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What are manipulator robots? Understanding their Design, Types, and Applications

This article was discussed in our <a data-saferedirecturl="https://www.google.com/url?q=https://www.wevolver.com/profile/the.next.byte&source=gmail&ust=1651619086659000&usg=AOvVaw31M1Y-wsRw4c0h8-at-VxZ" href="https://www.wevolver.com/profile/the.next.byte" id="isPasted" rel="noopener noreferrer" target="_blank">Next Byte podcast</a>.&nbsp;<iframe height="200px" width="100%" frameborder="no" scrolling="no" seamless="" src="https://player.simplecast.com/e2238814-9212-4010-afb6-ac48d637140f?dark=false" class="fr-draggable" data-gtm-yt-inspected-1_19="true" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true"></iframe>The full article will continue below.<hr>Watching a bird like an ostrich running reveals a locomotive mechanism far closer to a creature like the mighty Tyrannosaurus Rex than the human leg, and few could doubt its efficacy &mdash; leading a team at the Dynamic Locomotion Group of the Max Planck Institute for Intelligent Systems (MPI-IS) to wonder if current approaches for bipedal robot designs could benefit from being more bird.&ldquo;No current bipedal robot can run quickly, untethered, in natural environments over long distances,&rdquo; the researchers explain in a recently-published paper. &ldquo;However, these activities are commonplace for terrestrial animals. Paradoxically, animals vastly outperform current robots despite considerably slower sensing and information transfer rates.&rdquo;<h1>Inspired by, and defining, nature</h1>Before you can take inspiration from bird locomotion, however, you need to ascertain why it&rsquo;s so effective &mdash; and that&rsquo;s not necessarily an easy task. &ldquo;It&rsquo;s not the nervous system, it&rsquo;s not electrical impulses, it&rsquo;s not muscle activity,&rdquo; claims senior author Alexander Badri-Spr&ouml;witz. &quot;We hypothesized a new function of the foot-leg coupling through a network of muscles and tendons that extends across multiple joints.&ldquo;These multi-joint muscle-tendon coordinate foot folding in the swing phase. In our robot, we have implemented the coupled mechanics in the leg and foot, which enables energy-efficient and robust robot walking. Our results demonstrating this mechanism in a robot lead us to believe that similar efficiency benefits also hold true for birds.&rdquo;<iframe src="https://www.youtube.com/embed/wwH40rYJt9g?&wmode=opaque&rel=0&enablejsapi=1&origin=https://www.wevolver.com" allowfullscreen="" class="fr-draggable" width="640" height="360" frameborder="0" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" data-gtm-yt-inspected-1_19="true" id="501349169"></iframe> Dubbed BirdBot, the resulting design is used to prove the team&rsquo;s hypothesis in two directions: firstly that taking inspiration from the leg of a bird can boost the performance of a bipedal robot while simultaneously boosting energy efficiency; and secondly using the resulting robot design to determine the aspects of the leg which contribute most to the efficiency of its living inspiration.Each leg of the BirdBot design uses just two actuator motors, with a traditional third replaced by a clever joint system featuring a joint based on intrinsic engaging and disengaging abilities. As the robot&rsquo;s foot touches the ground and experiences load, the joint system tenses and stiffens to support the weight; as it&rsquo;s lifted off and swung, a bi-stable snap-through joint driven by elastically-stored energy unlocks the leg into a slack configuration.<h1>Simply better</h1>The BirdBot approach comes with a host of improvements over traditional designs, its creators claim. The most immediately obvious: It&rsquo;s electronically simpler, using only two motors and with no need for on-board sensing or complicated control circuitry. Instead, the leg itself handles locking and unlocking automatically &mdash; and can even handle stabilization using a single feed-forward motor command.Its biggest enhancement: Efficiency. Compared to the Cheetah-Cub design published back in 2013, BirdBot requires around a quarter of the energy for locomotion &mdash; putting its performance within the range, its creators say, of &ldquo;an animal of equivalent weight.