How it Works
PASCO
Loading...
PS-2138
User Manual
26 pgs337.46 Kb0
Table of contents
Loading...

PASCO PS-2138 User Manual

Instruction Manual
Goniometer
PS-2138, PS-2137
No. 012-08904A
Goniometer Model No. PS-2138
Contents
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Probe Mounting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Sensor Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Suggested Activities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Model No. PS-2138 Goniometer
ANGLE
12
PS-2139
ä
SENSOR
Mounting Straps
Goniometer
PS-2137, PS-2138
Equipme nt In clu ded Part Number
Probe Mounting straps (two small, one large) Angle Sensor (included in PS-2137 only)
Model PS-2137 includes probe, straps an d angle sensor; mod el PS-2138 includes probe and straps only.
PS-2138
PS-2547
PS-2139
Required or Op t io nal Eq ui pm e n t
PASPORT Interface (required) Second Goniometer Probe (optional)
See PASCO catalog or www.pasco.com
PS-2138

Introduction

With the PASPORT Goniometer students can analyze motions such as walking, running, throwing and kicking. They can also explore the physics of rotational dynamics using their arms and legs as experimental apparatus.
The Goniometer, in conjunction with a PASPORT interface, measures and records the angle, angular velocity and angular acceleration of an elbow, knee or hip. The sensor can be used with a single Goniometer
®
3
Goniometer Probe Mounting
Increasing Angle
Increasing Angle
Right Left
Probe (included) or with an optional second probe to measure two joints simultaneously. You can use multiple sensors together to support even more probes. The probe is easily attached to the body using the included hook-and-loop mounting straps.
The Goniometer Probe consists of two arms and a potentiometer. As the angle between the arms changes, the resistance of the potentiometer changes. The Angle Sensor, connected to the probe, measures the resistance of the potentiometer and converts it to an angle measurement. The sensor also calculates the angular velocity and angular acceleration from the rate at which the angle changes. The data is sent digitally to your PASPORT interface at up to 100 samples per second.
The probe measures zero degrees (or radians) when it is fully open. A clockwise rotation of the narrow arm relative to the wide arm (as pictured) is measured as increasing
Angle
angle.

Probe Mounting

The mounting straps can be used in two ways. The easier method is to place the straps on the limbs, then stick the probe to the outside of the straps. For more secure attachme nt, tuck the probe arms inside the overlapping portions of the straps.
When mounting the Goniometer probe, the wide and narrow arms of the probe are interchangeable; the only difference will be the sign of the data collected. Attach the wide arm of the probe to the subject’s upper arm when used on the left elbow, and to the subject’s forearm when used on the right elbow. This will result in a flexion of either joint measured as a positive displacement. Similar revers als can be applied to knee and hip mounting.
Elbow
Place one strap around the upper arm midway between the elbow and shoulder. Place a second strap around the lower arm midway between the elbow and wrist.
With the hand relaxed, bend the elbow at a right angle. Align the probe’s hinge with the elbow. Attach one arm of the probe to the subject’s upper arm parallel to the humerus.
Extend the elbow and attach the other probe arm parallel to the ulna. Flex and extend the elbow a few times to check for proper alignment.
4
®
Model No. PS-2138 Sensor Setup
Knee
Place the large strap around the thigh just above the knee. Place a small strap around the upper part of the calf (combine both small straps end-to-end if neces sar y) .
Bend the knee at a right angle. Align the probe’s hinge with the knee. Attach one arm of the probe to the thigh parallel to the femur.
Extend the knee and attach the other probe arm parallel to the tibia.
Flex and extend the knee to check for proper alignment. Have the subject stand on both feet and make sure that the probe does not shift significantly .
Hip
Place the large strap around the waist. Combine both small straps end-to-end (if necessary) and place them around the upper thigh.
Have the subject stand and place his or her foot on a chair so that the thigh is horizontal. Align the probe’s hinge with the hip joint. Attach one arm of the probe to the thigh parallel to the tibia.
Have the subject stand on both feet; attach the other probe arm vertically to the waist strap.
Move the hip joint through its full range of forward and backward rotation to check for proper alignment.

