Stepper Motor Achieve Close Loop Control Technology
Stepper motor due to its compact size,low cost,stable operation,are widely used in low-end industry.To achieve full closed loop of stepper motor motion control,is a major problem of the industrial sector.
There are two main problem,uncertainty original and step lost.At present,the use of high-speed photoelectric switch as the origin of the stepping system,the error in the millimeter,so in the field of precise control is unacceptable.In addition,in order to improve the operating accuracy,stepper motor system drive apply with multiple subdivision,and some greater than16,if use in the process of reciprocating,the error is too large.It is unable to adapt to the field of processing.
Therefore,bring forward full-closed-loop control system of stepper motors to meet current needs of motion control field.
1, hardware connection
Hardware connection install the encoder,according to subdivision requirements,use different levels of resolution encoder for real-time feedback.
According to the Z signal of the encoder,identify and calculate the coordinate origin,which is the same as the numerical control system,the precision can reach 2 /encoder resolution*4
3,Step lost control
According to the encoder feedback data,real-time adjust the output pulse,according to step lost to adjust degree,take corresponding
Below is the circuit theory picture:
4,the circuit principle description
Circuit use ultra-large-scale circuit FPGA,input and output can reach the corresponding frequency of megapixel,power 3.3V,the use of 2596 switching power supply,change 24V to 3.3V,it is convenient and practical.Input pulse and feedback pulse 4 times the frequency of quadrature decoding calculation,timely correct the output pulse and frequency.
The circuit has two modes,return to the origin mode and operating mode.When the origin enable switch is positioned,enter to origin
mode;otherwise,enter the operation mode.
In the origin mode,the output pulse is synchronized with the frequency of the input pulse.When touch the origin switch,the output pulse frequency is reduced,and the coordinate origin is identified and calculated based on the Z signal of the encoder.After return to the origin,output signal.This signal and its data are kept in the case of uninterrupted power.
In the operation mode,the output pulse is synchronized with the frequency of the input pulse,and the feedback data is calculated at the same time.If error occurs,it is corrected in time.In addition,the high inertia operation,under acceleration and deceleration settings unreasonable circumstances,may be timely reverse correction.
(1) Input and output corresponding frequency: ≤ 1M;
(2) Pulse synchronization time error: ≤ 10ms; (main delay in the reverse correction,do not consider the reverse correction, ≤ 10us)
(3) Relocation electrical accuracy: ≥2 / encoder resolution × 4 / motor resolution × subdivision)
(4) Relocation of the origin electrical accuracy ≥ 2 / encoder resolution × 4 / motor resolution × subdivision)
(5) Adapt PNP, NPN interface
(6) Adapt to servo pulse control
(7) Adapt to the various encoder interface
Stepping motor motion ontrol Once sovle above problem,the full closed-loop control can be achieved in the case of increasing
the cost a little,no less inferior to the servo system.In particular,its low price,simple control,long life characteristics in some occasions, may be better than the servo system.Now ECON has several models closed loop stepper control system,customer can based on their demand to choose our product: closed loop stepper motor&driver,Canopen closed loop stepper motor&driver,two axis in one closed loop stepper motor controller& motor,four axis in one closed loop stepper driver& motor.