eug_titles/BallBot/Part2

Home » Personal collection » Acorn hard disk » misc » misc3 » eug_titles/BallBot/Part2

This website contains an archive of files for the Acorn Electron, BBC Micro, Acorn Archimedes, Commodore 16 and Commodore 64 computers, which Dominic Ford has rescued from his private collection of floppy disks and cassettes.

Some of these files were originally commercial releases in the 1980s and 1990s, but they are now widely available online. I assume that copyright over them is no longer being asserted. If you own the copyright and would like files to be removed, please contact me.

Tape/disk:	Home » Personal collection » Acorn hard disk » misc » misc3
Filename:	eug_titles/BallBot/Part2
Read OK:	✔
File size:	1B97 bytes
Load address:	0000
Exec address:	0000

Duplicates

There is 1 duplicate copy of this file in the archive:

Personal collection » Acorn ADFS disks » Electron » EUG_submission.ADF » BallBot/Part2
Personal collection » Acorn hard disk » misc » misc3 » eug_titles/BallBot/Part2

The Motor Control Circuitry

The computer software which controls BallBot communicates with the
hardware by means of the BBC's output lines from the User Port and the
Printer Port. The hardware of the BBC means that the printer port is only
available for output, whereas the user port is also available for input,
making it necassary to be careful to to use up the facilities to the user
port too much for output, when they are the only possible source of input.
Output should be controlled as much as possible from the printer port.

The computer output lines switch between 0V when they are off, and 5V for
on. The first large problem encountered with the output circuitry was that
the computer's output ports can only source a maximum of 100uA. The motors
will need much more than this, and even a low-power relay draws 1mA.
Therefore I found it necessary to use an NPN transistor to switch the
power to the relay, as shown in the figure. The 10k resistor between the
computer and the transistor is used to limit the current drawn from the
port to around 80uA. This is sufficient to allow the collector -> emitter
current through the transistor to switch the relay, and allows a safety
margin for surges without risking blowing the computer's output by drawing
too greater current. There is a diode wired across the relay to protect
the transistor from any large negative back-voltages which might be
generated due to induction in the relay when it is switched off. These
flow away quickly and harmlessly through the diode. The motor is then
connected across the relay, so that it can be switched under computer
control.

The relays are wired up in the circuit shown to the side. There are five
control relays: left, right, turbo, reverse and on/off. The left and right
relays are used for steering. If either one is closed, the motor on the
inner side of the robot slows down, and the outer motor speeds up to turn
the robot. This is achieved because a resistor is connected in parallel
with the inner motor. This reduces the current flowing through the motor,
and, as the total resistance across the terminals of the motor is reduced,
the voltage also falls. The outer motor has a greater voltage across it,
as the voltage across the inner motor has fallen, and the sum of the two
must be constantly the EMF of the power supply.

The "turbo" relay is used to select the speed at which the robot travels.
When it is open, the motors are both slowed down, because there is a large
resistor cutting the voltage across them. Ideally, I intend the robot to
travel at 2ms-1 with turbo closed, and 0.5ms-1 with it open. These are the
values which are assumed in the computer simulation. For this to be the
case, the resistor would clearly need to be a high-power variety to avoid
over-heating. It might be a better approach to use a variable power
supply, and connect the circuit to different voltages depending upon
whether turbo is selected or not, so as to conserve power, and avoid
having such a resistor.

The "reverse" relay is used to switch between driving forwards and
backwards. It simply reverses the polarity of the power supply, and so
reverses the direction in which the motors spin to move BallBot.

The "on/off" relay, as the name suggests, is used to switch the motors on
or off. It is actually not an independent relay at all, but is actually
part of the left/right relay system, as shown by the circuit diagram to
the side. Looking at the main control circuit diagram above, it is clear
that it would be a dangerous situation if the left and right relays were
both closed at the same time, because the power supply would be shorted
out. Therefore the on/off relay is set as off when both these relays are
closed. Not only does this save an extra relay in the circuit, but it also
acts as a fail-safe in a potentially very dangerous situation.

Mechanical Work

The BallBot mechanical team has done much work in designing the final
robot. The first task has been to build a Lego prototype which we can use
to test out the AI and ultrasonics systems before incorporating them into
the final robot design. Many issues have been raised by this design, such
as how to collect the balls reliably without the risk of dropping them,
and similarly how to drop them reliably. We have found that there is a
risk, for example, that the robot will get integestion, and refuse to
'eat' any more balls if one ball should be collected incorrectly. This
Lego prototype will eventually have the motor control circuitry all
mounted on board, with all of the computer program software running on a
BBC off the model tennis court. The two are connected by means of two
parallel cables - one for the BBC user port, and the other for the printer
port. This system is shown below:


The basic mechanical design of BallBot is shown by this diagram. There are
ultrasonic sensors placed around the edge of BallBot, which are angled to
give the robot a fairly complete vision of its surroundings. The sensors
where placed under the assumption that they all have a range of vision of
30 degrees. The robot is powered by two drive wheels, one each side, and
there is one support wheel to make BallBot a three-wheel vehicle. The
balls collect in an area in the centre. This diagram is actually a
simplified version of the Lego robot, not the final robot, which will
probably be hemispherical, not square.

At the moment, the mechanics team is working on installing a new collector
mechanism to the prototype - this will work using two large rollers
spinning on opposite directions to 'suck' the ball into the robot. Care
must be taken to ensure that this works equally well to release the balls
by spitting them out of the front, and also that there is no risk of
sucking up too much. There could difficult situation if the robot were to
try to suck up a ball which is up close against the net, and the net
became entangled in the collector.

Another problem which is in need of attention is that of steering the
robot. The original idea, as stated in the control section, was to have
one motor speed up and the other slow down to turn the robot. At the
moment, however, there is too much friction between the robot's wheels and
the ground, such that the robot cannot turn. Under the power of one motor,
the robot drives straight forward rather then turning. Therefore we must
try to reduce friction between the wheels and the ground. This should not
be difficult, as it simply means replacing the support wheels with wheels
which can turn more easily, similar to casters.

The exact design of the final robot is still being finalised, but it will
probably look something like the artist's impression shown to the right.
The outer shell will be plastic, with the circuitry and batteries mounted
at the back, inside the shell. There will be rollers at the front to
collect the balls, which collect in the middle of the robot, in front of
the circuitry at the back. All of the controls will be mounted on the top
of the hemisphere, where they are easiest for the user to access.

