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AKARIN Servo

Turning 3-phase BLDC motors into high performance torque, velocity and position servo, with an integrated motion trajectory generator.

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AKARIN servo is an open source AC servo solution. It provides high performance torque servo, velocity servo and position servo, with an integrated motion trajectory generator. It is implemented based on Analog Devices' floating point DSP. Multiple AKARIN servo drives can be daisy-chained together to form a motion control array, which can achieve high precision synchronized multi-axis motion control. It is ideal for CNC machines, robotic arms and other applications that require high performance AC servo motion control. The AKARIN servo provides a simple Modbus-RTU interface over RS-485 for real-time commands and a custom protocol for setting up and tuning.

Akarin Servo PCB (Rev. F)

  • Processor: ADSP-21479 floating point DSP
  • Bus voltage(max): 60v
  • Output power(max): 400W
  • Modulation frequency(max): 24000Hz
  • Servo mode: position, velocity, torque
  • Encoder resolution: 14bit
  • Modbus-RTU over RS-485

Features:

  • Motor state estimation using the Kalman filter

A Kalman filter is utilized to estimate the kinematic state of the motor. Smooth velocity estimation is accomplished to achieve high performance velocity control, even at very low speed.

  • Real-time vibration detection and suppression

The hardware FFT accelerator provided by the digital signal processor is utilized to analyze the error signal. Ten IIR notch filters are tuned in real-time based on the FFT result to detect and suppress mechanical vibration.

  • Jerk limited trigonometric velocity profile

A trigonometric velocity profile with jerk limitation is applied in the trajectory generation and interpolation for optimum kinematic performance.

  • Space vector modulation(SVPWM) / Field orientation control(FOC)

The modulation method applied is FOC based on SVPWM.

Multi-axis synchronized motion test
A multi-axis CNC milling machine is built to test the servo drives. It has 6 degrees of freedom - X, Y, Z, A, B and spindle. All axes are driven by AKARIN AC servos. X, Y, Z servos are rated 200W, A axis is rated 125W, B axis is rated 150W and spindle is rated 400W.

In this demonstration, two pencil leads were chucked onto the A axis, a flange with corresponding holes and two screws was installed on the spindle servo. A series of complicated motions were implemented using the AKARIN servos, running at very high speed(up to 3000RPM), without breaking the pencil leads.

High speed arc interpolation

Drawing demo

Adobe Portable Document Format - 893.85 kB - 01/20/2017 at 01:56

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Morten Olsen wrote 03/06/2017 at 19:41 point

I can think of at least 10 projects who can benefit from this. Great job. I'm impressed!! 

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Oskar Weigl wrote 01/17/2017 at 15:08 point

Hi, great work!

Is the hardware design also open source?

Cheers!

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Yuchong Li wrote 01/17/2017 at 17:33 point

Thanks Oskar!

Yes, the hardware design will be open source as well. But I', still tweaking the design. I'll post the design as soon as I finalize the design.

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Oskar Weigl wrote 01/17/2017 at 17:39 point

Cool! Is this reffering to the 1kw design, or Rev. F ?

Why not publish it with a note to describe that it is not finalised? ;D

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Yuchong Li wrote 01/20/2017 at 01:59 point

That's a good idea Oskar, I've posted the design documents for the power board and DSP board.

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Oskar Weigl wrote 01/21/2017 at 15:48 point

Cool! Thanks for sharing ;D

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Boris van Galvin wrote 01/11/2017 at 00:03 point

This would have to be one of the most satisfying demo videos i have seen all week, Totally impressed with the speed !

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Yuchong Li wrote 01/11/2017 at 01:03 point

Thanks!

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