How to design a gripper for any robot

Why create your own robot gripper design?

You may want to design your own gripper if you have specific needs that commercial models are not meeting. 

Here's why customization can be a great option for you: 

• Handle unique parts or products. If you manufacture irregularly shaped items, you'll need a gripper that fits them perfectly. Custom design allows grippers to match your parts exactly the way you need them. 
• Optimize for your application. Commercial grippers are general-purpose end-effectors. But, for specialized tasks like delicate electronics assembly, designing your own gripper opens up customization options that will get you optimal performance.
• Add more advanced features. Want advanced sensing to detect slippage? Force and touch feedback? Programming custom grippers lets you integrate capabilities like these – and way more. 
• You’ll save money. Commercial robotic grippers are expensive, often thousands, and potentially hundreds of thousands of dollars. Designing your own using 3D printing and off-the-shelf components can significantly cut these costs. 
• Make rapid design iterations. Having an in-house gripper design capability allows for much faster prototyping and incremental improvements.
• Learn useful skills. Gripper design teaches valuable mechatronics, 3D modeling, and programming skills that you and your team can apply to future projects. Also, it doesn’t hurt to mention that you can later commercialize your bespoke gripper design, if that’s an avenue you want to consider. 

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How to choose your method of actuation

The method you use to power and control the movement of the gripper fingers is called the "actuation method". This is a necessary design choice that depends on your application.

Here are the types of actuation you’ll need to consider: 

• Electric actuation: This is by far the most popular choice, with precise control through motors and servos. What’s it good for? Tasks that require accuracy or gentle handling, but its complexity can lead to larger, more cumbersome gripper sizes.
• Pneumatic actuation: Known for its rapid action and mega-strong grip force, these grippers are suitable for tasks where speed is necessary. However, their need for compressed air and less gentle handling make them less suitable for delicate tasks.
• Hydraulic grippers: The go-to option for heavy-duty tasks, using compressed fluid for immense power. While they can be very strong, they tend to lack the speed and finesse of their electric and pneumatic cousins. 

When choosing the right gripper, pay attention to the balance between the actuation power and the task. 

For example, painting requires far less arm strength but a steady grip, whereas heavy lifting demands a robust robotic arm and gripper that made huge gains in the gym.

Also make a note to mind the grip force, speed, precision, and duty cycles. Other things to factor in are the power supply, control complexity, and maintenance. This makes electric or pneumatic actuators common starter choices.

For light duty precision tasks, electric servo motors usually work well. For higher grip forces, pneumatics are a good option. Electromagnets can grip without contact for delicate tasks.

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Choosing your gripping method

When designing a robotic gripper, you'll need to decide on the gripping method that matches your chosen application to a tee.  

Here are some of the most common options: 

• Mechanical grippers use jaws, fingers, or other mechanical means to grab objects. Some of the examples you’ll see most regularly include two-finger parallel jaw grippers, three-finger angular grippers, and concentric grippers. Mechanical grippers have high grip forces and precision.
• Vacuum grippers use suction cups or vacuum pads to grip smooth, non-porous objects like glass and metal sheets. They shine when handling fragile, delicate objects, but vacuum generators or pumps are required.
• Magnetic grippers use electromagnetic fields (sounds futuristic!) to grip and handle ferromagnetic materials like steel, so no contact is necessary. This makes them a great fit for handling hot, sharp, or hazardous items.
• Adhesive grippers use tape, glue, or sticky polymers to grip objects, which means they can handle a wide variety of shapes and materials. But yes, you must clean them up after each use. 
• Impactive grippers smash, staple, or pierce objects to achieve a death grip. Therefore,  they’re used for irregular shapes when damage is not an issue. 

Material and payload

Something else that you should always consider is the material of the jaws.

For instance, rugged materials work well for industrial tasks, but for delicate operations, such as handling electronics, softer materials like rubber are essential to prevent damage.

Also never forget this: The robot arm's payload should include the weight of the gripper. Something else to keep in mind is the maximum and minimum grip force - a gripper for heavy lifting might not be suitable for delicate tasks like picking fruit. 

For these scenarios that require a more careful approach, a "compliant gripper" designed for specific objects or force requirements is ideal. 

These are perfect for delicate or niche applications where standard grippers might just not cut it. 

