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Overview

Using drone flight control function of OSDK, you can set and obtain various basic parameters of the drone, control the drone to perform basic flight actions, and complex flight actions through the Joystick function.

Concepts

Basic Parameters

OSDK has opened interfaces for setting basic parameters of drones:

• Turn on or off the RTK function and obstacle avoidance function (horizontal obstacle avoidance and top obstacle avoidance)
• Set the home point and back altitude of the drone

The application with Message Subscription could help users to obtain information about the basic parameters of the drone：

• Get the status of RTK and obstacle avoidance (horizontal and top obstacle avoidance)
• Back home point and altitude

Basic Action

The basic flying actions of drones include three types: lock, takeoff and landing, and back to home. Developers can use the interface provided by OSDK to control the drone perform the specified flight action.

NOTE

• Different drones may have different heights when taking off, landing and returning. Please refer to the User's manual of the drone for details.
• After unlocked, if the takeoff command is not received, the drone will automatically lock and the propeller will stop rotating. If the drone fails to unlock, please query the reason for the unlock failure according to the error code.

Joystick

Joystick is a comprehensive drone control function. When using the Joystick function, need set the Coordinate System, Horizontal Mode, Vertical Mode, Yaw Angle Mode and Self-Stability Mode at same time.

Coordinate System

• Body Coordinate System The Body Coordinate System uses the center of gravity as the origin, the direction of the head is the X axis, and the right side of the head is the Y axis. The Z axis is perpendicular to the X axis and the Y axis(follow the "right-hand rule"). In the body coordinates, the flying action rotates around the X axis, Y axis and Z axis,it also can be called roll (the drone only rotates around the X axis), pitch (the drone only rotates around the Y axis) And yaw (the drone only rotates around the Z axis).

• Geodetic Coordinate System The Geodetic Coordinate System is also called the Ground Coordinate System or the Local Horizontal Coordinate System. In this coordinate system, the direction of the drone pointing to the north of the earth is the X axis, and the direction of the east is the Y axis. The X axis and the Y axis are perpendicular to each other, The Z axis points vertically below the drone.(follow the "right-hand rule"), the Z axis will adjust the angle according to the actual situation of the drone, so this coordinate system is also called "North-East-Earth (NED) Coordinates System".

Horizontal Mode

• Attitude angle control mode: In this mode, the command in the horizontal direction is the attitude angle of the drone. (In the body coordinate system, the angle is roll and pitch)
• Speed ​​control mode: In this mode, the command in the horizontal direction is the speed of the drone
• Position control mode: In this mode, the command in the horizontal direction is the position of the drone

  NOTE If the mode of the position command is not 0, the drone will fly forward at the specified speed, otherwise, the drone will hover at the specified position.

• Angular speed control: In this mode, the horizontal direction is the rotation angular speed of the drone

Hover mode

Only in the speed control mode in the Horizontal mode, the developer can set the hovering mode of the drone:

• Turn on the stable mode: After the stable mode is turned on, the drone will hover at the specified position
• Turn off the stable mode: After turning off the stable mode, the drone will fly according to the speed command. When the forward speed of the drone is 0, the drone may flutter with the wind

Vertical Mode

• Speed ​​control mode: Control the vertical speed of the drone
• Position control mode: Control the vertical position of the drone, which is an absolute position relative to the take-off point
• Accelerator control mode: Control the accelerator of the drone

Yaw Control Mode

• Angle control mode: In this mode, the command rotate the drone in the yaw direction is the yaw angle
• Angular rate control mode: In this mode, the command rotate the drone in the yaw direction is the angular rate of the yaw

Drone Height

The basic height concept of DJI's drone during the flight is shown in Table 2.

FlightSample* flightSample = new FlightSample(vehicle);

flightSample->monitoredTakeoff();
vehicle->flightController->setCollisionAvoidanceEnabledSync(
  FlightController::AvoidEnable::AVOID_ENABLE, 1);

/*! Move to higher altitude */
flightSample->moveByPositionOffset((FlightSample::Vector3f){0, 0, 30}, 0);

/*! Move a short distance*/
flightSample->moveByPositionOffset((FlightSample::Vector3f){10, 0, 0}, 0);

/*! Set aircraft current position as new home location */
flightSample->setNewHomeLocation();

/*! Set new go home altitude */
flightSample->setGoHomeAltitude(50);

/*! Move to another position */
flightSample->moveByPositionOffset((FlightSample::Vector3f){20, 0, 0}, 0);

vehicle->flightController->setCollisionAvoidanceEnabledSync(
FlightController::AvoidEnable::AVOID_DISABLE, 1);
/*! go home and confirm landing */
flightSample->goHomeAndConfirmLanding();

vehicle->flightController->setCollisionAvoidanceEnabledSync(
FlightController::AvoidEnable::AVOID_ENABLE, 1);

FlightController::JoystickMode joystickMode = {
  FlightController::HorizontalLogic::HORIZONTAL_POSITION,
  FlightController::VerticalLogic::VERTICAL_POSITION,
  FlightController::YawLogic::YAW_ANGLE,
  FlightController::HorizontalCoordinate::HORIZONTAL_GROUND,
  FlightController::StableMode::STABLE_ENABLE,
};
vehicle->flightController->setJoystickMode(joystickMode);

while (elapsedTimeInMs <timeoutInMilSec) {

Limited flying range
...

/* Set Joystick control instruction */
FlightController :: JoystickCommand joystickCommand = {
                    positionCommand.x, positionCommand.y,
                    offsetDesired.z + originHeightBaseHomepoint, yawDesiredInDeg};
vehicle-> flightController-> setJoystickCommand (joystickCommand);

/* Execute the Joystick function */
vehicle-> flightController-> joystickAction ();
...
Threshold for judging whether the drone has entered the set position
                                         }