low-level-api"}]

  6. The robot in the visualization should move into the pose shown below

Running the Example in Hardware

  1. Connect ethernet cable to Digit and computer
  2. Apply the lowlevelapi_example.toml configuration file to Digit by going to http://10.10.1.1/configuration/ and uploading the file
    • Due to bug in the configuration browser, the file must be uploaded via ssh (see ssh page for more details)TODO: add ssh page link
    • Robot must be rebooted to apply changes
  3. Modify the publisher_adress variable in lowlevelapi_example.c so it matches the following: const char* publisher_address = "10.10.1.1";
  4. Rebuild the example program
  5. Turn on the robot
  6. When the robot has finished booting and you can view the visualization on the gamepad, release the e-STOP to enable motor torques
    • If you wish to use the simple terminal instead of gamepad go to: http://10.10.1.1:8080/examples/terminal.html
  7. Run the lowlevelapi_example code
  8. Set command priveleged by sending the following mesage in the mesage composer: ["request-privilege", {"privilege": "change-action-command"}] in the simple terminal
  9. Using the message-composer, send an action-set-operation-mode to set the operation mode to low-level-api. ["action-set-operation-mode", {"mode": "low-level-api"}]
  10. The robot should move into the same pose as in simulation
Tags: tutorials digit example lowlevel api