Why Robot Hands Won’t Take Over the Warehouse Anytime Soon

Vacuum grippers are unbeatable

Will robot hands take over the warehouse? Of course not! Vacuum grippers are faster, thinner, lighter, simpler, more rugged, and cheaper than any robot hand on the drawing board. 

Comparing vacuum grippers with hands

Investors are spending billions of dollars to develop humanoid robots, including anthropomorphic robot hands. Believers say the robot hands will do everything human hands can do. But this is an ambitious goal. For example, the number one wear point will be the fingertip skin, with thousands of embedded touch sensors. In human hands this problem is managed by constant self-repair, renewing the skin as it wears, from the inside. Will the robots be repairing themselves from the inside? Doubtful.

Another thing. Scientists and roboticists are still trying to catalog the vast number of human hand behaviors. As an example, in a recent blog post (The Inner Robot) I discussed the ulnar grasp, which is quite common, and yet had escaped notice. Scientists have been producing grasp taxonomies for well over fifty years, but missed the ulnar grasp, and many other behaviors. How much longer will it take, for us to achieve a thorough understanding of human manipulative behaviors? The limitations of our knowledge are well-known in the robotics research community. There are regular discussions of the need for metrics and benchmarks. Some have been offered, but nobody would claim to have captured or delineated the limits of human manipulation skills. Keep that in mind when you watch the dazzling online videos. As impressive as they are, we still have a long way to go — longer than anyone can say.

In short, reproducing the capabilities of the human hand is a grand research project, to be supported and celebrated. But it is still a research project, and nobody knows when it might lead to practical robotic hands.

Nonetheless, let’s just concede the point and move on to the next question. Let’s suppose that robot hands are available, and as good as human hands. Would they replace vacuum grippers in the warehouse?

No. The comparison is quite easy. If the robot designs copy the human hand, they will have:

• Five fingers,
• Three joints per finger for a total of 15, 
• Four expensive servomotors per finger for a total of 20,
• An additional joint and motor in the palm,
• Tens of thousands of tactile sensors.

A typical vacuum gripper has

• One “finger,”
• No joints,
• One or two motors, typically off board,
• One pressure sensor.

As a result, the vacuum gripper will be simpler, lighter, more rugged, less bulky, faster, and less expensive. These differences are not minor. In some respects, the vacuum gripper wins by an order of magnitude. Even if some researchers dialed back their ambitions and simplified their designs, they could not match the elegant simplicity of a vacuum gripper.

Vacuum grippers also have a dramatic performance advantage in logistics: they can grip an object with only one contact point. Imagine a card lying flat on the bottom of a cardboard box, in the corner. A hand, whether human or robotic, could fiddle around for quite a while, trying to get two fingers on opposite sides of the card. The vacuum gripper only needs to touch it, and it has it. Or suppose you are taking the first box from a densely packed case. The vacuum gripper can touch any box in the top layer, and it has it. The hand will need to force fingers into the gaps, without damaging the product. That takes time, in the best case.

Vacuum grippers are ideal for the warehouse. 

No seal required

We need to address one common misunderstanding. Some say that vacuum grippers need a good seal. That is true for some grippers, but not all. Berkshire Grey’s grippers do not need a seal. We pick across open seams, we pick porous objects, we even pick loofahs and bath sponges. In terms of SKU coverage, Berkshire Grey leads all competitors.

No seal required! A BG SpectrumGripper picking a variety of hard to handle SKUs.

Vacuum grippers are the wheels of manipulation

There is an interesting parallel between vacuum grippers and wheels. For centuries, humanity has been using wheels to do the job of legs: supporting and transporting stuff. But now, there is an intense effort to develop robot legs. They are making excellent progress. 

Will legs replace wheels? In some specific areas, they might. There are already a few legged humanoids deployed in warehouses. But will legs replace wheels broadly? No chance. Wheels are one of the most celebrated inventions of humanity, and for good reason. They are simple, light, rugged, and inexpensive, like vacuum grippers. They require a minimum of motors and sensors, like vacuum grippers. The case for wheels is remarkably similar to the case for vacuum grippers. 

Wheels will be with us forever. So will vacuum grippers.

Matthew T. Mason is the Chief Scientist at Berkshire Grey, and Professor Emeritus at Carnegie Mellon. He blogs at mtmason.com.