Milford Instruments BigFoot Manual de usuario

Milford Instruments Limited, Milford House, 120 High Street, South Milford, LS25 5AQ England

Tel 01977 683665, Fax 01977 681465 www.milinst.com

Milford Instruments Ltd

BigFoot

Contents:

Kit Contents page 2

Introduction page 3

Electronics Board page 4

Programming page 5

Fitting the Servos page 6

Ankle construction page 7

Foot construction page 8

Body board/Pace wires page 9

Leg Tendons page 10

Assembling the Toe switches page 11

PCB Mounting- Setup and run page 12

Fine tuning page 13

Schematic page 15

Milford Instruments Limited, Milford House, 120 High Street, South Milford, LS25 5AQ England

Tel 01977 683665, Fax 01977 681465 www.milinst.com

Kit Contents

Printed Circuit Board 1

“Toe” circuit board 2

4 x AA Battery Holder 1

Set Pre-cut body parts 1

150mm 48thou dia piano wire 3

150mm 22thou dia piano wire 2

25x1mm dia brass tube 2

20x2mm dia brass tube 2

300 mmx1mm dia brass wire 2

50mmx2.5mm cable sleeving 1

500mm twin wire 1

2 way plug socket 2

Cable pins 4

2-way header pins 2

Foam Pads 2

Manual 1

Diskette 1

Additional Items:

PBASIC 1.4 Chip 1

93LC56 Chip 1

Servo Motor 2

Milford Instruments Limited, Milford House, 120 High Street, South Milford, LS25 5AQ England

Tel 01977 683665, Fax 01977 681465 www.milinst.com

Introduction

BigFoot is a fully walking humanoid robot. It achieves this by using only two servo

motors controlled by the Parallax BASIC Stamp microcontroller.

One servo operates to roll the centre of gravity from one foot to the other whilst the

second servo controls the pace of the legs.

BigFoot is fitted with twin LED “eyes” and “Toe” switches that make him back-up

when he contacts anything.

If fitted with good quality NiCad type batteries, BigFoot should continue to wander

for about 1 hour.

If you bought BigFoot in the UK or directly from Milford Instruments, then the

operating programme will have been pre-loaded into the EEPROM chip and will

require no further programming.

If you bought BigFoot in the USA or if you wish to experiment by changing the

programme, you may need to make a programming cable (as shown on page 5)

and to load the programme from diskette.

Once you have checked the kit items against the contents list, we suggest you work

in the order presented in this manual.

In addition to the assembly sketches shown in this manual you may also wish to

view actual construction stage photographs in the BigFoot section of our web site-

www.milinst.com

If you have any problems, please e-mail us at [email protected]

Milford Instruments Limited, Milford House, 120 High Street, South Milford, LS25 5AQ England

Tel 01977 683665, Fax 01977 681465 www.milinst.com

Electronics Board

If not already fitted, fit the 18-pin chip marked PBASIC1.4 and the 8-pin chip

marked 93LC56. Ensure the depression on one end of the chip corresponds to the

diagram below.

Connect the two servos to the 3-pin headers on the board- ensure they are fitted

the correct way round.

With the ON-OFF switch set to OFF, insert 4xAA Nicad batteries into the holder

and connect to the circuit board using the flying lead provided.

Switch the board ON- the servos should move to their center position for 2

seconds and then move in an oscillating manner and the LEDs toggle on and off. If

not- immediately switch OFF and check the installation of the two chips and

battery.

The electronics board is now ready and tested.

If you bought the kit in the USA then you may need to load the programme -

please do this as indicated on page 5 before proceeding further.

Note on BatteriesNote on Batteries

Servo motors have a high current requirement- for this reason it is important thatServo motors have a high current requirement- for this reason it is important that

onlyonly NiCadNiCad oror NiMH (NiMH (Nickle Metal Hydride) batteries are used.Nickle Metal Hydride) batteries are used.

Standard Zinc, Alkaline or Alkaline/Manganese batteries will not work and mayStandard Zinc, Alkaline or Alkaline/Manganese batteries will not work and may

cause loss of the embedded programme.cause loss of the embedded programme.

Milford Instruments Limited, Milford House, 120 High Street, South Milford, LS25 5AQ England

Tel 01977 683665, Fax 01977 681465 www.milinst.com

Programming

This section is only applicable if you bought the kit in the USA or wish to modify the

programme

If you weren’t supplied with a programming cable, make up a suitable cable as

shown in figure 2.

Connect the programming cable to the PC printer port and to the 3-pin header on

the electronics board.

Ensure your PC is in MSDOS mode (if you are running Windows ’95 etc then you

will have to instruct the machine to re-boot in MSDOS mode).

