Tyre Traction
Introduction
The ‘Tyre Traction’ test is a plugin for the VBOX Test Suite software.
The test itself allows the user to compare the traction forces and wheel slip of different tyres.
In order to successfully complete the test, the user will need access to the driven wheels speed sensors as well as a throttle position sensor.
Ribbon Bar
The Tyre Traction test has a unique 'Test Setup' ribbon bar, from which the test and test area can be configured.
Note: Ribbon bar icons may move/ resize dependent on the Software window size.
Test
Configure
The 'Configure' button displays a pop up window whereby the parameters of the test can be defined.
Report
The 'Report' button creates a report from the current test results.
Edit Data
the 'Edit Data' button allows the user to enter session specific data such as tyre specification.
Test Configuration
Selecting the 'Configure' button will display a pop up window where the user can define the parameters of the test. These include the start and end conditions, as well as the pass conditions.
Use the up and down buttons to the right of the parameters to Expand and Collapse the parameter headings.
Test Details
Within this area, the user can define the following Test details:
- Test Request Number
- Date
- Track
- Vehicle
- Vehicle mass (kg) – This will be used to calculate the Force value
- Driver
These entered details will form the header of the report page.
Test Condition
Start Speed
This parameter denotes at what speed the test will start.
Note: In Racelogic’s experience, we do not recommend starting this test from zero due to the presence of noise that occurs at low GPS and Wheel speeds.
End Slip (%)
This parameter denotes at what percentage wheel slip the test will end at.
Wheel Speeds
There are separate drop down boxes that allows the user to choose the channel that the software will use to calculate the Front Left, Front Right, Rear Left and Rear Right wheel speeds.
There is also a tick box to specify which are the driven wheels to allow for both Two and Four wheel drive vehicles.
Selecting 'Omit Calibration' will calculate the wheel slip channel from the start of the test without calibration.
Slip Analysis
The Slip analysis area allows the user to enter a Slip% Low and High condition that will denote the upper and lower limits that will be used in the ‘Area under the curve’ evaluation.
Throttle Rate Pass Conditions
Channel
This allows the user to select which channel the software will reference when calculating Throttle Rate.
Limits
To ensure that the tests are undergoing the same rate of throttle application, it is possible to enter upper and lower limits for the Average and Standard Deviation of the Throttle application.
If any test run exceeds the set criteria, the run will be highlighted in the results table for easy identification.
These parameters are an optional channel that is only required if the user wishes to look at the throttle application.
Completing a Test
To start an online test, the user must first select the correct COM port from the ‘Online’ drop down menu in home tab. Once connected to a VBOX, the dashboard will change to show the 'START', 'STOP' and 'RESET' buttons.
Starting, Stopping and Resetting a Test
By pressing the 'START' button, the software will add a tab to the Test Results area ready to be populated with results once the start and end criteria have been met. The 'START' button will also change to a 'PAUSE' button, allowing the user to pause the test. To resume the test, simply press the 'RESUME' button.
To finish a test, simply press the 'STOP' button. This will stop all open tests. Once the stop button has be pressed, future results cannot be added to that results tab. Pressing the 'START' button will open up a new results tab, however once the stop button has been pressed, the user will be required to calibrate the wheel speeds again before a new test can be started.
If, for any reason, a mistake has been made during the test, it is possible to restart the test by pressing the 'RESET' button and again this will require a calibration of the wheel speeds.
Calibrating the Wheel Speeds
To allow for different wheel diameters to be easily and consistently used in the test, the software has an auto calibrate function that automatically applies a scaling factor to the CAN wheel Speeds to match the GPS Speed.
When the user first presses the 'START' button, a dialogue window will appear that contains the calibration instructions.
To successfully calibrate the wheel speeds, the user must drive at constant speed of 20 km/h (+/- 2 km/h) for 5 seconds, ensuring not to rapidly accelerate, decelerate or any other manoeuvre that may induce wheel slip. Once this period has been completed, the software will display a ‘Calibrated’ message and the test is able to be started.
