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Parallax feedback 360° high speed servo arduino

This paper introduces a scheme of controlling servo motor with single chip microcomputer.The scheme has been successfully applied to the color computer printer, which can realize the stable control of the printing process and accurately control the printing position.
   

Servo motor belongs to a class of control motor, divided into dc servo motor and ac servo motor.Because ac servo motor has the advantages of small size, light weight, large torque output, low inertia and good control performance, it is widely used in the automatic control system and automatic detection system as an executive element to convert the control electrical signal into the mechanical rotation of the shaft.Due to the high positioning accuracy of the servo motor, more and more modern position control systems have adopted the ac servo motor as the main part of the position control system, the design of this paper is also used in the position control system of the printer.

 This control system adopts panasonic MSMA082A1C ac servo motor, and realizes the control of the servo motor through the single-chip microcomputer controller.The control mode of servo motor mainly includes position control and speed control. In order to improve the smoothness of driving the nozzle to run, the control mode of speed control is selected to realize the control of servo motor, so as to make use of the s-shaped curve control model of servo motor system to achieve the ideal control effect.System composition block diagram is shown in figure 1, in which the single chip microcomputer controller output to the servo drive control signal, and then by the movements of the servo actuator servo motor as required, at the same time, the controller receives a fixed photoelectric coding on servo motor rotor plate as derived from the rotation of the motor feedback pulse signal, so as to realize the nozzle of the servo motor to drive the detection and control of running position, form a closed-loop control system.In order to realize the accurate control of the printing position, the photoelectric coding disc with resolution of 2000p/ r is selected as the position sensing unit to convert the rotation Angle position of the servo motor into electrical pulse signal, so as to provide the single-chip microcomputer controller with tracking control of the printing position

Parallax feedback 360° high speed servo arduino

This system chooses panasonic MINAS A series full digital ac servo driver MSDA083A1A (its main performance index is: the power supply voltage is three-phase 200V, the rated power of the adaptive motor is 750W, the encoder type is 3000p/ r).The servo driver connector CN I/ F (50 pin) signal serves as the input/output of the external control signal, and the connector CN SIG (20 pin) serves as the connection wire of the servo motor encoder.

At the end of the life of the bearing, the vibration and noise of the motor will increase significantly. When the radial clearance of the bearing reaches the following value, the bearing should be replaced.

Remove the motor, from the shaft extension end or non-extension end of the rotor can be taken out.If it is not necessary to remove the fan, it is more convenient to remove the rotor from the non-axial extension. When the rotor is extracted from the stator, damage to stator windings or insulation should be prevented.

Replace the winding must record the form of the original winding, size and turns, wire gauge, when the loss of these data, should be asked from the manufacturer, change the original design of the winding, often make the motor one or several performance deterioration, or even unable to use.

1. Parallax feedback 360° high speed servo arduino

Parallax feedback 360° high speed servo arduino are widely used in various control systems. They can convert the input voltage signal into the mechanical output of the motor shaft and drag the controlled components to achieve the control purpose.

Servo motor has dc and ac, the earliest servo motor is a general dc motor, in the control accuracy is not high, the use of general dc motor servo motor.In terms of structure, dc servo motor is a low-power dc motor. Its excitation is usually controlled by armature and magnetic field, but it is usually controlled by armature.

Parallax feedback 360° high speed servo arduino

Step motor

Stepper motor is mainly applied in the field of nc machine tool manufacturing. Because stepper motor does not need A/D conversion and can directly convert digital pulse signal into angular displacement, it has been considered as the most ideal execution element of nc machine tool.

In addition to its application in CNC machine tools, stepping motors can also be used in other machines, such as motors in automatic feeder machines, motors in general floppy disk drives, printers and plotters.

3. servo arduino

 servo arduino has the characteristics of low speed and large torque.Generally in the textile industry often used ac torque motor, its working principle and structure and single-phase asynchronous motor the same.

4. Switched reluctance motor

Switched reluctance motor (SRM) is a new type of speed regulating motor with simple and strong structure, low cost and excellent speed regulating performance.

5, brushless dc motor

Brushless dc motor of the mechanical characteristics and adjusting characteristics of the linearity, speed range, long life, maintenance convenient noise, there is no brush caused by a series of problems, so this motor in the control system has a great application.

Parallax feedback 360° high speed servo arduino

6. Dc motor

Dc motor has the advantages of good speed regulation performance, easy starting, can load starting, so the application of dc motor is still very wide, especially after the emergence of thyristor dc power supply.

7. Asynchronous motor

Asynchronous motor has the advantages of simple structure, convenient manufacture, use and maintenance, reliable operation, lower quality and lower cost.Induction motor is widely used in driving machine tools, water pumps, air blower, compressors, lifting winch equipment, mining machinery, light industrial machinery, agricultural and sideline products processing machinery and most of the industrial and agricultural production machinery as well as household appliances and medical equipment.

