Part 2 — Industrial Robots: How They Are Programmed & Controlled

 In Part 1 of this series, we got introduced to the big picture — Industrial Robotics, PLCs, and SCADA working together as the backbone of modern manufacturing. In this part, we zoom into one of the most exciting pieces of that puzzle: Industrial Robots — specifically, how they are programmed and controlled.

Most people imagine robots as science fiction — humanoid machines with glowing eyes. The reality on a factory floor is far more interesting. These robots are precision-engineered arms, guided by carefully written programs, capable of performing tasks that human hands simply cannot match in terms of speed, accuracy, and endurance.

"A robot is not just a machine — it is a machine that has been taught. And the quality of what it does depends entirely on the quality of how it was taught."

Anatomy of an Industrial Robot

Before understanding how a robot is programmed, it helps to know what it is made of. An industrial robot typically consists of the following key components:

Manipulator (Arm)

The mechanical structure with joints and links that physically moves and performs tasks.

End Effector

The "hand" of the robot — a gripper, welding torch, spray gun, or suction cup depending on the task.

Controller

The computer unit that processes the program and sends motion commands to each joint.

Teach Pendant

A handheld device used by engineers to manually guide and program the robot's movements.

Sensors

Vision systems, force sensors, and encoders that give the robot awareness of its environment.

Drive System

Electric servo motors (most common), hydraulic, or pneumatic actuators that power each joint.

Degrees of Freedom (DOF)

One of the most fundamental concepts in robotics is Degrees of Freedom (DOF) — the number of independent movements a robot can make. A human arm has about 7 DOF. Most industrial robots have 6 DOF, which allows them to position their end effector at any point in 3D space with any orientation — just like a human arm and wrist combined.

Each DOF corresponds to one joint in the robot. More DOF means more flexibility — but also more complexity in programming and control.

How are Industrial Robots Programmed?

Robot programming is the process of defining what the robot should do, where it should move, and how it should interact with its environment. There are several methods used in industry:

1

Online Programming (Teach & Playback): The engineer physically guides the robot to each position using a teach pendant, saving each point. The robot then replays these recorded positions in sequence. This is the most common method on the shop floor — simple, fast, and practical.

2

Offline Programming (OLP): The robot is programmed virtually using 3D simulation software — without stopping the actual production line. Programs are created in a digital twin environment and then uploaded to the real robot. Tools like KUKA.Sim, RobotStudio (ABB), and ROBOGUIDE (FANUC) are widely used.

3

Manual Programming (Textual): Writing code directly in the robot's proprietary language. Every major robot manufacturer has its own language — RAPID (ABB), KRL (KUKA), Karel (FANUC), and Inform (Yaskawa). These resemble structured programming languages with motion commands, I/O handling, and conditional logic.

4

Lead-Through Programming: The engineer physically grabs and moves the robot arm by hand (used mostly with cobots), and the robot records the path. This is intuitive and requires no coding knowledge.

Robot Programming Languages — A Quick Look

Each robot manufacturer uses its own proprietary programming language, though the logic behind all of them is similar. Here's a quick overview:

RAPID — ABB

High-level structured language. Supports modular programming, interrupts & multitasking.

KRL — KUKA

KUKA Robot Language. C-like syntax, widely taught in engineering courses.

Karel — FANUC

Pascal-based language. Used for complex logic beyond simple motion commands.

Inform — Yaskawa

Job-based programming language, simple and well-suited for welding applications.

While each language is different in syntax, the core concepts remain the same — defining positions, controlling motion speed, handling I/O signals, and managing program flow with conditions and loops.

How is a Robot Controlled?

Robot control happens at multiple levels simultaneously. At the lowest level, servo controllers drive individual joint motors with precision using feedback from encoders. At the mid level, the motion controller coordinates all joints to achieve smooth, synchronized movement along a defined path. At the highest level, the robot controller interprets the program logic and manages communication with external systems like PLCs and sensors.

Two key types of motion control are used:

Point-to-Point (PTP)

Robot moves from one position to another without a defined path in between. Fast and efficient for pick-and-place tasks.

Continuous Path (CP)

Robot follows a precise, predefined path continuously. Essential for welding, cutting, and painting applications.

Safety in Robot Programming

Safety is not an afterthought in industrial robotics — it is built into every layer of the system. Programmed safety zones (also called virtual fences) prevent the robot from moving into areas where humans might be present. Hardware safety devices like emergency stop buttons, light curtains, and safety PLCs add further layers of protection. Modern cobots use force-torque sensors to detect unexpected contact and immediately stop motion.

The ISO 10218 standard governs the safety requirements for industrial robots, covering everything from design and installation to programming and maintenance.

What should EE students focus on?

As electrical engineering students, the most valuable skills to develop in this domain are understanding servo drive systems and motor control, learning at least one robot programming environment (KUKA or ABB simulators are freely available), understanding how robots interface with PLCs through digital I/O and fieldbus protocols, and getting familiar with safety standards and interlocking systems.

Servo Motor ControlKRL / RAPID basicsRobot-PLC interfacingSafety InterlocksOffline Programming ToolsFieldbus Protocols