Tuesday, April 30, 2013

Robo Raven: A Step towards Bird-Inspired Flight

I have always been fascinated by birds. To me they represent beauty, freedom, and a design marvel. I am envious of bird watchers. What a wonderful hobby! Bird watching requires patience and traveling to exotic places where birds like to hang out. Unfortunately patience is not my forte. Also, at this stage in my life I am unable to travel to exotic places. So for now,I have compromised and have settled for the next best thing - creating and watching my own “birds”. I am interested in building robotic birds, not the kinds that look pretty on the shelf, but the ones that can actually flap their wings and fly. 
Eight years of experiments have taught me that designing and building robotic birds is hard, despite the apparent simplicity of the idea - flap wings to generate thrust to propel forward and use the moving air to generate lift to stay afloat. I am glad that this looked deceptively straightforward in the beginning; otherwise we would have never started on this adventurous journey. How hard can it be to build two wings and flap them using a motor? It turns out to be quite challenging if you want the bird to actually fly! This requires a long trial and error process due to the absence of accurate simulation tools. Many concepts that look good on the paper lead to a spectacular crash during the flight test, often causing a fatal injury to the robotic bird! So design iterations are painfully slow.

We had the first successful flight in 2007. +Arvind Ananthanarayanan, Wojciech Bejgerowski, +Dominik Müller  were the main architects behind this feat. Hugh Bruck, my faculty colleague at the University of Maryland, offered valuable help with the wing evaluation. We subsequently created three more flying versions using similar ideas. The last one in this series was completed in 2010. John Gerdes played a major role in building the last version in this series. Please click here to see videos of these “birds” in action. We were able to put a tiny video camera on them and get the “bird’s eye view”. We were able to launch them using a small ground robot. They were able to fly in moderate winds of around 10 mile per hour. As I mentioned before, every design flaw led to a fatal crash. But to our surprise, a very successful design also led to a fatal crash for our “birds” for a different reason. A hawk felt threatened by our "bird" and tore it apart in the mid-flight on multiple occasions!

Real birds are able to precisely control each wing during flight which enables them to do all sorts of aerobatic maneuvers. This has been a very difficult feat to achieve in bird-inspired robots. In fact, prior efforts (including our own mentioned above) utilized only simple wing motions where both wings are driven by a single motor. So motions of two wings are coupled. Minor adjustments can be made in wing motions by using small secondary actuators. But two wings cannot move completely independently. In the past, any major change in the wing motion had to be accomplished by doing a hardware change on the ground. Clearly this limited how close a robotic bird came to the real bird in terms of the flight characteristics.

I wanted to build a bird with completely independent wings that can be programmed with any arbitrary motion profiles. We did a preliminary experiment five years ago, but unfortunately it was not successful at that time. So we shelved the idea for few years. Hugh Bruck and I revived the idea again about a year ago. I am happy to report that we finally had a breakthrough last week. The students responsible for this success are Eli Barnett, John Gerdes, Johannes Kempny, Ariel Perez-Rosado, and Luke Roberts. Our new robot is based on a fundamentally new design concept. We call it Robo Raven. It features programmable wings that can be controlled independently. We can now program any desired motion patterns for the wings. This allows us to try new in-flight aerobatics that would have not been possible before. For example, we can now dive and roll. Please see below for the video of Robo Raven. 


The new design uses two actuators that can be synchronized electronically to achieve motion coordination between the two wings. The use of two actuators required a bigger battery and an on-board micro controller. All of this makes our robotic bird overweight. So how do we get Robo Raven to “diet” and lose weight? We used advanced manufacturing processes such as 3D printing and laser cutting to create lightweight polymer parts to reduce the weight. However, this alone was not sufficient. We needed three other tricks to get Robo Raven to fly. First, we programmed wing motion profiles that ensured that wings maintain the optimal velocity during the flap cycle to achieve the right balance between the lift and the thrust. Second, we developed a method to measure aerodynamic forces generated during the flapping cycle. This enabled us to quickly evaluate many different wing designs to select the best one. Finally, we had to perform system level optimization to make sure that all components worked well as an integrated system.

Robo Raven will enable us to explore new in-flight aerobatics. It will also allow us to more faithfully reproduce observed bird flights using robotic birds. I hope that this robotic bird will also inspire more people to choose “bird making” as their hobby!

Robotic birds (i.e., flapping wing micro air vehicles) are expected to offer advances in many different applications such as agriculture, surveillance, and environmental monitoring. Robo Raven is just the beginning. Many exciting developments lie ahead. The exotic bird that you might spot in your next trip to Hawaii might actually be a robot! 

