Robots and the Human Touch


Jim Lawton, Contributor

March 15, 2015

Have you thought much about what touch means to us as humans? Watch carefully a pianist and wonder at the range of sounds created by the seemingly simple touch of fingers on the keys. Observe a craftsman building a piece of furniture and count the times hands meet wood to measure smoothness, shape and feel. Or see a watchmaker tightening gears and screws at the perfect level of tension to create a masterful timepiece.

Our ability to touch and feel the environment around us is an extraordinary aspect of what makes us human. It also allows us to perform a wide variety of delicate and intricate tasks without harming the people around us or the objects with which we interact.

It may seem odd to write about human touch in a piece on robots and automation, but until now, lacking this ability has sorely limited the use of robots in manufacturing environments. That’s all changing. While robots may never experience the emotions conjured in humans by the feel of a baby’s breath on their neck, they are more and more able to apply the incredible value of touch to tasks.

Consider what it takes to test a printed circuit board (PCB). A worker picks up an untested PCB, moves it through the air and carefully inserts it into a fixture that may have no more than 100 micron clearance. Once the results are known, the PCB is passed on to the next step in the manufacturing process or is set aside to be reworked or scrapped.

Humans are not particularly precise creatures. And yet without thought to what needs to happen, thousands of workers perform this task extraordinarily well every single day. How is this possible?

First, the worker can move the untested PCB through free space, stably and purposefully, into the test fixture. While high precision is not necessary for this step, collisions, erratic movement and rapid acceleration must all be avoided.

Next, the worker feels the forces being applied by the fixture as the PCB is inserted. They dynamically adjust the stiffness of their arm to securely snap the PCB into place without damaging the PCB or the fixture of the tester. The direction and the forces applied change constantly until the task is achieved.

Rigidity is not an option in this scenario or in many others. This spring-like nature of our limb allows us to use our arms to guide a dance partner or our legs to navigate uneven terrain and myriads of other tasks.

Why is this easy for humans and so hard for robots? Consider the difference between a bouncing ball and a human jumping. The ball hits the ground, forces interact, power is transferred, and the ball bounces back up. Unlike the ball, humans jump through free space, absorb the initial impact of the ground through the springiness in the legs, and then gradually stiffen the leg muscles to stabilize position.

Until now, robots have not been able to master this give-and-take that gives humans the ability to apply just the right amount of pressure to respond and react as needed:

  • Point-to-point, position-controlled robots work based on careful alignment of the object in play. This approach is fine, until the object isn’t exactly aligned or something gets in the path between point A and point B. The robot will keep applying force until the object is aligned, removed or more likely, damaged. Avoiding this requires sophisticated vision systems or complex, integration-heavy fixturing. These solutions are costly and very inflexible. The result? Robots are rarely used to perform tasks like PCB test.
  • Alternatively, force-controlled robots interact with objects more gracefully and are better suited to tasks that require the finesse exemplified by the insertion of the PCB into the tester. Again fine, until we talk about moving around in free space. Then the robot becomes dangerous as it will move faster and faster until it finds something to stop it.

Neither option offers that “spring-like” nuance so essential to not damaging limbs or objects.

Today, cheap sensor technology and advances in robot design architecture make it possible to combine mechanical compliance (the ability to mimic the give-and-take of a human arm) and impedance control (dynamically controlling stiffness or springiness as described by the differences between a human jumper and a bouncing ball). As a result, smart, collaborative robots now bring the long-sought after ability to “touch” and “feel” their way through tasks like humans do. Today, robots can load PCB’s for testing.

It’s hard to imagine our lives without the ability to touch. As manufacturers look to move to build the factories of the future, where human brain power will be more essential in every corner of the operation, robots able to perform tasks that require the abilities made possible through touch will be a critical asset .

Where do you see robots with human-like touch fitting into your operation? Share your perspectives with me @jim_lawton or tweet us @rethinkrobotics.

This article was written by Jim Lawton from Forbes and was legally licensed through the NewsCred publisher network.

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