Ubuntu Linux for Robotics · Lesson 96 of 96

Building full manipulator robots

Project: an arm with ros2_control, MoveIt 2 and a safe deployment on Ubuntu.

Estimated time · 120–180 min

Learning goals

What you will understand

Explain building full manipulator robots in your own words
Use it in a small workstation example
Verify the result instead of assuming it worked

Understand the idea first

The mental model

A manipulator stack on Ubuntu has a URDF with limits and inertia, a ros2_control hardware interface (a mock first), joint_state_broadcaster and a joint_trajectory_controller, and MoveIt 2 for motion planning. It runs as several services: the hardware and controllers in a real-time-friendly process, MoveIt and perception as separate ones.

Bring it up in stages: model in RViz2, mock hardware with controllers, planning in MoveIt, then real hardware with velocity scaling at 10–20% and an emergency stop within reach. Log every trajectory, and verify joint limits and collisions in simulation before executing on the arm.

Guided lesson

Work through these steps

1.
Open a terminal and record the current state before changing anything.
2.
Read the building full manipulator robots commands and predict what each one does.
3.
Run the commands one at a time and compare each output with your prediction.
4.
Write the commands that worked in a setup note you can repeat later.

Worked example

Read it before you run it

ros2 launch arm_bringup arm.launch.py use_mock:=true
# Start the arm with mock hardware.
ros2 control list_controllers
# Check that the controllers are active.
ros2 launch arm_moveit_config move_group.launch.py
# Start MoveIt 2 planning.
ros2 action list | grep -E 'move_action|follow_joint_trajectory'
# Confirm the planning and execution actions exist.
ros2 param set /move_group robot_description_planning.joint_limits.shoulder.max_velocity 0.3
# Reduce a joint's speed limit for the first hardware test.

What the example is doing

1.Lines without sudo only inspect or change files you own; sudo authorizes a system-wide change.
2.Read command output before moving to the next line. Stop if names, versions, disks, or paths differ from the lesson.
3.Comments beginning with # explain safety checks and are not executed by the shell.

Watch it run · Robot arm

See what this code does

The terminal types this lesson's practice solution and runs it. The scene shows the kind of robot behaviour that code drives. It plays by itself and loops.

Practice code

Now type it yourself

Open a terminal, run the starter line by line (or save it as practice.sh and run bash practice.sh), and replace every TODO with your own command.

# TODO: list the active controllers of the controller manager

Expected output

arm_controller and joint_state_broadcaster are active

Stuck? Show the full solution (try it yourself first)

ros2 control list_controllers

Expected result

How you know it worked

Each command completes without an unexplained error.
Your notes contain the command, the important output, and what it proves.

Practical exercise

Apply the lesson

Build a 3-joint arm with mock hardware and MoveIt, plan around a box, execute at 20% speed, and write down the checks you would run before connecting real motors.

Before you continue

You recorded the starting state
Every command and output is understood
The change can be repeated from your notes

If something goes wrong

A command says permission denied.

Check ownership and permissions first. Do not add sudo unless the command changes a documented system location.

A command or package is not found.

Check spelling, Ubuntu version, enabled repositories, and whether the previous installation command succeeded.