Design & Technology
Form 2
Project : One gearbox - Two legged - Two arm - robot
Situation : We have completed a robot with 1 gearbox & 4 walking legs last
year in Form One (1999-2000 ).
Design Brief : Can we modify this 4 walking legs robot to be a 2 walking
legs robot ?
Design Specification :
 It can stand up on 2 legs.
 It can walk with 2 legs in a straight line.
 It can move 2 arms.
 It can keep balance.
Research :
 Research on terms like equilibrium , center of gravity , base area ,
moment & stability. (‘www.bbc.co.uk/education )
 Research on Form & Shape of two leg – walking – animal.
(Search engine : ‘www.hotbot.lycos.com )
 Research on electronics :
sound & light input signal ,
LED, capacitor, resistor, mic , LDR
(‘www.dtonline.org )
Sketch :
 At least one sketch on 2 leg-animal.
 At least one sketch on standing up mechanism. ( i.e. lever & linkage ,
Label : center of gravity., base area )
Explorations :
 One spreadsheet ( Excel table ) to show speed &
length of straight line travelled
with variations of linkage , feet & crank length , friction
or any other combinations
Solutions :
 One final drawing on 2 leg-animal with wood color. ( label : materials ,
size )
 One final drawing on standing up mechanism. ( label : center of gravity.,
base area , gear combination , crank , lever & linkage , friction )
 Comic drawing to show the movements of 2 arms & 2 legs.
 Draw block diagrams to show input , process & output for :
Sound sensor + motor control + robot movement
Light sensor + motor control + robot movement
Sample 1 : Spreadsheet ( Excel )
linkage
arm1
10
12
(mm)
arm2
50
50
leg1
10
12
leg2
20
20
gear speed straight line 7 ft (sec)
low
10
15
low
25
12
linkage combination vs speed & straight line
travelled
30
25
20
10 50 10 20
low
15
10
5
0
12 50 12 20
low
straight line
7 ft (sec)
Arm
Ice cream stick
foot
Leg
Sample 2 : Spreadsheet ( Excel )
Linkage combination to build up a spreadsheet :
Sample 3 : Block Diagram
 Sound sensor I/O diagram :
Carbon mic
Input sound signal
Sound
sensor
Circuit
board
?
?
Sample research on 2 legs standing animal
Form & Shape
Newspaper cutting or magazine cutting or internet research graphics
head
eye
Allosaurus
neck
leg
mouth
tail
arm
belly
hand
foot
AL-oh-SAW-russ
NAME: Different lizard
TIME: 145 million years
ago
SIZE: up to 40 feet long
PLACE: North American
West
Allosaurus was the largest Jurassic
predator, with three-fingered strong
hands and powerful jaws.
Locate & label parts of the animal :
Head
x
eye
neck
x
shoulder
leg
x
foot
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
13.
14.
15.
16.
x
x
mouth
x
nose
ear
arm
x
hand
x
tail
x
belly
x
hip
Workshop Evaluations :
( cross ‘x’ if the problem happened to you )
Asymmetrical : length of left hand side motor shaft different from right
(
)
Asymmetrical : motor shaft not horizontal
(
)
Asymmetrical : length of left leg different from right leg
(
)
Asymmetrical : length of arm linkage at left different from right
(
)
Friction : robot hits the wall of track & stops
Friction : robot steps on the same location
Friction : robot walks in a curve
Friction : screw & nut too tight
Friction : Linkage arms too tight to move
Friction : Linkage arms rub with each other
Center of gravity : Robot too tall
Center of gravity : Legs too long
Center of gravity : too high & robot falls
Center of gravity : battery case too high
Base Area : too small & robot falls
Base Area : foot too big
x
(
(
(
(
(
(
(
(
(
(
(
(
Measurements :
a
a’
wood screw
y
glue
z
screw & nut*
w
Left hand side
mm
Right hand side mm
a
motor shaft
a’
x
Between “wood screw” & “screw & nut”
x’
y
Between “top of leg” & “screw & nut”
y’
z
Between “top of leg” & “screw & nut*”
z’
w
Between “foot” & “screw & nut”
z’
Phase
task
no. of cycle
)
)
)
)
)
)
)
)
)
)
)
)
one
research
two
lever & linkage :
three
four
form & shape
electronic control :
five
report & evaluation
1
stand up
walk in balance ( 7 ft. track )
sound
light
total
1
2
2
3
1
1
11