IMPORTANT - Unless 'Omit Calibration' is selected within the Test Configuration, the calibration period is also required when in ‘Offline’ mode, so it is extremely important that the unit is logging before the calibration procedure is carried out, otherwise the software will not produce any test results.
Test Results Area
The test results area is the area that displays all of the results from the current test. Within this area it is possible to include/exclude results from the chart area, display the average/max/min values and also easily identify any runs which have not met the pass criteria.
Every time a new test is started (via the 'START' button on the dashboard), or a new file is loaded, a new tab will be added to the test results area, allowing the user to switch between separate tests or files and compare runs from each. A session can be removed from the results area by pressing the ‘x’ icon on the tab.
Session Data
By pressing the 'Edit Data' button next to the name of the file/run or in the ‘Test Setup' ribbon bar, it is possible to edit the session information for that test. This includes:-
- Tyre Size
- Pattern Name
- Rim Size
- Inflated Pressure
- Purpose
- Comments
When in 'Offline' mode, this information will be saved into the .vbo file meaning that this information will be recalled every time the file is loaded into VBOX Test Suite.
When in 'Online' mode, a newly-created session will be populated with session data from the previous session.
This information will be included in the test report to allow the user to understand which result applies to which tyre.
Note: This data is purely optional and has no effect on the test or test results.
Once the session information has been completed, it is possible to export the data to a .vbses file. This file will contain all the session information that can then be imported into the open session information field.
Result Columns
Along the top of the Test results area are some default columns. These columns are:-
- Run – Indicates which run number the results relate to, with run one being the first run completed. There is also a selection box that, when ticked, includes that run in the graph and into the Average/Max/Min/Standard Deviation calculations. Once selected, a coloured square will appear to indicate which colour this run is displayed as on the graph.
- Time – The total time the run has taken.
- Distance – The total distance travelled in that run.
- Force Max – The maximum force experienced during the run.
- Slip @ Force Max – The slip % experienced at the maximum force measurement.
- Speed (max) – The maximum speed attained during the run.
- Throttle rate Max – The maximum rate of throttle application.
Note: This result is only displayed if a Throttle Rate channel has been selected. - Throttle Rate Average – The average rate of throttle application.
Note: This result is only displayed if a Throttle Rate channel has been selected. - Throttle Rate StdDev – The standard deviation of the rate of throttle application.
Note: This result is only displayed if a Throttle Rate channel has been selected.
Dashboard
Along with the usual dashboard functionality, the ‘Tyre Traction’ test has some extra options that can be displayed to the user.
By selecting the 'Add Gauge' button from the dashboard tab, a drop down menu will appear whereby the user can select 'Test' and then the desired parameter to be displayed. On selection, a gauge will be automatically added to the dashboard. Any gauges displaying a result of a test, such as an average or maximum value, will have a 'Result' icon to the left of the gauge name to indicate that it is either a result of the previous run if viewing live data, or the currently selected run if viewing a saved file.
All Result Column parameters are also available as a gauge.
Creating a Report
VBOX Test Suite allows the user to turn the results table into a custom report whereby the user can easily compare the average data between different sets of tyres.
Once the user has added the 'average' to a session as well as completing the test details in the Test configuration screen and the session information for each session, the user can create a custom report using the 'Report' button in the ribbon bar. This will create a report that contains the test details, a chart of the selected runs and the session information.
The chart will show tell tale lines that relate to the ‘Slip Analysis’ high and low constraints that were entered in the test configuration. These lines denote the upper and lower limits of the 'Area Under the Curve' analysis.
The session data will be displayed as a table of results that contains:-
- Tyre Size
- Rim Size
- Pattern Name
- Pressure
- Force Max (N) – The Maximum force attainted by the 'average' run.
- Area under the curve – The area under the 'Average' curve.
- Purpose
- Comments
The user can then choose to print or save this report.