00000000  54 68 65 20 4d 6f 74 6f  72 20 43 6f 6e 74 72 6f  |The Motor Contro|
00000010  6c 20 43 69 72 63 75 69  74 72 79 0d 0d 54 68 65  |l Circuitry..The|
00000020  20 63 6f 6d 70 75 74 65  72 20 73 6f 66 74 77 61  | computer softwa|
00000030  72 65 20 77 68 69 63 68  20 63 6f 6e 74 72 6f 6c  |re which control|
00000040  73 20 42 61 6c 6c 42 6f  74 20 63 6f 6d 6d 75 6e  |s BallBot commun|
00000050  69 63 61 74 65 73 20 77  69 74 68 20 74 68 65 0d  |icates with the.|
00000060  68 61 72 64 77 61 72 65  20 62 79 20 6d 65 61 6e  |hardware by mean|
00000070  73 20 6f 66 20 74 68 65  20 42 42 43 27 73 20 6f  |s of the BBC's o|
00000080  75 74 70 75 74 20 6c 69  6e 65 73 20 66 72 6f 6d  |utput lines from|
00000090  20 74 68 65 20 55 73 65  72 20 50 6f 72 74 20 61  | the User Port a|
000000a0  6e 64 20 74 68 65 0d 50  72 69 6e 74 65 72 20 50  |nd the.Printer P|
000000b0  6f 72 74 2e 20 54 68 65  20 68 61 72 64 77 61 72  |ort. The hardwar|
000000c0  65 20 6f 66 20 74 68 65  20 42 42 43 20 6d 65 61  |e of the BBC mea|
000000d0  6e 73 20 74 68 61 74 20  74 68 65 20 70 72 69 6e  |ns that the prin|
000000e0  74 65 72 20 70 6f 72 74  20 69 73 20 6f 6e 6c 79  |ter port is only|
000000f0  0d 61 76 61 69 6c 61 62  6c 65 20 66 6f 72 20 6f  |.available for o|
00000100  75 74 70 75 74 2c 20 77  68 65 72 65 61 73 20 74  |utput, whereas t|
00000110  68 65 20 75 73 65 72 20  70 6f 72 74 20 69 73 20  |he user port is |
00000120  61 6c 73 6f 20 61 76 61  69 6c 61 62 6c 65 20 66  |also available f|
00000130  6f 72 20 69 6e 70 75 74  2c 0d 6d 61 6b 69 6e 67  |or input,.making|
00000140  20 69 74 20 6e 65 63 61  73 73 61 72 79 20 74 6f  | it necassary to|
00000150  20 62 65 20 63 61 72 65  66 75 6c 20 74 6f 20 74  | be careful to t|
00000160  6f 20 75 73 65 20 75 70  20 74 68 65 20 66 61 63  |o use up the fac|
00000170  69 6c 69 74 69 65 73 20  74 6f 20 74 68 65 20 75  |ilities to the u|
00000180  73 65 72 0d 70 6f 72 74  20 74 6f 6f 20 6d 75 63  |ser.port too muc|
00000190  68 20 66 6f 72 20 6f 75  74 70 75 74 2c 20 77 68  |h for output, wh|
000001a0  65 6e 20 74 68 65 79 20  61 72 65 20 74 68 65 20  |en they are the |
000001b0  6f 6e 6c 79 20 70 6f 73  73 69 62 6c 65 20 73 6f  |only possible so|
000001c0  75 72 63 65 20 6f 66 20  69 6e 70 75 74 2e 0d 4f  |urce of input..O|
000001d0  75 74 70 75 74 20 73 68  6f 75 6c 64 20 62 65 20  |utput should be |
000001e0  63 6f 6e 74 72 6f 6c 6c  65 64 20 61 73 20 6d 75  |controlled as mu|
000001f0  63 68 20 61 73 20 70 6f  73 73 69 62 6c 65 20 66  |ch as possible f|
00000200  72 6f 6d 20 74 68 65 20  70 72 69 6e 74 65 72 20  |rom the printer |
00000210  70 6f 72 74 2e 0d 0d 54  68 65 20 63 6f 6d 70 75  |port...The compu|
00000220  74 65 72 20 6f 75 74 70  75 74 20 6c 69 6e 65 73  |ter output lines|
00000230  20 73 77 69 74 63 68 20  62 65 74 77 65 65 6e 20  | switch between |
00000240  30 56 20 77 68 65 6e 20  74 68 65 79 20 61 72 65  |0V when they are|
00000250  20 6f 66 66 2c 20 61 6e  64 20 35 56 20 66 6f 72  | off, and 5V for|
00000260  0d 6f 6e 2e 20 54 68 65  20 66 69 72 73 74 20 6c  |.on. The first l|
00000270  61 72 67 65 20 70 72 6f  62 6c 65 6d 20 65 6e 63  |arge problem enc|
00000280  6f 75 6e 74 65 72 65 64  20 77 69 74 68 20 74 68  |ountered with th|
00000290  65 20 6f 75 74 70 75 74  20 63 69 72 63 75 69 74  |e output circuit|
000002a0  72 79 20 77 61 73 20 74  68 61 74 0d 74 68 65 20  |ry was that.the |
000002b0  63 6f 6d 70 75 74 65 72  27 73 20 6f 75 74 70 75  |computer's outpu|
000002c0  74 20 70 6f 72 74 73 20  63 61 6e 20 6f 6e 6c 79  |t ports can only|
000002d0  20 73 6f 75 72 63 65 20  61 20 6d 61 78 69 6d 75  | source a maximu|
000002e0  6d 20 6f 66 20 31 30 30  75 41 2e 20 54 68 65 20  |m of 100uA. The |
000002f0  6d 6f 74 6f 72 73 0d 77  69 6c 6c 20 6e 65 65 64  |motors.will need|
00000300  20 6d 75 63 68 20 6d 6f  72 65 20 74 68 61 6e 20  | much more than |
00000310  74 68 69 73 2c 20 61 6e  64 20 65 76 65 6e 20 61  |this, and even a|
00000320  20 6c 6f 77 2d 70 6f 77  65 72 20 72 65 6c 61 79  | low-power relay|
00000330  20 64 72 61 77 73 20 31  6d 41 2e 0d 54 68 65 72  | draws 1mA..Ther|
00000340  65 66 6f 72 65 20 49 20  66 6f 75 6e 64 20 69 74  |efore I found it|
00000350  20 6e 65 63 65 73 73 61  72 79 20 74 6f 20 75 73  | necessary to us|
00000360  65 20 61 6e 20 4e 50 4e  20 74 72 61 6e 73 69 73  |e an NPN transis|
00000370  74 6f 72 20 74 6f 20 73  77 69 74 63 68 20 74 68  |tor to switch th|
00000380  65 0d 70 6f 77 65 72 20  74 6f 20 74 68 65 20 72  |e.power to the r|
00000390  65 6c 61 79 2c 20 61 73  20 73 68 6f 77 6e 20 69  |elay, as shown i|
000003a0  6e 20 74 68 65 20 66 69  67 75 72 65 2e 20 54 68  |n the figure. Th|
000003b0  65 20 31 30 6b 20 72 65  73 69 73 74 6f 72 20 62  |e 10k resistor b|
000003c0  65 74 77 65 65 6e 20 74  68 65 0d 63 6f 6d 70 75  |etween the.compu|
000003d0  74 65 72 20 61 6e 64 20  74 68 65 20 74 72 61 6e  |ter and the tran|
000003e0  73 69 73 74 6f 72 20 69  73 20 75 73 65 64 20 74  |sistor is used t|