Insert the diskette in drive A

Type AA:: press Enter

Type stamptamp press Enter

Press ALT- LALT- L this will display the available .bas files

Scroll using the Up/Down keys until bigfoot.basbigfoot.bas is highlighted press Enter

The bigfoot.basbigfoot.bas programme should now be showing on the screen

Switch the electronics board ONON

Press ALT- RALT- R

The loading window should now appear and a white bar shows the programming

status.

If all is well the programme will indicate programming success and the LEDs on the

electronics board will start to flash. If programming has not been successful a

warning message will be shown- if this occurs check that the 3-pin header is the

correct way round, that the cable connections are correct and that the electronics

board switch is set to ON.

If you wish to experiment with the programme, the programme may be altered

using straightforward text when displayed on the screen. Any new version may be

saved by pressing ALT S- give the file a name other than bigfoot.bas otherwise your

original file will be overwritten!

Now return to complete the testing of the electronics board.

Programming Cable Details- Figure 2

D-25 PlugD-25 Plug

Pin 25 GND

Pin 11 BUSY

Pin 2 DO

3-Way header and socket

Milford Instruments Limited, Milford House, 120 High Street, South Milford, LS25 5AQ England

Tel 01977 683665, Fax 01977 681465 www.milinst.com

Fitting the Servos

Please take care with the following steps- it is important that the servos are squarePlease take care with the following steps- it is important that the servos are square

within the side cheeks and that the side cheeks are parallel to one anotherwithin the side cheeks and that the side cheeks are parallel to one another

Using a glue gun or double sided tape, stick one servo to the side cheek as shown

in figure 3.

Make sure the FRONT edge of the servo is parallel to the edge of the cheek

otherwise it will affect the way BigFoot walks.

Figure 3

Front of servo parallel to the front edge of side cheek and against top edge. Fit with circular horn

Now fit the second servo- this time make sure the REAR edge of the mounting

flange is parallel to the edge of the side cheek.

Figure 4

Milford Instruments Limited, Milford House, 120 High Street, South Milford, LS25 5AQ England

Tel 01977 683665, Fax 01977 681465 www.milinst.com

Rear edge of servo flange parallel to edge of side cheek and positioned mid-way. Fit with 2-lever

horn.

Fit the second side cheek to the servos. Make sure the edges of both cheeks are

parallel and aligned with one another.

Ankle Construction

Take a length of 1mm diameter brass wire and bend to the following shape:

Insert the wire into the ankle piece and fix in place with hot-melt glue or similar.

Fix, using hot-melt glue, an 85mm long piece of brass wire along the bottom

edge.

Repeat for the other ankle piece noting that they are handed

15mm 53mm

Stage 1

30mm 23mm

Stage 2

51mm

Bend upwards here

Figure 5

Milford Instruments Limited, Milford House, 120 High Street, South Milford, LS25 5AQ England

Tel 01977 683665, Fax 01977 681465 www.milinst.com

Foot Construction

Build the right foot as shown below

Fit the leg sections to the foot. Use short lengths of sleeving pushed over the ends

of the brass wire to secure in place.

Build the left foot and leg in a similar manner (note again that it will be the mirror

image of the right foot).

Secure with short piece

of sleeving

Figure 9

Ensure ankle support pieces are

perpendicular to the edge of the

foot and aligned with the edge

15mm

Hole for leg tendon

Figure 8

Milford Instruments Limited, Milford House, 120 High Street, South Milford, LS25 5AQ England

Tel 01977 683665, Fax 01977 681465 www.milinst.com

Body Board

Fix the servo block to the top board with hot-melt as shown- it must be

perpendicular to the top board.

Cut two 50mm lengths of brass wire. Push these through the holes in the top of the

legs and side cheeks to secure the legs to the body. Slip pieces of sleeving over the

ends to keep in place.

Bend the Left hand “Pace” wires as shown below and fit to the Left leg and “pace”

servo.

Stage 1 Stage 2 (Plan view)

Make and fit a similar (but right-handed) piece for the right leg. Secure in place

with sleeving.

30mm

10mm

18mm

Bend here

Figure 11

Figure 12

51mm

15mm

Figure 10

Milford Instruments Limited, Milford House, 120 High Street, South Milford, LS25 5AQ England

Tel 01977 683665, Fax 01977 681465 www.milinst.com

Leg Tendons

Support the legs and top board with the legs vertical and with the feet together and

horizontal.

Choose two diametrically opposite holes in the circular “roll” servo horn and

ensure these are level above the feet.

Cut and bend the lengths of piano wire as shown. Epoxy (or solder) the brass tube

to the lower wires making sure the end is approximately ½ way up the tube.

Thread the upper wires into the holes on the servo horn- make sure they are level.

Slip the lower wire tube onto the end and insert the lower end into the foot hole.

Ensure everything is vertical and symmetrical as shown above before completingEnsure everything is vertical and symmetrical as shown above before completing