kabibo The variable Robot-Kit

8 remarkable functions

8 different constructions

8 available color variants

Building and Experiment Manual

Introduction With the help of a clever combination of brightness sensors, kabibo can pick up the tiniest contrasts in his environment and react to them in various ways. kabibo’s brain cells are two transistors. The simple control circuits can be set up on a breadboard, making them interchangeable and expandable. Now you can learn about electronic basics in a fun way!

By using various circuitries and changing the position of three sensors, you can explore eight different ways of setting up circuits and their amazing results. It takes about 30 minutes to build kabibo. You will need a 9 V battery, wire cutters, and pliers. The battery is ex-changeable. The appearance of kabibo can be designed individually using different construction methods.

kabibo Can Do Lots of Things 1. Avoiding Obstacles and the Flight Response

2. Race Track Driver Who Brakes in Tight Situations

3. Following Lines and Determining the Width of a Track

4. Pushing Objects and Judging Sizes

5. Pursuer Who Avoids Collisions

6. Shadow Follower Looking for a Roof Over His Head

7. Light Follower Who Can Identify Distances

8. Sun Worshipper or the Circling Gnat

Enclosed parts 1 mini-breadboard

2 twin cables for motors

1 battery connector

8 cable ties

1 metal bracket

1 piece of rubber caps

2 round grommets

3 phototransistors (sensors)

1 PNP Darlington transistor BC516

1 NPN Darlington transistor BC517

2 resistors: 3.3 M Ω

1 resistor: 150 Ω

2 5 mm LEDs

2 DC-Motors

Building Instructions 1. Slide the rubber caps over the motor shafts, so that they don’t touch the motor housing.

2. Attach the motors to the metal bracket using cable ties. Be sure the writing on the motors is facing upward.

3. The tips of the cable ties can be placed in any direction you would like.

4. Slide the cable ties to the end of the motors (next to the plastic parts) and use the pliers to pull them tight.

5. Put two cable ties through the bottom of the loops you just made. The corrugated side should be facing forward.

6. Use these to mount the 9 V battery onto the motors. The battery’s positive terminal should be facing forward.

positive terminal

7. Place the breadboard somewhat diagonally between the ends of the cable ties above the battery. The side with the writing (1,2,3,4,5,6,7,8,9) should be facing forward.

8. Make a loop out of two cable ties and put them around the middle of the robot. The back tip should be facing downward and the front one upward.

9. Now pull these cable ties so tight that the back conjunc-tion meets the metal bracket and the front conjunction the lower edge of the battery.

10. The cable tie that is facing forward needs to be bent upward as a skid. Assure that only this skid and the two motor shafts are contacting the ground.

11. Depending on what you want your robot to look like, you can also shorten the cable ties by cutting the ends with your wire cutters.

12. Slip the cables of the battery connector through the bottom opening between the battery and the motors.

writing

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Preparing the Electronic Parts 1. To move forward, the voltage at the back motor connection needs to be + and at the front one –. Put the flat connectors of the twin-cables into the slit-shaped sockets of the motors.

2. Bend the connecting wires of the two 3.3 MΩ resistors with the color code (orange, orange, green, gold) right next to the resistor (7.5 mm) to 90º. Shorten them, so that they are about 10 mm long. Bend the connecting wires of the 150 Ω resistor with the color code (brown, green, brown, gold) so that there ends are 10 mm apart. Again, they should be shortened to about 10 mm.

3. The two 5 mm LEDs have to have the proper polarity to light up. The anode (+) is the longer wire and the cathode (–) is the shorter one. Bend the wires at the casing about 60º, shorten them to 15 mm, and slip the white round grommets over the LEDs.

4. It is also important to install the 3 sensors correctly. The phototransistors have a longer wire (emitter or –) and a shorter wire (collector or +). Bend the wires of one sensor so they are 20 mm apart. For the other two sensors, bend the wires 90º at about 10 mm from the ends.

5. Darlington transistors with a very high current ratio of 30,000 are used to control the motors. A Darlington tran-sistor is made of two cascaded transistors and needs 1.4 V (V = volt) instead of 0.7 V between the base and emitter to go on. Since one motor needs to run with a positive and the other with a negative sensor signal, reverse transistors are used.

So that the transistors fit into the breadboard, you will need to bend the two outer wires 5 mm apart.