000003f0  6f 20 6c 69 6d 69 74 20  74 68 65 20 63 75 72 72  |o limit the curr|
00000400  65 6e 74 20 64 72 61 77  6e 20 66 72 6f 6d 20 74  |ent drawn from t|
00000410  68 65 0d 70 6f 72 74 20  74 6f 20 61 72 6f 75 6e  |he.port to aroun|
00000420  64 20 38 30 75 41 2e 20  54 68 69 73 20 69 73 20  |d 80uA. This is |
00000430  73 75 66 66 69 63 69 65  6e 74 20 74 6f 20 61 6c  |sufficient to al|
00000440  6c 6f 77 20 74 68 65 20  63 6f 6c 6c 65 63 74 6f  |low the collecto|
00000450  72 20 2d 3e 20 65 6d 69  74 74 65 72 0d 63 75 72  |r -> emitter.cur|
00000460  72 65 6e 74 20 74 68 72  6f 75 67 68 20 74 68 65  |rent through the|
00000470  20 74 72 61 6e 73 69 73  74 6f 72 20 74 6f 20 73  | transistor to s|
00000480  77 69 74 63 68 20 74 68  65 20 72 65 6c 61 79 2c  |witch the relay,|
00000490  20 61 6e 64 20 61 6c 6c  6f 77 73 20 61 20 73 61  | and allows a sa|
000004a0  66 65 74 79 0d 6d 61 72  67 69 6e 20 66 6f 72 20  |fety.margin for |
000004b0  73 75 72 67 65 73 20 77  69 74 68 6f 75 74 20 72  |surges without r|
000004c0  69 73 6b 69 6e 67 20 62  6c 6f 77 69 6e 67 20 74  |isking blowing t|
000004d0  68 65 20 63 6f 6d 70 75  74 65 72 27 73 20 6f 75  |he computer's ou|
000004e0  74 70 75 74 20 62 79 20  64 72 61 77 69 6e 67 0d  |tput by drawing.|
000004f0  74 6f 6f 20 67 72 65 61  74 65 72 20 63 75 72 72  |too greater curr|
00000500  65 6e 74 2e 20 54 68 65  72 65 20 69 73 20 61 20  |ent. There is a |
00000510  64 69 6f 64 65 20 77 69  72 65 64 20 61 63 72 6f  |diode wired acro|
00000520  73 73 20 74 68 65 20 72  65 6c 61 79 20 74 6f 20  |ss the relay to |
00000530  70 72 6f 74 65 63 74 0d  74 68 65 20 74 72 61 6e  |protect.the tran|
00000540  73 69 73 74 6f 72 20 66  72 6f 6d 20 61 6e 79 20  |sistor from any |
00000550  6c 61 72 67 65 20 6e 65  67 61 74 69 76 65 20 62  |large negative b|
00000560  61 63 6b 2d 76 6f 6c 74  61 67 65 73 20 77 68 69  |ack-voltages whi|
00000570  63 68 20 6d 69 67 68 74  20 62 65 0d 67 65 6e 65  |ch might be.gene|
00000580  72 61 74 65 64 20 64 75  65 20 74 6f 20 69 6e 64  |rated due to ind|
00000590  75 63 74 69 6f 6e 20 69  6e 20 74 68 65 20 72 65  |uction in the re|
000005a0  6c 61 79 20 77 68 65 6e  20 69 74 20 69 73 20 73  |lay when it is s|
000005b0  77 69 74 63 68 65 64 20  6f 66 66 2e 20 54 68 65  |witched off. The|
000005c0  73 65 0d 66 6c 6f 77 20  61 77 61 79 20 71 75 69  |se.flow away qui|
000005d0  63 6b 6c 79 20 61 6e 64  20 68 61 72 6d 6c 65 73  |ckly and harmles|
000005e0  73 6c 79 20 74 68 72 6f  75 67 68 20 74 68 65 20  |sly through the |
000005f0  64 69 6f 64 65 2e 20 54  68 65 20 6d 6f 74 6f 72  |diode. The motor|
00000600  20 69 73 20 74 68 65 6e  0d 63 6f 6e 6e 65 63 74  | is then.connect|
00000610  65 64 20 61 63 72 6f 73  73 20 74 68 65 20 72 65  |ed across the re|
00000620  6c 61 79 2c 20 73 6f 20  74 68 61 74 20 69 74 20  |lay, so that it |
00000630  63 61 6e 20 62 65 20 73  77 69 74 63 68 65 64 20  |can be switched |
00000640  75 6e 64 65 72 20 63 6f  6d 70 75 74 65 72 0d 63  |under computer.c|
00000650  6f 6e 74 72 6f 6c 2e 0d  0d 54 68 65 20 72 65 6c  |ontrol...The rel|
00000660  61 79 73 20 61 72 65 20  77 69 72 65 64 20 75 70  |ays are wired up|
00000670  20 69 6e 20 74 68 65 20  63 69 72 63 75 69 74 20  | in the circuit |
00000680  73 68 6f 77 6e 20 74 6f  20 74 68 65 20 73 69 64  |shown to the sid|
00000690  65 2e 20 54 68 65 72 65  20 61 72 65 20 66 69 76  |e. There are fiv|
000006a0  65 0d 63 6f 6e 74 72 6f  6c 20 72 65 6c 61 79 73  |e.control relays|
000006b0  3a 20 6c 65 66 74 2c 20  72 69 67 68 74 2c 20 74  |: left, right, t|
000006c0  75 72 62 6f 2c 20 72 65  76 65 72 73 65 20 61 6e  |urbo, reverse an|
000006d0  64 20 6f 6e 2f 6f 66 66  2e 20 54 68 65 20 6c 65  |d on/off. The le|
000006e0  66 74 20 61 6e 64 20 72  69 67 68 74 0d 72 65 6c  |ft and right.rel|
000006f0  61 79 73 20 61 72 65 20  75 73 65 64 20 66 6f 72  |ays are used for|
00000700  20 73 74 65 65 72 69 6e  67 2e 20 49 66 20 65 69  | steering. If ei|
00000710  74 68 65 72 20 6f 6e 65  20 69 73 20 63 6c 6f 73  |ther one is clos|
00000720  65 64 2c 20 74 68 65 20  6d 6f 74 6f 72 20 6f 6e  |ed, the motor on|
00000730  20 74 68 65 0d 69 6e 6e  65 72 20 73 69 64 65 20  | the.inner side |
00000740  6f 66 20 74 68 65 20 72  6f 62 6f 74 20 73 6c 6f  |of the robot slo|
00000750  77 73 20 64 6f 77 6e 2c  20 61 6e 64 20 74 68 65  |ws down, and the|
00000760  20 6f 75 74 65 72 20 6d  6f 74 6f 72 20 73 70 65  | outer motor spe|
00000770  65 64 73 20 75 70 20 74  6f 20 74 75 72 6e 0d 74  |eds up to turn.t|
00000780  68 65 20 72 6f 62 6f 74  2e 20 54 68 69 73 20 69  |he robot. This i|
00000790  73 20 61 63 68 69 65 76  65 64 20 62 65 63 61 75  |s achieved becau|
000007a0  73 65 20 61 20 72 65 73  69 73 74 6f 72 20 69 73  |se a resistor is|
000007b0  20 63 6f 6e 6e 65 63 74  65 64 20 69 6e 20 70 61  | connected in pa|
000007c0  72 61 6c 6c 65 6c 0d 77  69 74 68 20 74 68 65 20  |rallel.with the |
000007d0  69 6e 6e 65 72 20 6d 6f  74 6f 72 2e 20 54 68 69  |inner motor. Thi|
000007e0  73 20 72 65 64 75 63 65  73 20 74 68 65 20 63 75  |s reduces the cu|
