Optical Sensor Gives Robots Human Touch

In recent years, lots of efforts have been made to give robots the ability to hear and see. But what about the sense of touch? Unlike us, robots don’t have sensitive skin. But this is about to change. By using organic, or plastic, field-effect transistors as pressure sensors deposited on a flexible material, researchers at the University of Tokyo have created an artificial skin which will give the robots the sense of touch. The prototype has a density of 16 sensors per square centimeter, far from the 1,500 of our fingertips. When this density increases and when the problem of the reliability of this kind of transistors is solved, the researchers say this artificial skin will also be used for car seats or gym carpets. Expect to see them in four or five years. Read more…

Here are selected excerpts from the Technology Research News article.

Researchers from the University of Tokyo have devised pressure-sensor arrays that promise to give objects like rugs and robots the equivalent of one aspect of skin — pressure sensitivity.

The researchers’ pressure sensor arrays are built from inexpensive organic, or plastic, transistors on a flexible material. This allows for dense arrays that can be used over large areas.

The arrays could be used in pressure-sensitive coverings in hospitals, homes, gyms and cars to monitor people’s health and performance, and eventually as skin that would give robots the means to interact more sensitively with their surroundings, said Takao Someya, an associate professor of electrical engineering at the University of Tokyo.

The sensor skin works even when rolled around a cylinder as small as 4 millimeters in diameter, said Someya. The researchers’ prototype is an eight-centimeter-square sheet containing a 32-by-32 array of organic sensors — a density of 16 sensors per square centimeter. In contrast, humans have 1,500 pressure sensors per square centimeter in the fingertips, though far fewer in most other places.

Here is a picture of a robotic hand using organic transistors as pressure sensors. (Credit: Takao Someya)

And what are possible applications?

The active-matrix design allows the arrays to be smart enough to enable specific sensors at certain feedback points to, for instance, monitor the heart and breathing rate of a hospital patient who has fallen to the floor, said Someya. The skin could measure whether an elderly patient is just taking a rest, or needs help, he said.

The skin could also be used in car seats to monitor drivers’ mental and physical conditions, Someya said. “Our large-area pressure [sensing abilities] would be helpful” in obtaining information through drivers seats, he said.

And, of course, we’ll see home robots able to pick an egg in the fridge.

The research work has been published by the Proceedings of the National Academy of Sciences on July 6, 2004, under the title “A large-area, flexible pressure sensor matrix with organic field-effect transistors for artificial skin applications.”

Robotic Fish Helps Understand Changes In Open Waters

The above video shows an interesting new type of fish—one with a mission. Despite its impressive life-like movements, it is actually a robot prototype that has been developed by scientists and researchers at the University of Essex, England. It is still being perfected at the London Aquarium, with a number of the expensive fish (each at a cost around US $30,000) expected to be released off a port in Northern Spain in 2011.

Its realistic motions are the result of its electro-active polymer fins, which react to the voltage that flows through them. The fish are also equipped with chemical sensors, allowing them to scan the waters and collect information that will help create a better understanding of the changes affecting the seas and oceans. One specific target will be measuring the amount and the source of pollution in the water, such as from oil and chemical spills, which do great damage to the ecosystem. The fish will send out this data though the wireless transmitters installed in their bodies.

What is interesting is that its highly authentic appearance comes with both its positive and negative sides. At a length of a foot and a half, it closely resembles the common carp which it is modeled after, albeit with brighter colors that can be used to distinguish it from real fish. The robot blends in well with the surroundings without disrupting the environment, but concerns were it might suffer the fate of real fish as well. Because of that, it was designed with a tracking system which allows it to stay away from commercial fishing boats and other human obstacles. The electromagnetic field around its body also keeps large predators, like sharks, at bay, so hopes are it will not be mistaken for prey.

Robots and Actuators

A couple of important nuances of the robotics field came to my attention recently.  The relationship of the actuators themselves to the robot design, and of course, the kinematic framework of the robot itself.  I have some history in both areas but am regularly surprised by the way innovation continues to take place. Despite the appearance that we have reached some plateau of performance based on the existing solutions, and that further progress is marginal, man continues to change, and improve, his relationships with machines.

Actuators are a combination of mechatronic components that achieve linear or rotary motion.  This isn’t always apparent because we purchase many actuators as finished products.  The integration process is not easy and involves a number of technical disciplines.  For many factory floor applications, it is more cost effective to purchase the actuator as a product.

But aspects of actuators such as power density and accuracy become the building blocks of more complex systems, like robots. It turns out that robots which use parallel actuators have greater power density and accuracy due to the elimination of parasitic losses that result from the way that robots are organized.  This is a subtlety I missed.

On the topic of broad organization of the robot, the kinematics, there are two major families that have been defined.   The robots that have been around for a while doing welding, painting and material handling tasks are generally referred to as Serial robots. They are serial in the sense that the load and forces of each axis are dependent on the axis that follows in a series, regardless of whether the axes are rotary or linear.   The more axes, the more loads and error that must be compensated for in each preceding axis.

This is especially true for machining applications.  Most CNC’s are serial in their framework.  Its great from the control system standpoint since the axes can all be treated independently.  But when the cumulative error or each axis can be measures, with an orthogonal laser system, things can be pretty well out of hand.  The latest solution is a 3D compensation model added to the coordinate system of the machine.  Siemens has pioneered the development of such as system and it works.

So the alternative to serial robots is parallel kinematic machines.  PKM.  And you can find a few really interesting examples.  The now classic Delta robot available from Lenze, Siemens and others.  The Lenze version recently added a rotary axis in the center line of the machine making it more versatile.  Check out www.pkmtricept.com for  some insights from one of the pre-eminent suppiers of parallel kinematic machines.  There are also some excellent notes and applications from Physik Instrumente (www.hexapods.net).  In general the hexapod topic is now dominated by 6 legged robots, which is an interesting side note, but not really the core of the technology we’re looking at, but again, it is fun to see how people continue to apply robotics in unique and interesting ways.

RE2, Inc to Develop DMS for U.S. Navy

PITTSBURGH, PA – RE2, Inc. announced today that it has been competitively awarded a Phase II Small Business Innovation Research (SBIR) program by the U.S. Navy to develop a Dexterous Manipulation System (DMS) for mobile robots and explosive ordnance disposal (EOD) robotic platforms.
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More Mechatronic and Robotic Reflections

The blend of sensors and motion control become crucial in many applications. The dextrous robot hand of recent years cracks eggs like a chef with the aid of sophisticated pressure sensors at the tips of its “fingers”. Check out the Shadow Robot company for some amazing videos of their “air muscle” powered robot hand in action. Lots of interesting work has been done to mimic the human hand. A miracle of grace and efficiency that is hard to duplicate. Read more