diff options
Diffstat (limited to 'ROMFS/px4fmu_common/mixers/README')
| -rw-r--r-- | ROMFS/px4fmu_common/mixers/README | 154 |
1 files changed, 0 insertions, 154 deletions
diff --git a/ROMFS/px4fmu_common/mixers/README b/ROMFS/px4fmu_common/mixers/README deleted file mode 100644 index 6649c53c2..000000000 --- a/ROMFS/px4fmu_common/mixers/README +++ /dev/null @@ -1,154 +0,0 @@ -PX4 mixer definitions -===================== - -Files in this directory implement example mixers that can be used as a basis -for customisation, or for general testing purposes. - -Mixer basics ------------- - -Mixers combine control values from various sources (control tasks, user inputs, -etc.) and produce output values suitable for controlling actuators; servos, -motors, switches and so on. - -An actuator derives its value from the combination of one or more control -values. Each of the control values is scaled according to the actuator's -configuration and then combined to produce the actuator value, which may then be -further scaled to suit the specific output type. - -Internally, all scaling is performed using floating point values. Inputs and -outputs are clamped to the range -1.0 to 1.0. - -control control control - | | | - v v v - scale scale scale - | | | - | v | - +-------> mix <------+ - | - scale - | - v - out - -Scaling -------- - -Basic scalers provide linear scaling of the input to the output. - -Each scaler allows the input value to be scaled independently for inputs -greater/less than zero. An offset can be applied to the output, and lower and -upper boundary constraints can be applied. Negative scaling factors cause the -output to be inverted (negative input produces positive output). - -Scaler pseudocode: - -if (input < 0) - output = (input * NEGATIVE_SCALE) + OFFSET -else - output = (input * POSITIVE_SCALE) + OFFSET - -if (output < LOWER_LIMIT) - output = LOWER_LIMIT -if (output > UPPER_LIMIT) - output = UPPER_LIMIT - -Syntax ------- - -Mixer definitions are text files; lines beginning with a single capital letter -followed by a colon are significant. All other lines are ignored, meaning that -explanatory text can be freely mixed with the definitions. - -Each file may define more than one mixer; the allocation of mixers to actuators -is specific to the device reading the mixer definition, and the number of -actuator outputs generated by a mixer is specific to the mixer. - -A mixer begins with a line of the form - - <tag>: <mixer arguments> - -The tag selects the mixer type; 'M' for a simple summing mixer, 'R' for a -multirotor mixer, etc. - -Null Mixer -.......... - -A null mixer consumes no controls and generates a single actuator output whose -value is always zero. Typically a null mixer is used as a placeholder in a -collection of mixers in order to achieve a specific pattern of actuator outputs. - -The null mixer definition has the form: - - Z: - -Simple Mixer -............ - -A simple mixer combines zero or more control inputs into a single actuator -output. Inputs are scaled, and the mixing function sums the result before -applying an output scaler. - -A simple mixer definition begins with: - - M: <control count> - O: <-ve scale> <+ve scale> <offset> <lower limit> <upper limit> - -If <control count> is zero, the sum is effectively zero and the mixer will -output a fixed value that is <offset> constrained by <lower limit> and <upper -limit>. - -The second line defines the output scaler with scaler parameters as discussed -above. Whilst the calculations are performed as floating-point operations, the -values stored in the definition file are scaled by a factor of 10000; i.e. an -offset of -0.5 is encoded as -5000. - -The definition continues with <control count> entries describing the control -inputs and their scaling, in the form: - - S: <group> <index> <-ve scale> <+ve scale> <offset> <lower limit> <upper limit> - -The <group> value identifies the control group from which the scaler will read, -and the <index> value an offset within that group. These values are specific to -the device reading the mixer definition. - -When used to mix vehicle controls, mixer group zero is the vehicle attitude -control group, and index values zero through three are normally roll, pitch, -yaw and thrust respectively. - -The remaining fields on the line configure the control scaler with parameters as -discussed above. Whilst the calculations are performed as floating-point -operations, the values stored in the definition file are scaled by a factor of -10000; i.e. an offset of -0.5 is encoded as -5000. - -Multirotor Mixer -................ - -The multirotor mixer combines four control inputs (roll, pitch, yaw, thrust) -into a set of actuator outputs intended to drive motor speed controllers. - -The mixer definition is a single line of the form: - -R: <geometry> <roll scale> <pitch scale> <yaw scale> <deadband> - -The supported geometries include: - - 4x - quadrotor in X configuration - 4+ - quadrotor in + configuration - 6x - hexcopter in X configuration - 6+ - hexcopter in + configuration - 8x - octocopter in X configuration - 8+ - octocopter in + configuration - -Each of the roll, pitch and yaw scale values determine scaling of the roll, -pitch and yaw controls relative to the thrust control. Whilst the calculations -are performed as floating-point operations, the values stored in the definition -file are scaled by a factor of 10000; i.e. an factor of 0.5 is encoded as 5000. - -Roll, pitch and yaw inputs are expected to range from -1.0 to 1.0, whilst the -thrust input ranges from 0.0 to 1.0. Output for each actuator is in the -range -1.0 to 1.0. - -In the case where an actuator saturates, all actuator values are rescaled so that -the saturating actuator is limited to 1.0. |