Trimebutine maleate polyether parylene n 3-chloropropyltriethoxysilane THIOUREA 59572-10-0 Molybdenum disulfide 5089-70-3
Service Tel:+86-755-29370992    中文 | English
Company News Media reports Science and technology innovation
Company News
The difference between simulation and digital servo actuator
The traditional analog servo and digital proportional actuator (or the standardactuator) without MCU micro controller circuit, commonly called simulated rudder.The old analog servo power operational amplifier connected in a Wheatstone bridge, according to the received analog voltage control instructions and a mechanical linkage position sensor (potentiometer) generates the feedback voltageof the differential voltage between the brush DC motor, servo motor / anti runningposition drive. Digital proportional servo actuator is simulated by the best type, DC servo motor controller for DC servo motor, integrated circuit (IC), a gear reduction unit and feedback potentiometer, which is composed of DC servo motor control chip directly receive PWM (pulse Fang Bo, general cycle is 20ms, pulse width 1~2MS, pulse width of 1 ms as the upper limit position, 1.5ms as a lower limit position,2ms) forms of driving control signal, quickly drive motor execution position output,until the DC servo motor control chip to detect linkage position outputpotentiometer sent feedback voltage and the PWM control voltage equal toaverage effective, making driving signal stop the motor, to complete the output position.
Digital servo electronic circuit with MCU microcontroller so called digital servo,digital servo with than simulated rudder has faster response, no reaction zone in small range, high precision, strong anti-interference ability and other advantageshave gradually replace the analog actuator is widely used in robot, model aircraft.
Digital servo design generally has two kinds: one kind is MCU+ DC servo motor +DC servo motor controller integrated circuit (IC) + reduction gear group + feedbackpotentiometer, hereinafter referred to as scheme 1, another is a DC servo motor +MCU+ reduction gear group + feedback potentiometer, hereinafter called thescheme 2. Market with digital analog servo drive plate to digital servo belonging toplan 1.
Two, principle of steering motor drive and how to speed up the motor speed
Common actuator motor is a permanent magnet DC motor, such as DC coreless motor. DC motor with linear speed torque characteristics and torque current characteristic, good controllability, simple drive and control circuit, the drive controlwith current mode control and voltage control two models. Servo motor control is the implementation of the voltage control mode, namely the speed and the applied voltage is proportional to, is driven by four power switching bipolar H bridge circuit driving mode, the pulse width modulation (PWM) technique to adjust the supply DC motor voltage and polarity, the motor speed and direction of rotation (forward / reverse) control. The speed of the motor depends on the size of the average voltage applied to the motor, which depends on the PWM drive waveform duty ratio(duty ratio percentage width / cycle) size, increase the duty ratio, motor speed,reduce the duty ratio motor deceleration.
So to speed up the motor speed: 1, increase the motor voltage; 2, reduce the motor main loop resistance, increase current; two to achieve in steering geardesign, are involved in meet the load torque requirements of steering gear motor re select case.
The reaction rate of three, digital servo why than analog servo quickly
A lot of friends die wrongly think: "PWM 300Hz digital servo drive frequency is 6 times higher than in the 50Hz simulation, the steering gear motor speed 6 times faster, so the reaction speed digital servo is 6 times faster than the analogactuator". Here please note the duty ratio of the pulse width for each cycle concept,the effective level of time, duty ratio percentage width / cycle, so the size andfrequency independent. Duty ratio determines the voltage applied to the motor,when the load torque is constant, decided to motor speed, has nothing to do withthe frequency of PWM.
Simulation of the DC servo motor controller chips generally receive only 50Hzfrequency (20ms) external control signals for the PWM about ~300Hz, too highfrequency will not work. If the external control signals for the PWM 50Hz, is a DC servo motor controller chip to obtain location information of the time resolution is 20ms, PWM voltage control signal and feedback potentiometer voltage is proportional to the business value, the difference between the pulse widthexpansion (duty ratio is changed, change the size proportional Yu Chazhi) to drive a motor action, that is because external control signals for the PWM frequency limits, the fastest 20ms to make new adjustments to the actuator arm position.
Digital servo through MCU can receive frequency than the 50Hz (cycle 20ms) PWMexternal control signal much faster, you can tell the position information of external control signals for the PWM in a shorter time, calculate the duty cycle of PWM signal is proportional to the voltage and the feedback potentiometer voltagedifference, to drive the motor movement, do servos rocker position the new adjustment.
Conclusion: either analog or digital servo, the load torque is constant, the rotation speed of the motor depends on the drive signal duty ratio and frequency independent. External control signals for the PWM digital servo can receive higher frequency, can obtain the position information in a shorter cycle time, do theadjustment to the servo arm position. So the reaction speed digital servo actuatorfaster than simulation, instead of driving the motor speed than the analog servoquickly.
No reaction zone four, digital servo why than analog servo
Based on the above simulation servo analysis simulation servo about 20ms to do a new adjustment. And digital servo to a higher frequency of PWM motor drive.Speed up the PWM frequency of the motor's start / stop, acceleration / decelerationsofter, smoother, more efficient motor torque required to start. Like the automobileobtains smaller throttle control interval, start / stop, acceleration / deceleration performance better. So no reaction zone digital servo than analog servo.
Eight, the steering gear control know dead, hysteresis, positioning accuracy,resolution, back to the input signal in performance
Every closed loop control system due to the oscillations of the signal and other reasons, the input signal and a feedback signal may not be fully equal, which relates to the control dead zone and hysteresis problems, the system cannot distinguish between an input signal and a feedback signal range is controldeadband range. The automatic control system for signal concussion, mechanical precision caused by small scale control system to control the dead outside the scope of the adjustment to make do, steering gear in the small scope does notshock adjustment, it is necessary to introduce the hysteresis effect. Lag link control dead zone, general control deadband range is ± 0.4%, hysteresis can be set to2%, the input signal and the difference between the feedback signal in thehysteresis loop inside the motor does not work, the input signal and the difference between the feedback signal into the hysteresis motor starting, braking andstopping. The overall accuracy of location accuracy depends on the steering system: such as dead zone control, precision, accuracy, feedback potentiometerinput signal resolution. Input signal resolution refers to the steering system to the input signal range minimum resolution, digital actuator input signal resolution is much better than the analog actuator. Back in the performance depends on thehysteresis and positioning accuracy.
Nine, the why old creaks
The old sent back and forth positioning and adjusting sound squeaky, becausesome steering no hysteresis adjustment function, control deadband range small, as long as the input signal and a feedback signal is always fluctuating, their margin beyond the dead time control, servo signal drive motor. Another no hysteresisadjustment function, if the steering gear mechanical precision, diastema, drives the rotation step feedback potentiometer, step range has been beyond the control ofthe actuator will adjust the dead zone, stop stop, squeak.
Ten, why some of the frying machine burning circuit board
Power steering device current some selected Datong system design or chip withover-current protection function, can detect block turned the current and short circuit state quickly stop the motor drive signal. There can be connected in the motor circuit transient voltage sensitive resistor to prevent overvoltage and thepower device is provided with a absorption capacitor. This kind of actuator bombingblockage is not easy to burn the circuit board and motor. And the metal or plasticteeth there is no absolute relationship.
Eleven, why shake rudder actuator
Control dead time sensitive, input signal and a feedback signal for a variety of reasons beyond the scope of fluctuation, difference, rudder arm moving, so shakerudder.
Language Choice
About us
Public relations
Contact us
Copyright © 2005-2014 Shenzhen xq-power Model Electronics Co., Ltd All Rights Reserved.   Tel:+86-755-29370992 , 15013703880 , 13713987348