Drive Board Driver

The DriveBoard class (src/drivers/DriveBoard.h & DriveBoard.cpp) converts high-level speed and steering requests into physical motor powers and transmits them over RoveComm to the Core board microcontroller.

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1. Primary Responsibilities

1. Kinematics Processing: Accepts linear speed and heading requests and calculates left and right track power percentages using Differential Drive inverse kinematics.
2. Network Transmission: Formats track powers into RoveComm UDP DRIVELEFTRIGHT packets and transmits them to the Core microcontroller.
3. Terrain Slope Damping: Intercepts pitch and roll telemetry from the rover’s inclinometer to attenuate motor power on steep inclines, preventing tip-overs.
4. Master Throttle Regulation: Listens for Basestation SETMAXSPEED commands, scaling output powers across $[0.0, 1.0]$.
5. Emergency Stop Command: Provides SendStop() to immediately command $0.0$ power across both tracks.

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2. Kinematics Pipeline (CalculateMove)

void DriveBoard::CalculateMove(double dSpeed, double dGoalHeading, double dActualHeading);

The calculation follows three sequential steps:

1. Heading Error and PID Effort: Computes the angular delta: \(\theta_{\text{error}} = \theta_{\text{goal}} - \theta_{\text{actual}}\) The internal PID controller (DRIVE_PID_*) calculates a normalized rotational turn effort: \(\omega = \text{PID.Calculate}(\theta_{\text{error}}) \in [-1.0, 1.0]\)
2. Differential Drive Inverse Kinematics: Depending on configuration, the forward speed $v$ and turn effort $\omega$ are evaluated using:
   • Arcade Drive: \(\text{Left} = v + \omega, \quad \text{Right} = v - \omega\)
   • Curvature Drive: Scales turning sensitivity inversely with forward velocity to prevent dynamic rollovers at high speeds. Point-turning is permitted when forward speed is near zero.
   • Powers are normalized so neither track exceeds $\pm 1.0$, with optional input squaring (DRIVE_SQUARE_CONTROL_INPUTS).
3. Terrain Damping Multiplier: Multiplies raw track powers by VariableDriveEffort() and the global m_dMaxDriveEffort multiplier: \(P_{\text{final}} = P_{\text{raw}} \cdot \text{Damp}_{\text{slope}} \cdot \text{Multiplier}_{\text{throttle}}\) Final outputs are clamped to constants::DRIVE_MAX_SAFE_POWER.

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3. Inclinometer Safety Damping (VariableDriveEffort)

The driver registers a RoveComm callback listening for manifest::Core::TELEMETRY["INCLINOMETERDATA"]:

• Extracts chassis Pitch and Roll in degrees.
• Computes effective slope angle $\phi$: \(\phi = w_{\text{roll}} \cdot |\text{Roll}| + w_{\text{pitch}} \cdot |\text{Pitch}|\) where weights are defined by constants::DRIVE_BOARD_ROLL_WEIGHT and constants::DRIVE_BOARD_PITCH_WEIGHT.
• If $\phi \le \text{constants::DRIVE_BOARD_MIN_SLOPE}$ ($10^\circ$), damping factor is $1.0$.
• If $\phi \ge \text{constants::DRIVE_BOARD_MAX_SLOPE}$ ($30^\circ$), damping factor clamps to constants::DRIVE_BOARD_MIN_DAMP ($0.50$).
• Between these limits, linear interpolation smoothly decreases drive power.

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4. Public Interface Summary

// Kinematics and Movement
void CalculateMove(double dSpeed, double dGoalHeading, double dActualHeading);
void SendDrive();
void SendStop();

// Power Inspection & Setters
diffdrive::DrivePowers GetDrivePowers() const;
void SetMaxDriveEffort(const double dMaxDriveEffort);
double GetMaxDriveEffort() const;

// Differential Drive Mode Selection
void SetDifferentialControlMethod(diffdrive::DifferentialControlMethod eMethod);