Tag Archives: robots

Innovative plant: How does the dandelion drift its seeds?

How far do you think a dandelion seed can drift from its base plant?

The Common Dandelion (Taraxacum officinale) primarily relies on wind flow to scatter its seeds. The dandelion seed has a fluffy structure that enables it to hold the most prolonged wind-based dispersal record. Commonly the seeds land 2 meters away from their mother plant. Still, in windy, dry weather favored by the dandelion, the seeds can fly up to 30 kilometers and even far (150 kilometers in some conditions). The vital point in this extraordinary adventure of the dandelion is flying with a constant velocity and having a short descent time, which means it should stay stable in the air for a relatively long time.

A study tried to illuminate the mystery behind the dandelion seeds’ ability to stay aloft in the air. Researchers attempted to mimic the dandelion flight using similarly structured silicon disks in a wind tunnel that simulated the airflow around the pappus. Pappus, the flying seed of the dandelion, consists of radially oriented filaments, each interacting with other adjacent ones, resulting in a reduction in the airflow. They compared the flight of natural seeds collected from one plant with several silicon disks with different porosities.

Dandelion seeds and silicon disks in wind tunnel
Wind tunnel experiment, modified from Cathal Cummins & et al. 2018
vortex ring above pappus
Pappus & separated vortex ring, modified from Madeleine Seale & et al. 2019

Their results showed that when pappus separates into the air,  it forms an air bubble detached from its surface above it. This air bubble, known as a vortex, is unique to the dandelion seed. When the pappus is released in the air, it takes some time to reach a steady point, in which the vortex becomes symmetrical. An important feature affecting this symmetry is the porosity of the pappus, defined by the number of filaments and their dimension in each pappus— generally, the more the porosity, the steadier the flight. The best porosity for a stable vortex ring is greater than 84.97%, and the vortex ring begins to separate as the porosity falls below 77.42%. The experiment also indicated that the vortex is axisymmetric in low velocities, but it begins to lose its symmetry as the Reynolds increases.

Pappus with water drops on it
Pappus in moisture, photo by enfantnocta

This phenomenal plant has evolved techniques for mass germination, even in the absence of wind! Pappus’s hairy structure enables it to attach to an animal’s skin and soil particles, assuring the dandelion to have enough seed dispersion during the flowering season. More interestingly, the dandelion is known to have an informed dispersal in response to environmental fluctuations. When the plant experiences root herbivory, it intensifies the seed dispersal. The flight distance may vary from meters to kilometers to assure good germination in the absence of threatening conditions. Imagine a rainy day; the moist weather condition makes the pappus’ bristles come close together, reducing the possibility of separating from the plant. The moisture makes the current spot a suitable choice to stay. So even the detached seeds prefer to fall close to their base plant. 

It worth mentioning that this remarkable plant also inspired areas of science. In their study of Mars exploration, researchers presented a primary model of a dandelion-inspired rover. Considering the harsh environmental condition on Mars, other excavators find the wind flow as an obstacle that results in damaged parts and incomplete missions. In contrast, the new dandelion-shaped rovers use the wind flow as an accelerating point to explore locations on Mars that other robots couldn’t access.

Dandelion-shaped Mars rovers
Dandelion-shaped rovers ,modified from Michelle Sherman & et al. 2020

A Second Chance: Robotic Exoskeletons May Be the Future of Mobility for Patients with Spinal Cord Injuries

No one ever imagines themselves getting seriously injured. Accidents do happen though, like car crashes and unexpected sports injuries. These events can drastically change a person’s life, leaving them unable to perform simple daily tasks without assistance, such as walking. One injury that can radically impact a person’s life is a spinal cord injury. There are approximately a quarter of a million people in the United States with spinal cord injuries, and that number grows by 12,500 each year.

The spine is the center of support in the body. It adds structure and facilitates movement. Its other extremely important job is to protect the spinal cord, which is a column of nerves that runs down the length of the neck and back. The spinal cord is part of the nervous system, and it acts as a messenger, taking orders from the brain and relaying these messages to the rest of the body, telling the muscles what to do. If the spinal cord is injured, the messages can’t be delivered properly. This often results in a loss of mobility.

Diagram of the central and peripheral nervous system showing how the spinal cord connects the brain to nerves that run throughout the body
From OpenStax Anatomy and Physiology on Wikimedia Commons

Most people don’t think about the mechanics involved in the simple act of walking. However, in order to walk, various joints such as the hip, knee, and ankle need to work together, rotating and bearing loads to allow for movement. When your foot hits the ground, the ground imparts a force through the foot which is translated up through the lower extremities to the spine. When a spinal cord injury occurs, the brain is unable to communicate with our muscles which inhibits this load bearing and the resulting movement.