&rdquo;<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjQ5ODY0MDM4NzU4LWJpcmRib3QzLmpwZyIsImVkaXRzIjp7InJlc2l6ZSI6eyJ3aWR0aCI6OTUwLCJmaXQiOiJjb3ZlciJ9fX0=" style="width: 300px;" class="fr-fic fr-dib" alt="A picture of the BirdBot prototype, seen next to a diagram making its major parts including knee and hip motors and the tendons which allow it to engage and disengage a clutch-like leg. Further photographs are given of the robot being tested on a treadmill with tethered guidance.">The 3D-printed BirdBot prototype operates with just two motors per leg, relying on a mechanical &quot;clutch&quot; system inspired by birds&#39; legs for the remainder of its operation.&ldquo;Previously, our robots had to work against the spring or with a motor either when standing or when pulling the leg up, to prevent the leg from colliding with the ground during leg swing. This energy input is not necessary in BirdBot&rsquo;s legs,&rdquo; Badri-Spr&ouml;witz, who also led the Cheetah-Cub team, explains.Other advantages claimed in the paper detailing BirdBot&rsquo;s design include the ability to stand upright through torque loading, with all actuators unpowered &mdash; &ldquo;reminiscent,&rdquo; say its creators, &ldquo;of a flamingo standing while sleeping&rdquo; &mdash; and of being highly scalable, with one prototype created during the work standing 1.75m (around 5.7 feet) tall and able to hold the weight of a human being.&ldquo;On the basis of our analysis and physical demonstrations,&rdquo; the team concludes, &ldquo;we suggest that BirdBot&rsquo;s leg design can become a blueprint for large legged machines.&rdquo;<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjQ5ODY0MDUyNDkwLWJpcmRib3Q0LmpwZyIsImVkaXRzIjp7InJlc2l6ZSI6eyJ3aWR0aCI6OTUwLCJmaXQiOiJjb3ZlciJ9fX0=" style="width: 300px;" class="fr-fic fr-dib" alt="Photographs showing the small BirdBot prototype next to an unpowered large-scale 1.75m version based on the same principles. A researcher is seen placing his weight on the leg in its standing position, then stepping off to the floor and lifting the leg to its swinging position.">A large-scale version of the leg proved capable of holding the weight of an adult human &mdash; and its creators say it could be scaled up still further.That&rsquo;s not to say their work is finished, however. The current motorized BirdBot prototype, which uses off-the-shelf actuators fitted to a 3D-printed trunk and legs, has been tested on a treadmill with tethered guidance.To create a version capable of standing freely and moving in three dimensions will require further research to prevent pitching, potentially involving a revised design or a shift to hip-only actuation. While operable without sensor input, the team also suggests that an investigation into how the clutch mechanism could be used alongside direct actuation and sensory feedback control to &ldquo;merge the benefits of both systems.&rdquo;The team&rsquo;s work has been published in the journal <a href="https://www.science.org/doi/10.1126/scirobotics.abg4055" target="_blank"><cite>Science Robotics</cite></a>, with an open-access version available via author referral <a href="https://is.mpg.de/publications/bb01" target="_blank">on the MPI publication page</a>.<h1>References</h1>Alexander Badri-Spr&ouml;witz, Alborz Aghamaleki Sarvestani, Metin Sitti, and Monica A. Daley: <cite>BirdBot achieves energy-efficient gait with minimal control using avian-inspired leg clutching, Science Robotics Vol. 7 Iss. 64</cite>. DOI <a href="https://doi.org/10.1126/scirobotics.abg4055" target="_blank">10.1126/scirobotics.abg4055</a>.Alexander Badri-Spr&ouml;witz (as Alexander Spr&ouml;witz), Alexandre Tuleu, Massimo Vespignani, Mostafa Ajallooeian, Emilie Badri, and Auke Jan Ijspeert: <cite>Towards dynamic trot gait locomotion: Design, control, and experiments with Cheetah-cub, a compliant quadruped robot, The International Journal of Robotics Research Vol. 32 Iss. 8</cite>. DOI <a href="https://doi.org/10.1177/0278364913489205" target="_blank">10.1177/0278364913489205</a>.