The NPN transistor BC517 needs a positive voltage on the base pin (B) to get the electricity running between the collector (C) and emitter (E). The PNP transistor BC516 gets the electricity running at a negative voltage on the base pin.

So it is important that you install the transistors exactly where they belong instead of mixing them up. Even the direction of installation is vital if you want your robot to function.

10 mm

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7.5 mm

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kink

Function of the basic circuits The Common Collector Circuit

Transistors have three kinds of basic circuits: the common collector circuit, the common emitter circuit, and the com-mon base circuit. The first four experiments are done with a common collector circuit, in which the collector has a constant “+” voltage on the NPN transistor (BC517) and a “–” voltage on the PNP transistor (BC516).

kabibo uses three brightness sensors (right: S1, left: S2, middle: S3) that are connected in series between +9 V and –0 V. You can imagine this so-called phototransistor as a changeable resistor whose value decreases when the lighting in the environment becomes brighter. The resistance values define how the voltages are divided. Each of the two voltages generated by the sensors controls a transistor. To turn them on, they need a base emitter voltage of UBE = 1.4 V. Therefore, the voltage on motors M1 and M2 is about 1.4 V less than the base voltage. An example: The battery has 9 V. With the same lighting for all three sensors, U1 = U2 = U3 = 3 V. At the base of the transistors there is now a voltage of 6 V. The transistors go on, causing the emitter and, therewith, the motors to adjust their voltage to 6 V – 1.4 V = 4.6 V. Now both motors run at about half their potential speed. If the right sensor (S1) gets brighter, the left motor M2 will speed up and the right motor M1 will slow down. When S3 has much light, U3 becomes about 0 V, causing both U1 and U2 to become 4.5 V. The motors now run on 4.5 V – 1.4 V = 3.1 V. In this case, kabibo will slowly move toward a light. The LEDs L1 and L2 are connected with a series resistor, so they light up when both motors are running.

The Common Emitter Circuit

Experiments 5 through 8 are done with an emitter circuit. The emitter has a constant “–” voltage on the NPN transis-tor (BC517) and a “+” on the PNP transistor (BC516).

Here we see the transistors have traded positions in the circuit diagram. Since the emitter is permanently at 0 V or 9 V, the motor voltage cannot be regulated by the base voltage as with the collector circuit. If UBE were to exceed 1.4 V, the motors would immediately receive full voltage and run at maximum speed. For the 5th experiment, the sensors are put directly (without a series resistor) on the base terminals of the transistors. As soon as the voltage on the sensor S1 or S2 exceeds 1.4 V, the corresponding transistor will go on. For the other experiments (6-8), it is best to have the mo-tors running at different speeds. With resistors R1 and R2, the motors can be regulated using the current flow. The 3.3 MΩ resistors do not allow the motors to reach their full performance until U1 and U2 > 4.5 V (U3 = 0 V). If the volt-age for U1 or U2 is below 1.4 V the corresponding motor will stop. Each LED (L1 and L2) could alternatively be connected in series with one of the motors. In that case there would be no need for the resistor R3 anymore.

Eight Experiments with kabibo

1) Obstacle Avoidance and the Flight Response

Features: avoids obstacles, accelerates when there is light, accelerates when there is danger from above

Sensors: S1/S2 approx. 45° to the side, S3 facing upward

The breadboard has a matrix of 11 columns, each with five rows of plug-in positions that are electrically connected. The two outer columns are for electricity supply. The other nine columns are marked 1–9, both on the breadboard and the corresponding wiring diagram.

Put the red cable (+) of the battery connector to the far left and the black one (–) to the far right of the middle row. Use the 5th row for the motor connectors and the 4th row for the transistors and the resistor. Put the 150 Ω resistor between columns 3 and 7 over the cable tie. The transistor BC517 belongs in the columns +/1/2 with the writing facing the back. BC516 belongs in the columns 8/9/– with the writing facing the front. The left back motor connection belongs in + and the front one in 8. The right back motor connection belongs in 2 and the front one in –. The middle sensor S3 belongs upright with the short shaft in 1 and the long shaft in 9, so that the flat side of the sensor is facing the left. Put sensors S1 in +/1 and S2 in 9/– so that they are orientated 45º to the sides. Lastly, put both the LEDs in the columns 2/3 or 7/8, facing the front.

