Tutorial Presentation on MPC for Aircraft

Thank you to Pantelis Sopasakis from IMT Lucca for inviting me to participate in a tutorial session on Model Predictive Control for Aerospace at the European Control Conference in Linz, Austria.  Presentation topics ranged from spacecraft rendezvous to UAV guidance.  I limited my talk to fixed-wing aircraft, but covered three different case studies:

• Nonlinear MPC for a UAV avoiding oncoming aircraft
• Mixed-integer linear MPC for an aircraft flying in a forest
• Mxed-integer linear MPC for air traffic flow

Click here or on the image below to get the slides from my talk.

And to close, a nice picture of the Danube by night!

Flying a Drone in the Royal Institution Christmas Lectures

In December 2014, the first cohort of FARSCOPE Centre for Doctoral Training students developed an automated drone cymbal player to take part in an RI Christmas Lecture.  FARSCOPE Director Arthur Richards reflects on the experience.

The Royal Institution approached Bristol Robotics Lab in November 2014 to ask if we could contribute a drone to their robot orchestra project, inspired by this YouTube video and others.  The brief was quite broad: get a drone to play something somehow.  We agreed to investigate and see what we could do.  In particular, we made this a "crash project" for the new FARSCOPE students, perhaps a poor choice of term under the circumstance, but highlighting the emphasis on simplicity and timeliness of whatever we came up with.

Drones are tough to control with great accuracy, so we quickly narrowed our ideas down to percussion.  My personal, and slightly ironic, wish was to have a drone play the triangle This urge was quickly subdued, both by the drowning of the triangle sound by the motor noise, and the alarming response of the drone when affixed with a beater and flown into a triangle.  It was clear that some sort of transmission would be required to strike the instrument.  Electrical transmission was ruled out, as we wanted it to be obvious that it was really the drone making the noise.  Therefore, we had a requirement for a mechanism that would convert some motion of the drone into motion of the beater striking the instrument.

CDT Student Dave wheels the drone kit into the Faraday Lecture Theatre

Around this point, I started to have unsettling thoughts about a drone flying into a live audience of youngsters, never mind in front of TV cameras.  Consultation with the production team indicated that a perspex shield would give reflection problems, and our ideas for cages made fishing wire just seemed pretty outlandish.  So, the drone would have to be tethered.  This neatly solved the mechanism debates as well, as the tether would serve to actuate a beater.  So, with a few weeks to go, we had a concept: a drone tethered to a pivoting arm, which would crash into a cymbal when pulled upwards.  All this could be mounted on a trolley, conveniently also serving as transport and landing pad.

Meanwhile, other details had been falling into place.  Students had been building QAV250 quadrotor drones and equipping them with Naze32 flight stabilizers.  These turned out to be excellent machines, mechanically robust, well-stabilized, and easy to fly for beginners, so very suited to our needs.  Some Arduinos were programmed to take commands from our ROS environment and convert them to PWM streams for the trainer port of our radio transmitters, with an added emergency stop functionality.  With our Vicon motion capture system tracking the drone, we were able to close the loop.  One day we may share the radio control bridge and PID tuning packages with the ROS community, but it's the nature of crash projects that things aren't done as tidily as they could be.

Students put finishing touches to the drone landing pad in the RI library

With a van full of spare drones, computers, markers, cameras, tools and fishing wire, we headed to London for the first of two long days rehearsing and filming.  With plenty of practice in the lab and enough spare kit to do the whole project twice, we would be confident, but nevertheless the first successful cymbal clap when hooked up to the orchestra was a great relief all round.  As so often in robotics, the thing that came closest to stopping us was a flaky network.

One surprise was yet to come: the producers liked the drone so much they wanted to make more of it, so we quickly contrived a demo for it to follow an external target.  For comedy reasons and as a nod to the computer vision world, it had to be a teapot.  It's a great credit to the students involved that an extra function was written into the software at about an hour's notice, but that went on to work beautifully.

FARSCOPE students at the control station, backstage at the RI.

You can see the finished product late on in the video at the RI Channel: Sparks Will Fly: How to Hack Your Home  For the cynics, there was absolutely no cheating involved.  There was a manual transmitter out back but it was never used during filming, and the only manual intervention was me pressing the button to land the drone, giving lecturer Danielle a bit of a fright.  (Ground effect when the downwash hits a surface makes it hard to fly a drone very low and keep it tightly controlled - you're better off just cutting the power once low and slow.)  Everything you see in the video is genuinely automated, with students pressing only a start button and switching the teapot tracking on and off.

So what do we learn from all this?  Drones will clearly not be great musicians in the near future.  Still, the students learnt a wide range of practical skills through this exercise, from ROS use to drone construction.  Time management, teamwork and the importance of testing were also reinforced, although this was far from a good model of systems engineering.  Finally, it was great for those of us running FARSCOPE in its first year to explore the flexibility and responsiveness that the Centre for Doctoral Training gives us.

Show and tell

I've been doing lots of demonstrations and presentations lately - here's a collection.

First was a very interesting workshop at the ASAP group in Nottingham, supported by the LANCS initiative, talking about applications of operations research to air transport problems.  Agenda and talks are available for download here, including my report of our work on aircraft taxi optimization and air traffic flow management.