000007f0  72 72 65 6e 74 20 66 6c  6f 77 69 6e 67 20 74 68  |rrent flowing th|
00000800  72 6f 75 67 68 20 74 68  65 20 6d 6f 74 6f 72 2c  |rough the motor,|
00000810  0d 61 6e 64 2c 20 61 73  20 74 68 65 20 74 6f 74  |.and, as the tot|
00000820  61 6c 20 72 65 73 69 73  74 61 6e 63 65 20 61 63  |al resistance ac|
00000830  72 6f 73 73 20 74 68 65  20 74 65 72 6d 69 6e 61  |ross the termina|
00000840  6c 73 20 6f 66 20 74 68  65 20 6d 6f 74 6f 72 20  |ls of the motor |
00000850  69 73 20 72 65 64 75 63  65 64 2c 0d 74 68 65 20  |is reduced,.the |
00000860  76 6f 6c 74 61 67 65 20  61 6c 73 6f 20 66 61 6c  |voltage also fal|
00000870  6c 73 2e 20 54 68 65 20  6f 75 74 65 72 20 6d 6f  |ls. The outer mo|
00000880  74 6f 72 20 68 61 73 20  61 20 67 72 65 61 74 65  |tor has a greate|
00000890  72 20 76 6f 6c 74 61 67  65 20 61 63 72 6f 73 73  |r voltage across|
000008a0  20 69 74 2c 0d 61 73 20  74 68 65 20 76 6f 6c 74  | it,.as the volt|
000008b0  61 67 65 20 61 63 72 6f  73 73 20 74 68 65 20 69  |age across the i|
000008c0  6e 6e 65 72 20 6d 6f 74  6f 72 20 68 61 73 20 66  |nner motor has f|
000008d0  61 6c 6c 65 6e 2c 20 61  6e 64 20 74 68 65 20 73  |allen, and the s|
000008e0  75 6d 20 6f 66 20 74 68  65 20 74 77 6f 0d 6d 75  |um of the two.mu|
000008f0  73 74 20 62 65 20 63 6f  6e 73 74 61 6e 74 6c 79  |st be constantly|
00000900  20 74 68 65 20 45 4d 46  20 6f 66 20 74 68 65 20  | the EMF of the |
00000910  70 6f 77 65 72 20 73 75  70 70 6c 79 2e 0d 0d 54  |power supply...T|
00000920  68 65 20 22 74 75 72 62  6f 22 20 72 65 6c 61 79  |he "turbo" relay|
00000930  20 69 73 20 75 73 65 64  20 74 6f 20 73 65 6c 65  | is used to sele|
00000940  63 74 20 74 68 65 20 73  70 65 65 64 20 61 74 20  |ct the speed at |
00000950  77 68 69 63 68 20 74 68  65 20 72 6f 62 6f 74 20  |which the robot |
00000960  74 72 61 76 65 6c 73 2e  0d 57 68 65 6e 20 69 74  |travels..When it|
00000970  20 69 73 20 6f 70 65 6e  2c 20 74 68 65 20 6d 6f  | is open, the mo|
00000980  74 6f 72 73 20 61 72 65  20 62 6f 74 68 20 73 6c  |tors are both sl|
00000990  6f 77 65 64 20 64 6f 77  6e 2c 20 62 65 63 61 75  |owed down, becau|
000009a0  73 65 20 74 68 65 72 65  20 69 73 20 61 20 6c 61  |se there is a la|
000009b0  72 67 65 0d 72 65 73 69  73 74 6f 72 20 63 75 74  |rge.resistor cut|
000009c0  74 69 6e 67 20 74 68 65  20 76 6f 6c 74 61 67 65  |ting the voltage|
000009d0  20 61 63 72 6f 73 73 20  74 68 65 6d 2e 20 49 64  | across them. Id|
000009e0  65 61 6c 6c 79 2c 20 49  20 69 6e 74 65 6e 64 20  |eally, I intend |
000009f0  74 68 65 20 72 6f 62 6f  74 20 74 6f 0d 74 72 61  |the robot to.tra|
00000a00  76 65 6c 20 61 74 20 32  6d 73 2d 31 20 77 69 74  |vel at 2ms-1 wit|
00000a10  68 20 74 75 72 62 6f 20  63 6c 6f 73 65 64 2c 20  |h turbo closed, |
00000a20  61 6e 64 20 30 2e 35 6d  73 2d 31 20 77 69 74 68  |and 0.5ms-1 with|
00000a30  20 69 74 20 6f 70 65 6e  2e 20 54 68 65 73 65 20  | it open. These |
00000a40  61 72 65 20 74 68 65 0d  76 61 6c 75 65 73 20 77  |are the.values w|
00000a50  68 69 63 68 20 61 72 65  20 61 73 73 75 6d 65 64  |hich are assumed|
00000a60  20 69 6e 20 74 68 65 20  63 6f 6d 70 75 74 65 72  | in the computer|
00000a70  20 73 69 6d 75 6c 61 74  69 6f 6e 2e 20 46 6f 72  | simulation. For|
00000a80  20 74 68 69 73 20 74 6f  20 62 65 20 74 68 65 0d  | this to be the.|
00000a90  63 61 73 65 2c 20 74 68  65 20 72 65 73 69 73 74  |case, the resist|
00000aa0  6f 72 20 77 6f 75 6c 64  20 63 6c 65 61 72 6c 79  |or would clearly|
00000ab0  20 6e 65 65 64 20 74 6f  20 62 65 20 61 20 68 69  | need to be a hi|
00000ac0  67 68 2d 70 6f 77 65 72  20 76 61 72 69 65 74 79  |gh-power variety|
00000ad0  20 74 6f 20 61 76 6f 69  64 0d 6f 76 65 72 2d 68  | to avoid.over-h|
00000ae0  65 61 74 69 6e 67 2e 20  49 74 20 6d 69 67 68 74  |eating. It might|
00000af0  20 62 65 20 61 20 62 65  74 74 65 72 20 61 70 70  | be a better app|
00000b00  72 6f 61 63 68 20 74 6f  20 75 73 65 20 61 20 76  |roach to use a v|
00000b10  61 72 69 61 62 6c 65 20  70 6f 77 65 72 0d 73 75  |ariable power.su|
00000b20  70 70 6c 79 2c 20 61 6e  64 20 63 6f 6e 6e 65 63  |pply, and connec|
00000b30  74 20 74 68 65 20 63 69  72 63 75 69 74 20 74 6f  |t the circuit to|
00000b40  20 64 69 66 66 65 72 65  6e 74 20 76 6f 6c 74 61  | different volta|
00000b50  67 65 73 20 64 65 70 65  6e 64 69 6e 67 20 75 70  |ges depending up|
00000b60  6f 6e 0d 77 68 65 74 68  65 72 20 74 75 72 62 6f  |on.whether turbo|
00000b70  20 69 73 20 73 65 6c 65  63 74 65 64 20 6f 72 20  | is selected or |
00000b80  6e 6f 74 2c 20 73 6f 20  61 73 20 74 6f 20 63 6f  |not, so as to co|
00000b90  6e 73 65 72 76 65 20 70  6f 77 65 72 2c 20 61 6e  |nserve power, an|
00000ba0  64 20 61 76 6f 69 64 0d  68 61 76 69 6e 67 20 73  |d avoid.having s|
00000bb0  75 63 68 20 61 20 72 65  73 69 73 74 6f 72 2e 0d  |uch a resistor..|
00000bc0  0d 54 68 65 20 22 72 65  76 65 72 73 65 22 20 72  |.The "reverse" r|
00000bd0  65 6c 61 79 20 69 73 20  75 73 65 64 20 74 6f 20  |elay is used to |