Studies have shown that powered exoskeletons have numerous benefits for patients with spinal cord injuries to help with walking and mobility. These powered exoskeletons are built in various ways to bear loads and encourage movement, and a review of different exoskeletons, along with other rehabilitation devices, discusses differences in design and control of the systems. For example, to allow for control of movement, one exoskeleton was built with motors located at the joints while another was designed with a braking system at the joints.

Photo of the Indego powered exoskeleton
Indego Exoskeleton – From Indego.com

One study researched mobility outcomes for patients with injuries that varied in severity and location on the spine. Some patients were paraplegic, which means their lower extremities were paralyzed, and some patients were tetraplegic/quadriplegic, which means the paralysis affected both their lower and upper extremities. Also, some patients had complete spinal cord injuries, which means all feeling was lost below the injury, while others had incomplete spinal cord injuries, which means they had some feeling and some ability to control movement below the injury. This study showed that powered exoskeletons, specifically the Indego exoskeleton, could help a patient move in both indoor and outdoor settings, and there is potential for patients with paraplegia caused by injuries to the lower spine to use this device to allow greater ease of mobility in public spaces. For patients with more severe injuries, such as those with quadriplegia, the powered exoskeleton allowed for slower movement with supervision and occasional assistance from a therapist. These patients also needed assistance with putting on and removing the device. Therefore, the powered exoskeleton won’t help patients with more severe injuries move on their own in public settings, but it was excellent for exercise and rehabilitation.

These exoskeletons are also proven to be safe and feasible. Patients with complete spinal cord injuries did not report discomfort or injury, and they were able to use a powered exoskeleton more easily than previous rehabilitation technology.

Powered exoskeletons may be the future of movement for those who thought they would never walk again. This further reading contains examples of paraplegics who walked using a powered exoskeleton. Another man even walked marathons using one of these devices:

From Freethink on YouTube

There are limitations on these devices, but the robotics field is swiftly evolving, and the technology is giving patients something they never thought they would have: a second chance.

Soft Robotics: Humanizing the Mechanical

Cassie the robot, created by Dr. Mikhail Jones at Oregon State University
Cassie the Robot, developed by Mikhail Jones, Faculty Research Assistant in Mechanical Engineering at Oregon State University.

In media and science-fiction, robots have stereotypically, and perhaps somewhat unfairly, been depicted as mechanical, stiff assemblies of moving joints and complicated circuitry. While this still holds true for many robots designed today, whether for industry or research, the past few years have seen a growing interest in soft robotics in academia, industry, and popular culture. As the name implies, many research groups have begun investing in constructing robots from compliant, softer materials.

Stickybot, a gecko-inspired robot.
Stickybot, a biomimetic robot.

Inspired by the way organisms in nature survive and adapt to their surroundings (formally known as biomimicry), the advantages of soft robotic components lie in their flexibility, sensitivity, and malleability – delicate tasks or interactions involving other people would be better accomplished by robots made of compliant materials rather than one that could potentially cause harm to the object or person. To that end, many of the applications of soft robotic research have already seen results in the medical industry, from invasive surgery to assistive exosuits. By taking inspiration from biological creatures or mechanisms, softer materials like rubbers and plastics can be actuated to accomplish tasks conventional, “hard” robots could struggle with.

Animation of pneumatic muscle.
Animation of pneumatic air muscle used as robotic actuators.

The most common method of moving these robotic parts is with changes in internal pressure. By creating a “hard”, skeletal frame, and surrounding it with soft, sealed membranes, changes in pressure allow the designer to control its components precisely. By decreasing the pressure and creating a vacuum, the robotic section would shrink or crumple, and increasing it would do the opposite. Researchers at Harvard developed “artificial muscles” by taking this concept a step further; using origami, they were able to design soft robotic mechanisms that could orient themselves into tunable positions as the pressure was changed inside the membrane (as a side note, origami is used in a surprising number of research fields, one of the most famous being satellite deployment). Compared to the challenge of precisely controlling prismatic (sliding) joints and servos in conventional robotics, the compliance of the materials used allow for finer control and smaller ranges of applied forces that are better suited for precise tasks.

Animation of a person demonstrating the Miura fold on a piece of paper
The Miura fold pictured here is often used to deploy large surfaces while minimizing volume, such as for satellites.

