Vehicle Dynamics
Vehicle Dynamics refers to the movement of the vehicle in terms of acceleration and rotation such as G-forces or Angular rates. The Nexus R5 ECU supports up to 3x G-Force and 3x Angular Rate inputs which can be sent to the ECU from an external Accelerometer via Analog Inputs, from the Vehicle CAN if supported by the selected vehicle, or from the ECU's Internal IMU (if fitted).
Your Nexus ECU (most models) is fitted with an Internal IMU (Inertial Measurement Unit) which has the capability to detect and measure changes in the ECUs movement and velocity on multiple axis. The IMU converts and outputs these movements into usable channels that can be used for data logging, chassis setup, and tuning. Since the IMU is a highly sensitive device, some experimentation with filtering and ECU mounting may be required to get the best results possible.
The main Vehicle Dynamics node is used to select which Vehicle Dynamics Sensor inputs you would like to use, along with the calibration section for calibrating the Internal IMU (if fitted)
Accel (G) Sensor Enables - allows the enabling of G-Force channels in 3 axis - Lateral, Longitudinal, and Vertical.
Angular Rate Sensor Enables - allows the enabling of Angular Rate channels in 3 axis - Pitch, Roll and Yaw.
IMU Calibration (if fitted)
The output quality of the IMU's generated channels greatly depends on a successful and accurate calibration of the IMU. This calibration process must be carried out before the IMU can be used.
Before beginning the calibration process, ensure the ECU is mounted securely in the vehicle in its intended position. Moving or reorienting the ECU will require a re-calibration of the IMU.
Click the 'Calibrate...' button to begin the calibration process. Follow the steps shown on screen, taking note of the step by step instructions relating to the physical level of the vehicle. This process must be followed precisely in order for the IMU to generate the Vehicle Dynamics Accel and Angular Rate channels correctly.
Diagnostics
If using Analog Inputs for Vehicle Dynamics inputs, Min and Max Voltage DTCs can be used for each input. Each DTC has an associated Severity level which will be activated if the DTC is triggered.
These DTCs are disabled with any other Input Type.
Analog Input Calibration
This section refers to all individual Vehicle Dynamics inputs as displayed when their input type is set to Analogue - Voltage. These nodes to not appear when using the internal IMU, as no calibration is required.
When using an external accelerometer, calibration of the input is required. This node is used to conver the analog voltage sent by the accelerometer to the relevant calibrated channel. Calibrations can be loaded directly into the calibration table by using the 'Load from File' button. Calibrations can be saved to file by using the 'Save to File' button.
G-Force Filter
This node is used to filter the G-Force sensor values. Due to the high sensitivity of the IMU, large filter values may be required to provide a smooth sensor value. Too small a filter value will result in a rapidly changing value that is unusable. Experimentation will be required to obtain a suitable filter value for each installation.
Angular Rate Filter
This node is used to filter the Angular Rate sensor values. Due to the high sensitivity of the IMU, large filter values may be required to provide a smooth sensor value. Too small a filter value will result in a rapidly changing value that is unusable. Experimentation will be required to obtain a suitable filter value for each installation.
Wiring
This node is used to enable or disable each of the Vehicle Dynamics sensor inputs, and set their input Type. The Enabled/Disabled state matches the state of each sensor input on the main Vehicle Dynamics mode.
Options - set the input type depending on the source of each sensor. For most installations using a Nexus ECU, choose 'Inertial Measurement Unit (IMU)'.
Connections - depending on the sensor Input Type, different wiring options will be made available to you.
Inertial Measurement Unit (IMU) sensors - Each sensor has a matching IMU channel which will be automatically selected.
Analogue - Voltage sensors - Any available AVI can be used for sensor input. Ensure each sensor is calibrated under its relevant node.
CAN Input sensors - Select the Vehicle CAN if your vehicle supports the transmission of Vehicle Dynamics information over the Vehicle CAN.
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