Parameters¶
The ROSflight firmware has several dozen parameters which it uses to customize performance. Parameters are considered semi-static variables. That is, parameters do not change during flight, but they may change between vehicles. Examples of parameters you may wish to change are:
- Fixed-wing vehicle flag
- PID gains
- Mixer choice
- IMU low-pass filter constant
- RC receiver type (PPM or SBUS)
and so on. Access to all parameters is enabled via ROS services advertised by rosflight_io while the flight controller is connected.
Parameter Interface¶
Getting Parameter Values¶
Sometimes it is handy to ask the flight controller what the current value of a parameter is. This is accomplished using the param_get service. As an example, let's retrieve the roll angle controller proportional (P) gain.
rosservice call /param_get PID_ROLL_ANG_P
You should get a response similar to the following (this happens to be the default value with floating-point error):
exists: True
value: 0.15000000596
Changing Parameters¶
Parameters are changed via the param_set service. As an example, let's change the roll angle controller P gain. (I will assume that the flight controller is connected and rosflight_io is running in the root namespace.)
rosservice call /param_set PID_ROLL_ANG_P 0.08
You should get a prompt from rosflight_io saying
[ INFO] [1491672408.585339558]: Parameter PID_ROLL_ANG_P has new value 0.08
[ WARN] [1491672408.585508849]: There are unsaved changes to onboard parameters
Notice that the parameters have been set, but not saved. Parameter changes take effect immediately, however they will not persist over a reboot unless you write them to the non-volatile memory. This brings us to the next task.
Writing Parameters¶
To ensure that parameter values persist between reboots, you must write the parameters to the non-volatile memory. This is done by calling param_write
rosservice call /param_write
rosflight_io should then respond with
[ INFO] [1491672597.123201952]: Param write succeeded
[ INFO] [1491672597.123452908]: Onboard parameters have been saved
Important
It is highly recommended that you write parameters before arming and flying the vehicle. Among other things, this will ensure that in the rare case that a hard fault is encountered and the flight controller must reboot during flight, the correct configuration will be loaded on reboot.
Error
Parameter writing can only happen if the flight controller is disarmed. If the param write failed for some reason, you may want to make sure your FC is disarmed and try again.
Backing Up and Loading Parameters from File¶
It is good practice to backup your parameter configuration in case you have to re-flash your firmware or you want to share configurations between vehicles. We can do this via the param_save_to_file and param_load_from_file services.
First, let's back up our current parameter configuration:
rosservice call /param_save_to_file ~/parameters.yml
Parameters are saved in YAML format. You must also specify the absolute file name of where you would like your parameters to be saved. The current active set of parameters will be saved, regardless of what is saved in non-volatile memory on the flight controller.
Now, let's say we want to re-load this parameter file
rosservice call /param_load_from_file ~/parameters.yml
Fixed-Wing Parameter Configuration¶
Because ROSflight ships with default parameters for multirotors, you will probably want to change the following parameters if you want to fly a fixed-wing aircraft.
| Parameter | Description | Type | Fixed-Wing Value |
|---|---|---|---|
| MOTOR_PWM_UPDATE | Refresh rate of motor commands to motors and servos (Hz) - See motor documentation | int | 50 |
| ARM_SPIN_MOTORS | Enforce MOTOR_IDLE_PWM | int | false |