00000be0  73 77 69 74 63 68 20 62  65 74 77 65 65 6e 20 64  |switch between d|
00000bf0  72 69 76 69 6e 67 20 66  6f 72 77 61 72 64 73 20  |riving forwards |
00000c00  61 6e 64 0d 62 61 63 6b  77 61 72 64 73 2e 20 49  |and.backwards. I|
00000c10  74 20 73 69 6d 70 6c 79  20 72 65 76 65 72 73 65  |t simply reverse|
00000c20  73 20 74 68 65 20 70 6f  6c 61 72 69 74 79 20 6f  |s the polarity o|
00000c30  66 20 74 68 65 20 70 6f  77 65 72 20 73 75 70 70  |f the power supp|
00000c40  6c 79 2c 20 61 6e 64 20  73 6f 0d 72 65 76 65 72  |ly, and so.rever|
00000c50  73 65 73 20 74 68 65 20  64 69 72 65 63 74 69 6f  |ses the directio|
00000c60  6e 20 69 6e 20 77 68 69  63 68 20 74 68 65 20 6d  |n in which the m|
00000c70  6f 74 6f 72 73 20 73 70  69 6e 20 74 6f 20 6d 6f  |otors spin to mo|
00000c80  76 65 20 42 61 6c 6c 42  6f 74 2e 0d 0d 54 68 65  |ve BallBot...The|
00000c90  20 22 6f 6e 2f 6f 66 66  22 20 72 65 6c 61 79 2c  | "on/off" relay,|
00000ca0  20 61 73 20 74 68 65 20  6e 61 6d 65 20 73 75 67  | as the name sug|
00000cb0  67 65 73 74 73 2c 20 69  73 20 75 73 65 64 20 74  |gests, is used t|
00000cc0  6f 20 73 77 69 74 63 68  20 74 68 65 20 6d 6f 74  |o switch the mot|
00000cd0  6f 72 73 20 6f 6e 0d 6f  72 20 6f 66 66 2e 20 49  |ors on.or off. I|
00000ce0  74 20 69 73 20 61 63 74  75 61 6c 6c 79 20 6e 6f  |t is actually no|
00000cf0  74 20 61 6e 20 69 6e 64  65 70 65 6e 64 65 6e 74  |t an independent|
00000d00  20 72 65 6c 61 79 20 61  74 20 61 6c 6c 2c 20 62  | relay at all, b|
00000d10  75 74 20 69 73 20 61 63  74 75 61 6c 6c 79 0d 70  |ut is actually.p|
00000d20  61 72 74 20 6f 66 20 74  68 65 20 6c 65 66 74 2f  |art of the left/|
00000d30  72 69 67 68 74 20 72 65  6c 61 79 20 73 79 73 74  |right relay syst|
00000d40  65 6d 2c 20 61 73 20 73  68 6f 77 6e 20 62 79 20  |em, as shown by |
00000d50  74 68 65 20 63 69 72 63  75 69 74 20 64 69 61 67  |the circuit diag|
00000d60  72 61 6d 20 74 6f 0d 74  68 65 20 73 69 64 65 2e  |ram to.the side.|
00000d70  20 4c 6f 6f 6b 69 6e 67  20 61 74 20 74 68 65 20  | Looking at the |
00000d80  6d 61 69 6e 20 63 6f 6e  74 72 6f 6c 20 63 69 72  |main control cir|
00000d90  63 75 69 74 20 64 69 61  67 72 61 6d 20 61 62 6f  |cuit diagram abo|
00000da0  76 65 2c 20 69 74 20 69  73 20 63 6c 65 61 72 0d  |ve, it is clear.|
00000db0  74 68 61 74 20 69 74 20  77 6f 75 6c 64 20 62 65  |that it would be|
00000dc0  20 61 20 64 61 6e 67 65  72 6f 75 73 20 73 69 74  | a dangerous sit|
00000dd0  75 61 74 69 6f 6e 20 69  66 20 74 68 65 20 6c 65  |uation if the le|
00000de0  66 74 20 61 6e 64 20 72  69 67 68 74 20 72 65 6c  |ft and right rel|
00000df0  61 79 73 20 77 65 72 65  0d 62 6f 74 68 20 63 6c  |ays were.both cl|
00000e00  6f 73 65 64 20 61 74 20  74 68 65 20 73 61 6d 65  |osed at the same|
00000e10  20 74 69 6d 65 2c 20 62  65 63 61 75 73 65 20 74  | time, because t|
00000e20  68 65 20 70 6f 77 65 72  20 73 75 70 70 6c 79 20  |he power supply |
00000e30  77 6f 75 6c 64 20 62 65  20 73 68 6f 72 74 65 64  |would be shorted|
00000e40  0d 6f 75 74 2e 20 54 68  65 72 65 66 6f 72 65 20  |.out. Therefore |
00000e50  74 68 65 20 6f 6e 2f 6f  66 66 20 72 65 6c 61 79  |the on/off relay|
00000e60  20 69 73 20 73 65 74 20  61 73 20 6f 66 66 20 77  | is set as off w|
00000e70  68 65 6e 20 62 6f 74 68  20 74 68 65 73 65 20 72  |hen both these r|
00000e80  65 6c 61 79 73 20 61 72  65 0d 63 6c 6f 73 65 64  |elays are.closed|
00000e90  2e 20 4e 6f 74 20 6f 6e  6c 79 20 64 6f 65 73 20  |. Not only does |
00000ea0  74 68 69 73 20 73 61 76  65 20 61 6e 20 65 78 74  |this save an ext|
00000eb0  72 61 20 72 65 6c 61 79  20 69 6e 20 74 68 65 20  |ra relay in the |
00000ec0  63 69 72 63 75 69 74 2c  20 62 75 74 20 69 74 20  |circuit, but it |
00000ed0  61 6c 73 6f 0d 61 63 74  73 20 61 73 20 61 20 66  |also.acts as a f|
00000ee0  61 69 6c 2d 73 61 66 65  20 69 6e 20 61 20 70 6f  |ail-safe in a po|
00000ef0  74 65 6e 74 69 61 6c 6c  79 20 76 65 72 79 20 64  |tentially very d|
00000f00  61 6e 67 65 72 6f 75 73  20 73 69 74 75 61 74 69  |angerous situati|
00000f10  6f 6e 2e 0d 0d 4d 65 63  68 61 6e 69 63 61 6c 20  |on...Mechanical |
00000f20  57 6f 72 6b 0d 0d 54 68  65 20 42 61 6c 6c 42 6f  |Work..The BallBo|
00000f30  74 20 6d 65 63 68 61 6e  69 63 61 6c 20 74 65 61  |t mechanical tea|
00000f40  6d 20 68 61 73 20 64 6f  6e 65 20 6d 75 63 68 20  |m has done much |
00000f50  77 6f 72 6b 20 69 6e 20  64 65 73 69 67 6e 69 6e  |work in designin|
00000f60  67 20 74 68 65 20 66 69  6e 61 6c 0d 72 6f 62 6f  |g the final.robo|
00000f70  74 2e 20 54 68 65 20 66  69 72 73 74 20 74 61 73  |t. The first tas|
00000f80  6b 20 68 61 73 20 62 65  65 6e 20 74 6f 20 62 75  |k has been to bu|
00000f90  69 6c 64 20 61 20 4c 65  67 6f 20 70 72 6f 74 6f  |ild a Lego proto|
00000fa0  74 79 70 65 20 77 68 69  63 68 20 77 65 20 63 61  |type which we ca|
00000fb0  6e 20 75 73 65 0d 74 6f  20 74 65 73 74 20 6f 75  |n use.to test ou|
00000fc0  74 20 74 68 65 20 41 49  20 61 6e 64 20 75 6c 74  |t the AI and ult|
