ardupilot/Rover/fence.cpp

#include "Rover.h"

#if AP_FENCE_ENABLED

// async fence checking io callback at 1Khz
void Rover::fence_checks_async()
{
    const uint32_t now = AP_HAL::millis();

    if (!AP_HAL::timeout_expired(fence_breaches.last_check_ms, now, 100U)) { // 10Hz update rate
        return;
    }

    if (fence_breaches.have_updates) {
        return; // wait for the main loop to pick up the new breaches before checking again
    }

    fence_breaches.last_check_ms = now;
    const uint8_t orig_breaches = fence.get_breaches();
    // check for new breaches; new_breaches is bitmask of fence types breached
    fence_breaches.new_breaches = fence.check();

    if (!fence_breaches.new_breaches && orig_breaches && fence.get_breaches() == 0) {
        // record clearing of breach
        LOGGER_WRITE_ERROR(LogErrorSubsystem::FAILSAFE_FENCE, LogErrorCode::ERROR_RESOLVED);
    }
    fence_breaches.have_updates = true; // new breaches latched so main loop will now pick it up
}

// fence_check - ask fence library to check for breaches and initiate the response
void Rover::fence_check()
{
    // only take action if there is a new breach
    if (!fence_breaches.have_updates) {
        return;
    }

    // return immediately if motors are not armed
    if (!arming.is_armed()) {
        fence_breaches.have_updates = false;
        return;
    }

    if (fence_breaches.new_breaches) {
        // if the user wants some kind of response and motors are armed
        if ((FailsafeAction)fence.get_action() != FailsafeAction::None) {
            // if within 100m of the fence, it will take the action specified by the FENCE_ACTION parameter
            if (fence.get_breach_distance(fence_breaches.new_breaches) <= AC_FENCE_GIVE_UP_DISTANCE) {
                switch ((FailsafeAction)fence.get_action()) {
                case FailsafeAction::None:
                    break;
                case FailsafeAction::SmartRTL:
                    if (set_mode(mode_smartrtl, ModeReason::FENCE_BREACHED)) {
                        break;
                    }
                    FALLTHROUGH;
                case FailsafeAction::RTL:
                    if (set_mode(mode_rtl, ModeReason::FENCE_BREACHED)) {
                        break;
                    }
                    FALLTHROUGH;
                case FailsafeAction::Hold:
                    set_mode(mode_hold, ModeReason::FENCE_BREACHED);
                    break;
                case FailsafeAction::SmartRTL_Hold:
                    if (!set_mode(mode_smartrtl, ModeReason::FENCE_BREACHED)) {
                        set_mode(mode_hold, ModeReason::FENCE_BREACHED);
                    }
                    break;
                case FailsafeAction::Loiter_Hold:
                    if (!set_mode(mode_loiter, ModeReason::FENCE_BREACHED)) {
                        set_mode(mode_hold, ModeReason::FENCE_BREACHED);
                    }
                    break;
                case FailsafeAction::Terminate:
                    arming.disarm(AP_Arming::Method::FENCEBREACH);
                    break;
                }
            } else {
                // if more than 100m outside the fence just force to HOLD
                set_mode(mode_hold, ModeReason::FENCE_BREACHED);
            }
        }
        LOGGER_WRITE_ERROR(LogErrorSubsystem::FAILSAFE_FENCE, LogErrorCode(fence_breaches.new_breaches));
    }
    fence_breaches.have_updates = false;
}

#endif // AP_FENCE_ENABLED