It is widely used in household appliances, such as fans, refrigerators, air conditioners and vacuum cleaners.[3]

8. Synchronous motor

Synchronous motors are mainly used in large machinery, such as blowers, water pumps, ball mills, compressors, rolling mills, as well as small and micro instruments or as control elements.Among them three-phase synchronous motor is the main body.It can also be used as a tuner to transmit inductive or capacitive reactive power to the grid.

Frequency conversion technology is actually the use of motor control theory, through the so-called frequency converter, the motor control.The motor used for such control is called a variable frequency motor.

Common frequency conversion motor includes: three-phase asynchronous motor, dc brushless motor, ac brushless motor and switched reluctance motor.

Control principle of variable frequency motor

In general, the control strategy of frequency conversion motor is as follows: constant torque control at base speed, constant power control above base speed, weak magnetic control at ultra-high speed range.

Base speed: because the motor will produce a counter electromotive force when running, and the size of the counter electromotive force is usually proportional to the speed.Therefore, when the motor runs to a certain speed, because the size of the reverse electromotive force is the same as the size of the applied voltage, the speed at this time is called the base speed.

Constant torque control: motor at the base speed, constant torque control.At this point, the motor's counter electromotive force E is proportional to the speed of the motor.And the motor output power and the motor torque and speed product is proportional, so the motor power and speed is proportional.

Constant power control: when the motor exceeds the base speed, the reverse electromotive force of the motor is kept basically constant by adjusting the excitation current, so as to improve the speed of the motor.At this point, the output power of the motor is basically constant, but the motor torque and speed decrease in inverse proportion.

Weak magnetic control: when the motor speed exceeds a certain value, the excitation current is quite small and basically cannot be adjusted. At this time, it enters the weak magnetic control stage.

Motor speed regulation and control is one of the basic technologies of various industrial and agricultural machinery, office and minsheng electrical equipment.With the amazing development of power electronic technology and microelectronic technology, the adoption of "special frequency conversion induction motor + frequency converter" ac speed regulation mode is leading a change to replace the traditional speed regulation mode in the speed regulation field with its excellent performance and economy.The Gospel that it brings to all walks of life lies in: make machine automation degree and production efficiency rise greatly, save energy, raise product pass rate and product quality, power system capacity rises accordingly, equipment miniaturization, increase comfortable condition, replace traditional machine speed regulation and dc speed regulation program with very fast speed.

Due to the particularity of variable frequency power supply and the system's demand for high-speed or low-speed operation and dynamic response of rotating speed, the motor as the main body of power has been put forward with strict requirements, which has brought new problems to the motor in electromagnetic, structure and insulation.

Application of variable frequency motor

Variable frequency speed regulation has become the mainstream of the speed regulation scheme, can be widely used in all walks of life stepless transmission.

Parallax feedback 360° high speed servo arduino

Especially with the inverter in the field of industrial control increasingly widespread application, the use of frequency conversion motor is increasingly widespread, it can be said that due to the frequency conversion motor in frequency conversion control than the advantages of ordinary motor, where the frequency conversion is used we are not difficult to see the figure of frequency conversion motor.

The traditional feed drive mode of "rotating motor + ball screw" on the machine tool, due to the limitation of its own structure, is difficult to make a breakthrough in the feed speed, acceleration, fast positioning accuracy and other aspects, has been unable to meet the ultra-high speed cutting, ultra-precision machining on the servo performance of the machine tool feed system put forward higher requirements.Linear motor converts electrical energy directly into linear motion mechanical energy, without any transmission device of intermediate conversion mechanism.It has the advantages of large starting thrust, high transmission stiffness, fast dynamic response, high positioning accuracy and unlimited stroke length.In the feed system of machine tool, the biggest difference between the direct drive of linear motor and the original rotating motor drive is to cancel the mechanical transmission link from the motor to the table (dragging plate) and shorten the length of the feed transmission chain of machine tool to zero, so this transmission mode is also called "zero transmission".It is because of this "zero drive" mode that the performance index and advantages that the original drive mode of rotating motor cannot reach are brought.

1. High-speed response

Because some mechanical transmission parts (such as lead screw, etc.) with large response time constant are directly eliminated in the system, the dynamic response performance of the whole closed-loop control system is greatly improved and the response is extremely sensitive and fast.

2, precision,

The linear drive system eliminates the transmission clearance and error caused by the mechanical mechanism such as the lead screw, and reduces the tracking error caused by the lag of the transmission system during interpolation movement.Through the feedback control of linear position detection, the positioning accuracy of machine tool can be greatly improved.

3, high dynamic stiffness due to "direct drive", to avoid the start, change speed and direction of the intermediate transmission link due to elastic deformation, friction wear and reverse clearance caused by the motion lag phenomenon, but also improve the transmission stiffness.

4. Fast speed and short acceleration and deceleration process

Since the linear motor is mainly used for maglev train (up to 500km/h) at the earliest, it is of course no problem to meet the maximum feed speed (up to 60 ~ 100M/min or higher) of ultra-high-speed cutting in the feed drive of machine tools.Also because of the above mentioned "zero drive" high-speed response, the acceleration and deceleration process is greatly shortened.In order to achieve the start of the instantaneous high speed, high speed operation can be instantaneous quasi-stop.High acceleration can be obtained, generally up to 2 ~ 10g(g=9.8m/s2), while the maximum acceleration of ball screw drive is generally only 0.1 ~ 0.5g.

