PASCO ME-6807A User Manual
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Instruction Manu al with
Experimen t Guide and
Human Arm Model
ME-6807A
Teacher’s Notes
012-10359A
Human Arm Model Table of Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Parts of the Arm Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4
Clamping the Arm Model to a Lab Bench . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Locking or Limiting Shoulder Movement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Adjusting the Wrist Angle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Attaching the Mass . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Holding a Ball. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5
Attaching Cords to the Arm Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
How Angles are Measured. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Using Sensors with the Arm Model . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .7
Replacing the Elbow-stop Pad. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Replacement Parts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
About the Experiments. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Experiment 1: Biceps Force versus Perpendicular Load. . . . . . . . . . . . . . . . . . . . . . . . . 9
Experiment 2: Biceps Force versus Weight. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Experiment 3: Triceps Force versus Perpendicular Load . . . . . . . . . . . . . . . . . . . . . . . 13
Experiment 4: Biceps Curl . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Experiment 5: Biceps Force versus Shoulder Angle, Constant Elbow Angle . . . . . . . . 17
Experiment 6: Biceps Force versus Elbow Angle, Constant Forearm Orientation. . . . .19
Experiment 7: Triceps Extension. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Experiment 8: Rotational Inertia of the Forearm . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Demonstrations: Complex Movements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Teacher’s Notes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Technical Support . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Human Arm Model
ME-6807A
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Included with ME-6807A Replacement Part Number
1. Human Arm Model ME-6807A
2. 45 cm Rod ME-8736
3. Sensor-mounting Clamp
4. Sensor-mounting Studs, 2 pieces
5. 100 g Mass
6. Hollow Rubber Ball, 57 mm diameter
7. Cord Locks, 2 pieces
ME-6808 (Human Arm Model Spares Kit)
8. Cord, 2 90 cm pieces
9. Elastic Cord, 60 cm
10. Tubing for replacing elbow stop pad, 29 cm
11. Thumbscrew and nut for attaching mass
Also included with PS-2611 Part Number
Angle Sensor PS-2139
Other recommended equipment
Angle Sensor PS-2139
Force Sensors (2 recommended) PS-2104
C-clamp
SE-7286 (6-pack)
or
Large Table Clamp
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ME-9472
or
PS-2189
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Human Arm Model Introduction
Introduction
The Human Arm Model simulates the muscles and motion of an actual hum an a r m.
Changes in position are measured at the shoulder and elbow using the two built-in
potenti o me ters. Cords representi ng the biceps and tr iceps muscles attach to the arm.
Students can pull the cords to make the arm move and use f orce sensors to measure
the forces exerted by the muscles.
This manual includes:
• instructi ons for setting up the arm model (s tarting on page 5),
• various experiments (page 9),
• demonstrations of complex movements (page 25), and
• teacher’s notes and sample data for the experiments (page 28).
Parts of th e Arm Mo del
pulleys
screw for
attaching mass
attaching co rd
base
post for
cutout for
C-clamp
holes for
sensor-mounting
studs
biceps insertion
points
screw for
locking wrist
forearm
center of
mass
triceps insertion point
shoulder
stops
angle
sensor
plugs
rod clamp
Figur e 1: Parts of the arm mo de l
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ME-6807A Clamping the Arm Mo del to a Lab Bench
Clamping the Arm Model to a Lab Bench
The base of the arm model must be clamped to a stable obje ct such as a lab bench.
This can be done with a C-clamp or with a model ME-9472 Large Table Clamp.
Depending on how you will use the mode l, you can clamp the base horizontally, vertically, or upside down.
Figure 2: Various ways
to orient and secur e
the arm model
Locking or Limiting Shoulder Movement
The shoulder can be locked at an angle, or its movement can be limited, using the
adjustable s houlder stops (see Figure 3). L oosen one of the shoulder sto p nuts , s lide
the stop to the desi red positio n, an d tighten the nut. Repeat for the ot her shoulder s top.
Adjusting the Wrist Angle
Loosen the wrist nut, change the position of the hand, and tighten the nut (Figure 4a).
Attaching the Mass
Use the included scre w and nut to attach the 100 g mass to the hand (Figure 4b).
Holding a Ball
Adjust the angles of the shoulder, elbow, and wrist to make the hand horizontal. Place
the ball on the hand (Fi gure 4c).
