Sep. 01, 2025
There are various types of robot joints. It’s helpful to learn about these different joints so you can better understand the workings of the robots you are using.
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Each joint type will affect the range of motion and capabilities of your robot.
The challenge for newer robot users is that there are different ways to categorize robot joints. This can make them confusing.
A basic understanding of the types of joints can really help you get the most from your robots. In this article, we explore the various ways you can look at robot joint types.
Like many people, you might just look at a robot and see it as a single machine. The robot operates as a single unit. However, you can also “zoom in” on the robot and look at its component parts.
All industrial robots are basically just a chain or collections of “joints.” Robot joints are mechanisms that create motion in one or more of the robot’s axes. Together, the robot’s joints create the desired motions of a robot’s limbs.
It’s helpful to know about robot joint types so you can understand which robots will be most suitable for your needs.
There are 3 basic ways you can categorize robot joints:
Each of these offers a useful perspective as to what makes a particular robot joint work. We’ll look at each of them in turn below.
The first way to categorize robot joints is by their actuation type. An actuator refers to any mechanical or electromechanical device that creates motion. The actuator generates a force using a particular type of energy.
Here are the 3 basic types of robot actuators:
An electric actuator converts electrical energy into motion with an electric motor. This creates a torque that moves the robot joint.
Electric actuators are probably the most common actuator type in robotics. They are fast, precise, and very portable. Although they are not as powerful as the other 2 types of actuator, they offer a good cost-to-strength ratio.
A pneumatic actuator creates force through the application of compressed air. As many manufacturing facilities already have pneumatic lines installed, this can be a handy option and is often used for robot tools.
Benefits of pneumatics include its fast speed and simplicity. However, it offers limited power compared to hydraulics and requires a lot more extra hardware (pumps and pipes) compared to electric systems.
A hydraulic actuator uses pressurized liquid to create motion. They offer more strength than the alternatives, which is why hydraulics are often used for heavy-duty applications.
Hydraulic robots are often the strongest with a high range of mobility. However, they are expensive, require high maintenance, and can be very messy if the liquid leaks.
Another way to look at robot joints is to classify them by how they move. This is determined by their kinematic design. Each joint will have one or more degrees of freedom which are arranged differently depending on the joint type.
Here are the 3 most common joint types by kinematic design:
A linear or prismatic joint can move in a translational or sliding movement along a single axis.
It is probably the simplest type of joint to imagine and is the easiest to control. Actuating the joint makes it longer or shorter.
A revolute or rotational joint moves around a point about one degree of freedom. You can think of a revolute joint as being like the elbow joint in your arm — it can bend only in one direction.
Most industrial robots comprise a series of revolute or rotational joints. As a result, there are well-established control strategies for revolute joints.
A spherical joint can move in multiple degrees of freedom around a single point. You can think of a spherical joint as being like the top shoulder joint of your arm — it can move in multiple directions but around the same point.
Spherical joint control can get quite complex. Sometimes, it’s easier to describe the spherical joint as being 3 revolute joints with an axis that intersects at a common point.
The last way to look at robot joints is often the most useful for industrial robotics. Here, we look at the robot joint by its function or role in an industrial manipulator.
The 3 functions of an industrial manipulator joint are:
The shoulder joint sits at the base of a robotic manipulator.
It is often the biggest joint and determines how much the robot can turn around. It has the most significant effect on the size of the robot’s workspace.
The elbow joint sits in the middle of the robotic manipulator.
It has the most impact on the robot’s lifting strength and sets a large proportion of the robot’s range of motion. If the elbow joint is restricted, the robot’s workspace will also be restricted.
The wrist joint sits at the end of the robotic manipulator.
It has the most effect on the position of the robot’s end effector. Often, wrist joints can spin a full 360 degrees. It is also subjected to more vibrations caused by the environment than other joints.
Now that you know the basics of robot joints, you can understand a little more about how robots are designed.
