Alexmos New Firmware Release 2.56B7 – Basecamelectronics

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2.56b7

GUI (Windows, OS X, Linux): SimpleBGC_GUI_2_56b7.zip (8Mb 20.01.2016)
User Manual (English): SimpleBGC_32bit_manual_2_5x_eng.pdf (1Mb 24.12.2015)

New hardware

  • Support of ICM20608 gyroscope+accelerometer sensor.
  • New option “I2C high-speed”. Use it carefully: high-speed mode may cause I2C errors.
  • Support for saving and restoring of calibration data to the IMU’s EEPROM (if present).
  • Support of analog encoder (rotary position sensor) on YAW axis in the regular firmware.
  • New option “Advanced” ? “Order of hardware axes” that supports several configurations besides the standard “Camera – PITCH – ROLL – YAW” configuration.
  • Support of magnetometer sensor (compass) to prevent drift of gyroscope. Can be combined with the frame IMU or the main IMU.

Control algorithms:

  • New setting: “RC” -> “Order of Euler angles” that allows extending the possible trajectories of a camera and the range of working angles.
  • Improved the precision of RC control in the “Follow” mode
  • New option “Follow” – “Apply an offset correction when an axis is not following.”
  • New option “Follow” – “Follow rate inside dead-band” to apply very soft control to keep camera always in the center of the dead-band.

Sensors calibration:

  • Regular calibration of Accelerometer and gyroscope does not discard the results of temperature calibration but improves it.
  • ACC calibration at “normal” Z-top position does not discard the results of 6-point calibration.
  • Magnetometer (compass) calibration was significantly improved:
    • you do not need a GUI connection (allows to calibrate in the field by menu button);
    • an ellipsoid approximation is used;
  • New option to skip gyro calibration if gimbal is not fixed well during startup: it allows to start with fresh calibration for best quality, or to start immediately with the previous calibration.

IMU improvements:

  • Advanced algorithms for correction of mutual drift in both IMUs.
  • “2nd IMU above YAW” position is more reliable now.
  • New option “ACC low-pass filter” that helps to improve the stability of the IMU angles. Under dynamic conditions like motion with short lateral accelerations.

Other functionality:

  • New adjustable variables GYRO_HEADING_CORRECTION and FRAME_HEADING_ANGLE that helps to manually correct YAW axis drift.
  • New option “Advanced” – “Set to the normal position on profile switch”.
  • Better handling of high-speed control from scripts.
  • Improved the range of working angles in 1- and 2-axes systems, making use of 2nd IMU or encoders; all possible 2-axes configurations are supported now.
  • New menu command: “Untwist cables”.
  • New checkbox “Advanced” – “Upside-down PITCH auto-rotation” to turn camera when turning frame upside-down.
  • New option “Follow” – “Use frame IMU, if possible” to use 2nd IMU for the “Follow Mode” control, to make it more reliable.
  • New menu command: “Center YAW axis” to move a camera to the neutral position by YAW.
  • New menu command: “Level Roll, Pitch to the horizon”.
  • New option “Service” – “Blink profile number” – onboard LED will show currently selected profile.
  • Proper handling of “gimbal lock” condition – when YAW and PITCH motor axes are parallel.
  • (GUI) New “Emergency stop” option (stop motors in case of the big rate of I2C errors).
  • (GUI) Serial-over-UDP connection is supported to configure remote devices via a network (WiFi, Ethernet, Internet).
  • Menu button pressed 12 times in series will reset “Serial speed” setting to default value 115200.
  • OuterP, OuterI gain increased 5x times.

Encoder-enabled firmware:

  • Option to emergency stop if the motor angles reported by the encoder differs a lot from the angle reported by the 2nd IMU.
  • Encoder-to-motor gearing ratio can be adjusted.
  • In the case of geared setup, the uncertainty of the motor or the frame angle detection at startup can be removed with the help of 2nd IMU.
  • Option to enable Briefcase position auto-detection on-the-fly when in “Follow” mode: just hold the camera by hand and turn frame 90° degrees.
  • More reliable soft limits; option to enable/disable them for each motor independently.
  • Back-EMF compensation is applied at full battery voltage amplitude. It allows getting the maximum speed from the motor (that is limited by the Kv parameter of a motor) even with the low “POWER” setting.

Serial API

  • CMD_CONTROL command with the extended format allows specifying different control modes for each axis.
  • CMD_AHRS_HELPER command allows accessing internal IMU attitude in DCM form, to use it in the external system or to replace or correct it by the information acquired from the high-grade external IMU.

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