Demystifying gripping methods further

We’ve already established that at the heart of a gripper are fingers (or jaws) designed in various layouts to suit different tasks. 

Let’s take a more detailed look at these: 

• Angular layout: Similar to pliers, great fit for gripping with a pinching motion.
• Concentric layout: The jaws form a hand-like arc, which provides a more natural grip.
• Parallel layout: Resembling a wrench, these jaws align in a parallel way and are perfect for uniform gripping.

Among the various types, "Impactive" grippers dominate the market because of their versatility and breadth of uses. 

Still, other specialized types include:

• Ingressive grippers: Penetrating the object, akin to a needle through fabric, a tailor-made match for textile handling.
• Astrictive grippers: Use suction or magnetic forces, perfect for handling smooth or ferrous materials.
• Contigutive grippers: Use adhesion methods like glue or freezing (yes, freezing), a unique approach for delicate or tricky surfaces.

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How to configure your gripper fingers and layout

When getting into robot gripper design, you'll need to decide on the number of fingers, their arrangement, and the type of motion they'll use.

• Go with 2 or 3 fingers for simplicity, or 4+ for more general-purpose dexterity. Just remember that more fingers means more complexity.
• Look at parallel, angular, and concentric arrangements. Parallel is the easiest but concentric can adjust better to oddly shaped objects. Angled fingers help guide objects into the grip.
• What’s the motion style? Will fingers move independently or together? Scissor-like opposing motion is common but sometimes synchronous motion (when all fingers move together) works better.
• Do your research on anthropomorphic designs that mimic the human hand. These tend to be quite complex but can allow many more ways of grabbing objects. 

Also make a note to optimize the shape, material and padding on the "fingertips". Rubberized pads can conform to objects and cushion force, while grooved surfaces may help grip round or smooth objects.

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Test your gripper for optimum performance

Robot gripper design is no joke, and grippers can get complex really fast. If you don’t test comprehensively, you run the risk of botching your application or causing accidents. 

Here’s how you can get started with basic functional tests:

• Does your robot gripper design open and close smoothly across the full range you need? Keep an eye out for binding, uneven motion, or weak areas.
• How repeatable is the motion when you cycle the fingers? Check for variability in all grasping positions.
• Are the finger placements accurate? Improper alignment can cause objects to slip or fingers to collide – and we don’t want that.
• How fast is your gripper’s operational speed? You want to optimize this for productivity, but also keep accuracy as high as possible. 

Then move on to performance metrics:

• Measure the maximum gripping force at various points along the fingers.
• Test grip force control, if equipped. Make sure it modulates grip strength precisely.
• Check slip resistance with sample materials! Friction, soft pads, or textured fingers will prevent slippage, and thus accidents or material breakage (costly!) 
• Test weight capacity and durability by continuous loading, having your gripper lift progressively heavier items. Yes, apparently robots need progressive overload too. 
• Assess precision over time. Does performance drift during operations? 

Iterate your robot gripper design based on real-world testing while paying special attention to potential failure points. 

Test, re-test, refine, and re-test as needed until your gripper achieves reliable, optimum performance for the task at hand. 

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Summing up

This guide can help you get started with custom robot gripper design, but now it’s up to you to put in the legwork; you’re going to have to prototype, iterate, and test thoroughly. 

And if it still seems too daunting, hey, don't be afraid to buy an off-the-shelf electric gripper that gets the job done! Not everyone has to be a design genius to bring the benefits of automation to their business. 

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Next steps

If you’re looking to find the perfect pairing of robot arm and end-effector for any application, RO1 by Standard Bots comes with a variety of grippers out of the box, universal M8 connectors, integration with OnRobot end-effectors and is the best choice for machine shops large and small:

• Cost-effective: RO1 is the most affordable robotic arm in its class, starting at almost half the price of incumbent competitors, and lease models starting at $5/Hr. 
• All-seeing: RO1 is equipped with best-in-class vision systems. Easy no-code programming makes it easy to detect the smallest of defects and imperfections.
• Collaborative: RO1 comes equipped with safety sensors and built-in collision detection, for safe operation anywhere on your shop floor.

Talk to our solutions team right now to set up a free, 30-day onsite trial and get expert advice on everything you need to deploy your first robot.