Depending on how the Spin module is connected, the speed on wheel A or B must be a negative number to make Spin move forward.
If Spin is connected like the picture above, the speed on A must be negative and B positive, for Spin to move forward.
Try driving forwards and backwards:
What is the speed at engine power 50?
Drive for 2 seconds, how far does the Spin module go?
Calculate speed as:
Where d is distance in metres, t is the time in seconds, and v is the speed in m/s
3a) Make a calibration curve. Drive 2 seconds:
Speed in m/s
Speed in m/s
Make a linear regression, find the residuals
3b) Does Spin drive at a constant Speed?
Choose for instance motor speed 50
Time driven (sec.)
How far does Spin go?
Make a linear regression.
Drive 0,5 metres at engine speed 50
First, see how far Spin drives, when you use this program:
Then try to calculate what time should be used, if you assume Spin drives at a constant speed.
Here d is 0.5 m, v is the speed you calculated in 3a),
t is then inserted into the program as “wait in sec” ⃝
Does Spin drive 50 cm. in both of these ways?
Now take into consideration, that Spin does not drive at a constant speed.
Use you regression equation from 3b) to find out for how long Spin has to drive, for it to drive 50 cm.
Assignment 5) Ride in a circle.
Drive with engine speed -20 on wheel A and engine speed 50 on wheel B.
Try to change the engine speed on the two wheels. In this video it’s tested with -20, 50 and -50, 100.
Because Spin has two wheels that pull, we can assign different speeds for the two wheels, and thus Spin will drive in a circular motion with the radius r.
Radius r can be calculated using the formula:
Here d is the distance between the wheels,
Radius r is the radius of the circle, that the outer wheel drives,
V-inner is the speed of the inner wheel
V-outer is the distance of the outer wheel. We only do the calculations with positive numbers.
Prove this formula through an experiment.
You do not need to understand the underlying math, but if you want to see, it’s in the end of the compendium.
Assignment 6) Try to create a program, where Spin drives in a square or a hexagon.
Assignment 7) (Proximity sensor) Stop within a short distance from the wall
For this assignment, Spin needs to be connected, so that the sensors are facing forward.
Start by getting to know the proximity sensor.
The proximity sensor goes from 0 to 100% proximity in the distance 3 cm – 15 cm, where 100% is at the wall.
Try to calibrate the proximity sensor.
Begin with placing Spin 15 cm from a wall.
Stops at which distance from wall
Try saving your results in a log-file, to see what the variable shows:
The log-file can be found in the Fable–folder (under documents)
Here distance is a variable that is either false or true
Assignment 8) (Proximity sensor) Drive more slowly when Spin gets closer to the wall, make a complete stop right before the wall
Here you have to set the proximity percent to a number that is 100%, when it right at the wall.
Assignment 9) (Colour sensor) Get Spin to react to colours on the floor.
Connect the Spin module, so the sensors are facing down.
Try to get Spin to stop on a red line.
Be aware, that engine A, now must be a positive number,
for the robot to move forward.
Assignment 10) (Colour sensor) Keep Spin within a playpen using red tape.
(If using black tape, be aware, that it has to be really close to the robot or have a matt finish)
Continue working on the following draft, using yellow and red tape:
Assignment 11) (Colour sensor) Try to create a program, that makes Spin follow a red (or a white) curve, and stop at a yellow line.
Here you can use white tape, if the floor is a contrasting colour. The tape can be bought at a hardware store.
Assignment 12) (Light sensor) Follow the light
(This programme can be found under Spin Examples. Look below for help finding it)
Assignment 13) Use the Fable Face app on your phones, and control your Spin module.
When you use the Fable Face App, remember to use the name of the Hub.
Get the remote control programme from examples.
Try to remote control the Spin module with your mobile phones.
Try to play with a ball, by attaching the “plow” to the Spin module (to do this, you have to reconnect Spin, so that the sensors are facing forward. Otherwise the “plow” won’t fit underneath the Spin Robot).
Physics B at a high school level (US) or college level (GB)
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The Fable story starts in 2011 at the Technical University of Denmark just outside Copenhagen.
Moises Pacheco started his collaboration with David Johan Christensen, an associate professor and robot researcher.