00000fd0  72 61 73 6f 6e 69 63 73  20 73 79 73 74 65 6d 73  |rasonics systems|
00000fe0  20 62 65 66 6f 72 65 20  69 6e 63 6f 72 70 6f 72  | before incorpor|
00000ff0  61 74 69 6e 67 20 74 68  65 6d 20 69 6e 74 6f 0d  |ating them into.|
00001000  74 68 65 20 66 69 6e 61  6c 20 72 6f 62 6f 74 20  |the final robot |
00001010  64 65 73 69 67 6e 2e 20  4d 61 6e 79 20 69 73 73  |design. Many iss|
00001020  75 65 73 20 68 61 76 65  20 62 65 65 6e 20 72 61  |ues have been ra|
00001030  69 73 65 64 20 62 79 20  74 68 69 73 20 64 65 73  |ised by this des|
00001040  69 67 6e 2c 20 73 75 63  68 0d 61 73 20 68 6f 77  |ign, such.as how|
00001050  20 74 6f 20 63 6f 6c 6c  65 63 74 20 74 68 65 20  | to collect the |
00001060  62 61 6c 6c 73 20 72 65  6c 69 61 62 6c 79 20 77  |balls reliably w|
00001070  69 74 68 6f 75 74 20 74  68 65 20 72 69 73 6b 20  |ithout the risk |
00001080  6f 66 20 64 72 6f 70 70  69 6e 67 20 74 68 65 6d  |of dropping them|
00001090  2c 0d 61 6e 64 20 73 69  6d 69 6c 61 72 6c 79 20  |,.and similarly |
000010a0  68 6f 77 20 74 6f 20 64  72 6f 70 20 74 68 65 6d  |how to drop them|
000010b0  20 72 65 6c 69 61 62 6c  79 2e 20 57 65 20 68 61  | reliably. We ha|
000010c0  76 65 20 66 6f 75 6e 64  20 74 68 61 74 20 74 68  |ve found that th|
000010d0  65 72 65 20 69 73 20 61  0d 72 69 73 6b 2c 20 66  |ere is a.risk, f|
000010e0  6f 72 20 65 78 61 6d 70  6c 65 2c 20 74 68 61 74  |or example, that|
000010f0  20 74 68 65 20 72 6f 62  6f 74 20 77 69 6c 6c 20  | the robot will |
00001100  67 65 74 20 69 6e 74 65  67 65 73 74 69 6f 6e 2c  |get integestion,|
00001110  20 61 6e 64 20 72 65 66  75 73 65 20 74 6f 0d 27  | and refuse to.'|
00001120  65 61 74 27 20 61 6e 79  20 6d 6f 72 65 20 62 61  |eat' any more ba|
00001130  6c 6c 73 20 69 66 20 6f  6e 65 20 62 61 6c 6c 20  |lls if one ball |
00001140  73 68 6f 75 6c 64 20 62  65 20 63 6f 6c 6c 65 63  |should be collec|
00001150  74 65 64 20 69 6e 63 6f  72 72 65 63 74 6c 79 2e  |ted incorrectly.|
00001160  20 54 68 69 73 0d 4c 65  67 6f 20 70 72 6f 74 6f  | This.Lego proto|
00001170  74 79 70 65 20 77 69 6c  6c 20 65 76 65 6e 74 75  |type will eventu|
00001180  61 6c 6c 79 20 68 61 76  65 20 74 68 65 20 6d 6f  |ally have the mo|
00001190  74 6f 72 20 63 6f 6e 74  72 6f 6c 20 63 69 72 63  |tor control circ|
000011a0  75 69 74 72 79 20 61 6c  6c 0d 6d 6f 75 6e 74 65  |uitry all.mounte|
000011b0  64 20 6f 6e 20 62 6f 61  72 64 2c 20 77 69 74 68  |d on board, with|
000011c0  20 61 6c 6c 20 6f 66 20  74 68 65 20 63 6f 6d 70  | all of the comp|
000011d0  75 74 65 72 20 70 72 6f  67 72 61 6d 20 73 6f 66  |uter program sof|
000011e0  74 77 61 72 65 20 72 75  6e 6e 69 6e 67 20 6f 6e  |tware running on|
000011f0  20 61 0d 42 42 43 20 6f  66 66 20 74 68 65 20 6d  | a.BBC off the m|
00001200  6f 64 65 6c 20 74 65 6e  6e 69 73 20 63 6f 75 72  |odel tennis cour|
00001210  74 2e 20 54 68 65 20 74  77 6f 20 61 72 65 20 63  |t. The two are c|
00001220  6f 6e 6e 65 63 74 65 64  20 62 79 20 6d 65 61 6e  |onnected by mean|
00001230  73 20 6f 66 20 74 77 6f  0d 70 61 72 61 6c 6c 65  |s of two.paralle|
00001240  6c 20 63 61 62 6c 65 73  20 2d 20 6f 6e 65 20 66  |l cables - one f|
00001250  6f 72 20 74 68 65 20 42  42 43 20 75 73 65 72 20  |or the BBC user |
00001260  70 6f 72 74 2c 20 61 6e  64 20 74 68 65 20 6f 74  |port, and the ot|
00001270  68 65 72 20 66 6f 72 20  74 68 65 20 70 72 69 6e  |her for the prin|
00001280  74 65 72 0d 70 6f 72 74  2e 20 54 68 69 73 20 73  |ter.port. This s|
00001290  79 73 74 65 6d 20 69 73  20 73 68 6f 77 6e 20 62  |ystem is shown b|
000012a0  65 6c 6f 77 3a 0d 0d 0d  54 68 65 20 62 61 73 69  |elow:...The basi|
000012b0  63 20 6d 65 63 68 61 6e  69 63 61 6c 20 64 65 73  |c mechanical des|
000012c0  69 67 6e 20 6f 66 20 42  61 6c 6c 42 6f 74 20 69  |ign of BallBot i|
000012d0  73 20 73 68 6f 77 6e 20  62 79 20 74 68 69 73 20  |s shown by this |
000012e0  64 69 61 67 72 61 6d 2e  20 54 68 65 72 65 20 61  |diagram. There a|
000012f0  72 65 0d 75 6c 74 72 61  73 6f 6e 69 63 20 73 65  |re.ultrasonic se|
00001300  6e 73 6f 72 73 20 70 6c  61 63 65 64 20 61 72 6f  |nsors placed aro|
00001310  75 6e 64 20 74 68 65 20  65 64 67 65 20 6f 66 20  |und the edge of |
00001320  42 61 6c 6c 42 6f 74 2c  20 77 68 69 63 68 20 61  |BallBot, which a|
00001330  72 65 20 61 6e 67 6c 65  64 20 74 6f 0d 67 69 76  |re angled to.giv|
00001340  65 20 74 68 65 20 72 6f  62 6f 74 20 61 20 66 61  |e the robot a fa|
00001350  69 72 6c 79 20 63 6f 6d  70 6c 65 74 65 20 76 69  |irly complete vi|
00001360  73 69 6f 6e 20 6f 66 20  69 74 73 20 73 75 72 72  |sion of its surr|
00001370  6f 75 6e 64 69 6e 67 73  2e 20 54 68 65 20 73 65  |oundings. The se|
00001380  6e 73 6f 72 73 0d 77 68  65 72 65 20 70 6c 61 63  |nsors.where plac|
00001390  65 64 20 75 6e 64 65 72  20 74 68 65 20 61 73 73  |ed under the ass|
000013a0  75 6d 70 74 69 6f 6e 20  74 68 61 74 20 74 68 65  |umption that the|
000013b0  79 20 61 6c 6c 20 68 61  76 65 20 61 20 72 61 6e  |y all have a ran|
000013c0  67 65 20 6f 66 20 76 69  73 69 6f 6e 20 6f 66 0d  |ge of vision of.|
