Power System

The Pioneer 3 is powered by 1 to 3 lead-acid wet cell batteries.  These provide a nominal 21AHr of energy, and under normal use should provide power for Selene well over the 2 hour time limit for the challenge.

However, they are particularly large and heavy.  So thanks to the guys at Lincad, we now have a Li-Ion battery pack roughly half the volume (casing aside) and less than half the weight while retaining the same 21AHr capacity of the originals!

 

The new, smaller Li-Ion battery underneath the original Lead-Acid cells.

The new battery provides a number of benefits, the most significant of which is the more convenient shape.  The new battery sits in the belly of our chassis, lowering the center of gravity and providing easy access through the bottom of the rover.  The smaller size leaves room for the additional flipper control mechanisms inside the chassis.

Sample collection

As promised here is some more info on one of our subsystems, used to collect the sand sample we’re going to be looking for once inside the crater.

The robot arm is a 5 degree of freedom manipulator provided by Mobile Robots as a Pioneer 3 accessory.  As standard it is equiped with a two-finger gripper, however we have modified this to carry a scoop/storage container tool.

Robot arm, here attached to our development Pioneer, holding a sand sample

This over-sized scoop is placed in position by the arm.  Once collected the sample will remain safely in the container as we return the rover to the lander, where it can be detatched and deposited.

Updates are a’coming…

It’s been quiet on the blog recently as we’ve been hard at work getting our rover up and running ready for the challenge on the 20th October!

We’ll be posting some photos later but here’s a quick run down of our progress to date…

The track lifting mechanism is now completed and working, using our microcontrollers we can stow and deploy the tracks as required depending on the terrain.  Due to the total size of our tracks we just now have to wait for the (patient, brilliant) workshop guys to drill and tap the hundreds of holes needed to attach our grousers to the belts!

The navigation system has been completed, and works in two parts.  We have a stereo camera mounted on a pan-tilt unit for our primary navigation once on-site.  We’re ironing out a few bugs but its nearly there.  The second part is a “home-beacon” system, incorporating our secondary rover/relay station, positioned on the rim of the crater.  As well as acting as a communications relay the rovers on-board camera will detect coloured LEDs on the primary rover in the crater, and the ground-station software will use this to help orientate the rover toward our entry/exit point on the rim.  With the dark environment this is likely to be a crucial aid in the task of returning the sample back to the lander site.

Our communications system is also now completed.  Based on 802.11b/g wireless ethernet, we have successfully completed remote teleoperation and range testing of our development rover, with a total record distance of over 300m, non-line of sight connectivity from the control site!  We also incorporated endurance tests of our new, smaller and light-weight Li-Ion battery pack, and were thoroughly impressed by the results.

More info and pictures will be coming up, and we’ll be posting more regular updates as we approach the challenge date.

A mid(ish) week update

We’re working hard now to finialise our track deployment system. Unfortunately the Mobile Robots Pioneer 3-AT we’re using isn’t too accustomed to being rejigged inside, so we now have a large Pioneer jigsaw puzzle!

Pioneer Jigsaw Puzzle

This required some “delicate” modifications to achieve!

Gently does it...

Now we have individual components we can look at how to rearrange them inside the Pioneer chassis. We’ve done plenty of modeling using CAD to give us some confidence that our modifications *can* fit inside, however it is extremely difficult to tell without trying it on the actual rover, those cables really take up a lot of space! We’re looking at replacing our big, heavy lead acid batteries with much smaller Li-Poly ones, but other than that we need to rearrange all of the existing rover equipment to a way that allows us to fit the track pitch control motors and gearing, a slightly difficult feat due to the requirement for an axle to pass across the entire width of the rover at both the front and back.

We’ve also started range testing the 802.11-based wireless equipment we plan on using to control Selene once its out in the field. This has started with the nanorover we want to use as a comms relay/video link. With some new, high-gain antennae attached to my laptop and the Surveyor SRV1 we managed to boost the link strength a significant distance over its poorly performing standard configuration. It’s difficult to see in the picture below but the tiny rover made it all the way to the bus and was still going strong, giving us a live video link.

Long distance shot

Attaching a similar antenna to the Pioneer gave us a range of nearly 200m line of sight! Check out the pictures below.

A large chunk of our campus for reference

The SRV1 nanorovers 70m range

The 180m the Pioneer got before we ran out of field!

That’s it for now. Stay tuned for more updates soon!

CDR Done and Dusted

A little late coming but here’s the latest news from the Surrey camp!

Last week we attended the Critical Design Review at ESTEC in Noordwijk, Holland, with the other 7 competitors to present our work to date to ESA.  This was followed by discussion of our (and each of the other University entrants) designs.  Fortunately for us our design was met with mostly encouraging noises.  You can see an early CAD model of it below.