However, unless you are building your own robots, you probably don’t need to know much more. It’s most useful when you know the type of robot that you will use and how you can apply them to your particular application.
With the right robot programming tool, the software handles most of the complexity.
Robotic arm mechanisms are everywhere, from factory floors and surgical suites to research labs and theme parks.
Robotic arms work by performing complex, repetitive, or high‑precision tasks with consistent accuracy. Whether you’re buying, designing, or programming one, it’s important to understand the components, motion systems, and control methods that power them.
A robotic arm mechanism is a mechanical device built to mimic the movements of a human arm, only faster, stronger, and far more precise. Made up of segments connected by joints, it moves in multiple directions and can be programmed for anything from simple pick‑and‑place work to delicate surgical procedures.
It combines mechanical, electrical, and software systems to bring that motion to life, whether you need high speed, heavy payload capacity, or surgical‑level precision for complex, repeatable tasks.
The core components of a robotic arm mechanism include the base, joints, links, wrist mechanism, and end effector.
Let’s break down the main parts of the mechanism.
The base anchors the arm and often contains motors for rotating the entire unit. In factory setups, the base may be bolted to a floor, pedestal, or track system to enable mobility. The stability and torque handling of the base directly affect how precisely the rest of the arm can operate.
Joints define how the arm bends or slides. Most arms use rotational joints (revolute), allowing movement like a shoulder or elbow. Others may include prismatic joints that enable linear extension. Complex arms often combine multiple joint types to increase dexterity.
These are the rigid “bones” of the arm, connecting joints. Manufacturers typically make them from materials like aluminum or steel, but lighter alternatives like carbon fiber are growing in use to reduce inertia and improve speed.
For example, this carbon fiber robot arm offers a lighter frame without compromising strength.
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Positioned near the end of the arm, the robot wrist mechanism adds fine rotational control, often enabling three degrees of freedom (pitch, yaw, and roll). This is vital for tasks requiring precise orientation, such as screwdriving, inspection, or tool alignment.
This is where the arm interacts with the world by gripping, welding, painting, or assembling. There are many types of robotic arm grippers, from simple parallel jaws to suction cups, magnetic pads, or adaptive designs for irregular objects.
Movement and kinematics determine how a robotic arm translates joint rotations into precise end effector positioning.
A robotic arm follows a precisely calculated path defined by the system’s structure and math. This coordination of joints and links is governed by kinematics, the foundation of all robotic motion.
The first thing to understand is degrees of freedom (DoF), which is a way of measuring how many independent motions an arm can make. A basic 3-axis robot arm offers three directional movements and is well-suited for simple, repetitive actions like stacking or sorting items along a fixed path.
But when a task demands more flexibility, more axes are needed. A 7-axis robot arm, for example, behaves more like a human limb. It can bend, rotate, and reach around obstacles without having to reposition the base. This makes it ideal for workspaces or tasks where tool orientation needs constant adjustment mid-process.
To make these motions possible, engineers use two types of kinematic models:
This math allows robotic arms to perform tasks like welding curved seams, inserting parts into tight assemblies, or following precise motion paths in real time.
The layout of joints also matters. In a jointed arm robot, movement is highly versatile, which is perfect for painting contoured surfaces, navigating awkward angles, or performing tasks with varying orientations. Combined with smart path planning, this setup defines the full range and smoothness of robotic arm movement.
The gripper or end effector is what turns a robotic arm into a working tool. It’s the part that physically handles objects, and the type of gripping mechanism you choose directly shapes the robot’s capabilities.
The most common option is the mechanical gripper mechanism, which uses jaws or fingers to grip an object. These are ideal for structured tasks involving consistent part sizes like bin picking or automated assembly. For softer or irregular items, adaptive grippers offer more flexibility by adjusting their grip using compliant materials or shape-conforming fingers.
Other common types include:
In high-mix production environments, versatility is key. This is where quick-change gripper systems make a difference. They let operators swap tools in seconds with no manual recalibration or coding changes. This saves a lot of time in packaging, inspection, or assembly lines.
