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Exploratory testing of Washing Machine using Hardware-in-Loop Testing
Akshay P Chouhan
GTEC, Whirlpool
Myrtle Binil R
ETAS Automotive India Private Limited
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Agenda
Introduction
Washing Machine Validation- Challenges
Hardware in Loop Testing for Washing Machine
Plant Model – For closed loop testing
Advantages
Summary
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Requirement Specification
Introduction
– Product Life Cycle
Design & Coding
Validation
SOP
– Validation refers to set of tasks that ensures the component is build as per the specification.
– In Whirlpool,
– These validations are done manually
– Validation are done with real prototypes
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Washing Machine Validation – Challenges
– Difficulty to test different sequence of test case in the real prototype.
– Difficulty to generate different test conditions such as
– Eg: Testing over flow error
– For this user have to tweak the sensor signal in precise manner
– Wait until the overflow occurs in the machine (This also requires to disconnect the
feedback signals to the controller which will lead to some other diagnostic errors)
– More features into washer, complex functionality
Simple rotary type controlAdvanced touch interface control
Early ’90s Later 2000’s
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– Standards and safety features in the washer make the software complex
and therefore thorough validation w.r.t these should be done to get the
product certified.
– More intelligence in the product increase the complexity of diagnostics
routines which is time consuming to test manually
– Expensive prototypes for testing
– Time to market
– On-Time delivery of product
– Quality of product
Washing Machine Validation – Challenges
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Washing Machine Validation – Overcoming the challenges
– To overcome these challenges in validation, hardware in the loop testing
concept which is widely used in automotive industry was explored.
– With the help of ETAS, the possibilities are studied and this brought
sufficient improvement in testing w.r.t quality of testing and time.
– ETAS DESK-LABCAR system with efficient signal conditioning unit was used
for testing the washer.
– ETAS LABCAR automation software was used to automate the test cases for
washer.
– ETAS Variant Management system was used to manage different variants of
washer of same hardware platform.
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IO Cards
Real Time Controller
Hardware in Loop Testing for Washing Machine
Control Unit
Signal Conditioning
Actuators
Acquisition Generation
Simulink Plant Model
Other Process
Design
SensorsReal Loads
User Interface PanelWIDE
AC mains
The main control unit of washing machine
User interface panel, where all user controls are presents
(Like knobs, touch screen controls)
WIDE protocolProprietary to whirlpool
IO Card Modules
Signal conditioning unit for AC to DC isolation
Real time controller
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Real Time PC
Hardware in Loop Testing for Washing MachineDesign Realization
ETAS DESK-LABCAR system as shown below is used to realize the design
Control Unit
Signal Conditioning Unit
ES5340 Multi-IO Cards
Host PC
Break out BoxWIDE
IP EE
– In Mini-LABCAR, PCIe based
Multi-IO card ES5340
Master and Slave are used
to simulate and acquire
different signals of control
unit.
– Signal Conditioning unit
acts as a isolation between
AC and DC signals and
signal conversion
– In LCO-EE, interface is
developed to communicate
with the WIDE interface
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Plant Model – For Closed Loop Testing
– To cover most of the test cases during validation, a closed loop setup is required.
– This is achieved by developing a plant model of washer in MATLAB®/Simulink and
integrating this to LABCAR
– With the different features of Simulink modeling, a structured mathematical model of
washing machine was developed in short duration.
Parameter-Washing Machine -Environmental
Washing machine functionalityMath model of washing machine components
Interface to LABCAR components
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Plant Model – For Closed Loop Testing
Water Inlet :Functionalities of inlet pipe for hot water, cold water, steam fill etc.
Temperature Control :Maintaining the temperature based on heater status, water temperature
Drum Model :All functionalities related to drum such as cloth soaking, agitation etc..
Drain Control :All functionalities related to draining of water from the washer.
Switches:Simulation of all kind of switches related to washer, such as lid lock, lid close etc...
Detergent Dispense:The detergent dispense module model, containing all the functionality to dispense the detergent
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Plant Model – For Closed Loop Testing
In the same manner, all the sensors are also modeled and integrated in the LCO-IP
Washer Plant Model
Different Sensor Models
– With this a structured way of development and integration was possible
– The actuator models were also integrated into the system, on need
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ETAS Real Time PC
Plant Model – For Closed Loop Testing
The complete flow of system
Control Unit
Plant Model
Sensor Models
LABCAR IO ES 5340
LABCAR IO ES 5340
Actuator models
Physical QuantityElectrical Value
Electrical Value
Physical Quantity
Signal Conditioning
Host PC
WIDECommunication
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Advantages
– Example: Overflow Error check
– Stuck conditions on inlet value will continuously fill water into the drum. This creates the over flow error, which can be validated very easily and in precise manner
Testing of different conditions are now simple with click of buttons
Inlet stuck subsystem
Simulation of stuck with LCO -EE
– Example: Invalid Pressure
– Providing an invalid pressure to the system and verifying the behavior is also simple by click of button, by overriding the actual values from plant
Overriding pressure value
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Advantages
– More over different types of simulation such as leakage in the drum, over temperature error validation, different fill error validation can be simulated in the system in very simple steps and verified in précised manner.
Different control in EE for simulation of different test conditions
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Advantages
– Automation of Test Case– With the closed loop setup, full automation of test cases which runs for hours are easily executed
and the test results are studied. Test reports are generated which also ensure that documentations are in place.
– Integration with Variant Management System– LCO integrated with ETAS variant management system also ensures that the generic plant
model can be used across different variants only by changing the sensor parameters.
– Changing the generic model parameters such as drum volume, pipe diameters will ensure that the plant model is ready for the next variant.
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Summary
– Having an closed loop HiL system with detailed plant model built in Simulink ease the
validation and improve efficiency.
– With the help of automation, it was able to repeat different test cases at any point of
time with the same artifacts.
– Tweaking of sensor values are now no more an difficulty, as they are now done just
with change values and click of buttons.
– The HiL validation was extended to different products such as
– Dish washer
– Refrigerator
– Food Processor etc…
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Thank You
Q&A