| MOTOR_IDLE_THR | min throttle command sent to motors when armed (Set above 0.1 to spin when armed) | float | 0.1 |
| ARM_CHANNEL | RC switch channel mapped to arming [0 indexed, -1 to disable] | int | 4 |
| FIXED_WING | switches on passthrough commands for fixed-wing operation | int | true |
| MIXER | Which mixer to choose - See Mixer documentation | int | 10 |
| ELEVATOR_REV | reverses elevator servo output | int | 0/1 |
| AIL_REV | reverses aileron servo output | int | 0/1 |
| RUDDER_REV | reverses rudder servo output | int | 0/1 |
| CAL_GYRO_ARM | Calibrate gyros when arming - generally only for multirotors | int | false |
Description of all Parameters¶
This is a list of all ROSflight parameters, including their types, default values, and minimum and maximum recommended values:
| Parameter | Description | Type | Default Value | Min | Max |
|---|---|---|---|---|---|
| BAUD_RATE | Baud rate of MAVlink communication with companion computer | int | 921600 | 9600 | 921600 |
| SERIAL_DEVICE | Serial Port (for supported devices) | int | 0 | 0 | 3 |
| SYS_ID | Mavlink System ID | int | 1 | 1 | 255 |
| STRM_HRTBT | Rate of heartbeat stream (Hz) | int | 1 | 0 | 1000 |
| STRM_STATUS | Rate of status stream (Hz) | int | 10 | 0 | 1000 |
| STRM_ATTITUDE | Rate of attitude stream (Hz) | int | 200 | 0 | 1000 |
| STRM_IMU | Rate of IMU stream (Hz) | int | 250 | 0 | 1000 |
| STRM_MAG | Rate of magnetometer stream (Hz) | int | 50 | 0 | 75 |
| STRM_BARO | Rate of barometer stream (Hz) | int | 50 | 0 | 100 |
| STRM_AIRSPEED | Rate of airspeed stream (Hz) | int | 50 | 0 | 50 |
| STRM_SONAR | Rate of sonar stream (Hz) | int | 40 | 0 | 40 |
| STRM_SERVO | Rate of raw output stream | int | 50 | 0 | 490 |
| STRM_RC | Rate of raw RC input stream | int | 50 | 0 | 50 |
| STRM_GNSS | Maximum rate of GNSS data streaming. Higher values allow for lower latency | int | 1000 | 0 | 1000 |
| STRM_GNSS_FULL | Maximum rate of fully detailed GNSS data streaming | int | 0 | 0 | 10 |
| STRM_BATTERY | Rate of battery status stream | int | 0 | 0 | 50 |
| PARAM_MAX_CMD | saturation point for PID controller output | float | 1.0 | 0 | 1.0 |
| PID_ROLL_RATE_P | Roll Rate Proportional Gain | float | 0.070f | 0.0 | 1000.0 |
| PID_ROLL_RATE_I | Roll Rate Integral Gain | float | 0.000f | 0.0 | 1000.0 |
| PID_ROLL_RATE_D | Roll Rate Derivative Gain | float | 0.000f | 0.0 | 1000.0 |
| PID_PITCH_RATE_P | Pitch Rate Proportional Gain | float | 0.070f | 0.0 | 1000.0 |
| PID_PITCH_RATE_I | Pitch Rate Integral Gain | float | 0.0000f | 0.0 | 1000.0 |
| PID_PITCH_RATE_D | Pitch Rate Derivative Gain | float | 0.0000f | 0.0 | 1000.0 |
| PID_YAW_RATE_P | Yaw Rate Proportional Gain | float | 0.25f | 0.0 | 1000.0 |
| PID_YAW_RATE_I | Yaw Rate Integral Gain | float | 0.0f | 0.0 | 1000.0 |
| PID_YAW_RATE_D | Yaw Rate Derivative Gain | float | 0.0f | 0.0 | 1000.0 |
| PID_ROLL_ANG_P | Roll Angle Proportional Gain | float | 0.15f | 0.0 | 1000.0 |
| PID_ROLL_ANG_I | Roll Angle Integral Gain | float | 0.0f | 0.0 | 1000.0 |
| PID_ROLL_ANG_D | Roll Angle Derivative Gain | float | 0.05f | 0.0 | 1000.0 |
| PID_PITCH_ANG_P | Pitch Angle Proportional Gain | float | 0.15f | 0.0 | 1000.0 |
| PID_PITCH_ANG_I | Pitch Angle Integral Gain | float | 0.0f | 0.0 | 1000.0 |
| PID_PITCH_ANG_D | Pitch Angle Derivative Gain | float | 0.05f | 0.0 | 1000.0 |
| X_EQ_TORQUE | Equilibrium torque added to output of controller on x axis | float | 0.0f | -1.0 | 1.0 |
| Y_EQ_TORQUE | Equilibrium torque added to output of controller on y axis | float | 0.0f | -1.0 | 1.0 |
| Z_EQ_TORQUE | Equilibrium torque added to output of controller on z axis | float | 0.0f | -1.0 | 1.0 |
| PID_TAU | Dirty Derivative time constant - See controller documentation | float | 0.05f | 0.0 | 1.0 |
