Hatched in the heart of California’s Silicon Valley, robotics start-up, Grabit is harnessing static electricity, machine learning and automation to assemble the uppers of Nike trainers at 20-times the pace of a human worker.
Material handling is one of the most labour-intensive and expensive aspects of manufacturing, and when dealing with an array of different materials, the process is almost impossible to automate.
Assembling a pair of Nike trainers can require up to 40 pieces of material to be stacked and heated to create the upper — the flexible part that sits on top of your foot.
For a human worker, arranging the pieces of material can take up to 20 minutes. Grabit’s technology, however, reportedly allows a machine to do this in less than one.
Despite its evocative name, Grabit’s material handling invention does not mimic the human grabbing motion present in many robots. Instead, the start-up harnesses static electricity — referred to as electroroadhesion — to handle materials.
The concept of electroroadhesion was discovered at non-profit organization, SRI International, by Grabit’s co-founder and chief technology and products officer, Dr Harsha Prahlad.
Electroroadhesion uses a flat pad of electrodes to generate positive and negative charges on the surface. When charged correctly, the electrodes create an electric field that adheres to nearly any surface, allowing the robot gripper to pick up the part that is being handled.
Upon identifying that materials handling was responsible for between 60 – 80% of labour in manufacturing, Prahlad decided that it should be the first application in which he applied the technology.
Following Grabit’s inception in 2013, global sportswear manufacturer Nike Inc. made an investment in the company and later became one of the first customers to buy its materials handling robot system, ‘Stackit’. Using Stackit, Nike can reportedly manufacture 600 pairs of shoes in just one eight-hour shift.
The new system would ultimately be able to assemble precise layers, such as those found in the Nike shoe upper, 20-times faster than a human being, with an expected payback period of around 24 months.
The creation of Stackit began in summer 2015, but before the manufacturing process could begin, the company needed to decide on the right robot to mount its innovative electroadhesive gripper on.
Having seen a Toshiba Machine robot arm used to mount one of its grippers by a Japanese circuit board manufacturer, Grabit was intrigued to see how the machines could be used as a part of Stackit’s development.
Prahlad explained: “Because of the vast applications for Stackit, we needed a robot with a large reach, that would not lose the high levels of precision needed for exacting material handling applications like the shoes from Nike.
“What’s more, because Grabit’s electroadhesion gripper is so large, the robot needed to be able to withstand a big moment of inertia and offer the ability to rotate accurately.”
The off-the-shelf (OTS) Toshiba Machine robot that the company experimented with, didn’t meet Grabit’s unusual requirements. Unlike many robotics applications, there was no need for a lot of complex motion and the company did not require the range of movement provided by a standard, six-axis robot.
However, because Grabit wanted to use its own control system to oversee the whole machine, they needed deep access to low level internal control code and the control package needed to be small enough to fit into a tight space in the design.
Prahlad noted: “Meeting Stackit’s ’20-times faster’ productivity goals rely heavily on the inertia of the gripper and ensuring that the settling time of the robot remained accurate. But the robot also needs to move fast enough to provide customers with the cycle times we wanted.
“It became plainly obvious that there was no standard robot that could meet every one of our requirements.”
With manufacturing in the footwear and apparel industry driven by costs, combined with the further financial pressure of low labour rates in many manufacturing countries, Grabit needed a cost-effective robot.
Grabit used a modified Toshiba Machine’s THL1000 SCARA robot in the Stackit application, a horizontal multi-joint machine with four controlled axes.
As standard, the robot offers a maximum payload of 10kg against a total mass of 37kg. With a tested load of 2kg, the machine can achieve a cycle time of just 0.48 seconds.
However, due to the specific load requirements for Stackit, Grabit’s customised version was created using a different ratio of gears, causing an enhancement in payload capability.