Fasten the battery connector to the battery and test kabibo’s ability to respond to obstacles and shadows from the front and above. Be sure the obstacles are big enough and darker than the background!

2) Race Track Driver Who Brakes in tight Situations

Features: masters a track with dark boundaries, brakes in tight situations, accelerates when pursued

Sensors: S1/S2 45º to the outside and facing downward, S3 facing the back

You probably noticed in the first experiment that the ob-stacles are usually a different color tone than the back-ground, and that kabibo reacts to these contrasts by dodg-ing the obstacles.

So that he can pick up speed on the race track and be in good shape for a race, put the pins of sensor S3 in the 5th row between the motor connections and bend the sensor toward the back. You should also bend sensors S1 and S2 a little bit downward. The closer these are to the ground, the closer kabibo will get to the boundaries and the more reliably he will respond to narrow marks on the floor.

Now choose a space that is well lit from above and has a light-colored background, so that there will be sufficient color contrast. You can use black duct tape, black strips of paper, or black objects to make the race track.

Try making some parts of the track narrower than others and see if kabibo adjusts his speed to the various widths. What happens when you cover his back sensor with your hand? You can also try bending the sensors in various directions and to various degrees.

3) Following Lines and Determining the Width of the Track

Features: follows lines on the ground, accelerates on straight stretches and where the lines are wide

Sensors: S1/S2 parallel to the ground, S3 facing the front

For the first two circuitries, the motors were controlled in such a way that kabibo followed light colors. Check what happens when you switch the left and right motor connec-tions, by switching the matching-colored pins on the breadboard. Now the right transistor should be controlling the right motor and the left transistor the left motor.

Make sure all three sensors are parallel and diagonal to the ground. By adjusting the distance between S1 and S2, you define just how exactly your mini-bot will ride along the line. Ideally they need to be placed a little outside of the line. If they are too close to the line, kabibo will 1) have to constantly be regulating where he is at, causing him to swerve side to side and 2) be unable to activate his “turbo-gear”, since it needs more light to fall on the outside sen-sors than on the middle one.

Now you can stick a dark track, for example with black duct tape, onto a light colored background. Check if mibo can take 90º curves, use side roads and crossroads, and deal with lines of various widths.

You might also want to try positioning the sensors at vari-ous angles.

4) Pushing Objects and Judging Sizes

Features: follows lines on the ground, accelerates on straight stretches and where the lines are wide

Sensors: S1/S2 parallel to the ground, S3 facing the front

Can kabibo identify objects? Well, he does not have eyes, but as you have probably noticed, he is very sensitive to small color-tone differences. When placed against a light-colored background, a block creates just as much of a color contrast as a black line. Depending on which of the three sensors has the shadow of an object cast upon it, kabibo will change his direction or speed.

You can try that with the circuitry that was described in the last experiment, positioning all three sensors to the front and a little diagonal to the floor. The speed at which kabibo clears objects out of his way depends on whether kabibo has a small block (S3 darker than S1 and S2) or a large block (all three sensors darkened) in front of him.

You can adjust the inclination angle of S3 and the position of sensors S1 and S2 more or less to the left or right to match the size of the objects, causing kabibo to push them straighter and match his speed to the size of the object.

An interesting observation: When pushing a small block toward a pile or collection of blocks, kabibo will slow down.

5) Pursuer who Avoids Collisions

Features: pursues a (dark) object, stops with a set distance in front of it

Sensors: S1/S2 45° to the side, S3 facing forward

For the following four experiments, you will need to use the emitter circuit described on page 6. That means that both transistors will trade positions. The PNP transistor BC516 should still have the writing facing forward and the BC517 facing the back.

The motor connections will be connected as in the first circuitry. The left transistor will control the right motor and the right transistor the left motor.

The 3.3 MΩ resistors seen in the circuit diagram will not yet be used in this circuitry.

In the first four experiments with the collector circuit, shad-ing the middle sensor S3 caused U3 to rise and kabibo to accelerate. With the emitter circuit, on the other hand, the motors will stop if the voltage U3 rises and UBE < 1.4 V. That makes totally new behaviors possible for the MiniBot.

Now you can put the sensors S1 and S2 approximately 45º to the side and S3 facing forward. Check if kabibo follows dark objects or your hand and then stops in front of them. The angle of sensor S3 adjusts the distance between kabibo and the pursued object.