Next was a more high level event at Southampton, the Autonomous and Advanced Systems Showcase event.   This covered various opportunities and initiatives at the intersection of aerospace and autonomous systems, ranging from market opportunities to the latest research details.  Extensive video reporting can be found here, including my report on the work of Bristol Robotics Lab in this area.

The Duke of York visited BRL on Feb 10th and was treated to, among other things, a display of our autonomous flying robots in a building exploration scenario.  The photos are here.

And finally, I was asked to comment on the recent Amazon UAV delivery proposals by a packaging trade magazine.  The article is here.

FARSCOPE Centre for Doctoral Training - NEW WEBSITE

The new and settled home for information on the FARSCOPE Centre for Doctoral Training in Robotics and Autonomous Systems is: farscope.bris.ac.uk

FARSCOPE

In 2014, the Bristol Robotics Lab (BRL) will be launching a new Centre for Doctoral Training in robotics and autonomous systems.  The Centre will offer a joint PhD degree run by BRL's two partner universities, the University of Bristol and the University of the West of England.  The Centre is funded by EPSRC following their CDT 2013 competition.

The new CDT is entitled "Future Autonomous Robotic Systems Centre of PhD Education" - FARSCOPE.  In time FARSCOPE will have its own website with full information on the programme and how to apply.  Until then, the latest information and news for prospective students will be found here.

Theme

FARSCOPE is all about making robots more adaptable.  Instead of doing the same jobs over and over in  large factories, they'll help us in our homes, work alongside us in small businesses, and deal with hazardous situations while we keep a safe distance.  To make all this happen, we face three challenges:

•  robots being part of society, interacting with people, machines or other robots, and handling all their unpredictable behaviour
•  robots operating in uncertain environments, sensing, mapping and moving where existing maps and plans are inaccurate or unusable.
•  requiring different roles of robots with regular changes, for small batch jobs in small businesses where two days downtime to reprogram isn't an option.

Together, these challenges make up our theme of adaptability.  The technologies involved are diverse and the applications are many, but anything to do with the three challenges above is within the remit of FARSCOPE.

Programme

FARSCOPE enhances the "traditional" PhD content of individual research with taught content on a range of robotics topics and more general skills.  Not only does this better prepare you for PhD research, but it gives you a broad view of robotics and autonomous systems that we believe is essential. There's so much to be learnt by seeing what's been done in different fields and applications: manufacturing benefits from autonomous exploring ideas and spacecraft can exploit UAV breakthroughs, to name just too.  In short, we want you to be adaptable too, in your skills and what you can do with them.

Year 1

• Research methods training
• Seminars in modern robotics methods
• Robotics, mechanics and programming
• Robotics context and applications (industry delivered)
• Robot intelligence and systems
• Specialist robotics topics (chosen from list of options)
• Group robot project (eg IMAV contest, robot soccer or Mars rover field test)
• Initial research project
• Communications training and research presentation

Year 2

• PhD research
• Industry study workshop
• Innovation and entrepreneurship
• Complementary skills training

Year 3

• PhD research
• Industry study workshop
• Partner placement (optional: opportunities at partner universities in Europe, Asia, North America or partner companies in the UK and Japan)
• Public engagement training and group activity

Year 4

• PhD research
• Complementary skills training (including thesis preparation)
• FARSCOPE conference presentation

More Information

More details will appear here and on our website as it becomes available.  For questions or if you're interested in applying, please contact arthur.richards@bristol.ac.uk

Flying Robots

This video actually dates back to January and we've done more since, but I've been meaning to post it anyway.  The video shows three different runs of the same controller, flying a Parrot AR.Drone through a virtual array of obstacles (i.e. the computer thinks they're there, but they're not).  The controller uses Model Predictive Control (MPC), solving a constrained optimization every 20ms to decide what to do next.  The clever bits are converting the global problem into a convex local optimization that we can solve quickly and deploying the solver in Simulink so the whole thing can be controlled by a dSpace MicroAutobox.  THe control is a little wobbly here but we've fixed that now, with disturbance estimation, better terminal constraints, and some careful tuning.

This work was carried out in our indoor flying arena.  (Much of the purpose of this post is to provide an excuse to post the photo of this arena below.)  This is an empty space 15m x 12m x 4m high, enclosed by curtains and instrumented with a Vicon motion capture system, now up to ten cameras.  We don't currently build our own aircraft - we just buy them off the shelf, so we can concentrate on developing the controllers for them.  The end goal is to make micro air vehicles (MAVs) that are more autonomous, able to say fly into a damaged building, explore and then come back out, without needing a highly skilled pilot to fly it and keep track of where it is.



One way you can get involved in research like this is our joint Robotics MSc, run by the University of Bristol and the University of the West of England.  The degree is based at the Bristol Robotics Lab and includes the opportunity to do research projects using our flying robots.  More details can be found at http://www.bristol.ac.uk/engineering/interdisciplinary/robotics/ 

Visiting

Use the map below to help find me! Visitor parking at the University can be found at the yellow "P" markers. Spaces must be pre-booked. Zoom out for the airport.
View Visiting Arthur Richards in a larger map