Selene: The University of Surrey Lunar Rover

The results!

surreylunarrover — Thu, 30 Oct 2008 12:00:32 +0000

Congratulations to Bremen University for winning the ESA Lunar Robotic Challenge! And congratulations to all the other teams for building and bringing their robots to Tenerife. It seems the challenge was a lot trickier than anticipated with Bremen being the only team to complete the challenge in full, and bad weather on day 6 halted the trials for both Pisa teams.

We on the like to extend our thanks to everyone to has helped us and organised the event. Thanks to ESA and Active Connect on site for getting everything up and running for a smooth and well organised week on site. Thanks to the other teams for their kind words after we encountered problems with Selene, thanks to everyone in the University of Surrey FEPS workshop and UG labs, thanks our sponsors, thanks to the admin staff at Surrey FEPS for putting up with all of our requests, thanks to Excel Air Freight for getting our equipment to Tenerife and back, thanks to Lincad for providing us with an excellent set of batteries and thanks to everyone else who helped us out over the past 4 months, sorry if I haven’t named you specifically!

Check back for the videos from the week soon!

Day 5 – Bad news…

surreylunarrover — Sun, 26 Oct 2008 01:17:33 +0000

Unfortunately our trip to hunt for replacement motors was unsuccessful. As such our current motors are in too poor a state to continue as a participant on the LRC, and we have had to retire from the challenge

The damage to our bearings prooved too great for repairs and the available torque in our motors is not great enough to compensate. Thanks to everyone for their offers of help and condolences!

Our earlier attempt at salvaging the track design

We have stayed, however, to observe how the remaining teams get on in the live challenge events this evening and Saturday evening.

Michel venting his anger on Selene!

The teams selected for Friday night were ourselves, Oulu, Jacobs and Madrid.

Oulu had a great start, and quickly made it into the crater, however after searching the crater floor for a short while they had a fatal failure, which later turned out to be a blown fuse, which ended their run in the LRC.

Oulu setting off!

Jacobs were up next, and after some interesting communication issues at the start (both their rovers performing the same movements in an odd little dance!), and several resets managed to make it into the crater floor using their flippers for additional support. They were successful in finding and approaching the sample however due to its location and sprocket issues they were unable to complete the mission as well.

Jacobs setting off!

Madrid were the last competitors of the night and had a great run into the crater floor, however camera and motor issues also ended their run prematurely.

Madrid preparing Moonhound

Overall it was a very long, and very cold night, with the terrain and mission challenges proving to be far more taxing for all the teams than expected! We’ll have videos up next week, in the mean time here are a selection of photos!

Dr Lappas and Sam, wrapped up warm against the bitter wind and cold conditions

Beatrice and Chris (me!) wrapped up against the elements

Michel in a cheesy self shot!

Day 4 – Problematic

surreylunarrover — Sun, 26 Oct 2008 00:42:56 +0000

Today we started late to allow for night trials. After stuggling to get our flippers working correctly we decided to get the rover drive system online and on the ground. Unfortunately luck was not on our side.

Selene on her only trip outside

Soon after getting Selene out and onto the ground we quickly had issues with the drive system, our power was misbalanced between the left and right tracks and the rover was suffering from constant stalls. Once back in the workshop van we quickly found out that the bearings on our motor drive shafts had spectacularly failed, littering the gear boxes with tiny ball bearings and completely shattering the metal collar holding them in place. The implication of this was to leave the drive shaft unlubricated and unbalanced.

Our only hope was to try and find replacement motors in the morning, our drill has a 20Nm motor, we hoped to find similar replacements in Santa Cruz!

In the mean time Sam and Michel continued to work on improving and tweaking our software. Sam managed to incorporate the majority of our system controls into a single application, while Michel tried an alternative method of receiving our video stream.

Michel slacking off again

We also got at better idea of how the site would be at night. Here is the test area in the day time:

Lunar testing site by day

And the challenge crater at night!

Challenge crater at night

We also got a look at the sample sand we would have to collect once in the crater.

Red gravel!

We could only hope for better luck in the morning and try to replace our motors.

Here’s a video log from earlier in the day (it is actually from day 4, even though I say day 3!)

Day 3 Videos!

surreylunarrover — Thu, 23 Oct 2008 09:27:29 +0000

Here a a couple of videos we shot on site yesterday. First a quick tour of our workshop:

And a video log at the end of the day:

We’ll try and get some more vids up after tonights trials!

Day 3 – A bit of a washout!

surreylunarrover — Wed, 22 Oct 2008 22:21:31 +0000

Unfortunately one of our mechanical systems has been giving us problems after the fix we prepared before flying out failed to work as well as we had hoped. We have now finished rebuilding Selene however by the time we were ready to test the performance on the “lunar” ground thick cloud had moved in and soaked the entire LRC site! Hopefully tomorrow will bring better weather and we’ll find out how Selene performs!

You can't really tell from this photo but it's really cold and wet here! Everyone has had to retreat into their workshop vans

The Bremen University guys came prepared!

Luckily the friendly ESA support guys have plenty of biscuits and hot tea and coffee available!

Day (1 and) 2 – setting up

surreylunarrover — Wed, 22 Oct 2008 07:30:50 +0000

The first day was pretty tiring, after leaving the UK at 5am and driving across the island to the north airport to pick up the last member of our team to arrive, Michel. We also found the great hotel a 40 minute drive away from the site. Things were still being set up there however and we had to head to the kick off meeting.

Gianfranco from ESA welcomed us and the support team, however it looked like everyone was eager to get started on the challenge!

Day 2 was the first day on site. We got given our van/workshop and unpacked the gear!

Our on-site workshop

Silly euro plugs!

We still have some parts to incorporate into the chassis, so most of the day was spent rebuilding Selene.

