Archive for the ‘Pneumatics in Robots’ Category

2004 – OctArm – Christopher Rahn et al (American)

Penn State Research Team Develops OctArm Soft Robot Manipulator
Recent interest in expanding the capabilities of robot manipulators has led to significant research in continuum manipulators. The idea behind these robots is to replace the serial chain of rigid links in conventional manipulators with smooth, continuous, and flexible links. Unlike traditional rigid-linked robots, continuum robot manipulators can conform to their surroundings, navigate through unstructured environments, and grasp objects using whole arm manipulation. Soft continuum manipulators can be designed with a large number of actuators to provide hyper-redundant operation that enables dexterous movement and manipulation with robust performance. This improved functionality leads to many applications in industrial, space, and defense robotics.
Previous continuum robots used cable-tendon and pressurized tube actuators with limited performance. Cable-tendons must be tensioned or the cables become snarled or fall off drive pulleys, limiting the robot speed. Pneumatic bellows have low shear stiffness, limiting load capacity. Thus, there exists a need for a highly dexterous, fast, and strong soft robot manipulators.
Dr. Christopher Rahn, Professor of Mechanical Engineering at Penn State along with his students Dustin Dienno and Mike Pritts, and assisted by Dr. Michael Grissom developed the OctArm manipulator using air muscle actuators. These actuators are constructed by covering latex tubing with a double helical weave, plastic mesh sheath to provide the large strength to weight ratio and strain required for soft robot manipulators.
OctArm is divided into three sections. Each section is capable of two axis bending and extension which allows nine degrees of freedom. The manipulators are actuated with pressurized air (Maximum pressure = 120 psi) pressure control valves and polyurethane connective tubing.
The air muscle actuators are optimized to provide the desired wrap angles and workspace. The distal section of each OctArm is designed to have a minimum wrap diameter of 10 cm. The length of each section is chosen so that the manipulator can provide a range of 360 degrees wrap angles to accommodate a wide range of objects sizes. To provide the desired dexterity, OctArm is constructed with high strain extensor actuators extend up to 80%.
To provide two-axis bending and extension, three control channels are used. selected. Six actuators are used in sections one and two and three actuators are used in section three. The six sections have two actuators for each control channel and results in actuators located at a larger radius, corresponding to higher stiffness and load capacity. Secondary layers of mesh sleeving are used to group individual actuators in control channels. Three closely-spaced actuators provide high curvature
for the distal sections. The third, visible, mesh layer or fabric skin is designed to
protect the manipulator from abrasion and wear.
For the field tests, OctArm was mounted to the second link of a Foster-Miller TALON platform. The control valves and two air tanks provided nine channels of controlled pneumatic pressure. Clemson University provided the control electronics and operation interface for these tests. The OctArm /Talon system underwent extensive field trials in the spring of 2005 at the Southwest Research Institute (SwRI) in San Antonio, Texas.
Initial tasks included stacking and unstacking traffic cones. The ability of the system to grasp objects such as spheres and cylinders over a wide range of scales was recorded. The system was also operated in water. The OctArm was submerged in water, while attempting to grasp various payloads and to maintain grasps under turbulent flow. The system was also operated in rubble piles. The trials described demonstrate that OctArm continuum robots are a feasible and attractive alternative to conventional robot manipulators in unstructured environments, and also that there is room for improvement.
To further test the robot in real-world conditions, Dr. Rahn and his post-doc, Mike Grissom, took the Talon to the Radio Park Elementary School for demonstrations in three classrooms. First, the robot was teleoperated by Dr. Grissom while Dr. Rahn introduced the students to the vehicle and the electrical, mechanical, and computer engineering required to build it. The robot “responded” to audio commands (it has a microphone). Eventually, the fifth graders guessed that the robot was teleoperated after it answered some tough true/false questions. The third graders (and some of the teachers) initially thought it was just an extremely intelligent robot. The kindergarteners treated it like a pet dog – Robbie the Robot. The students were extremely excited about the visit and even wrote thank-you letters. Many said “I want to be an engineer!”

See selected pdfs here, here, here, and here.

See other Pneumatic, Fluidic, and Inflatable robots here.

2011 – “Ant-Roach” – Otherlab (American)

Here is the Otherlab’s 15 foot inflatable walking robot, the Ant-Roach.  We thought this conceptual elephant looked more like a cross between an anteater and a cockroach.  The goal of building the Ant-Roach was to demonstrate the carrying capacity and high strength-to-weight ratios possible with inflatable structures.

Comments November 21, 2011 by Travis Deyle of Hizook – see original article here.

"I'm really excited about inflatable robots… they have the potential to be low-cost, lightweight, extremely powerful, and yet "human safe" — ie. perfect for many robotics applications.  With that in mind, I would like to introduce you to two new (breakout) inflatable robots: a 15-foot-long walking robot (a Pneubot named Ant-Roach) and a complete, inflatable robot arm (plus hand).  Both of these robots were developed by Otherlab as part of their "pneubotics" project (in collaboration with Meka Robotics and Manu Prakash at Stanford University), with some funding from DARPA's Maximum Mobility and Manipulation (M3) program.    These robots use textile-based, inflatable actuators that contract upon inflation into specially-designed shapes to effect motion.   Since these robots are built out of lightweight fabric-and-air structural members and powered via pneumatics or hydraulics, they exhibit large strength-to-weight ratios.  For example, Ant-Roach is less than 70 lbs and can probably support up to 1000 lbs; the inflatable robot arm is less than 2 lbs and can lift a few hundred pounds at 50-60 psi.  Be sure to read on for details and lots of videos!"

