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Overview

Using the "Gimbal Control" function of the OSDK, developers could control the gimbal execute the action according to the logic designed by developer.

Concept

Gimbal Angle

Joint angle and attitude angle

Figure 1 shows the joints of the gimbal. The joint of the gimbal is the motor to drive the payload. This tutorial uses the body coordinate system to describe the joint angle of the gimbal.

Attitude and attitude angle

Figure 2 shows the attitude of the payload, according to the control command, the gimbal could spin the payload to a different position. This tutorial uses the geodetic coordinate system (NED, North East Coordinate System) to describe the attitude angle of the payload, this angle is also called Euler-Angle.

Gimbal Control

Control Method

There are three control methods:

• Absolute Angle Control
  According to the user's command, the gimbal will rotate from the current position to the specified position within a specified time.

• Speed ​​Control
  Users could control the rotation speed of the gimbal.

  NOTE

  • In the Angle Control, the rotation time of the gimbal is limited by the maximum rotation speed and maximum acceleration of the gimbal, and the actual rotation angle is limited by the limit angle of the gimbal.
  • In the Speed Control, the gimbal rotates for 0.5s according to the speed specified by the user. When the gimbal rotates to the limit angle, it will stop.

• Gimbal mode
  The current gimbal control function of OSDK only supports free mode, in this mode, when the drone's attitude changes, the gimbal will not rotate.

Gimbal’s Information

Applications developed based on the OSDK can obtain the current information of the specified Gimbal. For details, please refer to OSDK API Documentation.

Develop With GimbalManager

1. Initialization

Befor using GimbalManager developer need call the class GimbalManagerSyncSample to create the object of the GimbalManager and initialize the gimbal specified.

GimbalManagerSyncSample *g = new GimbalManagerSyncSample(vehicle);
ret = vehicle->gimbalManager->initGimbalModule(PAYLOAD_INDEX_0,
                                                "Sample_gimbal_1");

if (ret != ErrorCode::SysCommonErr::Success)
{
  DERROR("Init Camera module Sample_gimbal_1 failed.");
  ErrorCode::printErrorCodeMsg(ret);
}
ret = vehicle->gimbalManager->initGimbalModule(PAYLOAD_INDEX_1,
                                                "Sample_gimbal_2");

2. Obtain The Information

After initial the GimbalManager developer could obtain the information of the gimbal.

DSTATUS("Current gimbal %d angle (p,r,y) = (%0.2f°, %0.2f°, %0.2f°)", PAYLOAD_INDEX_0,
      g->getGimbalData(PAYLOAD_INDEX_0).pitch,
      g->getGimbalData(PAYLOAD_INDEX_0).roll,
      g->getGimbalData(PAYLOAD_INDEX_0).yaw);

3. Route The Gimbal

Using the interface GimbalManagerSyncSample to control the attitude of the gimbal.

GimbalModule::Rotation rotation;
        rotation.roll = 0.0f;
        rotation.pitch = 25.0f;
        rotation.yaw = 90.0f;
        rotation.rotationMode = 0; 
        rotation.time = 0.5;
        g->rotateSyncSample(PAYLOAD_INDEX_0, rotation);

4. Gimbal Reset

The application developed based on OSDK support reset the pitch and yaw axes of the gimbal.

g->resetSyncSample(PAYLOAD_INDEX_0);