000013d0  33 30 20 64 65 67 72 65  65 73 2e 20 54 68 65 20  |30 degrees. The |
000013e0  72 6f 62 6f 74 20 69 73  20 70 6f 77 65 72 65 64  |robot is powered|
000013f0  20 62 79 20 74 77 6f 20  64 72 69 76 65 20 77 68  | by two drive wh|
00001400  65 65 6c 73 2c 20 6f 6e  65 20 65 61 63 68 20 73  |eels, one each s|
00001410  69 64 65 2c 20 61 6e 64  0d 74 68 65 72 65 20 69  |ide, and.there i|
00001420  73 20 6f 6e 65 20 73 75  70 70 6f 72 74 20 77 68  |s one support wh|
00001430  65 65 6c 20 74 6f 20 6d  61 6b 65 20 42 61 6c 6c  |eel to make Ball|
00001440  42 6f 74 20 61 20 74 68  72 65 65 2d 77 68 65 65  |Bot a three-whee|
00001450  6c 20 76 65 68 69 63 6c  65 2e 20 54 68 65 0d 62  |l vehicle. The.b|
00001460  61 6c 6c 73 20 63 6f 6c  6c 65 63 74 20 69 6e 20  |alls collect in |
00001470  61 6e 20 61 72 65 61 20  69 6e 20 74 68 65 20 63  |an area in the c|
00001480  65 6e 74 72 65 2e 20 54  68 69 73 20 64 69 61 67  |entre. This diag|
00001490  72 61 6d 20 69 73 20 61  63 74 75 61 6c 6c 79 20  |ram is actually |
000014a0  61 0d 73 69 6d 70 6c 69  66 69 65 64 20 76 65 72  |a.simplified ver|
000014b0  73 69 6f 6e 20 6f 66 20  74 68 65 20 4c 65 67 6f  |sion of the Lego|
000014c0  20 72 6f 62 6f 74 2c 20  6e 6f 74 20 74 68 65 20  | robot, not the |
000014d0  66 69 6e 61 6c 20 72 6f  62 6f 74 2c 20 77 68 69  |final robot, whi|
000014e0  63 68 20 77 69 6c 6c 0d  70 72 6f 62 61 62 6c 79  |ch will.probably|
000014f0  20 62 65 20 68 65 6d 69  73 70 68 65 72 69 63 61  | be hemispherica|
00001500  6c 2c 20 6e 6f 74 20 73  71 75 61 72 65 2e 0d 0d  |l, not square...|
00001510  41 74 20 74 68 65 20 6d  6f 6d 65 6e 74 2c 20 74  |At the moment, t|
00001520  68 65 20 6d 65 63 68 61  6e 69 63 73 20 74 65 61  |he mechanics tea|
00001530  6d 20 69 73 20 77 6f 72  6b 69 6e 67 20 6f 6e 20  |m is working on |
00001540  69 6e 73 74 61 6c 6c 69  6e 67 20 61 20 6e 65 77  |installing a new|
00001550  20 63 6f 6c 6c 65 63 74  6f 72 0d 6d 65 63 68 61  | collector.mecha|
00001560  6e 69 73 6d 20 74 6f 20  74 68 65 20 70 72 6f 74  |nism to the prot|
00001570  6f 74 79 70 65 20 2d 20  74 68 69 73 20 77 69 6c  |otype - this wil|
00001580  6c 20 77 6f 72 6b 20 75  73 69 6e 67 20 74 77 6f  |l work using two|
00001590  20 6c 61 72 67 65 20 72  6f 6c 6c 65 72 73 0d 73  | large rollers.s|
000015a0  70 69 6e 6e 69 6e 67 20  6f 6e 20 6f 70 70 6f 73  |pinning on oppos|
000015b0  69 74 65 20 64 69 72 65  63 74 69 6f 6e 73 20 74  |ite directions t|
000015c0  6f 20 27 73 75 63 6b 27  20 74 68 65 20 62 61 6c  |o 'suck' the bal|
000015d0  6c 20 69 6e 74 6f 20 74  68 65 20 72 6f 62 6f 74  |l into the robot|
000015e0  2e 20 43 61 72 65 0d 6d  75 73 74 20 62 65 20 74  |. Care.must be t|
000015f0  61 6b 65 6e 20 74 6f 20  65 6e 73 75 72 65 20 74  |aken to ensure t|
00001600  68 61 74 20 74 68 69 73  20 77 6f 72 6b 73 20 65  |hat this works e|
00001610  71 75 61 6c 6c 79 20 77  65 6c 6c 20 74 6f 20 72  |qually well to r|
00001620  65 6c 65 61 73 65 20 74  68 65 20 62 61 6c 6c 73  |elease the balls|
00001630  0d 62 79 20 73 70 69 74  74 69 6e 67 20 74 68 65  |.by spitting the|
00001640  6d 20 6f 75 74 20 6f 66  20 74 68 65 20 66 72 6f  |m out of the fro|
00001650  6e 74 2c 20 61 6e 64 20  61 6c 73 6f 20 74 68 61  |nt, and also tha|
00001660  74 20 74 68 65 72 65 20  69 73 20 6e 6f 20 72 69  |t there is no ri|
00001670  73 6b 20 6f 66 0d 73 75  63 6b 69 6e 67 20 75 70  |sk of.sucking up|
00001680  20 74 6f 6f 20 6d 75 63  68 2e 20 54 68 65 72 65  | too much. There|
00001690  20 63 6f 75 6c 64 20 64  69 66 66 69 63 75 6c 74  | could difficult|
000016a0  20 73 69 74 75 61 74 69  6f 6e 20 69 66 20 74 68  | situation if th|
000016b0  65 20 72 6f 62 6f 74 20  77 65 72 65 20 74 6f 0d  |e robot were to.|
000016c0  74 72 79 20 74 6f 20 73  75 63 6b 20 75 70 20 61  |try to suck up a|
000016d0  20 62 61 6c 6c 20 77 68  69 63 68 20 69 73 20 75  | ball which is u|
000016e0  70 20 63 6c 6f 73 65 20  61 67 61 69 6e 73 74 20  |p close against |
000016f0  74 68 65 20 6e 65 74 2c  20 61 6e 64 20 74 68 65  |the net, and the|
00001700  20 6e 65 74 0d 62 65 63  61 6d 65 20 65 6e 74 61  | net.became enta|
00001710  6e 67 6c 65 64 20 69 6e  20 74 68 65 20 63 6f 6c  |ngled in the col|
00001720  6c 65 63 74 6f 72 2e 0d  0d 41 6e 6f 74 68 65 72  |lector...Another|
00001730  20 70 72 6f 62 6c 65 6d  20 77 68 69 63 68 20 69  | problem which i|
00001740  73 20 69 6e 20 6e 65 65  64 20 6f 66 20 61 74 74  |s in need of att|
00001750  65 6e 74 69 6f 6e 20 69  73 20 74 68 61 74 20 6f  |ention is that o|
00001760  66 20 73 74 65 65 72 69  6e 67 20 74 68 65 0d 72  |f steering the.r|
00001770  6f 62 6f 74 2e 20 54 68  65 20 6f 72 69 67 69 6e  |obot. The origin|
00001780  61 6c 20 69 64 65 61 2c  20 61 73 20 73 74 61 74  |al idea, as stat|
00001790  65 64 20 69 6e 20 74 68  65 20 63 6f 6e 74 72 6f  |ed in the contro|
000017a0  6c 20 73 65 63 74 69 6f  6e 2c 20 77 61 73 20 74  |l section, was t|
000017b0  6f 20 68 61 76 65 0d 6f  6e 65 20 6d 6f 74 6f 72  |o have.one motor|