100 g
loosen nut to
adjust wrist
mass
loosen nut
and slid e
into positio n
Figure 3: Adjustable
shoulder stops
ball
abc
Figure 4: The hand
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Human Arm Model Attaching Cords to the Arm Model
Attaching Cords to the Arm Model
Cords ar e us ed to re p r esent the mu s c le s of
inner biceps insertion po int
standard biceps insertion point
the upper arm. Depending on how you will
use the model, you can attach one or two
cords, u se s ta n d ar d co rds o r elastic cord s ,
and run the cords over and under the pulleys
in various ways.
The biceps cord can be atta ch ed at the stan-
triceps
insertion
point
Figure 5: Muscle insertion points
dard muscle in sertion point, represen ting a
human arm, or at one of the other two insertion points, for more or less leverage (Figure 5).
1. Tie a knot near the end of a cord and thread the other end through one of the
insertion poi nt holes. Pull the cord th rough until the knot stops aga inst the hole
(Figure 6).
2. Run the cord over and under the pulleys in the desired configuration. (For exam-
ples, see the expe riments and demonstrations starting on page9.)
3. Use one of th e in clu d e cor d lo cks to make a loo p in t he f r ee end of the co rd . Pl ac e
the loop over a post or a force sensor hook. Adjust the length of the cord. Push
the cord lock against the post or hook and tie a knot against the cord lock to prevent it from slipping (F igure 7).
outer biceps insertion point
Figure 6: Cord attached
to insertio n poin t
How Angles are Measured
The angle sensor determines the shoulder and elbow angles from the resistance of the
potentiometers built into the joints. Figure 8 shows how the angles are measured.
shoulder
angle
elbow
angle
Figure 7: Cord attached
to force sensor with
cord lock
Figure 8: H ow ang les are meas ur e d
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ME-6807A Using Sensors wi th the Ar m Model
Using Sensors with the Arm Model
Note: For more information about angle sensors, force sensors, and interfaces, see the instructions supplied with those devices.
Angle Sensor
1. Connect the cable from the elbow to Channel 1 of the angle sensor.
2. Connect the cable from the shoulder to Channel 2 of the angle sensor.
3. Connect the angle sensor to y o u r PASPORT interface.
4. If you are using a compute r, connect the PASPORT interface to it and start
DataStudio.
Force Sens or
1. Conne ct a fo rc e sensor to th e s ame PASPO RT inter f ac e as th e ang l e s en so r (i f it
is a multi-port interface) or to a separate inte r f ace.
2. Use one of the included cord locks to make a loop in the biceps or triceps cord
and attach it to force sensor’s hook (see “Attaching Cords to the Arm Model” on
page 6).
3. Clamp the include d 45 cm rod to the base of the arm model (Figure 9).
4. Secure the inc luded se nsor cl amp to t he rod. Sc rew the sen sor st ud into t he cla mp
(Figure 10).
5. Mount the force sensor on the stud (Figure 11).
Repeat steps 1 and 2 to add a second force sensor.
For some experiments, the second force sensor is used to apply a load to the model’s
hand. You can hook the force sensor dir ectly onto t he hand, or , for more fl exibi lit y, tie
a loop of string to the hand (Figure 12).
rod
Figure 9: Rod clamped
in base
Figure 10: Sensor stud
and clamp
To mount a force sensor on the upper arm , screw a sensor stud into one of the
threaded holes. (See Figure 13, and Experiment 5 on page 17.) Use the upper hole to
place the sensor in the biceps position or the lower hole for the triceps position. This
allows the elb o w an g le to stay consta n t w hi l e the shoul d er is r o ta ted.
Figure 11: Force sensor
on rod
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Figure 12: Force sensor attached to
hand with string
Figure 13: Force sensor attached to
upper arm and triceps cord
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Human Arm Mod el Replacing the Elbow-stop Pa d
Replacing the Elbow-stop Pad
The post that limits the trave l of the elbow is padded with pla sti c tubing. If the plas tic
become s worn, complete these steps to replace i t.
1. Use a sharp knife to remove the old pad.
2. Cut a 10 mm piece from tubing inclu d ed with the arm model.
3. Press the piece of tubing onto the post (F igure 14).
Figure 14: Elbow-stop
pad replacement
Replacement Parts
The Human Arm Mode l Spares Kit (PASCO part ME-6808) is available to replace
lost or worn parts. It contains:
• Cord, inelastic (120 cm)
• Elastic cord (60cm)
• Cord locks (10)
•Balls (3)
• 100 g masses (2)
• Screws and nuts for attaching mass to hand (2 of each)
• Sensor-mounting clamps (2)
• Sensor-mounting studs (2)
• T-screws for rod clamp (4)
• Shoulder stops (2)
• Bumper that contacts s houlder stops (1)
• Screws and nuts for locking wrist (2 of each)
• Tubing for replacing elbow stop pad (30 cm)
About the Experiments
Experiments are presented on the following pages as examples of ways to set up and
use the arm model. In many of these exp eriments, students are asked to perform an
action with the ir own arms and make predic tions before rep roducing the acti on on the
arm model. Teacher's notes and sample data can be found on page 28.
