Vernier MEU-VDS User manual

Motion Encoder
Upgrade Kit
(Order Code: MEU-VDS)
The Motion Encoder Upgrade Kit is
an add-on product to be used with an
existing Vernier Dynamics System,
which is part of the Vernier Motion Encoder System*. It cannot be used on its own.
The encoder system allows the precise study of dynamics cart motion without the
use of ultrasonic motion detectors. The system consists of several parts:
A track with an encoder strip along the length of the track
A dynamics cart with an optical encoder and infrared (IR) transmitter
A receiver, attached to the end of a track
The encoder strip consists of alternating black and white bars with a 4 mm period,
allowing the optical sensor to detect the passage of the bars as the cart moves. With
two sensors appropriately placed, a change in position with 1 mm resolution can be
determined, as well as the direction of travel. A narrow infrared beam transmits
motion data to a receiver.
No alignments or adjustments are necessary, as the receiver attaches firmly to the
track, and the cart rides in slots on the track. The IR beam is not disturbed by
reflections from nearby objects.
The system is designed for use in physics and physical science courses for motion
and energy experiments. An optional Optics Expansion Kit (order code: OEK)
converts the track to an optics bench.
Some typical experiments done with the system include
Motion under zero acceleration
Motion under constant acceleration with the ramp inclined
Inelastic collisions using the included hook and pile tabs
Elastic collisions using the included magnetic bumpers
Parts Included with the Motion Encoder Upgrade Kit
Motion Encoder Transmitter
Motion Encoder Receiver
Motion Encoder Strip for application to 1.2 m or 2.2 m track
Mounting hardware for Dual-Range Force Sensor and accelerometers
Allen wrench 3/32 inch
*Patent Pending
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One-Time Assembly Instructions
Motion Encoder Strip Application
The track must have an encoder strip applied for the cart to determine its motion.
The strip is applied immediately next to the center slot, between the slot and the
numeric scale on the top surface of the track.
1. Clean the track surface with a damp cloth, and allow to dry.
2. Pull about 10 cm of backing off of the strip.
3. Align the strip next to the center slot, within 1 cm of the track end. The strip need
not extend all the way to the end of the track, but it can.
4. Carefully press down the strip, working your way along the track and removing
the backing as you go. Keep the strip edge right next to, but not hanging over, the
center slot. Do not stretch the strip.
5. Remove the rest of the backing, and press the strip down on full length of the
track.
6. Trim any excess strip from the track end.
If a track is to be used with a second encoder system, apply a second strip to the
other side of the center slot.
Motion Encoder Transmitter Installation
The Motion Encoder Upgrade Kit includes the parts to convert an existing dynamics
cart to a Motion Encoder Cart. Either a Standard Cart (CART-S) or a Plunger Cart
(CART-P) can be converted.
1. Remove the four end cap screws using the 3/32-inch Allen wrench.
2. Remove the end cap.
3. Place the cart upside down and press the wheels down towards the body to
compress the springs. Remove the pins holding the axle in place.
4. Lift out the axle and wheels.
5. Slide the encoder transmitter assembly into the cart body, battery end first, so the
power button and LED will be at the open end of the cart.
6. Replace the axle and pins.
7. Tighten the four bottom screws holding the encoder assembly, but leave them a bit
loose for now to allow it to align properly with the end cap.
8. Take note of the LED. It will be parallel to the circuit board. The tip projects
about 23 mm past the circuit board.
9. Install the end cap, being careful to allow the LED and power button to find their
places in the end cap. There should be no force required at all.
10. Replace two of the screws from the original end cap into the new cap using the
Allen wrench.
11. Tighten the four bottom screws the rest of the way so everything is held tightly in
place.
12. Insert two AAA batteries as indicated on the circuit board.

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Collect Data with the Vernier Motion Encoder System
This sensor can be used with the following interfaces to collect data:
Vernier LabQuest®as a standalone device or with a computer
Vernier LabQuest®Mini with a computer
Vernier LabPro®with a computer
Essential steps for using the Vernier Motion Encoder System:
1. Attach the receiver to the end of the track, matching the encoder strip on the track
to the markings on the receiver.
2. Place the track on a level surface.
3. Insert two AAA batteries (not included) into the encoder cart.
4. Connect the receiver to an interface such as a LabQuest 2. If using a computer,
connect the interface to your computer, and launch Logger Pro.
5. Turn on the cart by pressing the power button. It will glow blue when the cart is
on.
6. Place the cart on the track, wheels in grooves, with the blue light facing the
receiver.
7. Begin data collection, and let the cart roll.
Data-Collection Software
This sensor can be used with an interface and the following data-collection software.
Logger Pro 3 This computer program is used with LabQuest or LabPro.
Version 3.8.6.2 or newer is required.
LabQuest App This program is used when LabQuest is used as a standalone
device. Versions 1.7.1 for the original LabQuest and 2.2.1 for the LabQuest 2,
or newer, are required.
NOTE: Vernier products are designed for educational use. Our products are not
designed nor are they recommended for any industrial, medical, or commercial
process such as life support, patient diagnosis, control of a manufacturing process, or
industrial testing of any kind.