000017c0  20 73 70 65 65 64 20 75  70 20 61 6e 64 20 74 68  | speed up and th|
000017d0  65 20 6f 74 68 65 72 20  73 6c 6f 77 20 64 6f 77  |e other slow dow|
000017e0  6e 20 74 6f 20 74 75 72  6e 20 74 68 65 20 72 6f  |n to turn the ro|
000017f0  62 6f 74 2e 20 41 74 20  74 68 65 0d 6d 6f 6d 65  |bot. At the.mome|
00001800  6e 74 2c 20 68 6f 77 65  76 65 72 2c 20 74 68 65  |nt, however, the|
00001810  72 65 20 69 73 20 74 6f  6f 20 6d 75 63 68 20 66  |re is too much f|
00001820  72 69 63 74 69 6f 6e 20  62 65 74 77 65 65 6e 20  |riction between |
00001830  74 68 65 20 72 6f 62 6f  74 27 73 20 77 68 65 65  |the robot's whee|
00001840  6c 73 20 61 6e 64 0d 74  68 65 20 67 72 6f 75 6e  |ls and.the groun|
00001850  64 2c 20 73 75 63 68 20  74 68 61 74 20 74 68 65  |d, such that the|
00001860  20 72 6f 62 6f 74 20 63  61 6e 6e 6f 74 20 74 75  | robot cannot tu|
00001870  72 6e 2e 20 55 6e 64 65  72 20 74 68 65 20 70 6f  |rn. Under the po|
00001880  77 65 72 20 6f 66 20 6f  6e 65 20 6d 6f 74 6f 72  |wer of one motor|
00001890  2c 0d 74 68 65 20 72 6f  62 6f 74 20 64 72 69 76  |,.the robot driv|
000018a0  65 73 20 73 74 72 61 69  67 68 74 20 66 6f 72 77  |es straight forw|
000018b0  61 72 64 20 72 61 74 68  65 72 20 74 68 65 6e 20  |ard rather then |
000018c0  74 75 72 6e 69 6e 67 2e  20 54 68 65 72 65 66 6f  |turning. Therefo|
000018d0  72 65 20 77 65 20 6d 75  73 74 0d 74 72 79 20 74  |re we must.try t|
000018e0  6f 20 72 65 64 75 63 65  20 66 72 69 63 74 69 6f  |o reduce frictio|
000018f0  6e 20 62 65 74 77 65 65  6e 20 74 68 65 20 77 68  |n between the wh|
00001900  65 65 6c 73 20 61 6e 64  20 74 68 65 20 67 72 6f  |eels and the gro|
00001910  75 6e 64 2e 20 54 68 69  73 20 73 68 6f 75 6c 64  |und. This should|
00001920  20 6e 6f 74 0d 62 65 20  64 69 66 66 69 63 75 6c  | not.be difficul|
00001930  74 2c 20 61 73 20 69 74  20 73 69 6d 70 6c 79 20  |t, as it simply |
00001940  6d 65 61 6e 73 20 72 65  70 6c 61 63 69 6e 67 20  |means replacing |
00001950  74 68 65 20 73 75 70 70  6f 72 74 20 77 68 65 65  |the support whee|
00001960  6c 73 20 77 69 74 68 20  77 68 65 65 6c 73 0d 77  |ls with wheels.w|
00001970  68 69 63 68 20 63 61 6e  20 74 75 72 6e 20 6d 6f  |hich can turn mo|
00001980  72 65 20 65 61 73 69 6c  79 2c 20 73 69 6d 69 6c  |re easily, simil|
00001990  61 72 20 74 6f 20 63 61  73 74 65 72 73 2e 0d 0d  |ar to casters...|
000019a0  54 68 65 20 65 78 61 63  74 20 64 65 73 69 67 6e  |The exact design|
000019b0  20 6f 66 20 74 68 65 20  66 69 6e 61 6c 20 72 6f  | of the final ro|
000019c0  62 6f 74 20 69 73 20 73  74 69 6c 6c 20 62 65 69  |bot is still bei|
000019d0  6e 67 20 66 69 6e 61 6c  69 73 65 64 2c 20 62 75  |ng finalised, bu|
000019e0  74 20 69 74 20 77 69 6c  6c 0d 70 72 6f 62 61 62  |t it will.probab|
000019f0  6c 79 20 6c 6f 6f 6b 20  73 6f 6d 65 74 68 69 6e  |ly look somethin|
00001a00  67 20 6c 69 6b 65 20 74  68 65 20 61 72 74 69 73  |g like the artis|
00001a10  74 27 73 20 69 6d 70 72  65 73 73 69 6f 6e 20 73  |t's impression s|
00001a20  68 6f 77 6e 20 74 6f 20  74 68 65 20 72 69 67 68  |hown to the righ|
00001a30  74 2e 0d 54 68 65 20 6f  75 74 65 72 20 73 68 65  |t..The outer she|
00001a40  6c 6c 20 77 69 6c 6c 20  62 65 20 70 6c 61 73 74  |ll will be plast|
00001a50  69 63 2c 20 77 69 74 68  20 74 68 65 20 63 69 72  |ic, with the cir|
00001a60  63 75 69 74 72 79 20 61  6e 64 20 62 61 74 74 65  |cuitry and batte|
00001a70  72 69 65 73 20 6d 6f 75  6e 74 65 64 0d 61 74 20  |ries mounted.at |
00001a80  74 68 65 20 62 61 63 6b  2c 20 69 6e 73 69 64 65  |the back, inside|
00001a90  20 74 68 65 20 73 68 65  6c 6c 2e 20 54 68 65 72  | the shell. Ther|
00001aa0  65 20 77 69 6c 6c 20 62  65 20 72 6f 6c 6c 65 72  |e will be roller|
00001ab0  73 20 61 74 20 74 68 65  20 66 72 6f 6e 74 20 74  |s at the front t|
00001ac0  6f 0d 63 6f 6c 6c 65 63  74 20 74 68 65 20 62 61  |o.collect the ba|
00001ad0  6c 6c 73 2c 20 77 68 69  63 68 20 63 6f 6c 6c 65  |lls, which colle|
00001ae0  63 74 20 69 6e 20 74 68  65 20 6d 69 64 64 6c 65  |ct in the middle|
00001af0  20 6f 66 20 74 68 65 20  72 6f 62 6f 74 2c 20 69  | of the robot, i|
00001b00  6e 20 66 72 6f 6e 74 20  6f 66 0d 74 68 65 20 63  |n front of.the c|
00001b10  69 72 63 75 69 74 72 79  20 61 74 20 74 68 65 20  |ircuitry at the |
00001b20  62 61 63 6b 2e 20 41 6c  6c 20 6f 66 20 74 68 65  |back. All of the|
00001b30  20 63 6f 6e 74 72 6f 6c  73 20 77 69 6c 6c 20 62  | controls will b|
00001b40  65 20 6d 6f 75 6e 74 65  64 20 6f 6e 20 74 68 65  |e mounted on the|
00001b50  20 74 6f 70 0d 6f 66 20  74 68 65 20 68 65 6d 69  | top.of the hemi|
00001b60  73 70 68 65 72 65 2c 20  77 68 65 72 65 20 74 68  |sphere, where th|
00001b70  65 79 20 61 72 65 20 65  61 73 69 65 73 74 20 66  |ey are easiest f|
00001b80  6f 72 20 74 68 65 20 75  73 65 72 20 74 6f 20 61  |or the user to a|
00001b90  63 63 65 73 73 2e 0d                              |ccess..|
00001b97

Our privacy policy is here.
Last updated: 28 Jul 2024, 23:31 UTC
Website designed by .