Friday, April 19, 2013

Cloud Robotics: Are We Ready to Put the Robot Brain in the Cloud?

Clouding computing is inspiring roboticists worldwide to break the mold on traditional robots and harness the power of clouds to create the next generation of robots. This new exciting development is being called cloud robotics. In my opinion, this development is very timely and not coincidental. As humans we are increasingly keeping at least a part of our brain in the cloud. You have outsourced a brain function to the cloud, if you
  • used Facebook to remember your friend’s birthday;
  • used iPhone app to get directions to your favorite restaurant;
  • used Wikipedia to recall the name of the fourth Beatle;
  • used Google to search recipes for making cheese sandwiches.
So why should robots not follow this trend? The cloud computing promises the following three major advances in the field of robotics.
  • Once the robot brain lives in the cloud, design constraints fundamentally change. Robots can have practically unlimited computing power. It eliminates design constraints and gives tremendous freedom to robot designers. I will list a few noteworthy opportunities. Performing faster than real-time high-fidelity simulations to aid the plan generation is currently an unrealizable goal using on-board computers. Two of my students, +Josh Langsfeld  and  +brual shah tell me that this is now practically within our reach using the cloud. We do not need to add unnecessary weight on the robot to protect its brain. Robots can be made really small if they don’t need on-board powerful computers. Hopefully, they will consume a lot less power and can work a lot longer on single a battery charge. As you can imagine, suddenly the world is full of new design possibilities!
  • Robots can access large databases (e.g., maps, images, videos). We may need to build different interfaces so that robots can use web to search and understand results they get back. But there is no reason why a robot should not be able to access Google, Facebook, Wikipedia, YouTube, and OSRF Blog.
  • As new information is discovered, it becomes instantly available to robots. This facilitates new modalities for operation of robot teams. If a robot learns a new skill, all robots with similar capabilities would be able to use that skill. I am sure that this last capability will make us human quite jealous of robots. Won’t it be nice if you are able to use the cool new golf swing the moment your friend masters it after spending three weeks in the miserable heat to learn it?
Many different kinds of robots such as self-driving cars, robot swarms, and healthcare robots can potentially benefit from cloud robotics. But there are three main challenges in embracing cloud robotics and using it in practice.
  • Using the cloud as the brain requires connectivity to the cloud. What happens if the connectivity to the cloud is poor or lost? We certainly will need to make sure that the robot will have on-board “little brain” to make sure that they remain safe while they are unable to use the “big brain” that resides in the cloud. We will need to figure out the coordination between two brains.
  • What happens if the cloud is hacked? Hackers could deliberately send malicious information or instructions to robots. How can a robot know if the information coming from the cloud is reliable or not? We will need to figure out new ways to authenticate information coming from the cloud to ensure that robots and people around them remain safe despite threats of compromised clouds.
  • Unwanted software upgrades are painful for many humans (this one of my pet peeves!). When you use the cloud, you have virtually no control over what gets upgraded and when it gets upgraded. Unfortunately, a really small change in the information structure might pose a big problem for robots. We will need well-defined semantics to exchange information with robots and will need to hope and pray that cloud providers are kind to our robots as they plan software upgrades. I am normally not worried about a robot rebellion. But unwanted software upgrades might push robot to rebel against humans.
I would like to hear your thoughts on how cloud computing will affect the field of robotics. Are we ready for cloud robotics?

Friday, April 12, 2013

Eight Innovations that are changing the manufacturing industry

I spent the summer of 1987 being an intern at a leading truck manufacturing factory in India. Every day as I walked around the factory floor, I saw machines giving “birth” to new parts. This was the beginning of my fascination with manufacturing and automation technologies.

The field of manufacturing gives humans the capability to make things that do not exist in the natural world. All comforts of the modern life can be directly or indirectly attributed to manufacturing. I believe that automation augments human capabilities and allows us to realize more with less human effort and so the standard of living rises for everyone.

This post is focused on the manufacturing innovations in the last twenty five years and their impact. I would like to set the stage by first reviewing six notable limitations and constraints that existed in late eighties despite remarkable advances in manufacturing enabled by the use of robots, numerically controlled machines, and computers.

First, it took days to program robots and machines. It took even longer to debug those programs to make sure that they did not cause any accidental damage. Going from engineering drawings to physical parts took weeks if not months.

