propeller_motor_control.rst

Propeller Motor Control

The Propeller Motor Controller is an open and closed loop controller designed to drive propeller loads. If given thrust coefficients, this controller can be commanded in units of thrust, seamlessly accepting values from flight controllers in their native units. An added benefit is the decoupling of flight controller gains from motor choice, propeller choice, battery level, and more. Thrust commands are fed into a PID velocity controller with a second order polynomial feed forward. This sits on top of a voltage controller, which compensates for varying input voltages. Finally, the core is a raw PWM controller. Any of the above controllers can be used by the user.

Note

The Propeller Motor Control will timeout and beep 3 times if it hasn't received a command before the timeout is reached. You can extend the timeout by changing the timeout client entry

Arduino

To use Propeller Motor Controller in Arduino, ensure iq_module_communication.hpp is included. This allows the creation of a PropellerMotorControlClient object. See the Message Table below for available messages. All message objects use the Short Name with a trailing underscore. All messages use the standard Get/Set/Save functions.

A minimal working example for the PropellerMotorControlMessaging is:

#include <iq_module_communicaiton.hpp>

IqSerial ser(Serial2);
PropellerMotorControlClient prop(0);

void setup() {
    ser.begin();
}

void loop() {
    ser.set(prop.ctrl_velocity_,50.0f);
}

C++

To use Propeller Motor Controller in C++, include propeller motor control client.hpp. This allows the creation of a PropellerMotorControlClient object. See the Message Table below for available messages. All message objects use the Short Name with a trailing underscore. All messages use the standard Get/Set/Save functions.

A minimal working example for the PropellerMotorControlClient is:

#include "generic_interface.hpp"
#include "propeller_motor_control_client.hpp"

float velocity = 100.0f; // rad/s

void main(){
    // Make a communication interface object
    GenericInterface com;

    // Make a Propeller Motor Controller object with obj_id 0
    PropellerMotorControlClient prop(0);

    // Use the Propeller Motor Controller object
    prop.ctrl_velocity_.set(com, velocity);

    // Insert code for interfacing with hardware here

}

Matlab

To use Propeller Motor Controller in Matlab, all Vertiq communication code must be included in your path. This allows the creation of a PropellerMotorControlClient object. See the Message Table below for available messages. All message strings use the Short Names. All messages use the standard Get/Set/Save functions.

A minimal working example for the PropellerMotorControlClient is:

% Make a communication interface object
com = MessageInterface(’COM18’,115200);

% Make a PropellerMotorControlClient object with obj_id 0
PropellerMotorControl = PropellerMotorControlClient(’com’,com);

% Use the PropellerMotorControlClient object
PropellerMotorControl.set(’ctrl_velocity’,100.0);

Python

To use the Propeller Motor Control Client in Python, import iqmotion and create a module that has the Propeller Motor Control Client within its firmware. See the Message Table below for available messages. All message strings use the Short Names. All messages use the standard Get/Set/Save functions.

A minimal working example for the Propeller Motor Control Client is:

import iqmotion as iq

com = iq.SerialCommunicator("/dev/ttyUSB0")
|variable_name| = iq.|module_name|(com, 0)

|variable_name|.set("propeller_motor_control", "ctrl_velocity", 5)  # Supplies 5V to motor

Message Table

Type ID 52 | Propeller Motor Controller

Propeller Motor Controller

Sub ID	Short Name	Access	Data Type	Unit	.. centered:: Note
0	ctrl_mode	get	int8	\text{Enum}	-1 = no change, 0 = brake, 1 = coast, 2 = pwm, 3 = volts, 4 = velocity, 5 = thrust
1	ctrl_brake	set			Shorts motor leads, slows motor down dissipating energy in motor
2	ctrl_coast	set			Disables all drive circuitry
3	ctrl_pwm	get, set	float	\text{PWM}	[-1, 1] fraction of input voltage
4	ctrl_volts	get, set	float	V	[-supply, supply] Voltage to apply to motor
5	ctrl_velocity	get, set	float	\frac{\text{rad}}{s}	Angular velocity command
6	ctrl_thrust	get, set	float	N	Thrust command (requires kt values)
7	velocity_kp	get, set, save	float	\frac{V}{(\frac{\text{rad}}{s})}	Proportional gain
8	velocity_ki	get, set, save	float	\frac{V}{\text{rad}}	Integral gain
9	velocity_kd	get, set, save	float	\frac{V}{(\frac{\text{rad}}{s^2})}	Derivative gain
10	velocity_ff0	get, set, save	float	V	Feed forward 0th order term
11	velocity_ff1	get, set, save	float	\frac{V}{(\frac{\text{rad}}{s})}	Feed forward 1st order term
12	velocity_ff2	get, set, save	float	\frac{V}{(\frac{\text{rad}}{s})^2}	Feed forward 2nd order term
13	propeller_kt_pos	get, set, save	float	\frac{N}{(\frac{\text{rad}}{s})^2}	T = ktω2thrust constant in positive direction
14	propeller_kt_neg	get, set, save	float	\frac{N}{(\frac{\text{rad}}{s})^2}	T = ktω2 thrust constant in negative direction
15	timeout	get, set, save	float	s	The controller must receive a message within thistime otherwise it is set to coast mode
16	input_filter_fc	get, set, save	uint32	\text{Hz}	Low pass cutoff frequency for input commands
17	timeout_meaning	get, set, save	uint8	\text{Enum}	This indicates if a timeout is intended to be used as an intentional disarm or as an error.
18	timeout_behavior	get, set, save	uint8	\text{Enum}	This detemines what behavior to perform when a timeout error occurs.
19	timeout_song_option	get, set, save	uint8	\text{Enum}	This determines how many times the timeout song will play on a timeout error.