Sensor Setup

Connect one or two Goniometer Probes to the Angle Sensor. Connect the Angle Sensor to a PASPORT interface. The interface will collect data for angle, angular velocity , and angular acceleration from each probe. You can select units of degrees or radians in the software.
The default sampling rate of the sensor is 20 Hz. In most cases this is sufficient, but for faster movements you may wish to increase the rate to 50 or 100 Hz.
Optional Data Smoothing
The sensor calculates the angular velocity and angular acceleration from the measured angle data. The angular velocity is the change in angle between consecutive samples divided by the time between samples.
®
5
Goniometer Suggested Activities
TL∝
*For a detailed analysis of t he leg as a physical pendulum see : A. Dumont and C. Waltham , 1997, Walking,
The
Physics Teacher
,
35 (6): 372–376.
Angular acceleration is the change between consecutive velocity calculations divided by the time between samples.
The Goniometer is very sensitive to small variations in the angular velocity , s o you may see a lot of variation i n angular acceleration. To make the angular acceleration data easier for students to interpret, use the smooth function (in DataStudio) or reduce/smooth averaging (Xplorer GLX). See DataStudio online help or the GLX users’ manual for details.
Optional Calibration
The Goniometer does not normally require calibration. To incr ease the accuracy of measurements made over a limited range of motion, the Goniometer may be manually calibrated. In DataStudio, click the Calibrate button in the Experiment Setup window. Set the probe at a known angle, enter the angle under Point 1 and click the Set button. Set the probe at another known angle, enter the angle under Point 2 and click the Set button.

Suggest ed Activiti es

Analysis of Gait and other motions
Collect angle data of the knee while walking. Does it approximate simple harmonic motion? Explain what you observe.
Collect angle data of the hips during walking, fast walking and running.
• How does the angle of forward rotation compare to the angle of backward rotation?
• Compare the left and right hips. Are they symmetrical?
• Compare the range of movement and period of oscillation for walking, fast walking and running? What patterns do you observe?
• Compare data from different students walking at the same speed (walk side-by-side or use a motion sensor to monitor speed).
• For that class, make histograms of range of motion and period of oscillation. Do any patterns emerge?
• Make graphs of range of motion and period vs. height. Is there a correlation?
Measure the period of the leg swinging freely and compare it to the period of oscillation when the subject is walking at his or her most comfortable pace. For the class, investigate the relations hi p between leg length, L, and walking period, T. For all pendulums ; is this true for human legs*?
Analyze non-periodic movements such as throwing, kicking, and lifting. When performing the movements, move only the joint that is being measured. You can collect data on the linear motion of lifted, kicked and
6
®
Model No. PS-2138 Suggested Activities
thrown objects using Photogate Tape (ME-6664), a Photogate (ME-9204B) and a Digital Adapter (PS-2159).
Collect data from two or more joints simultaneously while walking, running, jumping, throwing, kicking, etc. How do the joints work together when performing these actions?
Oscillations
Collect data for the following:
• Lower leg freely dangling about the knee showing simple harmonic motion, subject seated on a high surface.
• Leg with unbent knee freely dangling about the hip, subject standing on the opposite foot on a low surface.
• Leg with knee bent at right angle freely dangling about the hip.
Do angle, angular velocity, and angular acceleration approximate simple harmonic motion? Determine the period, frequency and amplitude of the oscillations.
What is the relationship between the phases of angle, angular velocity, and angular acceleration?
How does bending the knee affect the frequency of the dangling leg?
Skeletal Parts
Mount the Goniometer on articulated skeletal parts. In conjunction with force sensors attached with string the points of tendon attachment, measure the forces exerted by muscles when lifting objects of various mass, or performing throwing and kicking movements.
®
7
Goniometer Suggested Activities
8
®
Loading...
+ 18 hidden pages
Buy Points How it Works FAQ Contact Us Questions and Suggestions Privacy Policy Cookie Policy Terms of Use