The prototype motorized BirdBot, seen here with legs in the locked position, uses a quarter the energy of its immediate predecessor.

Created by the Dynamic Locomotion Group at the Max Planck Institute for Intelligent Systems (MPI-IS), BirdBot serves two purposes: Demonstrating a more efficient bipedal robot design, and furthering our understanding of how birds' legs work.

BirdBot, a 3D-printed bipedal robot, offers major efficiency gains through avian biomimicry

This article is a part of our <a href="http://www.wevolver.com/student-program" target="_blank">University Technology Exposure Program</a>. The program aims to recognize and reward innovation from engineering students and researchers across the globe.&nbsp;<h2 dir="ltr">About the project</h2>Woodpeckers have flexible and extendable tongues that they use to reach their prey through tiny openings in trees and insect burrows (Fig. 1). A robotic manipulator with these capabilities would be advantageous. For example, this kind of manipulator would be able to reach a product on the back of a cluttered shelf (Fig. 2). Such a concept is promising for applications that require picking and handling actions in unstructured environments, but to date only exists in science fiction and fantasy (e.g., Doctor Octopus in Marvel's Spider-Man).<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjQ1MjA2MTg3OTg5LTE2NDUyMDYxODc5ODkucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" class="fr-fic fr-dii" alt="woodpecker-tongue">Fig. 1: Woodpeckers prey worms through tiny openings in trees by using their surprisingly long tongue<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjQ1MjA2MTg4NTkyLTE2NDUyMDYxODg1OTIucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" class="fr-fic fr-dii" alt="traditional-robots-soft-robots">Fig.2: Extendable and bendable robotic arm can access hard-to-reach targets while avoiding obstraclesContinuum robots are those with manipulators that are inspired by the lightweight and flexible structures of animals such as an octopus-arm and elephant trunk. Although some of them can bend and extend their body in any direction (e.g., FESTO-Bionic Handling Assistant), they lack stiffness and restrict their applications, particularly those which require the grabbing and carrying of heavy objects. They also limit the extension distance, only about twice the maximum body length.<iframe src="https://www.youtube.com/embed/D7BvPoO5k0g?&amp;ab_channel=AyatoKanada&amp;wmode=opaque&amp;rel=0&amp;enablejsapi=1&amp;origin=https://www.wevolver.com" allowfullscreen="" class="fr-draggable" data-lf-yt-playback-inspected-kn9eq4roawkarlvp="true" width="640" height="360" frameborder="0"></iframe> To address this problem, we focused on a woodpecker tongue. Woodpeckers have unique anatomical features that manipulate their surprisingly long tongues. Unlike the human and anteater tongues, which are made mainly of muscle, the woodpecker's tongue is rigidly supported by the bones (Fig. 3). To store the long tongue inside a small head, it passes under the base of the jaw and wraps around the back and top of the head.<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjQ1MjA2MTg3OTU3LTE2NDUyMDYxODc5NTcucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" class="fr-fic fr-dii" alt="anatomy-woodpecker-tongue">Fig. 3: Anatomy of a woodpecker tongue [1]To reproduce these functions, we designed a robot manipulator that can substantially extend its length and bend its shape in 2D space (Fig. 4). This behavior is enabled by a backbone consisting of a chain of rigid joints and two flexible rack gears. The joints increase the payload by structurally supporting the robot. The proposed structure is 4.7 times stronger in vertical bending and 6.2 times stronger in torsion than without rigid links. Feeding the rack gears at the same and different speeds allows the robot to elongate and bend, respectively. Our robot has a long extension distance that depends on the length of the tongue. In addition, the manipulator body can be stored inside a small space (see the attached video). <img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjQ1MjA2MTg4MTQ1LTE2NDUyMDYxODgxNDUucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" class="fr-fic fr-dii" alt="proposed-mechanism-woodpecker-inspired-robotic-arm">Fig. 4: Schematic diagram of the proposed mechanism. (a) Overview. (b) Backbone. (c) Driving unit. [1]<h2 dir="ltr">Problems solved by the project</h2>To illustrate the