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Rough Science 4 Death Valley: Jonathan Hare's diary: Rover

Updated Tuesday 29th August 2006

Jonathan Hare's diary about the challenge for the Rover programme, from the BBC/OU series Rough Science 4

Jonathan builds his rover Copyrighted image Icon Copyright: Production team

Before the first challenge…

Fly over from London to Las Vegas in about 10 hours. All OK did some reading. Las Vegas on the other hand is a weird place. After having lunch in LV we all headed off in a convoy of cars to our destination – Lone Pine. Us Roughies all pile into Mike B’s car (he arrived before us) and we take the long roads via Death Valley to Lone Pine.

We pass through desolate valleys and at one moment my home-made altimeter goes off the bottom scale showing we are below sea level; then the next moment it stops at the other end because we go over 2000m above sea level. The long winding road snakes its way through spectacular rocky landscape – reds and browns of the rock with deep blue skies. It is strange to be in air conditioned cars as it feels so cool inside but one gets a feel for the heat outside when one touches the windows – the glass is so hot ! When we get out of the car the hot air feels like a warm liquid running through the nostrils and the mouth – drying up any moisture in a flash.

The air is dusty and makes it difficult to judge distances, one has to go on the speed of the car and how long it takes to get an idea of progress. By this judging one realises that the valleys are tens of miles across and that the road that makes its way through Death Valley area is over a 100 miles long ! Arrive at Lone Pine about 8pm Ellen and Kate waiting for us.

The day before…

Wake up about 5 am after going to bed about 10-11 pm last night. As we are going to be getting up about this time while filming the early start is not too bad. I feel tired but excited too and so it’s difficult to sleep.

Spend the day with Abbi (the programme’s production co-ordinator) in Bishop, one of the local towns buying equipment for the days ahead – chairs, water coolers, cool boxes etc. This was a nice day out and driving around made me start to realise just how big this area is and how the light plays tricks. On the way out in the morning the local hills near to Lone Pine were rocky, brown and bleak looking but coming back in the evening, with the light less harsh one can start to see the green and other colours in the landscape around – very magical – they are the Alabama Hills. In the evening we all go out to a local restaurant but have an early night for the big first day tomorrow.

 
Jonathan builds his rover Copyrighted image Icon Copyright: Production team

Day One

The first day of any filming is usually a long day as there are all sorts of shots to get to set-up the series. I get up about 4.30 am and am ready with the rest of the crew for a 5.30 am start. The series starts with us Roughies flying into the new location in a helicopter.

What is strange about this first day is that the desert is cool! Of course it is still early but it is surprising that it is so cool.

Our challenges for this first programme are varied and include finding water in the desert, purifying it to drink and - my personal challenge - to build a remote control ‘Mars Rover’ machine to explore the area!

For this challenge they have given us quite a lot of high-tech, though basic, household type equipment including battery powered power tools, a guitar tuner and various car type electrical parts and wires. I take one of the drills apart to see how the speed control works and to best understand how I might fix it in place and attach it to the wheels I found on the mine tip.

My first design uses 3 small bicycle wheels; 2 driven by modified electrical hand drills and the last wheel fixed in place on the rear. The thing looks like a sort of Reliant Robin but we have named it the Martian Tok-tok in honour of those 3 wheeled taxis in the Far East.

The idea is that the device is to be powered using the two motors from the power drills, with the wheels being fixed in the chucks of the drills. When power is applied to the drills they turn the wheels, moving the rover. If both the drills are on then the rover goes forward and reversing the motor connections will make the rover go in reverse. By reversing one motor wiring with respect to the other you can make the rover steer left, or with opposite connections - right.

I have already found a problem with this design, though. By reversing the power to the motors I have a simple way of making the Rover change direction. The problem is that as the power is adjusted to steer the vehicle to the left or right, the rear wheel tends to pull sideways when it's meant to be heading forward. It is especially bad if the rover is going slowly and in fact the effect brings the rover to a complete standstill. I hadn’t thought about this problem – what we need is a wheel that is free not only to go round but must also be free to follow the steering like a caster on a piano or the wheels on a trolley.

Good day – much progress.

The Rover
The idea of the rover would be to use the machine to navigate an assault course using only the remote control facilities we could make ourselves. One last challenge was that we could not see the Rover directly and that they would give us a wireless radio camera that would be fixed to the Rover so that it can send back pictures from it – we have then to navigate using this information from the live pictures!

Remote Control
There is a very simple but rather nice way to get the thing to be controllably remotely. Firstly they gave us two walki-talkies and a guitar tuner. The tuner has 5 LED’s that light when the correct note is played near to it (it has a built in microphone). I intend to take a wire from each of the lights and use this little signal to drive a relay that controls the motors. We can make use of what is called diode logic to program each LED output with a particular function.

For example the first LED will make both wheels go forward and so the rover will go forward. LED two will make the left wheel go forward but at the same time make the right wheel go backward – this should make the rover go left. LED three will do the reverse and make the rover go right. Finally LED four will make both wheels go backward and so the rover will reverse. No LED’s means there will be no signals and so the rover motors are off and the vehicle motionless.

 
Jonathan builds his rover Copyrighted image Icon Copyright: Production team

Day Two

There is always an apparently useless item put in the trunk as a sort of red herring. This time it seems to be a base ball. Last night I was thinking how I might actually make us of this. It seemed to me that we might be able to make a sort of caster for the rover and so get over our steering problem.

