In the realm of automotive engineering, where precision and safety are paramount, the testing of automotive clusters stands as a crucial step in ensuring a reliable and seamless driving experience. Automotive clusters, also known as instrument clusters or dashboards, encompass an array of gauges, displays, and indicators that convey critical information to drivers, ranging from speed and fuel levels to engine diagnostics. As vehicles evolve with advanced technologies, the complexity of testing these clusters escalates, presenting engineers with a myriad of challenges and a diverse toolkit of testing methods. Today, we delve into some of the important features of automotive cluster use cases to be tested.

Features in the instrument cluster

Modern instrument clusters are packed with a lot of features to provide insights to the vehicle as well as information about the environment so that the driver can be prepared for surprises that may arise. Today driver assistance systems play a crucial role in ensuring the safety of drivers and others. Clusters can also provide information about the driver's behavior.

• Digital Speedometer
• Tachometer
• Fuel Gauge
• Temperature Gauge
• Odometer and Trip Meter
• Turn-by-Turn Navigation
• Media Player Integration
• Phone Integration
• Driver Assistance Systems (DAS)
• Vehicle Settings and Controls
• Multi-Function Display (MFD)
• Warning and Indicator Lights
• Parking Assistance
• Driver Information Center (DIC)
• Voice Control

All this information needs to be presented in a uncluttered, clear and concise manner. From a validation standpoint, it is possible to test each of these interfaces and cluster functionality verified. Yet this article will explore validation of some of the key features of the cluster.

Digital Speedometer/Tachometer

Test Type	Methods
Accuracy	Developers need to test speed by simulating vehicle speed via CAN or PWM inputs
Sudden Maneuvers	Validate the speedometer responds to sudden maneuvers, such as swerving or emergency braking, to ensure it accurately reflects changes in speed smoothly
Speed Unit	The digital speedometer displays the speed value as per unit configuration m/h or km/h
Ignition/Restart	Turn off and on the car while driving. The speedometer display restarts correctly and show a smooth transition from 0 to current speed

Challenges:A proper HIL based simulation setup for every developer will be a challenge.

Solutions:Low-cost options like Busmaster scripts, signal generators and test jigs can be utilized to simulate various speed conditions

Fuel Guage/Computer

Test Type	Methods
Accuracy of Fuel & Consumption Calculation	Validate that the fuel computer accurately calculates fuel consumption based on fuel usage as per CAN input and distance traveled
Accuracy of Distance to empty	Verify that the fuel computer accurately calculates the past fuel consumption and derives the distance to empty with remaining fuel
Real-Time Fuel Efficiency & Display	Test the fuel computer's ability to display real-time fuel efficiency information, such as instantaneous fuel consumption and fuel economy Verify that the real-time fuel efficiency display updates accurately and responds to changes in driving conditions such as downhill/uphill, sudden acceleration, etc.
Fuel Gauge Accuracy in sudden & Acceleration/Deceleration	Variations in fuel sensor reading when accelerating and decelerating the car should not mislead the driver on available fuel in tank.
Fuel Gauge Response to Refueling/Drain	Smooth transition of Fuel indication during refuels and alert on low fuel warning
Trip Distance Calculation	Verify that the fuel computer accurately calculates and displays the distance traveled for each trip or journey
Reset Functionality	Test the reset functionality of the fuel computer to ensure it can be reset to zero for tracking fuel consumption and distance traveled over specific periods

Challenges:

• A knowledge of simulating fuel consumption based on speed and RPM for each developer is a challenge.
• Keeping the amount of fuel consumed and fuel left in tank in sync during testing is a challenge.

Solutions:

• Model based design and validation tools like Vector or TestBot shall be used to simulate exact fuel consumed based on speed and RPM.
• HIL setup with dynamically configurable resistance for fuel measurement.

Warning/Alert/Tell Tale Test cases:

Test Type	Methods
Light Activation Verification	Verify that each warning and alert light in the instrument cluster activates correctly during the respective triggering conditions. Verify only applicable warning and alert is coming for specific situations such as driving, parked, ignition off etc. Test individual lights such as check engine, oil pressure, battery charge, ABS, airbag, and others to ensure they illuminate when the corresponding condition occurs
Color and Intensity Verification	Ensure that warning and alert lights are displayed in the correct color (e.g., red, yellow, orange) according to their severity level. Verify that the intensity of each light is appropriate for visibility in various lighting conditions, including daytime and nighttime driving.
Audible Alerts Verification	Test warning lights that are accompanied by audible alerts (e.g., chimes, beeps) to ensure they activate synchronously and provide dual notification of the condition. Verify that audible alerts are clear and distinguishable from other sounds in the vehicle.

Challenges:

• Measuring latency taken to display alert to user from time signal induced is a challenge.
• Uniformity Testing, Contrast Ratio, Black Level Performance, Flicker Detection are a few challenges in normal light
• Testing for accuracy of audio decibel level, fading effect and ON duration

Solutions:

• A complete integrated simulator model such as Vector or TestBot with display inspection tool
• Dark Room environment brings in better visual testing
• Certain tools like Sound Level Meter (SLM), Audio analyzer can be used to test buzzers

Odometer

Test Type	Methods
Power On Test	Verify that the previous completed distance is displayed to user directly without showing intermediate values such as zero
Tamper test	Validate odometer skipping invalid or wrong data for processing
Partial Update test	Ensure that smaller distance travelled between ignition/power offs are accumulated without any loss of information

Challenges:

• Multiple restart and restart during driving is a challenge
• Manipulating the ODO data in the vehicle
• Disturbing the ODO data sending to cluster while driving

Solutions:

• HIL setup or TestBot shall be used to simulate all test types above.

Conclusion

In conclusion, the automotive cluster is a critical component of modern vehicles, providing drivers with essential information about the vehicle's status and performance. Ensuring the reliability, accuracy, and functionality of the cluster requires thorough testing of its features. From basic functions such as speedometer and fuel gauge to advanced features like navigation integration and driver assistance systems, each aspect of the cluster must undergo rigorous testing to meet safety standards and user expectations.

Test cases for automotive clusters should cover a wide range of scenarios, including normal operation, edge cases, and failure modes. These test cases should evaluate not only individual features but also their integration with other vehicle systems and the overall user experience. Additionally, test cases should consider various environmental conditions and user interactions to ensure the cluster performs reliably in real-world situations.

Choosing the right tools and test methods is an important element in cluster testing that helps to deliver a robust cluster to customer.