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Experiment 1: Biceps Force versu s Perpendicular Load
Required Parts of Human Arm Model
Arm
Cord ( 1 piece)
45 cm rod
Sensor- m o un t in g cl am p and stud
Other Required Equipment
or
2 Force Sensors PS-210 4
C-clamp SE-7286 (6-pack)
Introduction
Hold your arm in front of you with you r elbow bent at 90°. Now have your partner
pull your hand to try t o strai ghten yo ur elbow. Resist the load forc e so th at your e lbow
remains at 90°.
Predictions
1. Which muscle (the biceps or triceps) did you use to resist this load? How do you
know?
PS-2189
2. Was the muscle force greater than, less than, or equal to the load force applied to
your hand?
3. If you partner pulls your hand with a force of 1 N,
guess how much muscle f orce is needed to keep your
elbow at 90°.
Force Sensor 1
(Biceps Force)
Set-up
1. Clamp the arm model horizontally as illustrated.
2. Clamp the rod to t he bas e of the m odel a s ill ustra ted. Use
the sens o r clamp and stud to at tach a force sensor t o th e
rod.
3. Lock the shoulder at 0°.
4. Attach a cord as illustrated. Adjust the length
of the cord so that the elbow is held at about
90°.
5. Conn ect tw o f o rce sensors to your interf a c e .
The second force sensor will be held in your hand and
apply the load force to the model’ s hand.
6. Set the sampling rate of both force sensors to 20 Hz.
7. Prepare a graph to plot bic eps force versus load force.
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Human A rm Model Experiment 1: B iceps Force vers us Perpendicular L oad
Procedure
1. Start data collection.
2. Hook the second force sensor onto to the model’s hand and
pull in the direction indicated in the illustration. Slowly
increase the force while watching the graph.
3. When the load force reaches about 2 N, stop data collection.
Force Sensor 2
(Load Force)
Analysis
1. Using words and numbers, explain the relationship between load forc e and
biceps force.
2. Were your predictions accurate? Explain.
Further Analysis
1. Draw a free-body diagr am showi ng all forces (in the plane of rot ation) acting on
the forearm.
2. What is the net force on the forearm?
3. What is the net torque?
Furt her Study
1. Repeat the experiment with the elbow at a different angles, but keep the load
force perpendicular to the forearm. How does the ratio of biceps force to load
force change for elbow angles greater an d less than 90°?
2. Repeat the experiment wit h th e cord attached at t h e o ther two biceps ins er tion
points.
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Experiment 2: Biceps Force versu s Weight
Required Parts of Human Arm Model
Arm
Cord ( 1 piece)
45 cm rod
Sensor- m o un t in g cl am p and stud
Other Required Equipment
or
2 Force Sensors PS-210 4
C-clamp SE-7286 (6-pack)
Introduction
Let your arm hang vertically at your side. While keeping your upper arm vertical ,
bend your elbow at 90° so that your forearm is horizontal. Hold your palm up. Have
your partner place a mass in your hand, but don't let your arm move.
Predictions
1. If the mass in your ha nd is 10 0 g (so it s weigh t is 0. 98 N), how much bi ceps forc e
is needed to keep your elbow at 90°? (Assume that your triceps is relaxed.)
PS-2189
2. If you double the mass in your ha nd (so the load force doubles), does the biceps
force double?
3. If you remove the mass from your hand, does the
biceps force go to zero? Explain your answer.
Force Sensor 1
Set-up
(Biceps Force)
1. Clamp the arm mode l vertically as illustrated.
2. Clamp the rod to t he bas e of the m odel a s ill ustra ted. Use
the sens o r clamp and stud to at tach a force sensor t o th e
rod.
3. Lock the shoulder at 0°.
4. Attach a cord as illustrated. Adjust the length
of the cord so that the elbow is held at about
90°.
5. Conn ect tw o f o rce sensors to your interf a c e .
The second force sensor will be held in your
hand and apply the load force to the model’s hand.
6. Set the sampling rate of both force sensors to 20 Hz.
7. Prepare a graph to plot bic eps force versus load force.
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