Multi Turn Angle Control

The Multi-turn Angle Controller is a non-wrapping, PID, position controller. It is capable of storing angular to linear transmission information, mimicking a linear position controller. It also features a minimum jerk trajectory generator. The controller has a 32 trajectory buffer so that transitions between trajectories are seamless.

Arduino

To use Multi-turn Angle Controller in Arduino, ensure iq_module_communication.hpp is included. This allows the creation of a MultiTurnAngleControlClient object. See the Message Table below for available messages. All message objects use the Short Name with a trailing underscore.

A minimal working example for the MultiTurnAngleControlClient is:

#include <iq_module_communication.hpp>

IqSerial ser(Serial2);
MultiTurnAngleControlClient mult(0);

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

void loop() {
    ser.set(mult.trajectory_angular_displacement_,3.14f);
    ser.set(mult.trajectory_duration_,0.5f);
    ser.set(mult.trajectory_angular_displacement_,0.0f);
    ser.set(mult.trajectory_duration_,0.5f);
    delay(1000);
}

C++

To use Multi-turn Angle Controller in C++, include multi turn angle control client.hpp. This allows the creation of a MultiTurnAngleControlClient object. See the Message Table below for available messages. All message objects use the Short Name with a trailing underscore.

A minimal working example for the MultiTurnAngleControlClient is:

Note

Interfacing with Serial looks different on different machines. Therefore, this example does not include code for interfacing with the hardware.

For more, see Full C++ Code Example (w/ LibSerial)

#include "generic_interface.hpp"
#include "multi_turn_angle_control_client.hpp"

float angle;

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

    // Make a Multi-turn Angle Controller object with obj_id 0
    MultiTurnAngleControlClient angle_ctrl(0);

    // Use the Multi-turn Angle Controller object
    angle_ctrl.obs_angular_displacement_.get(com);
    angle_ctrl.ctrl_angle_.set(com,0.0f);

    // Insert code for interfacing with hardware here
    // Read response
    angle = angle_ctrl.ctrl_angle_.get_reply();

}

Matlab

To use Multi-turn Angle Controller in Matlab, all Vertiq communication code must be included in your path. This allows the creation of a MultiTurnAngleControlClient object. See the Message Table below for available messages. All message strings use the Short Names.

A minimal working example for the MultiTurnAngleControlClient is:

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

% Make a MultiTurnAngleControlClient object with obj_id 0
MultiTurnAngleControl = MultiTurnAngleControlClient(’com’,com);

% Use the MultiTurnAngleControlClient object
velocityFiltered = MultiTurnAngleControl.get(’obs_angular_displacement’);
MultiTurnAngleControl.set(’ctrl_angle’,0);

Python

To use the Multi-Turn Angle Control Client in Python, import iqmotion and create a module that has the Multi-Turn Angle Control Client within its firmware. See the Message Table below for available messages. All message strings use the Short Names.

A minimal working example for the Multi-Turn Angle Control Client is:

import iqmotion as iq
import math

com = iq.SerialCommunicator("/dev/ttyUSB0")
|variable_name| = iq.|module_name|(com, 0, firmware="servo")  # Servo Firmware uses this client

# Set the trajectory for the motor to complete 1 full rotation
|variable_name|.set("multi_turn_angle_control", "trajectory_angular_displacement", 2*math.pi)

# Sets trajectory duration for 2 seconds
|variable_name|.set("multi_turn_angle_control", "trajectory_duration", 2)

Message Table

Type ID 59 | Multi-turn Angle Controller

Multi-turn Angle Controller

Sub ID	Short Name	Access	Data Type	Unit	Note
0	ctrl_mode	get	int8	\(\text{Enum}\)	no_change = -1, brake=0, coast=1, pwm=2, volts=3, velocity=4, angle=5, trajectory=6
1	ctrl_brake	set			Shorts motor phases, slows motor down dissipating energy in motor.
2	ctrl_coast	set			Disables all drive circuitry, motor passively coasts.
3	ctrl_angle	get, set	float	\(\text{rad}\)	Angular location command
4	ctrl_velocity	get, set	float	\(\frac{\text{rad}}{s}\)	Angular velocity command
5	angle_Kp	get, set, save	float	\(\frac{V}{\text{rad}}\)	Proportional gain
6	angle_Ki	get, set, save	float	\(\frac{V}{\text{rad}*s}\)	Integral gain
7	angle_Kd	get, set, save	float	\(\frac{V}{(\frac{\text{rad}}{s})}\)	Derivative gain
8	timeout	get, set, save	float	\(s\)	The controller must receive a message within this time otherwise it is set to coast mode.
9	ctrl_pwm	get, set	float	\(\text{PWM}\)	Spins motor with this throttle [-1, 1].
10	ctrl_volts	get, set	float	\(V\)	Spins motor with this voltage.
11	obs_angular_displacement	get, set	float	\(\text{rad}\)	This represents the total distance that the module has spun measured in radians. Unless this value is set explicitly, it represents the distance, positive or negative, that the module has spun away from zero_angle. If this value is set, all future displacement controls and readings will be measured in reference to the set displacement.
12	obs_angular_velocity	get	float	\(\frac{\text{rad}}{s}\)	Observed angular velocity
13	meter_per_rad	get, set, save	float	\(\frac{m}{\text{rad}}\)	Transmission between angular and linear motion
14	ctrl_linear_displacement	get, set,	float	\(m\)	Linear equivalent to ctrl_angle
15	ctrl_linear_velocity	get, set,	float	\(\frac{m}{s}\)	Linear equivalent to ctrl_velocity
16	obs_linear_displacement	get, set,	float	\(m\)	Observed linear location
17	obs_linear_velocity	get	float	\(\frac{m}{s}\)	Observed linear velocity
18	angular_speed_max	get, set, save	float	\(\frac{\text{rad}}{s}\)	The controller will never attempt to exceed this speed.
19	trajectory_angular_displacement	get, set	float	\(\text{rad}\)	Final absolute displacement of trajectory.
20	trajectory_angular_velocity	get, set	float	\(\frac{\text{rad}}{s}\)	Final velocity of the trajectory. Defaults to 0.
21	trajectory_angular_acceleration	get, set	float	\(\frac{\text{rad}}{s^2}\)	Final acceleration of the trajectory. Defaults to 0.
22	trajectory_duration	set	float	\(s\)	Duration of trajectory. Trajectory is executed or queued once this is sent.
23	trajectory_linear_displacement	get, set	float	\(m\)	Final absolute displacement of trajectory.
24	trajectory_linear_velocity	get, set	float	\(\frac{m}{s}\)	Final velocity of the trajectory. Defaults to 0.
25	trajectory_linear_acceleration	get, set	float	\(\frac{m}{s^2}\)	Final acceleration of the trajectory. Defaults to 0.
26	trajectory_average_speed	get, set	float	\(\frac{\text{rad}}{s}\)	Average speed of a trajectory. Trajectory is executed or queued once this is sent. Must be >0.
27	trajectory_queue_mode	get, set, save	int8	\(\text{Enum}\)	append=0, overwrite=1
29	ff	get, set	uint32	\(V_{fix16}\)	Feed forward term
30	sample_zero_angle	set			Sets the module’s current postiion as the zero angle.
31	zero_angle	get, set, save	float	\(\text{rad}\)	The encoder position the module considers to be 0 radians. Since this is an encoder position, zero_angle is constrained to [-pi, pi]. Unless obs_angular_displacement is set explicitly, this is the position regarded as 0 radians, and all displacements are measured in comparison to this point.