Safety Force Field Actuation Workflow

Table of Contents

• Initialization
• Steering Weight
• Control Constraints
• Process Function
• Release

Note

SW Release Applicability: This tutorial is applicable to modules in NVIDIA DRIVE Software releases.

The Safety Force Field Actuation module takes the control constraints acquired from a Safety Force Field module. It corrects a given unsafe control (front wheel steering angle and longitudinal acceleration) of the ego-vehicle to a safe one.

Initialization

To initialize a Safety Force Field Actuation module

dwStatus dwSafetyForceFieldActuation_initialize(dwSafetyForceFieldActuationHandle_t* SafetyForceFieldActuation,
                                                dwContextHandle_t context);

Steering Weight

A steering weight can be set after a Safety Force Field Actuation module is initialized. The steering weight is a nonnegative floating point number, where the default value is 0.0, indicating the actuation only has braking and no steering. The larger the weight, the more steering there is over braking. To see steering in the actuation, you can set the steering weight to be a positive value such as a value between 0.1 and 0.5. After that, if the steering actuation is still not apparent, you can keep raising the steering weight until the steering actuation is observed.

To set a steering weight

dwStatus dwSafetyForceFieldActuation_setSteeringWeight(float32_t steeringWeight,
                                                       dwSafetyForceFieldActuationHandle_t SafetyForceFieldActuation);

Control Constraints

To update the actuation module's control constraints

dwStatus dwSafetyForceField_getControlConstraints(dwSafetyForceFieldControlConstraints* constraints,
                                                  dwSafetyForceFieldHandle_t handle);

dwStatus dwSafetyForceFieldActuation_setControlConstraints(const dwSafetyForceFieldControlConstraints* constraints,
                                                           dwSafetyForceFieldActuationHandle_t SafetyForceFieldActuation);

Process Function

To run the actuation, or correct a proposed control to a safe one

dwStatus dwSafetyForceFieldActuation_process(bool* isProposedControlSafe,
                                             dwSafetyForceFieldControl* newControl,
                                             const dwSafetyForceFieldControl* proposedControl,
                                             float32_t steeringLimit,
                                             float32_t minAccel,
                                             float32_t maxAccel,
                                             dwSafetyForceFieldActuationHandle_t SafetyForceFieldActuation);

Release

To release a Safety Force Field Actuation module

dwStatus dwSafetyForceFieldActuation_release(dwSafetyForceFieldActuationHandle_t SafetyForceFieldActuation);

For a more detailed workflow, please refer to the Safety Force Field Sample.