Everyone working hard (except for Michel slacking off to take photos!)

The location is over 2000m high, and it switches between moderately warm and almost freezing cold, and that’s during the day. The night time events are likely to be extremely cold! We do have some spectacular views however and even ended up in a cloud at one point! Here are a selection of photos from day 2.

Base camp

Tasty ESA snacks!

Sams soldering iron collection

A light mist at the end of the day!

And we’re off to the Canaries!

surreylunarrover — Sun, 19 Oct 2008 22:17:51 +0000

We’ve been getting all our last minute preparations done this week and in a few hours we’ll be flying out to the Canary Islands! We’ll be meeting Selene, who flew out earlier last week, at the LRC site, so it’s probably time to reveal the Surrey Lunar Rover!

You may remember we began with a Mobile Robots Pioneer 3-AT:

Mobile Robots Pioneer 3-AT during sample collection tests with the arm

For which we created a completely new mobility system, basing the control side on the Pioneer internal components:

Mobility design

Ladies and Gentlemen, after 4 months of extremely hard work, the University of Surrey LRC team give you Selene!

Selene, the University of Surrey Space Centre LRC Rover

We’ll be doing daily updates throughout the challenge, so check back to hear from us in Tenerife!

On-board computing

surreylunarrover — Fri, 03 Oct 2008 20:42:22 +0000

Thanks to the Pioneer’s background as a research ‘bot, it comes equipped with a rich C++ API allowing for easy programmatic access to the microcontroller, via a serial link from the on-board PC. This has given us a great head start getting control software for equipment like the robot arm and motor control working quickly and effectively.

As mentioned in one of the previous posts, we’re using a simple 802.11-based wireless ethernet link between the lander site, the navbot and our Pioneer rover. Our ground control station will consist of a setup of laptops and large screens, allowing us to view the various video streams and telemetry from the rover, as well as controlling its movement, track deployment and arm control. Mobile Robots provide a small suit of control applications designed for use over a wireless link, which we have applied and combined with additional applications to allow us complete control of the rover while it is performing its mission (or at least thats the theory!).

We have tested these application thoroughly and had great success in remotely controlling the rover once out of visual range. So control in the crater shouldn’t be a problem.

Integrating everything into the Pioneer shell

surreylunarrover — Fri, 03 Oct 2008 20:41:57 +0000

So the Pioneer, while a great base for software development for rover control and autonomy, wasn’t really designed to undertake quite such a heavy set of physical modifications as those we have applied. As we’ve spoken of before, the large, wet-cell batteries were replaced with a smaller, low-profile Li-Ion battery in order to make room for the additional equipment we have designed. This was just the beginning…

Without going into specifics, the new rover has a refined drive system, track pitch drivers and a reshuffle of the other odds and ends the rover needs to run (the microcontroller and OBC…!). Let’s start with the base model.

The Pioneer 3-AT is a four-wheel drive, wheeled rover. Internally there are 4 electric motors, with two each driving a pair of wheels each via a belt. The remainder of the internals are fairly inefficiently stacked around these motors and the wet-cell batteries.

So, while our new battery saved some space, we had to fit additional motors inside to adjust the the tracks and still retain enough space to fit all the original equipment back inside! Here’s the mounting bracket with the motors attached, ready to be fitted inside the chassis.

Motor mounting

Once securely in place we attach our replacement drive chains, providing a more compact and stronger drive system for the tracks. The remainder of the internals just about fit over these.

Our tracks are currently being tweaked to get the best performance and we hope to have them finalised early next week. The axles, while similar and in the same positions as the originals, have again been modified to allow the track structure to rotate independently of the track belts, not the easiest of problems to overcome, but so far our solution seems to be doing the trick!

Navigation

surreylunarrover — Mon, 29 Sep 2008 22:03:15 +0000

While we’re furiously working away to complete the rover construction in time for the challenge, the majority of our other systems are complete. The next one we’ll talk about is the navigation system.

While this is clearly crucial to completing the mission the on-board vision system is relatively basic. We are using a stereo-camera to provide a live video stream back to our ground-station/control centre. This will be our primary vision system and used to navigate the rover, search for the samples and aid the robot arm when collecting them. In order to make full use of the capabilities this provides we have mounted the camera to a pan and tilt unit. Coupled with a pair of bright headlights we will be able to use this unit to pan around the crater floor once inside to search for the samples, without wasting additional power driving around the site.

The video below shows the PTU with the camera and headlights attached, in both lit and and unlit conditions.

And here’s our dev-bot with the arm attached on the back and the camera on the front. These will be next to each other on the final rover however this allowed us to check the camera was capable of giving a clear view of the arm workspace. It looked great!

The devbot rover with arm and PTU/camera/headlights attached. The combined unit did a great job of illuminating and videoing our lab!

Also visible in the photo above is the prototype part for the secondary area of our navigation system, the long bar with coloured LEDs at each end. These lights will be attached at the very front and back of Selene, and will allow us to use our relaybot camera to orientate ourselves back toward our entry point once we have collected the sample.

The relaybot, with the camera visible mounted on the front

The principle is fairly simple, while the primary purpose of the relaybot is to allow for wireless communications between the lander site and Selene once inside the crater, the fact that it will have some element of mobility will allow us to position the relaybot on the edge of the crater rim, where we estimate that it’s field of view should cover the entire site we have to explore. Once we have located and collect the soil sample the relaybot camera will detect the alignment of the red and green LEDs mounted on Selene. Once directly pointing at the relaybot we will have a clear indicator that we are pointing at our entry point, and therefore the optimal location to exit (in order to achieve maximum points!). We anticipate becoming easily disorientated and lost after searching the crater floor, this system will allow us to quickly regain our bearings and direct the rover back home to the lander!