Hexa V - Is it possible?

tegwin · May 8, 2019, 8:28am

I recently noticed an addition to the frame types for Octo V and Octo H which is nice.
See here: http://ardupilot.org/copter/docs/connect-escs-and-motors.html#connect-escs-and-motors3

Is anyone aware of code to run a Hexa V or Hexa H?

I am trying to work out in my mind if you would get good control characteristics with a Hexa V versus a more conventional symmetrical hexa.

Anyone have any thoughts?

iampete · May 8, 2019, 10:00am

master has hexa H,

github.com

ArduPilot/ardupilot/blob/4d1c1bd3804cb0e31ecd253c2862f73bb5feb916/libraries/AP_Motors/AP_MotorsMatrix.cpp#L594


    add_motor(AP_MOTORS_MOT_6, 120, AP_MOTORS_MATRIX_YAW_FACTOR_CW,  3);
    break;
case MOTOR_FRAME_TYPE_X:
    add_motor(AP_MOTORS_MOT_1,  90, AP_MOTORS_MATRIX_YAW_FACTOR_CW,  2);
    add_motor(AP_MOTORS_MOT_2, -90, AP_MOTORS_MATRIX_YAW_FACTOR_CCW, 5);
    add_motor(AP_MOTORS_MOT_3, -30, AP_MOTORS_MATRIX_YAW_FACTOR_CW,  6);
    add_motor(AP_MOTORS_MOT_4, 150, AP_MOTORS_MATRIX_YAW_FACTOR_CCW, 3);
    add_motor(AP_MOTORS_MOT_5,  30, AP_MOTORS_MATRIX_YAW_FACTOR_CCW, 1);
    add_motor(AP_MOTORS_MOT_6,-150, AP_MOTORS_MATRIX_YAW_FACTOR_CW,  4);
    break;
case MOTOR_FRAME_TYPE_H:
    // H is same as X except middle motors are closer to center
    add_motor_raw(AP_MOTORS_MOT_1, -1.0f, 0.0f, AP_MOTORS_MATRIX_YAW_FACTOR_CW, 2);
    add_motor_raw(AP_MOTORS_MOT_2, 1.0f, 0.0f, AP_MOTORS_MATRIX_YAW_FACTOR_CCW, 5);
    add_motor_raw(AP_MOTORS_MOT_3, 1.0f, 1.0f, AP_MOTORS_MATRIX_YAW_FACTOR_CW, 6);
    add_motor_raw(AP_MOTORS_MOT_4, -1.0f, -1.0f, AP_MOTORS_MATRIX_YAW_FACTOR_CCW, 3);
    add_motor_raw(AP_MOTORS_MOT_5, -1.0f, 1.0f, AP_MOTORS_MATRIX_YAW_FACTOR_CCW, 1);
    add_motor_raw(AP_MOTORS_MOT_6, 1.0f, -1.0f, AP_MOTORS_MATRIX_YAW_FACTOR_CW, 4);
    break;
default:
    // hexa frame class does not support this frame type

I don’t think there is much difference in flight characteristics, you have slightly less roll authority and maybe slightly more pitch. The man reason these frames are use is packaging, frame can be a more convenient shape, V is good for a camera that can look up.

tegwin · May 8, 2019, 10:06am

Thanks Peter,

I did not realize it was in Master! This makes life much easier.
I want to try this precisely for the packaging reasons.

Hexa H can’t be selected using the “frame type” GUI in mission planner buy I assume the following params would enable it to work?
Frame_class (2) Hexa
Frame_type (3) H

iampete · May 8, 2019, 10:23am

yep, I should also give the usual disclaimer about flying on master its less tested than the stable release, may be bugs ect

tegwin · May 8, 2019, 11:11am

Ah, every day is a school day! I am slowly getting up to speed with how the community works.

I incorrectly assumed Master meant the latest release (3.9.8). Do you know if there are any intentions for Hexa H to appear in a full release? Is this something that can be requested?

Is there any documentation that explains how to use the master?

Thanks for your disclaimer.

iampete · May 8, 2019, 12:09pm

latest can be found here ArduPilot firmware : /Copter/latest

it will get there eventually, you could open a github issue.

The wiki is probably more up to date with master than stable, the wiki tends to get updated as the code is added to master rather than when it makes it into stable.