This seems to work well. I use a piece of metal threading bent in such a way that the ball always lags behind the machine and so follows the direction. But because the main body work on the rover is slanting a little (with the front two wheels being higher than the back) on reverse the ball is very close to the ground. This makes it easy to steer while going forward but a little erratic on reverse. I think partly because it takes a little distance for the ball to go from its fully backward to fully forward following position.

Take the day to carefully wire up the drill motors to two relays and these are then powered by another single relay. The idea is that the first two relays can swap power to the motors (as they are wired up as change-over relays) while the third turns the power on and off. I need to make sure these are correctly wired as I go along otherwise it will get confusing latter; especially as all the wire (that can take this sort of current) that we have is the same colour!

Make up the audio oscillator for ‘mission control’. This is a simple 2 transistor oscillator made up of NPN transistors taken from the radios they gave us. By selecting the correct timing resistor via a homemade keyboard one can make the thing play different notes. By playing this device near to the tuner one can adjust it so that key number-1 lights LED1, key-2 lights LED 2 … and so on. Each key then controls one function of the rover - that’s the theory anyway!

I tried this out but, as sod's law would have it. the signal from the LEDs is what is called negative logic, that is when one of the LED goes ON, the signal from this circuit actually goes from on to off state – so it is completely the wrong way round to drive the relays ! I have to make up an inverter circuit for each of the outputs so that it will behave correctly. This is no real problem but I have to hunt for the parts in the radios. This is one of those problems that we all have on RS that use up valuable time but won’t even be mentioned on the program … and meanwhile time is ticking by.

I also tried many different way of powering the rover and none of them were perfect. For example the 12V batteries from the drills were a little too high voltage and made the wheels go too fast which meant it was difficult to control the thing. Lower voltage batteries from a cordless power drill gave a much better speed but ran out of power too fast…

The first test runs looked pretty good today. I wired up four switches via a cable to test out the way the rover moved. The machine ran far too fast and was a bit crazy to control so it lived up to its name of a Martian tuk-tuk! However we showed the principles and it all looks like it is gong in the right direction, even if the wheels don’t always!

Robert Winston
Robert visits the RS crew for a couple of days. Talked about the events surrounding Harry’s Nobel Prize and my little involvement. Nice chap. He got stuck into helping Mike B with his filtering. With sleeves rolled up, and his Doctor bedside manner, it was like he was helping out with a birth ..!

 
Jonathan builds his rover Copyrighted image Icon Copyright: Production team

Day Three

Today is the day we wire up the remote control part of the electrics. After finding that I had correctly wired up the relays but in the wrong order from the LED control signals (!) it all seemed to be responding very well. It was possible for example to whistle at the machine and it would take off in various directions! One thing that came out of these experiments was that the noise of the motors sometimes drowned out the signal tones, which explained why the motors where not always as smoothly operating as they should have been.

 

Before the testing of the Rover out on location it was time for Iain, Ellen, Kathy and Mike to show the waters that they had collected and for poor Iain to do the drink test (unfortunately several times for the cameras)!

The final test – in the hot seat
We drove all the kit down to a part of the desert that really does resemble the pictures sent back from the planet Mars! It is a clay-like muddy surface having slight undulations – small hills about a meter or two high and upon them lie randomly spread about rocks and small boulders. It is as if rain or water flowing over has smoothed the surface but left the larger boulders in place.

I set up ‘Mission Control’ and we were allowed a TV monitor to show the picture sent back by the rover and picked up by the receiver. We stayed by the kit while Alexis (the director) and co took the rover to the start of a course set up nearby on the other side of a high hill. We Roughies gather by mission control. Even though it was the end of the day it was very, very hot.

When the crew where ready they turned on the rover's camera and we started to see the landscape that we were to try and navigate using our remote control rover.

This was hilarious! I pressed the control for forward and the rover lurched forward – this was very exciting! Of course a real Mars Rover would take about 15 minutes to respond because of the distance the signals have to cover. We were lucky that we didn’t have that problem but it was still amazingly difficult to see what you should be doing. Also, it was impossible to see what sort of terrain the wheels had to deal with just a few centimetres from the front, and so the rover got stuck quite often. A reverse signal sometimes solved the problems but of course the camera was pointing forward and so we were moving backward - blind.

Eventually the poor old power drill motors where struggling with the terrain and the batteries were running out with all our to-ing and fro-ing. Finally I hadn’t thought to check that the ratchets on the drills were at their maximum torque settings and I think this lead to the rover getting stuck a few times!

On the way we found the following things on ‘Mars’: a jug of water, flowers and finally an end race ticker tape. All this made for a rather dramatic and often hilarious ending for the first programme of this new series.

The Day After

Kate, Ellen, Jonathan R (the series producer) and I go up the main highway to near Bishop and then left up into the high Sierra Nevadas for a days walking. A lovely, lovely day out. We walked about 14 miles or so, following a well trod path higher and higher, up 1000m or so, into the alpine like mountains. We came across some glacier-fed lakes of the most amazing turquoise blue. We go skinny dipping into the ice cold lakes and dry out in the bright sunshine.

Toward the middle of the walk, near to the highest point, I feel slightly heady, slight sore throat and achy. We are up at about 3000m above sea level here and I guess our quick ascent has made me suffer because of the altitude (this makes sense as later on in the trip when I was well acclimatised I felt fine).

Really great day out and some time to catch up with everybody. We all agreed that it didn’t feel like a year had passed since the last RS. We all seemed to slot right back in to the Rough Science experience.

 

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