Picture above shows Pete Lynn hefting the whole thing.

The muscles are textile-based actuators which contract upon inflation.  The picture above shows a stack of them during construction.

The muscles are driven from several central manifolds which dispense compressed air.

All pictures and captions sourced from Otherlabs webpage unless noted otherwise. See Otherlabs webpage and other videos here.

See other Pneumatic, Fluidic, and Inflatable robots here.

2011 – Inflatable Robot Arm and Hand – Otherlab (American)

Otherlab's prototype articulated inflatable robot arm,  is apparently able to lift a person with 50-60 psi even though it weighs only 2 pounds.

All pictures and captions sourced from Otherlabs webpage unless noted otherwise. See Otherlabs webpage and other videos here.

See other Pneumatic, Fluidic, and Inflatable robots here.

2010 – Soft Arm – Siddharth Sanan (Otherlab)

Siddharth Sanand: is doing his PhD at the Robotics Institute at CMU. He is interested in making robots soft and safe to enable physical human robot interaction. On the other side, he has been sewing together various ideas on inflatable robots and actuators.  Recently interned at Otherlab.

All pictures and captions sourced from Otherlabs webpage unless noted otherwise. See Otherlabs webpage and other videos here.

See other Pneumatic, Fluidic, and Inflatable robots here.

2011 – Inflatable Walking Elephant – Otherlab (Saul Griffith)

Pneubot stands for "pneumatic robot", or a robot that is actuated by pneumatic technology. A pneumatic technology involves the use of compressed air to drive mechanical motion. The compressed air can be moved through soft, balloon-like tubes, which allows for both rigidity (when filled) and flexibility (when decompressed or empty). In this video, an elephant-shaped pneubot is used to demonstrate the level of motor control allowed using this technology.

MAKE #27
Pneubotics: Walking Bouncy Castles
By Saul Griffith

Sometimes I feel like a false nerd, or a geek with two important genes missing: I’m not particularly interested in space exploration, except as fiction, and I’ve never cared for robots. So I find it strange that I’m now working on a Defense Advanced Research Project Agency (DARPA) robotics program.

I think what I never liked about robots is that they’re complex machines that really don’t do much. They’re fragile and very expensive. I like simple, robust things; things that don’t cost more than they should.

What I’ve found myself working on (with Jack Bachrach, Geoffrey Irving, Pete Lynn, and the good guys from Meka Robotics) is completely soft, completely compliant, very lightweight, and very cheap. No joints. No servos. Just skins — inflated skins.

For a long while I’ve been fascinated by inflatable objects for their extreme strength-to-weight ratios (they can carry a lot of load for very little mass). I also love the challenge of designing something “human safe,” in the robotics lexicon. Biology doesn’t use metal, and it doesn’t use servos. Nature points to some very interesting alternatives.

To make it work, we had to invent a new kind of actuator. Think of it as a vascular system for robots. It’s fluidic — works equally well with air or water — and by pumping either of those around, you can change the dimensions of the skin and effect motion. Our first actuator was quite literally a bicycle inner tube in a sewn pair of membranes. It worked really well for a $5 prototype!

For the next trial, I asked my sister to return an inflatable 4-foot-high elephant I’d designed and given to my niece. When it arrived, Pete burned the midnight oil and sewed up some vascular “muscles,” and in a day or two we had four moving legs. It actually walked. About one mile every 24 hours, but hey — baby’s first steps! It moves like no machine you’ve ever seen; more like the way biology moves. A walking inflatable elephant might sound ridiculous, but it works, and the numbers on paper told us it should have incredible strength, good speed, extremely low weight, and cost very, very little to manufacture.

The next prototype was designed to walk with a human rider on it and to look less like an elephant. We built it in under a week for less than $1,000 in parts. A 15-foot-long, 5-foothigh robot with 28 muscle actuators (four in each of six legs, another four in the trunk). It worked too (after a few exploded actuators).

I like the idea of a robot you can sew together. I like that it has no heavy, sharp, or costly parts. Most of all, I like the intellectual challenges of it. There aren’t any CAD packages for designing highly elastic kinetic membrane structures. We had to write our own. There aren’t any analysis simulations. We had to write our own. There aren’t any walking bouncy castles out there. We built our own! We call our weird new style of robotics “pneubotics,” as in pneu for air (like pneumatic).

Who knows if the robotics community will like it or even care. Either way, that’s not why I built it. I built it because perhaps my niece will forgive me if she gets a walking elephant next Christmas that she can ride to school.

All pictures and captions sourced from Otherlabs webpage unless noted otherwise. See Otherlabs webpage and other videos here.

OtherLab is a collective of scientists and inventors involved in a number of projects, including proof-of-concept mechatronics that might be useful in building functionally adaptive and intelligent machines.

See other Pneumatic, Fluidic, and Inflatable robots here.