Second, if you were an inventor with a brilliant idea living in a small town, you had to physically travel to the nearest city that had an advanced manufacturing facility. So the access to the advanced manufacturing was limited.

Third, you would not use words “affordable” and “advanced manufacturing” in the same sentence unless you were telling a joke. The access to the advanced manufacturing required major capital investments.

Fourth, advanced manufacturing consumed a lot of energy and generated unwanted emissions and waste.

Fifth, your material choices were limited unless you had a multi-million dollar development budget. You simply could not open a catalog and find lightweight, thermally conducting, and electrically insulating material.

Finally, operating an advanced manufacturing facility required significant human expertise. For example, robots and machines had to be manually programmed using low level languages. You needed experienced operators to “babysit” machines and robots and be ready to hit emergency button if things went wrong.

The above described limitations and constraints had significant impact on the innovation process. It impacted who could participate in it, what kind of innovation could be realized, how long it would take to bring a new innovation to the market, and how much the resulting products would cost.

Many manufacturing innovations have emerged in the last twenty five years to address the above described constraints and limitations. The following eight, in no particular order, are my personal favorites:

  1. 3D Printing: 3D printing (AKA additive manufacturing) allows converting 3D CAD models into physical parts automatically. It does not use part-specific tooling or setup. It can make very complex shapes and can be operated with minimal expertise. Designers are now able to access 3D printing processes over the Internet. Please see an earlier post for more details on 3D printing.
  2. Second Generation Industrial Robots: The use of the first generation industrial robots was confined to simple tasks (e.g., welding, painting) on production lines. They were fixed in a cage and isolated from human workers to prevent injuries. Recent advances in robotics are fundamentally changing these norms. Mobile manipulators can go to workpieces to work on them. Dexterous hands enable robots to work on complex tasks. Robots can program themselves by observing human demonstrations (e.g., Baxter from Rethink Robotics). Safe Robots with novel safety features have been developed that enable human and robot collaboration on manufacturing tasks. Please see another post for more details on these developments.
  3. Low Cost Laser Cutters: One can get a brand new laser cutter for less than $10K and can use it to go from a CAD model to a physical part in a matter of minutes for reasonably complex geometries. Currently this technology is limited to mainly cutting two-dimensional shapes. I would also like to mention waterjet cutters that can cut a wide variety of materials and can easily cut through several inches thick steel. Both of these processes are quite accurate, extremely simple to use, and can be setup in less time than perhaps what will take you to read this post. Please see another post for more details on this development.
  4. Micro Manufacturing: Advances in manufacturing at small scale, especially micro molding and silicon micro machining have produced sensors and devices that are low-cost, small in size, energy efficient, and fast. These have helped in reducing the cost of manufacturing equipment and also led to many new products.
  5. Internet-Based Manufacturing Services: Today, if you have Internet connection, you have access to manufacturing facilities. You can directly order parts from manufacturers (e.g., www.protomold.com), let a broker find you a manufacturer (e.g., www.mfg.com), work with a representative for manufacturers (e.g., www.quickparts.com) on the Internet. Please see another post for more details on these developments.
  6. Desktop Virtual Manufacturing: The cost of computer-aided design and manufacturing has come down dramatically and these software tools can be used to speed up the manufacturing plan generation and simulate the manufacturing system before making the part. We have reached a point where we no longer need to do physical dry runs for programs and “babysit” machines and robots.
  7. Green Manufacturing: Recent advances in manufacturing have significantly reduced the energy consumption (e.g., electric injection molding machines) and reduced negative environmental impact (e.g., coolant free dry machining).
  8. Polymer Composites: By mixing polymers with micro and nano scale ingredients, new materials are being created that have remarkable properties. The ability to injection mold these polymer composites is reducing the processing cost and making polymer composites an economically viable option over metals in many applications. This development has created many new options for designers.
The purpose of this post is to celebrate ground-breaking manufacturing innovations that are reshaping the industry. But the limitations that I identified above still exist in many segments of manufacturing industry. Moreover, what appears to be a norm today is likely to appear a major limitation in the future. So we have to continue advancing the frontier.

I have shared my personal favorites based on my own biases and experiences. What are your favorite manufacturing innovations? I look forward to your comments.

Friday, April 5, 2013

Can open source hardware movement be used to realize low cost educational robots?

Robots are expensive! A simple robot arm costs more than ten thousand dollars. On the other hand, a state-of-the-art dish washer costs less than a thousand dollars. These two are not significantly different in terms of size or complexity, so what is the reason for such a large difference in their prices?