If you want the two LEDs to light up when the motors stand still, you have to change their polarity as described in the wiring diagram.

6) Shadow Follower Looking for a Roof over His Head

Features: looks for and stays in shadows, moves when the shadow does

Sensors: S1/S2 diagonal and upward, S3 upward

So that kabibo no longer changes his speed so suddenly, add both 3.3 MΩ resistors to the breadboard. One of them belongs in the columns 1 and 4, the other between col-umns 6 and 9. Accordingly, you move the sensors from column 1 to column 4 and from column 9 to column 6.

Now all three sensors should be facing upward. S1 and S2 should be at a slight angle to the side and facing forward. You will need to be careful to leave enough space between them and the LED connections that they do not short cir-cuit.

For this experiment, find a place that is under a lamp and try to navigate kabibo using the shadow of your hand. Ideally he should stay under your hand, only moving when light falls on him. Remember, as soon as S3 is shaded, kabibo will stand still. On the other hand, if S1 or S2 is shaded, kabibo will move accordingly in the direction of the shadow.

7) Light Follower who can Identify Distances

Features: follows a lamp or light on the floor, stops just outside of the light or when shaded from above

Sensors: S1/S2 a little to the side, S3 upwards

To change the shadow follower into a light follower, you will need to switch the motor connections once again. S1 and S2 will be positioned just a little to the sides, so they both simultaneously pick up light coming from the front. The more light that shines on S1 and S2 and the less that shines on S3, the sooner kabibo will come to a halt. This ratio can also be set by adjusting the angle of sensor S3. For this experiment, the room lighting should be dim.

Now you can control kabibo using a lamp in front of him or a bright beam of light pointed at the floor. With enough light contrast, the MiniBot should come to stop in both cases when it reaches the light. He will also come to a halt if you shade him from above. So you see, your light fol-lower is easy to catch!

It does not always have to be a light you have kabibo fol-low. If the ground is somewhat dark in color tone, he will also follow, for example, a sheet of white paper.

8) Sun Worshipper or the Circling Gnat

Features: moves into the light and stays there until you shade him / circles under a lamp

Sensors: S1/S2 upward toward the back, S3 upward and facing forward

Slight changes to the positioning of the sensors give this circuitry two more interesting possibilities:

a) The sun worshipper is a lazy robot, who simply stands around as long as he is in the light. Only shade can cause him to move, namely into the light.

b) As a gnat, kabibo endlessly circles around under a lamp. The radius of movement can be set by ad-justing the position of the sensors.

Like the shadow follower in experiment 6, the sun wor-shipper and the gnat have all three sensors upward, so they can precisely distinguish which direction the light is coming from. So sensors S1 and S2 are now positioned slightly toward the back and sensor S3 diagonally faces forward.

Adjusting the angle of sensor S3, you can regulate how far the gnat moves away from the light. The further this sen-sor is to the front, the less light hits it and the sooner kabibo changes direction. When sensor S3 is at a 45º an-gle, he will become a sun worshipper and remain still un-der a lamp. As soon as you shade him, though, he will be off into the light once again!

Error diagnostics If kabibo does not do what he should, you will find here common sources of error.

Problem Reasons

kabibo does not move at all: The left and right sensor S1 and S2 are connected with incorrect polarity.

The red or black battery cable is not inserted correctly in the breadboard or the battery clip is not on the 9 V battery.

The battery is empty or defective.

Only one of the two motors is running: The left or right sensor S1 or S2 connected with incor-rect polarity.

A transistor inserted incorrectly poled in the breadboard. (Note the flat side of the transistors.)

A motor connection cable is not inserted correctly in the breadboard.

The black silicon cap is too far on the motor shaft and blocks the engine.

A motor turns backwards: This motor is connected with incorrect polarity.

kabibo just goes straight ahead: The middle sensor S3 is connected with wrong polarity.

The LEDs do not light up: One or both LEDs are incorrectly polarized.

kabibo gets stuck on the ground: kabibo does not slidee well on the v-shaped bend of the forward skid.

The ground is too uneven for kabibo.

If none of these causes apply to your problem, check whether all components are installed as described in the drawing.

If you need help, please contact us with a specific error description: info@variobot.com

This version of the manual is preliminary and will be reworked by us successively and supplemented with various infor-mation and different construction methods.

SN 02x EN v20170304 www.variobot.com