Motors Underpowered

[samdrew]

The current settings and limits coming from the Betaflight FC are being interpreted such that even with the PWM output at full, the motors are still not spinning enough to enable flight.

[samdrew]

Comparing the code from ardupilot_gazebo plugin to the code from aeroloop_gazebo (based on an earlier version of ardupilot), it is likely just the multiplier in ardupilot_gazebo that needs adjusting, although the exact parameters are unclear.

ardupilot_gazebo:src/ArduPilotPlugin:1634

                // convert pwm to raw cmd: [servo_min, servo_max] => [0, 1],
                // default is: [1000, 2000] => [0, 1]
                const double pwm = _pwm[this->dataPtr->controls[i].channel];
                const double pwm_min = this->dataPtr->controls[i].servo_min;
                const double pwm_max = this->dataPtr->controls[i].servo_max;
                const double multiplier = this->dataPtr->controls[i].multiplier;
                const double offset = this->dataPtr->controls[i].offset;

                // bound incoming cmd between 0 and 1
                double raw_cmd = (pwm - pwm_min)/(pwm_max - pwm_min);
                raw_cmd = gz::math::clamp(raw_cmd, 0.0, 1.0);
                this->dataPtr->controls[i].cmd =
                    multiplier * (raw_cmd + offset);

aeroloop_plugin:src/BetaflightPlugin:588

        if (i < MAX_MOTORS)
        {
            // std::cout << i << ": " << pkt.motorSpeed[i] << "\n";
            this->dataPtr->rotors[i].cmd = this->dataPtr->rotors[i].maxRpm *
                    pkt.motorSpeed[i];
        }

Where maxRpm is double maxRpm = 838.0