Robot Arm

The most common manufacturing robot is the robotic arm. A typical robotic arm is made up of seven metal segments, joined by six joints. The computer controls the robot by rotating individual step motors connected to each joint (some larger arms use hydraulics or pneumatics). Unlike ordinary motors, step motors move in exact increments (check out Anaheim Automation to find out how). This allows the computer to move the arm very precisely, repeating exactly the same movement over and over again. The robot uses motion sensors to make sure it moves just the right amount.


An industrial robot with six joints closely resembles a human arm – it has the equivalent of a shoulder, an elbow and a wrist. Typically, the shoulder is mounted to a stationary base structure rather than to a movable body. This type of robot has six degrees of freedom, meaning it can pivot in six different ways. A human arm, by comparison, has seven degrees of freedom.

Your arm’s job is to move your hand from place to place. Similarly, the robotic arm’s job is to move an end effector from place to place. You can outfit robotic arms with all sorts of end effectors, which are suited to a particular application. One common end effector is a simplified version of the hand, which can grasp and carry different objects. Robotic hands often have built-in pressure sensors that tell the computer how hard the robot is gripping a particular object. This keeps the robot from dropping or breaking whatever it’s carrying. Other end effectors include blowtorches, drills and spray painters.

Industrial robots are designed to do exactly the same thing, in a controlled environment, over and over again. For example, a robot might twist the caps onto peanut butter jars coming down an assembly line. To teach a robot how to do its job, the programmer guides the arm through the motions using a handheld controller. The robot stores the exact sequence of movements in its memory, and does it again and again every time a new unit comes down the assembly line.

Most industrial robots work in auto assembly lines, putting cars together. Robots can do a lot of this work more efficiently than human beings because they are so precise. They always drill in the exact same place, and they always tighten bolts with the same amount of force, no matter how many hours they’ve been working. Manufacturing robots are also very important in the computer industry. It takes an incredibly precise hand to put together a tiny microchip.

Preparing For This Tutorial:

  • The LEGO Mindstorm EV3 Core set. The robot that coincides with this tutorial comes from building specific sections found in LEGO® MINDSTORMS® Education EV3 Software.

  • Information about color sensor and quiz form Sumo_robot lesson.

Setting up in 12 easy steps

  1. Obtain a suitable microSD memory card.

  2. Download the latest Linux Debian Stretch ev3dev image.

  3. Download and install Etcher, a free utility that will allow you to flash the ev3dev image to the microSD card.

  4. Use Etcher to flash the image to the card.

  5. Insert the card into the EV3, boot the EV3, do some minor configuring and establishing a connection to the computer via USB, WiFi, Bluetooth or Ethernet.

  6. Download and install Microsoft Visual Studio Code (VS Code). This is a free multi platform code editor, compatible with Windows, Mac OS and Linux.

  7. Write and run some non-EV3 Python scripts.

  8. Download and unzip the starter project.

  9. Open VS Code, open the starter project folder and install two extensions.

  10. Configure VS Code.

  11. Connect VS Code to your EV3.

  12. Write and run your first EV3 Python script!

Video tutorial link:

Link step by step:

Time constraints:

  • starting from 90 min - double lesson


NASA uses robotic arms to accomplish tasks that are potentially too dangerous, too difficult or simply impossible for astronauts to do. The robotic arm on the International Space Station can capture approaching cargo ships for docking or be used to assist astronauts on spacewalks. The Mars rovers Spirit, Opportunity and Curiosity were each designed with robotic arms that would help scientists on Earth conduct scientific experiments on Mars. While all of these arms look different, they are similar in that each robotic arm was designed to help it accomplish a given task.

In a martian environment, it won’t be feasible for the colonists to do everything outside in their space suits. Martian dust is toxic and much finer compared to what one would find on Earth. Therefore it is best to do as many things as possible with remote controlled drones and robots. One tool that would be very useful in such a case is a robot arm.

Can you write a program for a robot arm that can:

  1. Make the arm be able to turn clockwise and counter-clockwise.

  2. Make the arm be able to lift up and down.

  3. Make the arm be able to pick up and drop things.


  1. Place three objects in front of the arm.

  2. Pick up the first object with the arm and drop it 180 degrees counter-clockwise away from its original position.

  3. Pick up the second object with the arm and place it 90 degrees away from its original position.

  4. Pick up the third object with the arm and stack it on the second object.

Short help on programming

Commands/functions needed for the exercises:

Attach and the motors responsible for moving the robot

#!/usr/bin/env python3

LeftMotor = LargeMotor('outD')

LeftMotor.run_forever(speed_sp = 900)


#Attach the medium motor to port B

Grabber = MediumMotor('outB')

#Get the button reader

Buttons = Button()

#if the center or middle button is pressed

if Buttons.enter == True:

Next Section - Sumo robot