| MOTOR_PWM_UPDATE | Overrides default PWM rate specified by mixer if non-zero - Requires reboot to take effect | int | 0 | 0 | 490 |
| MOTOR_IDLE_THR | min throttle command sent to motors when armed (Set above 0.1 to spin when armed) | float | 0.1 | 0.0 | 1.0 |
| FAILSAFE_THR | Throttle sent to motors in failsafe condition (set just below hover throttle) | float | 0.3 | 0.0 | 1.0 |
| ARM_SPIN_MOTORS | Enforce MOTOR_IDLE_THR | int | true | 0 | 1 |
| FILTER_INIT_T | Time in ms to initialize estimator | int | 3000 | 0 | 100000 |
| FILTER_KP | estimator proportional gain - See estimator documentation | float | 0.5f | 0 | 10.0 |
| FILTER_KI | estimator integral gain - See estimator documentation | float | 0.01f | 0 | 1.0 |
| FILTER_KP_COR | estimator proportional gain on external attitude correction - See estimator documentation | float | 10.0f | 0 | 1.0 |
| FILTER_ACCMARGIN | allowable accel norm margin around 1g to determine if accel is usable | float | 0.1f | 0 | 1.0 |
| FILTER_QUAD_INT | Perform a quadratic averaging of LPF gyro data prior to integration (adds ~20 us to estimation loop on F1 processors) | int | 1 | 0 | 1 |
| FILTER_MAT_EXP | 1 - Use matrix exponential to improve gyro integration (adds ~90 us to estimation loop in F1 processors) 0 - use euler integration | int | 1 | 0 | 1 |
| FILTER_USE_ACC | Use accelerometer to correct gyro integration drift (adds ~70 us to estimation loop) | int | 1 | 0 | 1 |
| CAL_GYRO_ARM | True if desired to calibrate gyros on arm | int | false | 0 | 1 |
| GYROXY_LPF_ALPHA | Low-pass filter constant on gyro X and Y axes - See estimator documentation | float | 0.3f | 0 | 1.0 |
| GYROZ_LPF_ALPHA | Low-pass filter constant on gyro Z axis - See estimator documentation | float | 0.3f | 0 | 1.0 |
| ACC_LPF_ALPHA | Low-pass filter constant on all accel axes - See estimator documentation | float | 0.5f | 0 | 1.0 |
| GYRO_X_BIAS | Constant x-bias of gyroscope readings | float | 0.0f | -1.0 | 1.0 |
| GYRO_Y_BIAS | Constant y-bias of gyroscope readings | float | 0.0f | -1.0 | 1.0 |
| GYRO_Z_BIAS | Constant z-bias of gyroscope readings | float | 0.0f | -1.0 | 1.0 |
| ACC_X_BIAS | Constant x-bias of accelerometer readings | float | 0.0f | -2.0 | 2.0 |
| ACC_Y_BIAS | Constant y-bias of accelerometer readings | float | 0.0f | -2.0 | 2.0 |
| ACC_Z_BIAS | Constant z-bias of accelerometer readings | float | 0.0f | -2.0 | 2.0 |
| ACC_X_TEMP_COMP | Linear x-axis temperature compensation constant | float | 0.0f | -2.0 | 2.0 |
| ACC_Y_TEMP_COMP | Linear y-axis temperature compensation constant | float | 0.0f | -2.0 | 2.0 |
| ACC_Z_TEMP_COMP | Linear z-axis temperature compensation constant | float | 0.0f | -2.0 | 2.0 |
| MAG_A11_COMP | Soft iron compensation constant | float | 1.0f | -999.0 | 999.0 |
| MAG_A12_COMP | Soft iron compensation constant | float | 0.0f | -999.0 | 999.0 |
| MAG_A13_COMP | Soft iron compensation constant | float | 0.0f | -999.0 | 999.0 |
| MAG_A21_COMP | Soft iron compensation constant | float | 0.0f | -999.0 | 999.0 |
| MAG_A22_COMP | Soft iron compensation constant | float | 1.0f | -999.0 | 999.0 |
| MAG_A23_COMP | Soft iron compensation constant | float | 0.0f | -999.0 | 999.0 |
| MAG_A31_COMP | Soft iron compensation constant | float | 0.0f | -999.0 | 999.0 |
| MAG_A32_COMP | Soft iron compensation constant | float | 0.0f | -999.0 | 999.0 |
| MAG_A33_COMP | Soft iron compensation constant | float | 1.0f | -999.0 | 999.0 |
| MAG_X_BIAS | Hard iron compensation constant | float | 0.0f | -999.0 | 999.0 |
| MAG_Y_BIAS | Hard iron compensation constant | float | 0.0f | -999.0 | 999.0 |
| MAG_Z_BIAS | Hard iron compensation constant | float | 0.0f | -999.0 | 999.0 |
| BARO_BIAS | Barometer measurement bias (Pa) | float | 0.0f | 0 | inf |
