Clothes Washer, Wet Test
(3) Wet Test, with test clothes and water
The wet test was completed with different wash cycles and different spin speeds
using test clothes weighing approximately two lbs (dry weight), with a high water level
and a warm water temperature setting. The data acquisition device (refer to the Appendix
EQ) was set to acquire data at sample rates of 64, 128, 256 and 512 Hz, with the total
acquisition time of 3,120 seconds. The data acquisition device began collecting data
before the wash cycle began. The wash time was measured as the total time the clothes
washer takes to go through the entire wash cycle.
(3.a) Clothes Washer’s entire wash cycle spin characteristic
Wash Cycle
Rinse Cycle
Spin Cycle
Figure 3.a-1 From top to bottom, Regular Wash Cycle and Fast Spin Speed, Heavy Duty Wash Cycle
and Fast Spin Speed, Wool Washable Wash Cycle and Fast Spin Speed, Delicate Wash Cycle and
Medium Spin Speed, Permanent Press Wash Cycle and Medium Spin Speed. The charts were plotted
in Voltage versus Time.
Created by Phie Theng Lee
Michigan Technological University
16
Clothes Washer, Wet Test
The Figure 3.a-1 on page 16 shows the clothes washer’s spin characteristics for
the entire wash cycle. The charts were plotted in voltage versus time (V vs second) and
were measured using the laser tachometer. The zero voltage measurements between the
different wash sessions indicate when the drive motor of the clothes washer stopped. The
heavy-duty wash cycle has the longest wash time compared to the others, within 2,900
seconds. The Permanent Press wash cycle has the shortest wash time, within 2,300
seconds. Figure 3.a-1 on page 16 shows that only the Regular wash cycle and the HeavyDuty wash cycle complete the Rinse cycle three times. This event could be noted from
chart # 1 and chart # 2 of Figure 3.a-1 on page 16.
(3.b) Foot Force Measurement for entire spin cycle
The force measurement at each foot was simultaneously acquired with the
measurement laser tachometer, tri-axial accelerometers (situated at various location) and
load cells. The data acquisition device began collecting measurements before the clothes
washer was set to operate. This way, the entire response of the clothes washer during the
wash cycle will be preceded by a few seconds of blank data. Unfortunately, precise data
synchronization could not be achieved without involving complicated and expensive
measurement devices. Collecting measurements before the clothes washer was set to
operate and including a few seconds of blank data could amend this. In this case, the
measurement devices and the data acquisition device were not out of synchronization.
Including a few seconds of blank data at the beginning of the measurements allowed data
collection for the entire response of the clothes washer.
A segment of data from the last spin cycle was used in the analysis to obtain the
maximum foot force at each washing machine foot. The maximum foot force generally
Created by Phie Theng Lee
Michigan Technological University
17
Clothes Washer, Wet Test
occurred at the wash cycles maximum and steady spin speed. Thus the analysis was
performed at the last spin cycle. The data from the last spin cycle was extracted from the
entire wash cycle’s data and stored as an individual segment. The total acquisition time
was 3,120 seconds, using 64 Hz to 512 Hz sample rate measurements. The clothes
washer contained two lbs of test clothes (dry weights), with high water level and warm
water temperature setting. (Note that laundry detergent was not applied to the test clothes
since its added weight is insignificant compared to the overall weight of the washtub.)
The following tables are the foot force measurement results obtained in poundforce (lbf) for different wash cycles with different spin speeds. The PCB™ load cell was
used for this test (refer to Appendix EQ for calibration factors). The maximum foot force
obtained was highlighted in blue with the respective RPM colored in green.
As shown on Figure 3.b-1 and Table 3.b-2 on page 19, they were the maximum
foot force results computed from the first order cut based on frequency domain with
respect to the measured rpm with half a Hertz resolution. The variances as seen among
the results were largely due to the measurement sample rate used. That was clearly selfevident since it did exhibit the trend of converging toward better results with the increase
in measurement sample rates.
Created by Phie Theng Lee
Michigan Technological University
18
Clothes Washer, Wet Test
Regular wash cycle, Fast spin speed
7
64 Hz
128 Hz
256 Hz
512 Hz
6
Force, lbf
5
4
3
2
1
0
front left
front right
rear left
rear right
Load Cell Location
Figure 3.b-1
Table 3.b-2
Front Left
Front Right
Rear Left
Rear Right
Force measured on the clothes washer’s feet for Regular wash cycle,
Fast spin speed
Sample Rate
64 Hz
128 Hz
256 Hz
512 Hz
Lbf
3.9
4.1
3.1
6.1
RPM
1055.0
1001.1
812.0
1013.1
Lbf
5.6
4.0
5.7
5.0
RPM
1013.1
1008.2
1011.9
1011.0
Lbf
5.3
3.4
3.9
3.0
RPM
1013.1
1055.0
1001.1
807.1
Lbf
4.5
5.2
4.5
4.0
RPM
1013.1
1011.9
1010.0
1016.4
Created by Phie Theng Lee
Michigan Technological University
19