Another significant advantage of soft robots over their stiff counterparts is their adaptability to environmental conditions. Generally speaking, robots do not do well in water (or lava, for that matter), but it would have little effect on robots covered in a sealed, pressurized “skin”. This is what inspired NASA in 2015 to fund research into soft robots that could explore the oceans of one of Jupiter’s moons, Europa.  Similarly, a light-activated underwater robotic manta ray was designed at a centimeter scale to study the effect of environmental cues on controllable robots.

Schematic and pictures of soft robot design.
A soft-legged robot with walking capabilities.

While research in soft robotics is still relatively new, it has the potential to significantly affect the role of robots in our daily lives. As a softer, safer, and more environmentally robust alternative to “hard” robots, wearable robotic devices, exploratory robotic fish, and personal medical attendants could soon become commonplace for the general public.

Continue reading Soft Robotics: Humanizing the Mechanical

The Weight of Combat: Are powered exoskeletons the solution to heavy combat loads?

Have you ever wondered how much weight a soldier carries in a combat zone?

Military servicemembers, particularly those in physically demanding roles such as infantry, are routinely required to carry heavy combat loads ranging from 25- to over 100-lbs. This load potentially includes weapons, ammunition, body armor, food, sleeping equipment, and other necessities for the mission. Consider that these loads are often carried for hours or even days at a time in both deployed and non-deployed environments and it becomes clear that these loads take a physical toll on those who bear them.

The physiological demands of these loads often lead to servicemember injury or discomfort both during and after their time in service. The most common musculoskeletal injuries resulting from carrying heavy combat loads include increased lower back pain and injuries to the knee, ankle, and spinal cord. Such injuries lead to acute and chronic effects over the servicemembers’ lifetimes, increased military healthcare costs, and decreased military readiness.

While it would be advantageous to decrease both the weight of the combat load as well as the frequency of weight-bearing events, the reality of modern warfare gives little hope to these suggestions. However, there is another solution: external, electrically powered exoskeletons to aid with carrying combat loads.

American defense and technology company Lockheed Martin is currently developing a prototype exoskeleton for military use – the ONYX exoskeleton. Two prior-service soldiers are shown performing common physical tasks under load – walking up a steep incline and walking up flights of stairs – while aided by the exoskeleton. Both soldiers involved in the test indicated a high level of comfort with the exoskeleton as well as improved weight-bearing ability using the ONYX exoskeleton. Check out the video to learn more:

Powered exoskeletons come with drawbacks, namely mobility/comfort issues and the need for a mobile, long-lasting power source. While the devices may perform well in a laboratory or controlled setting, reliability in the field will require durable materials and electronics. Additionally, while Lockheed-Martin’s ONYX exoskeleton is designed to reduce load on the wearer’s knees and quadriceps muscles, it gives no such support to the lower back or other parts of the body. This shift in load distribution throughout the body may have unintended consequences and potentially lead to further injury. A 2006 study by researchers at Loughborough University in the UK found that existing military load carriage systems result in gait and posture changes (head on neck angle, trunk angle, etc.) which lead to muscle tensions that increase one’s risk for injury.

A figure visualizing the angles made by the head, torso, and legs when walking
Image taken from Attwells et al., Ergonomics, 2006.

Thus, while there have been many improvements in robotic and soft electronics technology in recent years, powered exoskeletons have much to prove before they see time in service.

What do you think – are powered exoskeletons going to be commonplace on the battlefields of tomorrow, or are they a passing fad?

For more information, check out the following articles from the Army Times and Breaking Defense on the ONYX exoskeleton.

Can we 3D print our own skin?

Can you imagine a world where amputees receive replacement limbs which are able to detect temperature and pressure like an actual limb? How about a world where when you get a cut, you can 3D print some of your own skin to patch the wound?

To the average citizen, this might seem like something out of a science fiction movie. To researchers at the Graz University of Technology, the Wake Forest School of Medicine, and the Universidad Carlos III de Madrid, this is a reality that they are helping bring ever closer. Both of these scenarios are discussed in a recent article by Mark Crawford, who investigated the recent breakthroughs in 3D printing human skin and creating sense-sensitive artificial skin.

photograph of an arm reaching into the sky to feel the rain in the palm of their hand
photo by Alex Wong on Unsplash

At the Graz University of Technology, researchers are working on creating an artificial skin that can sense temperature, humidity, and pressure. Currently, artificial skins can measure one sense at best, but with the use of the nanoscale sensors that these researchers are developing, sensing all three at once could be possible. This is achieved through the materials that the nanosensors are created out of: a smart polymer core and a piezoelectric shell. The smart polymer core can detect humidity and temperature through expansion, and the piezoelectric shell detects pressure through an electric signal that is created when pressure is applied. With this technology, prosthetics could be made which could allow the wearer to retain some of their lost senses.

At the Wake Forest School of Medicine, researchers have created a handheld 3D printer which produces human skin. This device could be used to replace skin grafts, as it can apply layers of skin directly onto the wound. Through the use of bioink, this handheld printer can create different types of skin cells. After scanning the wound to see what layers of tissue have been disrupted, it can print the appropriate skin needed to correct the injury.

Photograph of the 3D skin printer created at the Universidad Carlos III de Madrid, which is still in its prototype phase.
modified from Crawford, ASME January 2019

At the Universidad Carlos III de Madrid, researchers are also 3D printing human skin using bioink. They are creating both allogenic and autologous skin to create the optimal skin, which is a combination of the patient’s own cells and cells created from a stock. Although they have managed to print functioning skin in its natural layered state, it is tricky to create the cells in such a way that they do not deteriorate.

It is also tricky to correctly deposit the product. To illustrate, more research needs to be done on the mechanical properties of artificial skin before it could be used on humans. The artificial skin must be able to stretch and react to tension in a similar manner to the real skin it will be connected to. Additionally, researchers must figure out how to safely send the signals the artificial skin is detecting to the brain.

Overall, both advancing artificial skins and 3D printing human skins could largely impact humanity. Even though we have yet to use these skins on people, they are already being used in industries, such as L’Oreal, to limit testing on humans and animals. Already, these skins are being used on robots, as seen in this video, to help prepare the skin for human transplant:

 

Interested in seeing more? Check out some more articles on the advancement of artificial skin from Caltech and Time.

Robots Could Soon Replace Human Stunt-Doubles

Imagine an aerial acrobat soaring fifty feet above your head and executing gravity-defying stunts during a live performance. After your initial amazement that a human could be performing acts such as these so fearlessly, you look a bit closer to realize that the performer is actually not human at all. Thanks to a groundbreaking technology recently developed by Disney Research, this could soon become a reality.

Stuntronics robot soaring through air while holding heroic pose
Photo from Walt Disney Imagineering Research and Development, 2018

Over the past year, Disney has been working to produce a robotic stuntman that has the ability to replace its human counterpart in performing dangerous aerial acrobatics. This seamless blend of biomechanics and technology has the potential to ultimately create an immersive and unforgettable entertainment experience.

This project, known as “Stuntronics,” originated from a smaller research project known as Stickman. Stickman was a robot that consisted of a line of three metal rods connected by two flexible joints. Once cast into the air by swinging off a pendulum wire, the robot utilized sensors such as accelerometers and gyroscopes to relay to its microcontroller (or brain) information regarding its position and orientation while flying through the air. Using all of this information from the sensors, the robot then either tucked or untucked its sections to rotate more or less quickly, respectively, in order to land flat and untucked on its back. A diagram explaining the robot’s motion can be found below.

Diagram of Stickman robot's trajectory through the air with labels
Photo from Christensen et al., Disney Research 2018

In order to scale Stickman to a more lifelike and human-sized robot, it was necessary to take a closer look at the science behind how human performers are able to execute their movements. Researchers Spiros Prassas, Young-Hoon Kwon, and William Sands explored these questions in a review focused on the biomechanics of gymnastics.

An important part of acrobatics and gymnastics is the ability to shift angular momentum (the amount a body rotates) between body parts. As a gymnast gets closer to the ground, they can either speed up or slow down their rotation by rotating their arms in order to successfully stick a landing. Performers also are able to speed up or slow down their rotation by manipulating their moment of inertia (the amount a body resists rotating more quickly or slowly) through their body configuration. For example, if the performer needs to speed up their rotation, they could reduce their moment of inertia by tucking into a ball, whereas if they wanted to slow down, they could untuck their body into a full layout.

The Stuntronics robot utilizes these concepts by continually reading the feedback from all of its attached sensors and lasers to tell the entire body which configuration it should be in at any given time. After being launched in an arc from a swinging wire, it is capable of controlling its pose in order to either speed down or speed up its rotation, and thus land perfectly each time (see video below).

This advanced technology could be pushed to the limit to ultimately produce more engaging and immersive entertainment by carrying out stunts that would simply be too dangerous for human performers to attempt. In a world where robots are constantly being implemented to take the place of humans in performing dangerous, dirty, and tedious work, Stuntronics could serve as a foundation for generations of robots, both stuntmen and non-stuntmen, to come.

For further reading, check out these articles from TechCrunch and Popular Science.