importance of this project, one should think of a conventional robot's arms or legs, for instance. Rigid manipulators designed to be stiff to achieve precise and repetitive position control are helpful in well-defined and structured environments, primarily manufacturing factories. However, they struggle to operate in unstructured environments such as homes and open fields. This is a fundamental problem in robotics because of its limited ability to accurately recognize the surrounding environment and contact/deal with objects in the right way, and overcoming it will be a milestone.Our project leads to realizing systems that are safer, cheaper, and more adaptable than the level that traditional robots can achieve. In our mechanism, the extending actuation allows robots to select a safe path that serial manipulators cannot follow, as shown in Fig. 2. The inherent compliance of our manipulator is safe to an unexpected impact and provides environmental adaptability. We believe that this technology could be used for search and rescue, agricultural, space, maintenance, cleaning, and other applications.<h2 dir="ltr">The present state of the art</h2>Soft robots (or continuum robots) have gained a significant amount of traction over a decade to overcome rigid robot problems, but their applications are limited. The main reason for this is that while material softness provides safety and adaptability, it also reduces the stiffness and payload. On the other hand, soft robots without rigid components cannot lift heavy loads regardless of their exertion force. Variable stiffness mechanisms to temporarily stiffen soft materials have attracted much attention in the past few years, but they are not suitable for manipulators because robots cannot operate during hardening.<h2 dir="ltr">Team working on the project</h2>This research has mainly been conducted by Ryota Matsuda, a master-course student, Ujjal Mavinkurve, a master-course student, and Ayato Kanada, an assistant professor at Kyushu University. Our next step is to extend our manipulator into three dimensions to make it look like a real Doctor Octopus's tentacle. <img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjQ1MjA2MTg3Nzg2LTE2NDUyMDYxODc3ODYucG5nIiwiZWRpdHMiOnsicmVzaXplIjp7IndpZHRoIjo5NTAsImZpdCI6ImNvdmVyIn19fQ==" class="fr-fic fr-dii" alt="woodpecker-inspired-robotic-arm-condept-3D">Fig. 5: Concept of a robotic arm that can bend and extend in 3D space<h2 dir="ltr">Conclusion</h2>The unique design and build of the novel robotic arm combine the benefits of both conventional rigid robotics and soft robots. Robotic hands that can operate in unstructured environments can unlock multiple opportunities for application in biomedical instrumentation, manufacturing, space research, agriculture, and numerous other fields of engineering.<h2 dir="ltr">About the University Technology Exposure Program 2022</h2>Wevolver, in partnership with <a href="https://mouser.com/" target="_blank">Mouser Electronics</a> and&nbsp;<a href="https://www.ansys.com/academic" rel="noopener noreferrer" target="_blank">Ansys</a>&nbsp;is excited to announce the launch of the University Technology Exposure Program 2022. The program aims to recognize and reward innovation from engineering students and researchers across the globe. Learn more about the program <a href="http://www.wevolver.com/student-program" target="_blank">here</a>.<img src="https://images.wevolver.com/eyJidWNrZXQiOiJ3ZXZvbHZlci1wcm9qZWN0LWltYWdlcyIsImtleSI6ImZyb2FsYS8xNjQ1NTUxOTgxNDIwLUJyb3VnaHQgdG8geW91IGJ5ICgxKS5qcGciLCJlZGl0cyI6eyJyZXNpemUiOnsid2lkdGgiOjk1MCwiZml0IjoiY292ZXIifX19" class="fr-fic fr-dii" alt="Wevolver-Mouser-University-Technology-Exposure-Program"><h2 dir="ltr">Reference</h2>[1] R. Matsuda, U. Mavinkurve, A. Kanada, K. Honda, Y. Nakashima, M. Yamamoto, "A Woodpecker's Tongue-inspired, Bendable and Extendable Robot Manipulator with Structural Stiffness," IEEE Robotics and Automation Letters (RA-L), Vol. 7, No. 2, pp. 3334-3341.

The robot arm, which is inspired by a woodpecker's tongue, can be extended many times its length, bent into an S-shape, and stored in a small space, like Doctor Octopus from the Spider-Man series.

robot kinematics

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What are manipulator robots? Understanding their Design, Types, and Applications

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Design inspiration from woodpeckers could allow robotic arms to be bendable and extendable