5. The travel length is not restricted on the guide rail and can be extended indefinitely by series linear motor.

6. The movement is quiet and the noise is low.Because of the elimination of the transmission screw and other parts of the mechanical friction, and the guide rail can be used rolling guide rail or magnetic pad suspension guide (no mechanical contact), the noise will be greatly reduced when the movement.

7. High efficiency.Because there is no intermediate transmission link, the energy loss during mechanical friction is eliminated, and the transmission efficiency is greatly improved.

Parallax feedback 360° high speed servo arduino

The structure of three-phase asynchronous motor is composed of stator, rotor and other accessories.

(1) stator (stationary part)

1. Stator core

Function: part of the magnetic circuit of the motor on which the stator winding is placed.

Structure: the stator core is generally made of 0.35~0.5 mm thick silicon steel sheet with an insulating layer on the surface and superimposed. The internal punching of the core has evenly distributed slots for embedding stator windings.

The slot types of stator core are as follows:

Semi-closed slot: the efficiency and power factor of the motor is higher, but the winding embedding and insulation are more difficult.Generally used in small low voltage motor.Half-opening groove: it can be embedded into the formed winding. It is generally used for large and medium low-voltage motors.The so-called formed winding that is, the winding can be placed in the groove after insulation treatment in advance.

Opening groove: used for embedding forming winding, convenient insulation method, mainly used in high voltage motor.

2. Stator winding

Function: it is the circuit part of the motor, which is fed with three-phase alternating current and generates rotating magnetic field.

Structure: it is connected by three identical windings spaced at an electrical Angle of 120°, each of which is embedded in each slot of the stator according to a certain rule.

The main insulation items of the stator windings are as follows :(guarantee the reliable insulation between the conductive parts of the windings and the core and the reliable insulation between the windings themselves).

1) ground insulation: the insulation between the stator windings as a whole and the stator core.

2) phase insulation: insulation between stator windings of each phase.

3) inter-turn insulation: insulation between turns of each phase stator winding.

Wiring in the motor junction box:

Motor terminal box has a wiring board, six of the three-phase winding thread in two rows, up and down and from left to right are the three most wiring pile arrangement of Numbers for 1 (U1), 2 (V1), 3 (W1), pile bottom three wiring from left to right to arrange the Numbers for 6 (W2), 4 (U2), 5 (V2), the three phase windings into y connection or delta connection.All manufacturing and maintenance should be arranged according to this serial number.

3, stand

Function: the stator core and front and rear end covers are fixed to support the rotor, and play the role of protection and heat dissipation.

Construction: the frame is usually cast iron, large asynchronous motor frame is generally welded into steel plate, the frame of miniature motor is cast aluminum.There are heat dissipation ribs outside the frame of the enclosed motor to increase the heat dissipation area, and there are ventilation holes at both ends of the frame of the protective motor, so that the air inside and outside the motor can be directly convection to facilitate heat dissipation.

(2) rotor (rotating part)

1. Rotor core of three-phase asynchronous motor:

Function: as part of the magnetic circuit of the motor and place the rotor winding in the core slot.

Structure: the material used is the same as the stator, which is made of 0.5 mm thick silicon steel sheet punching and overlaying. The silicon steel sheet has evenly distributed holes in the outer round punching, which is used to place the rotor windings.The stator core is usually used to punch the backward silicon steel inner circle to make the rotor core.Generally, the rotor core of a small asynchronous motor is directly mounted on the rotating shaft, while the rotor core of a large or medium-sized asynchronous motor (the diameter of the rotor is more than 300~ 400mm) is pressed on the rotating shaft with the help of the rotor support.

2. Rotor winding of three-phase asynchronous motor

Function: cutting stator rotating magnetic field produces induction electromotive force and current, and forms electromagnetic torque to make the motor rotate.

Construction: divided into squirrel cage rotor and winding rotor.

1) squirrel cage rotor: the rotor winding is composed of several guide bars inserted into the rotor slot and two circular end rings.If remove the rotor core, the appearance of the entire winding like a squirrel cage, so called cage winding.Small cage motors are made of cast aluminum rotor windings, and copper strips and copper end rings are welded for motors over 100KW.

2) winding rotor: the winding of winding rotor is similar to the stator winding. It is also a symmetrical three-phase winding, generally connected into a star. The three outgoing wires are connected to the three collector rings of the rotating shaft, and then connected to the external circuit through the electric brush.

Features: the structure is more complex, so the winding motor is not as widely used as the squirrel cage motor.But through the collector ring and brush in the rotor winding loop string additional resistance and other components to improve the starting, braking performance and speed regulating performance of the asynchronous motor, so in a certain range of requirements for smooth speed regulating equipment, such as crane, elevator, air compressor, etc.

 

 

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