 

Selene Concept

We’re looking at taking the Pioneer 3-AT base and replacing the wheel with large, deployable tracks.  This will ensure the greatest amount of traction possible, while making tackling obstables far easier than our earlier designs.  We do this through a control mechanism allowing us to adjust the pitch of the tracks, this makes the rover retain its size constraints when stowed.  The video below shows the tracks deploying.

We’ve also been working hard to build a testing area for our rover designs.  We now have a (VERY) large sandpit giving us a 40° slope of sand to test our designs traction on.  Here’s a few photos of the pit being built.

Sandpit construction 1

Sandpit Construction 2

Sandpit construction 3

 Which has allowed us to try some preliminary track belt tests using one of our existing nanorovers using its standard tracks:

And the infamous video showing it is possible for a low, tracked rover to flip itself over trying to tackle a loose, sandy slope!

And finally our Qualisys motion capture equipment is up and running too, letting us accurately measure the traction properties of our rovers

We have also found out the challenge will be held on Mount Teide in Tenerife.  It’s a popular location for testing of this nature due to its similarities with the Martian and Lunar landscapes.  Here’s the view of our “crater” from Google Earth, it doesn’t look like much here but it definately is from the videos we were shown!

LRC Location

 Finally here’s the presentation we gave for info on all the work we’re doing.

We’re going to get back to work now to try and get our rover up and running for the Test Readiness Review in September!

Getting Started – The First Post

You’re reading the official blog of the University of Surrey ESA Lunar Robotics Challenge team. We’ll be regularly updating this site with pictures, videos and info as we progress through the design and construction of a rover suitable for use in a Lunar environment over the next 4 months.

Firstly, a little background. This summer ESA, the European Space Agency, selected 8 universities across Europe to take part in a Lunar Robotics Challenge. The task is to develop a mobile robot capable of descending into a lunar crater up to 15m deep, down a slope of up to 40°, exploring and searching for soil samples, collecting these samples and returning them back to a lander outside the crater. Simple. The Surrey Space Centre based here at the University of Surrey has a very rich history of successful space technology development. We’re planning on using this experience to help build a fully functional lunar rover capable of winning the ESA challenge.

Our team is a group of Surrey students led by Dr Vaios Lappas, Senior Lecturer in Space Vehicle Control.

Our student team includes myself, Chris Brunskill as the team captain and lead systems engineer.

Beatrice Smith, as a lead systems engineer.

Samian Humphrey, working on our communications system.

Akhmer Ahmad, developing the robotic arm control software.

Shakeel Baig, a power engineer.

Yen and Michel both working on the vision and navigation systems.

Chen, working on the mobility system.

Gareth Meirion-Griffith, analysing the traction properties of our designs.

We’ll be aided with the advice of Dr Paul Newman of the Oxford University Robotics Research Group, and Dr Yang Gao, Dr Eddie Moxey and Dr Chakravarthini Saaj from here at the University of Surrey.

Our rover, named after the mythological Greek Goddess of the Moon “Selene“, is based on a Mobile Robots Pioneer 3-AT. This is a durable platform suitable for off-road use with a whole suite of instruments and accessories (such as cameras, robotic arms and laser range finders) and an extensive development software suite. In its base specification it’s probably not much use in a lunar environment, although its out-of-the-box capabilities at tackling tricky terrain make it a great platform to build on.

We’ve spent some time investigating the P3-ATs mobility and looking at how it can be adapted to the dusty, loose terrain found in a lunar crater. We’ve started by considering how an adapted wheel and suspension system could be implemented. The picture below shows a P3-AT with its standard wheels intact, however its mobility has been enhanced with the addition of a pair of wheels and suspension arms at the front, making the rover more suited to attacking sloped terrain.

Alternatively a P3-AT with two additional wheels and a full suspension system could be used, allowing better distribution of weight to achieve better traction.

We’ve also been brainstorming designs which will allow us to adapt the P3-AT chassis to take a track-based mobility system. Here is a very simple example using the existing wheel hubs and standard wheel-sized sprockets.

And here’s a couple of more complicated designs. These were suggested to enable maximum surface contact area for good traction:

And to retain as much contact as possible while allowing for a more flexible suspension-type system to be implemented:

Once the mobility design is up and running the instruments allowing us to see where we’re going and to collect the samples can be added!

Hopefully that’s given a pretty good insight into what we’re up to down here in sunny Guildford! The blog will be updated weekly at a minimum so subscribe to the RSS feed or check back regularly for new content.

Finally a big thanks to our sponsors for this project: