Smart Shower Head – Lizzie Spinks & Liam Hopkins


For our project on sustainability we decided to look at ways in which to save water whilst showering. The two main issues focused on are the wastage of water and heat before the user has even begun to shower and opportunities, during the shower, in which the water need not be running. Can we make significant reductions to the environmental impact of showering, without implementing considerable behavioural change?


To decipher if simple sensors and coding can make a difference, a survey was taken outlining the showering behaviour of the average person. From this survey it was discovered that the average shower takes 48.1 seconds to get warm, taking in account the activities these people do whilst waiting for the shower to heat up, this means that the water is running, already hot, for 32.6 seconds unnecessarily. Once in the shower the participants were spending 2.1 minutes away from the water; again, letting in run without need.

Taking an average ml/s reading of various showers – a shower runs 77ml of water per second. From various energy and water supply companies it was found that 1kWh costs an average of 18.01p (in the Bristol area) and 1 litre of water will cost you 0.3p. Knowing that a 7.5kW shower uses 1.25kW in 10 minutes, it is possible to calculate just how much water and energy is wasted when we shower.

Over a year (12.2*365 = 4453) 4453 LITERS of water and (0.33*365 = 120.5) 120.5kWh of energy are being wasted by just ONE person wasting water whilst showering


By halting the flow of water once it has reached the desired temperature, alerting the user that the shower is ready and disallowing the stream to continue when no one is underneath the showerhead; we can significantly reduce the amount of energy and water wasted whilst showering.


We endeavoured to create a shower head that reduces energy and water consumption. To achieve this our product would stop the flow of water once it has reached the optimal temperature and only release water once a person is detected to be underneath the shower head.

fritz avec relay.jpg

This is the first look at our circuit. There are 4 main components;

  • Solenoid valve
  • Thermistor
  • Ultra-sonic sensor
  • Relay switch

The solenoid valve is the part that can control the flow of water, once power is passed through the component the valve opens. As ours is a 12v solenoid (Arduino Uno’s use 5v), we also plugged in a separate 12v power supply. The relay switch protects the Arduino from the extra power but bypassing it straight to the solenoid, this means that it does not affect any of the other components. Thus, controlling the solenoid valve without jeopardising the rest of the circuit. An ultra-sonic sensor can detect the distance of the nearest object, informing the s product that the user is within range. Finally, the thermistor measures the temperature of the water, which kickstarts the code.


Here you can see our circuit working (in this video we have used a red LED to represent the solenoid valve for a clearer display). The valve stays open as the shower turns on – this is to allow time for the water to warm up before requiring the user to stand underneath it (no one wants to stand under freezing cold water). Once the thermistor recognised the required temperature has been met, the solenoid valve closes. After this point the water will only flow if the user is detected below the ultra-sonic sensor. Therefore, you can see in the video that the valve opens and closes as motion passes past the sensor. If the water runs cold again, the thermistor will sense this, the valve will open and water will flow. This shows the same circuit with the solenoid added, if you listen carefully you can hear the valve opening and closing.

circuit n prototyp (2)

In our display unit we angled the ultra-sonic sensor to represent the placement of the sensor in the actual product, which would be just below the shower head.

circuit n prototyp (1)

At this stage we had the all of the components working, apart from our solenoid valve was reading the wrong way around – we have a video of this, with the intention to switch the code later to have the correct solenoid function

From this point we needed to change the code regarding the distance of the ultra-sonic reading, the solenoid function and the temperature gage (purely just for ease of presentation purposes).

Here is a flow chart of our code and the code itself



Seeing as the most power consuming part of our circuit is the solenoid valve, we will base our calculations upon this. The Arduino itself and the sensors do not take up a lot of power, therefore, in comparison to the solenoid valve they are negligible.

From looking at the specs on the solenoid valve we are using, we can see that it takes 8.5 watts of power. The solenoid valve only consumes power when the valve is open (when someone is standing under the shower and when the water is running cold)

Taking results from the earlier background research we can analyse whether our product will save more energy than it consumes.

Average shower time – 10mins

Average time away from water – 2.1mins

Average time under water – 7.9mins

Average heating up time – 48.1s

Time spent with the solenoid open = (7.9*60) +48.1 = 522.1 seconds of 8.5 watts

Energy = Power x Time. Therefore 8.5 * 522.1 = 4437.85 Joules (J)

4437.85J = 0.0012327361111 kWh or 1.23×10^-3 kWhs

The wastage we are saving (in energy alone) is 0.33kWh per shower – therefore, adding in the energy cost of our product – it will save you 0.329kWhs per shower, 120kWhs per year and 480kWhs per household per year

To properly analyse the data we took from our earlier survey, we took a look at two specific candidates; one that wasted a lot of water and one that didn’t waste much at all. As this survey was anonymous the names have been fabricated.

cartoon lasyChloe

Age: 18-24

Sex: Female

Time taken for shower to warm up: 30 seconds

Activity done whilst waiting: Phone scrolling for 1 minute

Shower length: 17.5 minutes

Time spent out of the water: 5 minutes

Total time of water flow wasted: 5.5minutes (330 seconds)

77ml/s. (77*330 = 25410ml) 25.4l of water wasted per shower. Showering uses 1/480kWh in energy per second. (330*(1/480) = 0.69kWh per shower.

Year-long: (0.69*365 = 250.9kWh) (25.4*365 =9271l) (250.9*(18.01p per kWh) = 4518.7) (9271*(0.3p per litre) = 2781.3) (2781.3 + 4581.7 =  7363)

In a year, Chloe will save 259kWhs of energy, 9271 litres of water and £73.63 – Very cost and energy effective

middle ages lady


Age: 45 – 54

Sex: Female

Time taken for shower to warm up: 120 seconds

Activity done whilst waiting: Brush teeth 2.5 minutes

Shower length: 9 minutes

Time spent out of the water: 0 minutes

Total time of water flow wasted: 30 seconds

77ml/s. (77*30= 107ml) 0.12l of water wasted per shower. Showering uses 1/480kWh in energy per second. (30*(1/480) = 0.06kWh per shower.

Year-long: (0.06*365 = 22.8kWh) (0.12*365 =43.8l) (22.8*(18.01p per kWh) = 410.6) (0.12*(0.3p per litre) = 0.036) (0.036+ 410.6 =  410.6)

In a year, Jackie will save 22.8Kwh of energy, 0.12 litres of water and £4.10 – Not very cost and energy effective


Adding extra energy saving features to a shower head can dramatically reduce the environmental impact of taking a shower.

We would look to build this product into excising electric shower units; as they already contain solenoid valve and a power supply, only the shower head . Again, reducing the energy and material consumption of the product. It uses considerably less energy than the vast amount saved, especially in a house-hold which uses the shower 4 time daily.


Making of the prototype – Lizzie Spinks & Liam Hopkins

Week beginning 16.04.18 (2)
To fully represent our concept, how it works and all of the included components we decided to do a prototype demonstration of the inner workings; we felt this would be much more informative to the audience than a closed shower head. Here is a quick sketch of how we intended to create our display.


As you can see, the thermistor is places just above the solenoid valve to read the temperature about to pass through. The ultra-sonic sensor is on an angle to represent the angle it would be in the final product – we have designed for the sensor to be situated just below the head of the shower pointing downwards but at a slight angle.
Our main board and all the fixings are all made from transparent Perspex, this makes it easy to see the water flow and all the components clearly.

making the prototype  (2).JPG

Bending the top allowed space for the bucket to be fastened securely and be properly supported by the base of the board also being bent for extra sturdiness.

Next, we fastened the shelf and supports for the pipe using a plastic welding solution which melts the desired pieces together – this is much securer than glue and is waterproof (essential for our design)

Smaller pieces of the board material hold the pipe slightly away from the back wall; this is to allow space for the solenoid valve and make sure the pipe does not move (as this could cause leakage!)


making the prototype  (6).JPG

After this it was just a case of setting our circuit up on the display unit, as our circuit was already all working and together this was a quick and simple task. Our intention is to improve the prototype by increasing the pressure flowing through the pipe (this gives for a more obvious change when the solenoid switches) and add a shower head to the base of the pipe – just to give a visual representation of the final product. We will also endeavour to create a more permanent solution to the water holder at the top.

making the prototype  (1).JPG



Moving our design forward we would add a circular strip of LEDs around the shower head. These would glow green and as time went on gradually turn red (like a timer). This would alert the user that they were spending too long in the shower which would change the behaviour of the user to save even more energy and water

led sketch.JPG

Building of the circuit – Lizzie Spinks & Liam Hopkins

Week beginning 16.04.18

Whilst waiting for our water proof thermistor to arrive, we used a normal thermistor to get the code and circuit working; with the hope that we could then just switch out the sensors to be appropriate for our prototype.


It works by the resistance caused by the lack of heat. As the sensor gets hotter the resistance goes down.

thermosister serial read

As you can see here it tells us the resistance but not the temperature. Therefore, we endeavoured to find a code that also showed us the temperature as well as the resistance. We found this following this link

temperature read


After a tutorial with our tutor we realised that our solenoid valve was, in fact, working but we were not using the right power supply. Therefore, once we tested it with the correct 12v it did work; our project reverted back to its original direction. As 12v is too powerful to run through an Arduino (it would just break it) a relay needed to be added. This was new territory for both of us so we tested out our circuit with an LED first; this way we wouldn’t have to risk breaking the Arduino with such high power.


Here is us testing out our circuit with the LED. As you can see, when the thermistor is cold the LED is on (valve open: as our solenoid valve is ‘power to open’), once it is warm the valve closes then when the ultra-sonic sensor detects the presence of my hand the light turns back on – user can shower.


We then switched the LED out with the solenoid valve and increased the power to 12v, this video of the solenoid valve working is a close-up so that you can hear the valve opening and closing.


This is a fritzing diagram of how our circuit is set up, at this stage we have all the components we intend to have in our final model apart from the buzzer (to signify that the shower is warm enough)

fritz avec relay


And here is our first draft of working code

code 1

code 2

Choosing our sensors – Lizzie Spinks & Liam Hopkins

Week beginning 09.04.18


We started looking at the PIR sensors that were available to use through the university. Through our initial trials we found that although it was detecting motion, after a couple of seconds it said ‘motion ended’ even if we were still moving in front of the sensor.

Another project we found online (for a motion-controlled tap) used an ultra-sonic sensor (, which conveniently we already owned. This sensor, in our experiments, was much more sensitive to our movement and could measure the distance of the object or person.

The next big test for our sensor was to see if it would detect water or not, ideally, we want it to not detect water as then we are not limited to where in the shower head the sensor could go. To test this, we did the most obvious thing we could think of and got in the shower. As you can see in this video, the water turning on does not affect the reading, whilst the hand moving towards the sensor changes the reading to approximately 50cm to 20cm.

ultra-sound sensor.JPG

We then got the PIR sensor to work more accurately but covering the peripheral vision with some tape; however, we still had some problems with the sensor detecting no movement when there was some.

PIR sensor with cone.JPG

Still exploring our options, we did a ‘shower test’ on the PIR sensor, even though we thought we would use the ultra-sonic (due to the accuracy of the readings). As PIR sensors work off detecting surfaces AND heat, it is unsuitable for our project as it detected the heat movement from the hot shower.


For the valve, to stop the water flow, we looked at several options. From our research earlier in the project we knew we wanted to get a solenoid valve the only question was which one. Speaking to an expert on ‘Solenoid Valve World’ he recommended a 12v plastic solenoid valve, this was perfect for us as we had previously seen many projects using this kind of valve. The data-sheet for the valves they had available can be found here . Although some of the more heavy-duty valves would’ve performed better, they were out of the price range needed to keep this is fairly affordable product.

This is the valve we chose. It is ideal for our project as it is a simple, power on opens the valve; therefore, we can easily see ahead to how we would code this using our ultra-sonic sensor.

It is a 12v sensor so also does not require too much power.



solenoid valve


Another feature of our design is to have the water run (without anyone needing to be underneath) until the water is warm enough. For this we needed a waterproof temperature sensor. These are very standard components so deciding which one to go with was fairly easy, requiring it was waterproof and compatible with Arduino.

temp sensor

Research – Will it be sustainable? – Lizzie Spinks & Liam Hopkins

Week beginning 29.03.2018

To gather data on how much energy our design would potentially save, we looked at a middle range electric shower.shower

This shower runs at 7.5kW. To find out how much electricity generally costs we compared a few different energy companies, putting in my address.

British Gas: 15.26p per kWh

EDF energy: 21.52p per kWh

e-On: 18.01p per kWh

Therefore, the average price in my area is £18.30 per kWh. Therefore, to shower for 10minutes (using this shower) would cost 22.5p; if you assume that the user showers every day, they’re spending £82.13 on showering every year and using 456.3 kWhs or energy.

The two main features of our product are turning off when it’s warm enough, alerting the user that they can get into the shower and the shower turning off when they’re not underneath. So, the opportunities for saving energy come from

  1. Unnecessarily running the water for longer than needed before the shower
  2. Running the water when not underneath the water.


For benefit 1 I decided to collect data from various people (who had 7.5kWh showers) – A lot of people didn’t know how long it took for their shower to warm up so for those participants I used the average of a few people I have asked.

My shower 37 seconds

Anjs shower 15 seconds

Alex Ns shower 35 seconds

Harry Trett – 15 seconds



From my survey I will find out:

How long it takes people’s showers to get hot

How long they spend waiting for it to get hot – thus, finding out how long they are waiting over the time it takes their shower to turn on

How long they spend in the shower

How much time they spend away from the water

We have also taken people’s ages and genders which will give us our target market. (this will be based on the people who would save the most amount of energy/water)
From the data we took from 64 participants of our survey we got some useful data about how much time people are spending with (wasted) water running.

SM results

Taking out the anomalies from our data – for example, some participants stated that their shower took more than 5 minutes to get warm, we concluded that this was an extreme case. We found that the average shower takes 48.1 seconds to get warm.

 An important factor to our product is alerting the user when the shower is warm, this is because a lot of people carry out an activity whilst they are waiting for the shower to warm up and therefore, could be unnecessarily running the shower warm. Considering the time it takes for the shower to warm up and the average time people spend doing something else whilst waiting; we concluded that on average the user will run hot water unnecessarily for 32.6 seconds.

Measuring how much time people believed they spend away from the water during a shower – this means time spent shampooing, shaving etc… – came to 2.1mins away from water (including everyone’s results). We the arranged our results to create different groups of people.

First, we removed all the participants who spent no time away from the water. We did this as these people would not be part of our target market as they, already, were not wasting a lot of water. After doing this the results were showing an average of 2.6mins away from water without the 0 values.

Then, just taking a look at those who spent a lot of time away from the water as these people were wasting a lot of water and would see a greater benefit from our product. 3.9mins away from water, only looking at those who spent more than a minute.

To work out how much water would be being saved I did an experiment to find out the flow of water in showers. This was to catch the water coming out of the shower for 5 seconds and measure how much had come out.

We did this in 4 different showers

Uni showers: 500ml in 5 secs (100ml/s)

Lizzie’s shower: 270ml in 5secs (54ml/s)

Liam’s shower: 320ml in 5 secs (64ml/s)

Emily’s shower: 440ml in 5 secs (88ml/s)

Our average: 382.5ml in 5 secs (77ml/s)


From this website ( I found out that water costs around £3 for 1000 litres, therefore 1 litre costs 0.3p

From this website I found that a 7.5kW shower will use 1.25kWhs per 10 mins. Therefore, per second a shower is costing (10mins = 600secs) 1.25/600 = 1/480 kWh, 1kWh = 18.01p therefore, 1second of showering costs 0.04p IN ENERGY COST


Combining our knowledge of the flow of water from a shower, energy prices, water prices and human behaviours we can work out how much of a sustainable benefit our product will have.

As discovered earlier, on average we run hot water at the beginning of our shower for 32.6secs, a shower generally runs at 77ml/s; therefore, at this stage we are wasting 2510.2ml of water or 2.5l – this costs the user 0.75p per shower. Assuming a 4 persons household where everyone showers once a day (0.75*365) *4 = £10.95 a year in running water before showering

As it cost 0.04p of energy to heat the shower per second, (0.04*32.6) it costs the user 1.3p in electricity to unnecessarily run hot water at the beginning of the shower. Again, if in a 4 persons house hold everyone is showering once a day. (1.3*365) *4 = 1898, the average household is spending £18.98 in heating the wasted water at the beginning of the shower a year – Looking at a more environmentally conscious figure this is using (32.6*(1/480) = 0.067) 0.067kWh per person per shower (0.067*365) *4) and therefore 99.3kWhs annually for a 4-person household

Looking at the average person (not someone who wastes a lot of water in the shower) 2.1minutes is spent away from the water per shower. Applying the same calculations, we can work out the wastage there. 2.1mins = 126seconds. At 77ml/s there would be (77*126=9702) 9702ml of wasted water or 9.7l (9.7*0.3 = 2.91) which will cost the user 2.9p per shower in water costs alone

Again, just looking at the average person, 126seconds of wasted water flow use (126*(1/480) = 0.2625) uses 0.26kWhs of electricity, costing 4.7p per shower in energy costs.

Let’s add this all up for one person in a year.

2510.2ml + 9702ml = 12212.2ml (12.2l) per shower

0.067kWh + 0.26kWh = 0.33kWh per shower

Over a year (12.2*365 = 4453) 4453 LITERS of water and (0.33*365 = 120.5) 120.5kWh of energy are being wasted by just ONE person wasting water whilst showering

This will be costing them ((4453*0.3) + (120.5*18.01) = 3506.105) £35.1

Applying this to the average house hold of 4 people wastes £140, 17812 litres of water and 482kWh of energy.

That’s how much money, water and electricity our product will save; however, it does use some electricity itself.

Seeing as the most power consuming part of our circuit is the solenoid valve, we will base our calculations upon this. The Arduino itself and the sensors do not take up a lot of power, therefore, in comparison to the solenoid valve (for now) the are negligible.

From looking at the specs on the solenoid valve we are using, we can see that it takes 8.5 watts of power.


soleniod spec


Obviously, there in only 12v passing through the solenoid valve when it is open (when someone is standing under the shower and when the water is running cold)

Average shower time – 10mins

Average time away from water – 2.1mins

Average time under water – 7.9mins

Average heating up time – 48.1s

Time spent with the solenoid open = (7.9*60) +48.1 = 522.1 seconds of 8.5 watts

Energy = Power x Time. Therefore 8.5 * 522.1 = 4437.85 Joules (J)

Using a converter ( we can now work out how many kWhs our product would use.

4437.85J = 0.0012327361111 kWh or 1.23×10^-3 kWhs

The wastage we are saving (in energy alone) is 0.33kWh per shower – therefore, adding in the energy cost of our product – it will save you 0.329kWhs per shower, 120kWhs per year and 480kWhs per household per year

Yes, it will be a sustainable design that helps the wastage of both water and electricity and changes the behaviour of the user.

Initial Questions for Shower Head – Lizzie Spinks & Liam Hopkins

Week beginning 19.03.18

We had decided to focus on solving the problem of water wastage during showering. To start we made an action plan of all the necessary research we would need to collate to make sure our idea was viable. This will include timing various people in the shower and asking certain questions;

  • What was the total time spent in the shower?
  • What was the total time spent ‘away’ from the water?
  • How long does the water take to warm up?

The concept of our proposed project is a shower head that turns off, or reduces the water flow, when the user has stepped away from the stream. Before even speaking to members of the public, we were aware that most people wait for a while for the water to heat up before getting into the shower; this is why we need to ask the question of how long the water takes to warm up so there can be a ‘time’ delay before the user needs to be underneath the shower head.

The main issue we are expecting to come across is how to restrict the water flow, we want to avoid a back log of water or just simply redirecting the flow as this would not save any energy. A quick brainstorm of various methods left us with a few ideas that stood out.

what valve type

The main ones we are considering is the wind up tap mechanism…

wind up tap

Or the mini solenoid valve (which can be controlled via Arduino)


first soleniod


We eventually decided on going for a solenoid valve due to the number of previous projects we found using this valve. This meant that we could access suitable code and get inspiration from the other coders.

Deciding on the Water Saving Shower Head. (Lizzie Spinks & Liam Hopkins)

Week beginning 12.03.18

From further thinking into our kidney palpitation equipment, we realised that our lack of medical knowledge was becoming a large hindrance to our progression.

Starting to look towards the sustainability brief we began to brainstorm some ideas and problems we could solve. To begin this process we looked at what costs a household the most energy, two of the most unnecessarily expensive household products seemed to be the shower and the fridge. A lot of this was because of time wastage. Such as, leaving the fridge door open and leaving the shower head on when the user is not directly using it.

We found this article comparing the prices of electric, gas or oil showers, This gave us a great insight into just how expensive showering can be (and potentially how much energy could be saved).

“A power shower could use around 15litres/min, so a 10 min shower would use 150litres of mains water, heated from around 8°C to 30°C.

Gas would cost 23p to heat this water, Using an oil boiler, this would be around 28p, and if using electricity (Immersion heater), the cost would be 46p.”


From a small calculation, judging on one of our estimations of our shower timings, we worked out that controlling the water flow could amount to saving almost £50 a year.

This is taking a 15min shower, spending 5 min away from the water on each shower. Thus, (0.46 x 365) x 0.3


We also found out from that on average a person will spend more than 10 hours a year looking in their fridge deciding what to eat. Furthering on from this article we found that The Institute of Food and Agricultural Sciences at the University of Florida suggested that this could waste enough energy to run a dishwasher 20 times


Being careful not to funnel our ideas too soon, we had a quick look at a solar panel that could track the light, generating maximum possible energy output.  However, after a brief look into this we found that someone else had already done the necessary research to realise this was not viable. We found out from that the sensors needed to track the light need a large flat space, not usually available in a household. Similarly, if being used in a business setting, to add motorised movement to a large enough solar panel is also not cost effective.


After a quick pros and cons list


we decided to go with the shower idea and have begun to look into ways in which we can save water when showering.


Starting looking into the Renal Ballottement Training Aid (Lizzie Spinks and Liam Hopkins)

Week beginning 05.03.18


After deciding to go with aiding the training of renal ballottement, we started to look what sensors we would need. First we needed to properly understand the process and how it works, from this video ( we gathered we would need at least 2 sensors to correctly monitor how the student was performing. These sensors would be a movement sensor and pressure sensors.

Our plan was to make a synthetic kidney that gives feedback to both the student and the tutor on how the procedure is being performed, this kidney would be designed to go into the already existing abdominal examination trainer  abdominal examination trainer.PNG

The movement sensor needs to be no more than a simple vibration, to check the student is stimulating the kidney enough for it to surface. This video shows how others have connected these kinds of sensors to an Arduino

Initially we were going to just have ¾ individual pressure sensors in the prosthetic kidney as it is fairly small so a hand pressing down should activate one of these. These would fit into the kidney like so,


However, from speaking to our peers within the course, we learnt of something called a FlexiForce which has a much greater range of where pressure can be applied, and can be manipulated into different shapes.

felxi force.jpg


We also considered the idea of the kidney relaying information to the tutor via Bluetooth. We would then have to have a look into processing to display the findings in an interesting way to give live feedback.

Making the Thirsty Flower Pot

Week beginning 19/01/2018

From last week we had a working IR line following circuit and a working moisture sensor. However, the two were not connected and neither were mounted to a prototype.

Having bought different motors, that connected easily to wheels, I needed to slightly adapt the circuit we had previously made to cater for the extra power these DC motors required.  To do this I took out the voltage regulator and added in a battery pack containing 4 AA batteries. Here is a video of the more powerful DC motor reacting to my TCRT5000

Using the line tracking code from before, we needed to turn the moisture sensor into a switch controlling the rest of the code. To do this we created an ‘if’ statement, that if the moisture sensor was wet the code wouldn’t run and if it was dry the robot would track the line towards the sink; to do this I took the basis from a code found at 

code with the moisture 2

Above, you can see the ‘if’ statement for when the moisture sensor is wet, followed by the ‘else’ statement which triggers the start of the line tracking code. Although this worked, we found that once the sensor was dry and the IR code had started, even if the moisture sensor got wet again the line tracker would continue to run.

We realised that this was because there was no function to be performed when the sensor was wet. Therefore the motors had no other instructions after they had started acting on the IR sensor code. To solve this we added that all 4 motor pins would be low during the ‘if’ statement.

code with the moisture 1

After adding all of this our circuits worked together and the IR circuit was controlled by the moisture sensor, here is a video of our circuit working. As you can see, when the probes are in the mug of water the IR sensor has no impact on the motor.

Earlier on in our testing we had noticed that one of our IR sensors was giving us opposite readings to the other, therefore the left sensor was somehow reversing data it was receiving. As we were short on time, instead of properly trying to understand why this was happening, we changed the (! – logical not) part of the left sensor code. This means that it reverses what it does with the data received.

After fixing all of these issues it was time to start building our robot. Because our IR sensors came from different suppliers they have different ranges, therefore they had to be at different heights away from the floor. The left sensor had to be 20mm away from the ground and the right sensor had to be 38mm away, any deviations in this height would mean that the sensors would not function.

sensors difference.jpg

Here you can see the different heights in which the sensors are placed.

When we first tried our robot tracking the black line it didn’t work, as you can see in this video (

This was because we had positioned our sensors at the back of the car, therefore, by the time the sensors were noticing they had to turn the middle of the car had already passed way over the corner. To change this we swapped what was the front and what was the back of the car, this also meant that we had to change the direction of the wheels. It would be possible ( and not too difficult) to do this by swapping around the HIGH and LOW values on the motors in the code; however, as they are DC motors we also were able to switch the positive and negative wires, thus, changing the direction.

After all these alterations, we had a working prototype!!!

Here are some pictures and videos of the ‘Thirsty Flower Pot’


By Lizzie Spinks

Research Project 1 – IR Optical Tracking Sensor (TCRT5000)


My first project was to research and become ‘an expert’ on an ‘Infra-red optical tracking sensor’, lesser known as the TCRT5000. So, the questions I challenged myself to answer were;

  • What is Infra-Red light?
  • How does the TCRT5000 ‘track’ this light?
  • Why, and how, is this utilised?

Literature Review

In an article by J.S. Sweitzer called “What is Infra-Red light?”, (‘’)  infra-red light is described as “one type of light that is invisible to us”. All types of light are made up of electromagnetic energy and the different types of light are defined by the frequency of their wavelengths. “Light with wavelengths from 0.7 micron to about 0.1 millimeter is called infrared light.” This is the type of light that the TCRT5000 measures , we can also feel infra-red light, with longer wavelengths, in the form of heat.

This article also taught me how our eyes perceive different colours, this is because the light bouncing off a surface will have a different wavelength to light bouncing off the same material but in a different colour. “Every color has a distinct wavelength. For example, violet light can be seen at light wavelengths of around 0.4 micron(*) and yellow light is made up of waves that are 0.6 microns long.” Therefore, the TCRT5000 can sense the colour of a material due to it’s wavelength.

I also found this tutorial online ( where I learnt all about how the sensor actually functioned. The sensor contains both an LED and a photo diode, the LED sends out a signal (in the form of infra-red light) which bounces off the surface in front of it, bounces back and is read by the photo-diode. This can measure wavelength of the returning signal and send information to the Arduino.


The Infra-Red tracking sensor will be able to tell if a surface is black or white.


If my hypothesis is correct, my sensor should be able to tell when I have drawn on paper in black pen. To test this, I found a short tutorial online to turn an LED on when the sensor is reading a reflection (

fritz for line tracking I followed the above ‘fritzing’ diagram and the code found on the website to create an experiment for myself. The TCRT5000 has a built-in LED which lights up when a reflection is being read. Therefore, on a dark surface, such as black pen, the LED will be off as there is no reflection being read.

Here is a video of my experiment. .  As you can see, the LED turns off as a pass the sensor over the black pen.


As you can see from my experiment, as my hand moves slightly in height from the paper, the light no longer reads the difference between the light and dark paper. However, when my hand was a steady height it was very accurate at picking up the colour of the paper below.



The IR tracking sensor can very accurately pick up the colour of the surface through the refection wavelength, although it has to be kept at an exact height from the surface. From the data-sheet I discovered this was 12-30mm. This could have many applications, commonly used in line-tracking robots, which appear in printers and many other common appliances.

By Lizzie Spinks