Specifications
Measurement Range
1 m range
2 m range
1.2 m track
2.2 m track
Accuracy and Resolution 1 mm
Optimum data-collection rate 15–30 Hz
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Calibration of the Vernier Motion Encoder System
This sensor is equipped with circuitry that supports auto-ID. When used with
LabQuest, LabQuest 2, or LabQuest Mini, the data-collection software identifies the
sensor and configures an experiment appropriately.
No calibration of the Vernier Motion Encoder System is necessary. The printed bars
on the track determine the scale, and the cart encoder counts the passage of the bars.
Available units are meters and feet, selectable in software.
In contrast, it is possible and desirable to zero the encoder. Unlike an ultrasonic
motion detector, there is no way for the system to have an unchanging reference
position; it can only count bars from the point at which the encoder cart is placed on
the track. As a result you may want to move the cart to the receiver end of the track
and zero the reading in software.
The positive direction can be reversed, so that readings increase as the encoder cart
moves toward the receiver. A reversed coordinate system is helpful when using two
Vernier Motion Encoder Systems to monitor the motion of two encoder carts, so that
the positive direction is the same in both cases.
Because the track strip must be continuous, the optical motion encoder cannot be
used with the Track-to-Track Coupler (order code: T2T-VDS).
Power
The Motion Encoder Cart requires two AAA batteries. Either NiMH rechargeable
batteries or alkaline disposable batteries can be used. The receiver is powered by the
interface.
Turn on the cart by pressing the clear power button on the cart endcap. It will glow
blue when power is on. Press again to turn off. The cart will turn itself off after
20 minutes of inactivity. Any motion on the track will cause the timer to be reset.
Battery life depends on use and the range setting. Low battery level may cause
erratic detection of the cart motion, including incorrect velocity signs. Replace the
batteries if this is seen.
Range Setting of the Motion Encoder Cart
The IR transmitter on the cart has two power levels available. The default 1 m
setting conserves battery power. If the cart is used on a 2.2 m track, set the cart to the
higher 2 m power level. If this setting is not used, the receiver will not reliably sense
the position of the cart at the far end of the track. The switch is located inside the
battery compartment.
Use of Two Vernier Motion Encoder Systems on the Same Track
Some experiments require measuring the motion of two carts. This can be done by
purchasing the Motion Encoder Cart and Receiver (order code: MEC-VDS) to add a
second encoder cart, receiver, and strip to your Vernier Motion Encoder System. A
Motion Encoder Receiver is placed at either end of the track, and two
Motion Encoder Carts are used on the track, each with its transmitter facing the

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unobstructed receiver. A second encoder strip must be applied to the track, one on
either side of the center slot.
Consider reversing the direction of one receiver so that the same direction is positive
for each system. Put the carts together, and zero both systems. This will put the carts
on the same coordinate system; if they move together in contact, their position
readings will be the same.
Use of Multiple Vernier Motion Encoder Systems in the Same
Room
Because of the narrow IR beam used for signaling between the cart and receiver,
interference should be rare. However, if one apparatus is apparently interfering with
another, the problem can be resolved by repositioning one of the tracks.
All Motion Encoder Carts are interchangeable; that is, there is no matching of cart to
receiver.
Data-Collection Notes for the Motion Encoder System
The optical motion encoder can only make relative position measurements, so that
the zero point is initially determined by where on the track the cart is first placed
when the power is on. If you want zero to be near the receiver, initially place the
cart next to the receiver. This behavior is very different from the ultrasonic
Motion Detector, which by default uses a fixed origin near the detector.
The motion encoder is nearly immune to interference, but it cannot work if the IR
beam between the cart and receiver is blocked. Keep your hand away from this
region.
Since the zero position (origin) of the encoder depends on where the cart is placed
initially, it is often useful to zero the encoder in the software. Place the cart in the
position you want to declare as zero. On LabQuest, tap the meter display to access
the zero command. In Logger Pro, use the toolbar button.
It can also be useful to reverse the direction of the coordinate system, so that
values increase as the cart moves toward the receiver. Do this from the meter
screen on LabQuest, or by using the sensor popup menu in the Set Up Sensors
dialog for your interface on Logger Pro.
High data-collection rates are not useful for the motion encoder. Rates above
30 Hz will produce noisy velocity and acceleration graphs because of few counts
during each time period.
Just like the ultrasonic Motion Detector, it can be useful to adjust the number of
points used to calculate derivatives for velocity and acceleration graphs. Higher
values create quieter graphs, while lower values result in more temporal detail.
Adjust this value in LabQuest preferences or in the Settings for… File menu item
in Logger Pro.
Suggested Experiments with the Vernier Motion Encoder System
The Vernier Motion Encoder System can be used wherever a Motion Detector could
have been used with a cart and track. The encoder depends on the presence of the
track, so that only cart and track experiments can be performed.