Most robots today get produced in relatively low volumes while popular dish washer models get produced in high volumes. This means they use different manufacturing approaches. Amortized setup and tooling costs are much lower in high volume production. High volume production lines use a high level of automation so human labor costs are reduced. Inventory costs are also much lower for products that sell in high volumes. Finally, amortized research and development costs are much lower for products that sell in high volumes. All of these factors combined together lead to higher sticker price for robots that are produced in low volumes. For obvious reasons, robots with high sales volume are relatively inexpensive (e.g., iRobot Roomba and Lego Mindstorms).

I am particularly concerned about high costs for educational robots.  Robots have emerged as wonderful teaching tools, and we ought to be using sophisticated robots in our classrooms. Unfortunately, most schools cannot afford them at current prices since we need robots that cost less than one thousand dollars. It is highly unlikely that production volumes for robots will go up dramatically over the next few years and bring costs down to below the one thousand dollar mark. We need to explore other ideas to reduce costs of educational robots.     

The open source software concept is revolutionizing the software industry. A newcomer can get started with very little initial investment and build upon the software created by others. The robotics community has embraced the open source software notion wholeheartedly.  The Open Source Robotics Foundation and Robot Operating System are leveling the field and giving an opportunity to a large number of participants to contribute to robot software development. Regardless, we still have a major problem in terms of access to the sophisticated hardware.    
The open source notion has been successfully used by the 3-D printing community in the context of hardware.  Open source hardware has led to a dramatic decrease in cost and helped in realizing low cost 3-D printers (e.g., RepRap and Fab@Home).  The robotics community is taking inspiration from this success and beginning to embrace the concept of open source hardware.   

The open source robot hardware idea calls for publishing the complete design details in an open forum. These details should include 3-D models for custom parts, instructions for making custom parts, detailed specifications for standard parts, instructions for assembling the robot, associated software for operation, and instructions for operating and maintaining the robot. 

Since people fabricate their own robots using open source design, this concept eliminates the need to pay for labor and inventory costs. People can buy components from low cost sources and reuse components from one robot design to other.  For example, a laptop can be shared across many different robots. Overall, this concept can be used to dramatically reduce the cost of acquiring a robot if one is willing to put time into building it.               

Curiously enough, the open source hardware cost model shares ideas from IKEA’s cost model that has allowed this Swedish company to sell furniture at low costs. IKEA’s model leverages three factors in reducing costs. First, it eliminates assembly costs. Second, shipping and storage costs associated with components are very small compared to shipping assembled furniture. Finally, despite offering a large variety of furniture, IKEA uses many shared components across furniture lines and is able to reduce component costs due to the economy of scale.   

Two undergraduate students in my lab, +Gregory Krummel and +Gina Knight have developed designs of two open source robots.  These designs were developed with educators and hobbyists in mind. The first one is an eight degree of freedom robot inspired by crocodile (please click here to see the video). This robot features an articulated tail, mouth, and legs, and it can demonstrate walking abilities and obstacle avoidance. The second one is a twelve degree of freedom robot that can climb stairs (please click here to see the video). Written instructions and computer-aided design (CAD) files can be found in the video descriptions. Individuals can fabricate and/or purchase their own parts from electronics suppliers and build these robots. These robots offer a new learning opportunity for those with an interest in robotics. 

Crocodile-Inspired Robot
Stair-Climbing Robot
I envision the following three different models around the open source robotics hardware movement.
  • People make custom parts on their own, purchase standard parts, and assemble the robot.
  • People buy pre-fabricated robot kits from suppliers and assemble robots.
  • People purchase preassembled robots from the suppliers based on open source design.
Once adequate numbers of open source robot designs are available, companies can use the free open source design files to fabricate parts and aggregate them with standard electronics into a kit to sell to those who do not have the equipment to make parts themselves.

The open source hardware concept is much more challenging in practice compared to open source software.  Hardware obsolescence is a major concern. Access to manufacturing equipment for making parts is also a challenge. We need to find ways to overcome these obstacles.  

Open source robotics can also promote innovation in the field of robotics. Interested individuals can begin with an open source robot design and improve parts of it. This is much easier to accomplish then designing and realizing a complete robot from scratch.  

I am looking forward to hearing from other groups that have developed open source robots. It will useful to compile a list of best practices in developing open source robot hardware.   

Can open source hardware movement be used to realize low cost educational robots? Please share your thoughts by posting comments on this post.