Most modern arms are modular by design. A well-integrated robotic arm gripper mechanism can evolve with your production setup, supporting tool changes, new materials, or tighter tolerances over time. That’s why understanding how the gripper fits into the larger system is essential.
The gripper also plays a huge role in factory robot arm performance, where speed, uptime, and safe handling are non-negotiable.
At the heart of every robotic arm mechanism is its actuation system that drives joint movement. These motors determine how fast, how accurately, and how smoothly the arm operates. Selecting the right motor setup involves balancing torque, precision, speed, and cost.
The two main motor types are servos and steppers.
Servos give real‑time feedback for precise, adjustable motion in tasks like welding, surgery, and precision machining. Steppers move in fixed increments without feedback, offering lower precision but simpler, cheaper operation for predictable, repetitive jobs like pick‑and‑place or inspection.
In heavy-load or high-torque environments, the type of drive system also matters:
Actuation is about controlled movement. Motors work alongside encoders, force sensors, and control software to ensure that every motion is executed with the right force, direction, and timing. Whether it’s gripping a fragile object or applying consistent pressure in a weld, this coordination is what separates basic motion from reliable, repeatable performance.
For a robotic arm to move with consistent accuracy, it needs real-time awareness. That’s where sensors provide constant feedback about the arm’s position, force, and surroundings, allowing it to adjust its actions on the fly.
The control system processes sensor data in real time to adjust motor actions and decision-making. This closed-loop system ensures that the robot doesn’t just follow a programmed path.
The performance of a robotic arm depends heavily on how it’s programmed. Behind every smooth, coordinated movement is a control system that translates instructions into precise motion.
Engineers now program and test many robotic arms in virtual environments. Simulation tools help map out motion paths, identify collisions, and optimize cycle times, reducing risk during deployment.
Here’s how robotic arms work across industries:
A robotic arm is a programmable machine built to move with precision and consistency, often outperforming human capability in speed, strength, and accuracy. It works by coordinating its structural parts, motion systems, and control software to carry out specific tasks.
Joints and links provide movement, motors drive that motion, and sensors feed real-time data, so the arm can adjust on the fly. Programming methods, whether through manual teaching or code, define how it responds to instructions and adapts to different tasks.
When designed for durability and maintained properly, a robotic arm can operate reliably for years, handling anything from heavy manufacturing work to delicate surgical procedures. Its adaptability means it can be re-tooled or re-programmed for new applications, making it a long-term investment for industries that depend on precision, efficiency, and repeatable results.
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Servo motors are better for high-precision tasks that require feedback and dynamic adjustment, like welding, inspection, or delicate assembly. Stepper motors are simpler and more cost-effective for fixed, predictable movements. Choose based on how much precision and responsiveness your application needs.
Safety standards that apply to industrial robotic arms are ISO -1 and ISO -2 standards for robotic safety. Additional certifications like CE, UL, or ANSI/RIA may apply depending on the region. These standards cover things like emergency stops, collaborative zones, and collision detection systems.
Yes, you can swap grippers on a robotic arm without redesigning the whole system. Many modern arms support quick-change gripper mechanisms, allowing you to switch tools without modifying the core structure. Just ensure compatibility with the arm’s flange type, payload limits, and control interface.
A SCARA robot arm typically handles payloads between 2 and 20 kilograms, depending on reach and motor configuration. Heavier-duty variants can go higher, but may sacrifice speed or precision.
Programming languages for robotic arm control may vary. ABB uses RAPID, KUKA uses KRL, and Universal Robots uses URScript. Many newer systems also support Python or C++ for easier integration with broader software platforms.
Kinematics matters for the accuracy of a robotic arm. It defines how joint movements translate to the position of the end effector. Accurate inverse kinematics ensures the arm reaches the right location every time. This is important in tasks like machining, surgery, or tight-tolerance assembly. Poor kinematic models lead to positional errors and inconsistent performance.
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