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Measure Cart Acceleration
The basic motion of a cart on a ramp can be studied. For example, perform
Experiment 3 from Physics with Vernier, “Cart on a Ramp.” Or, repeat Galileo’s
experiment of determining gusing an object and a ramp. This is Experiment 4
“Determining g on an Incline” from Physics with Vernier.
Newton’s Second Law
Use a force sensor on the encoder cart to record both applied force and acceleration.
The two will be proportional.
Or, set up a half-Atwood machine with a hanging mass and a pulley at the track end
opposite the receiver. Measure the acceleration of the encoder cart as a function of
the hanging mass.
Measure Fan Cart Acceleration
Add a Cart Fan (order code: FAN-VDS) to observe the motion of a cart under
constant thrust.
Measure Cart Acceleration with Friction
Add a Friction Pad (order code: PAD-VDS) to the encoder cart and observe the
motion of the cart with varying frictional forces.
Momentum-Impulse
Add a force sensor and a Bumper-Launcher Kit (order code: BLK) to observe the
relationship between momentum and impulse. Find the impulse by integrating under
a force vs. time graph.
Conservation of Energy
Use two Vernier Motion Encoder Systems to observe a change in energy due to a
collision between two carts.
Conservation of Momentum
Use two Vernier Motion Encoder Systems to observe a change in momentum due to
a collision between two carts. Try different kinds of collision: elastic, inelastic,
totally inelastic.
Products Related to the Vernier Motion Encoder System
Vernier Dynamics System (order code: VDS)
Vernier Dynamics System is a low-friction black anodized 1.2 m track and optics
bench combination designed for kinematics, dynamics, and optics experiments. It
includes two carts.
Vernier Dynamics System with Long Track (order code: VDS-LONG)
The long version of the Vernier Dynamics System includes a 2.2 m track instead of
the 1.2 standard track.
Track (order code: TRACK)
The Combination 1.2 m Track/Optics Bench comes with the Encoder System Strip
installed.

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Bumper Launcher Kit (order code: BLK)
The Bumper Launcher Kit includes accessories to integrate the Dual-Range Force
Sensor with the Vernier Dynamics System or Vernier Motion Encoder System,
allowing for many interesting experiments in momentum-impulse study.
Dual-Range Force Sensor (order code: DFS-BTA)
The Dual-Range Force Sensor measures pushes and pulls up to 50 N.
Wireless Dynamics Sensor System (order code: WDSS)
The WDSS is a wireless force sensor and accelerometer.
Replacement Parts
Motion Encoder Receiver (order code: MEC-BTD)
The receiver attaches to the end of the track and connects to an interface, such as a
LabQuest 2.
Motion Encoder Cart (order code: CART-MEC)
This is the complete Motion Encoder Cart, with no assembly required.
Motion Encoder Track Strip (order code: METS)
The strip can be attached to an existing track without an encoder strip, or it can be
attached as a second strip for use with two encoder systems. For 1.2 m track.
Motion Encoder Track Strip - Long (order code: METS-LONG)
The strip can be attached to an existing track without an encoder strip, or it can be
attached as a second strip for use with two encoder systems. For 2.2 m track.
Motion Encoder Transmitter Parts (order code: MECT)
The transmitter assembly is used to upgrade an existing cart to a Motion Encoder
Cart.
Suggested Accessories
Optics Expansion Kit (order code: OEK). The Vernier
Optics Expansion Kit extends the Vernier Dynamics
System or Vernier Motion Encoder System for use in
optics experiments.
Color Mixer (order code: CM-OEK). The Vernier Color Mixer Kit consists of a
three-color LED illuminator with power supply, a
lens, and a double-sided screen. Experiments in
additive and subtractive color mixing can be easily
and conveniently carried out using this kit. The
intensity of the red, blue and green LEDs can be
smoothly controlled from the light source.
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Ultra Pulley (order code: SPA). The pulley can be attached to
the end of a track using the Pulley Bracket to make a half-
Atwood machine.
Pulley Bracket (order code:
PB-SPA). The pulley bracket allows
easy attachment of an Ultra Pulley to
the end of a Vernier track. Compatible with a Photogate
Bracket for measuring motion using the pulley.
The Cart Friction Pad (order code: PAD-VDS) is a variable friction mechanism for
use with the Vernier Standard Cart, Plunger Cart, and Motion Encoder Cart. It can be
used on any flat surface or, for best results, with the Vernier Dynamics System or
Vernier Motion Encoder System to study the effects of friction.
The two-speed Dynamics Cart Fan (order code: FAN-VDS) magnetically attaches
to the Vernier Standard Cart, Plunger Cart, and Motion Encoder Cart. It can be used
on any flat surface or, for best results, with the Vernier Dynamics System or
Vernier Motion Encoder System to study motion, force, and momentum.
Warranty
Vernier warrants this product to be free from defects in materials and workmanship
for a period of five years from the date of shipment to the customer. This warranty
does not cover damage to the product caused by abuse or improper use.
Vernier Software & Technology
13979 S.W. Millikan Way Beaverton, OR 97005-2886
Toll Free [phone] [phone] FAX [phone]
[email protected] www.vernier.com
Revised 2/4/2014
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