| GROUND_LEVEL | Altitude of ground level (m) | float | 1387.0f | -1000 | 10000 |
| DIFF_PRESS_BIAS | Differential Pressure Bias (Pa) | float | 0.0f | -10 | 10 |
| RC_TYPE | Type of RC input 0 - PPM, 1 - SBUS | int | 0 | 0 | 1 |
| BATT_VOLT_MULT | Battery monitor voltage multiplier | float | 0 | 0 | inf |
| BATT_CURR_MULT | Battery monitor current multiplier | float | 0 | 0 | inf |
| BATT_VOLT_ALPHA | Batter monitor voltage filter alpha. Values closer to 1 smooth the signal more. | float | 0.995 | 0 | 1 |
| BATT_CURR_ALPHA | Battery monitor current filter alpha. Values closer to 1 smooth the signal more. | float | 0.995 | 0 | 1 |
| RC_X_CHN | RC input channel mapped to x-axis commands [0 - indexed] | int | 0 | 0 | 3 |
| RC_Y_CHN | RC input channel mapped to y-axis commands [0 - indexed] | int | 1 | 0 | 3 |
| RC_Z_CHN | RC input channel mapped to z-axis commands [0 - indexed] | int | 3 | 0 | 3 |
| RC_F_CHN | RC input channel mapped to F-axis commands [0 - indexed] | int | 2 | 0 | 3 |
| RC_ATT_OVRD_CHN | RC switch mapped to attitude override [0 indexed, -1 to disable] | int | 4 | 4 | 7 |
| RC_THR_OVRD_CHN | RC switch channel mapped to throttle override [0 indexed, -1 to disable] | int | 4 | 4 | 7 |
| RC_ATT_CTRL_CHN | RC switch channel mapped to attitude control type [0 indexed, -1 to disable] | int | -1 | 4 | 7 |
| ARM_CHANNEL | RC switch channel mapped to arming (only if PARAM_ARM_STICKS is false) [0 indexed, -1 to disable] | int | -1 | 4 | 7 |
| RC_NUM_CHN | number of RC input channels | int | 6 | 1 | 8 |
| SWITCH_5_DIR | RC switch 5 toggle direction | int | 1 | -1 | 1 |
| SWITCH_6_DIR | RC switch 6 toggle direction | int | 1 | -1 | 1 |
| SWITCH_7_DIR | RC switch 7 toggle direction | int | 1 | -1 | 1 |
| SWITCH_8_DIR | RC switch 8 toggle direction | int | 1 | -1 | 1 |
| RC_OVRD_DEV | RC stick deviation from center for override | float | 0.1 | 0.0 | 1.0 |
| OVRD_LAG_TIME | RC stick deviation lag time before returning control (ms) | int | 1000 | 0 | 100000 |
| MIN_THROTTLE | Take minimum throttle between RC and computer at all times | int | true | 0 | 1 |
| RC_ATT_MODE | Attitude mode for RC sticks (0: rate, 1: angle). Overridden if RC_ATT_CTRL_CHN is set. | int | 1 | 0 | 1 |
| RC_MAX_ROLL | Maximum roll angle command sent by full deflection of RC sticks | float | 0.786f | 0.0 | 3.14159 |
| RC_MAX_PITCH | Maximum pitch angle command sent by full stick deflection of RC sticks | float | 0.786f | 0.0 | 3.14159 |
| RC_MAX_ROLLRATE | Maximum roll rate command sent by full stick deflection of RC sticks | float | 3.14159f | 0.0 | 9.42477796077 |
| RC_MAX_PITCHRATE | Maximum pitch command sent by full stick deflection of RC sticks | float | 3.14159f | 0.0 | 3.14159 |
| RC_MAX_YAWRATE | Maximum pitch command sent by full stick deflection of RC sticks | float | 1.507f | 0.0 | 3.14159 |
| MIXER | Which mixer to choose - See Mixer documentation | int | Mixer::INVALID_MIXER | 0 | 10 |
| FIXED_WING | switches on pass-through commands for fixed-wing operation | int | false | 0 | 1 |
| ELEVATOR_REV | reverses elevator servo output | int | 0 | 0 | 1 |
| AIL_REV | reverses aileron servo output | int | 0 | 0 | 1 |
| RUDDER_REV | reverses rudder servo output | int | 0 | 0 | 1 |
| FC_ROLL | roll angle (deg) of flight controller wrt aircraft body | float | 0.0f | 0 | 360 |
| FC_PITCH | pitch angle (deg) of flight controller wrt aircraft body | float | 0.0f | 0 | 360 |
| FC_YAW | yaw angle (deg) of flight controller wrt aircraft body | float | 0.0f | 0 | 360 |
| ARM_THRESHOLD | RC deviation from max/min in yaw and throttle for arming and disarming check (us) | float | 0.15 | 0 | 500 |
| OFFBOARD_TIMEOUT | Timeout in milliseconds for offboard commands, after which RC override is activated | int | 100 | 0 | 100000 |