[introduction] the use of video monitoring grows continuously, partial reason is all sorts of ” wisdom city ” the artificial intelligence that innovation plans to lead (AI) develops, these plans include pair of communal and street, lane and meeting room to undertake monitoring of intelligence, automation. Wait in environment of old hall of the office, retailing shop, residence, supermarket, museum, construction site, industry and storehouse close area, the security application of video monitoring is increasing also. This kind of extensive use, impose the requirement that AI analyses, mean design personnel to be in contend for improve systematic efficiency and performance while reduce cost even.

The use of video monitoring grows continuously, partial reason is all sorts of ” wisdom city ” the artificial intelligence that innovation plans to lead (AI) develops, these plans include pair of communal and street, lane and meeting room to undertake monitoring of intelligence, automation. Wait in environment of old hall of the office, retailing shop, residence, supermarket, museum, construction site, industry and storehouse close area, the security application of video monitoring is increasing also. This kind of extensive use, impose the requirement that AI analyses, mean design personnel to be in contend for improve systematic efficiency and performance while reduce cost even.

Have the aid of is compact model, of low power comsumption, acute, high resolution into resemble IC, combinative intelligence, accurate motion controls a system, can achieve these improvement for the most part target. Use the element of this kind of method, design personnel can achieve high-energy effect long-range video monitoring, come so, because image faintness or incident happen outside photographing limits of line of sight resembling a head and the situation that needs personnel to visit the spot to examine area or site is less and less.

However, like the applied domain of any constant growth, still all sorts of technology challenges are overcome urgently, and the translation that undertakes photographing resembling a head through using subsystem of high-energy effect electron directly, tilt and scorch (PTZ) , can solve among them a lot of challenges.

The article discussed PTZ the action in monitoring, how does device of electron of electric machinery of the high-energy effect that discussed to be used at controlling PTZ function, nicety, low power comsumption and athletic control become the key of executive video supervisory system. Introduce subsequently and discussed TRINAMIC Motion Control GmbH (it is Analog Devices now, inc. The company below the banner) motion applies related control IC, return meeting introduction to evaluate at the same time board.

Through PTZ athletic control strengthens effective monitoring

No matter be used at how preventing establishment or process monitoring, contemporary video supervisory system is one is in those who secure azimuth to point to target area to photograph merely no longer resemble a head. Contrary, AI can decrease to sign up for by accident and ensure the optimal deploy of resource, what use place more efficiently to capture thereby is video, and the use of dynamoelectric PTZ allows to photograph left and right sides resembling a head to scan (translation) move with fluctuation (tilt) , thereby region of redefine inspect vision area (graph 1) . AI and PTZ conduce to implementation more efficient and general ” more environmental protection ” monitoring means. To PTZ, according to systematic design, motion is OK by photograph component resembling a head to guide independently, control remotely by safe system, OK even and long-range hand moves an operation.

Graph 1: Have the left and right sides translation, fluctuation tilts and adjustable scorch (the monitoring of PTZ) function is photographed formerer than securing like the head the static state is photographed provide flexibility more like the head. (picture origin: Aximmetry Technologies Ltd. )

This kind is mixed through translation tilt will move photographed the practice that resembles a head to overcome use wide-angle lens and wide visual field (the balance difficult position of FOV) (namely, can capture larger area, but mix with sacrificial setting detail introduce curvature distortion to be cost) . PTZ function still conduces to economic how to prevent systematic cost, because one is photographed,can finish a lot of static states to photograph the job that resembles a head like the head.

Photograph the movement that resembles a head to be able to guide through different technique. The monitoring that has PTZ function is photographed still support normally like the head many establish the position beforehand, the user can appoint the place that needs monitoring, and arrive from a position of another position book order and pace to take time. Can realize the long-range monitoring of pair of vast area so, need not user input.

Of electronic parts and PTZ electric machinery match

Although athletic control is the core that PTZ carries out, but the main factor of efficient PTZ system is to pass outstanding electric machinery to control implementation smooth and accurate track. Design personnel can consider to use already without brush dc machine, also can consider to have challenge sex more but often more favorable also situation enters electric machinery, in order to realize high accuracy, and can use the smooth stability with the Trinamic technology of ADI and IC necessary implementation and accuracy.

Operation of low power comsumption is very crucial also. A lot of monitoring that deployed accurate PTZ to control a function are photographed like the head now is power supply of supportive aether net (the equipment of PoE) . Newest PoE standard (the power supply that IEEE 802.3bt-2018) supports join of cable of every aether net to be as high as 100 W.

The design personnel of PTZ system has type of 3 kinds of electric machinery to be able to choose, and the control IC that the type of the choice decided to want to use. The choice includes to have classically brush dc machine, without brush dc machine (BLDC) and pace enter electric machinery (graph 2) .

Graph 2: Electric machinery of 3 kinds of basic dc is classical respectively have brush, without brush and the pace enters electric machinery. (picture origin: Analog Devices)

Configuration of every kinds of electric machinery mixes in function, function management / control demand side has actor of low quality each:

Have the dc electric machinery that brushing dc machine is the earliest development, use already successfully 100 old. Its design is simple, but control hard, the freedom that fits open pattern most runs a condition, and do not suit exact location or go to cease the operation that cease. In addition, the brush that brushs electric machinery can be worn away, put in dependability problem, and the possibility arises not acceptability electromagnetism disturb (EMI) . Although this is planted,electric machinery applies in the public marketplace of low cost (like the toy) in, even a few high end application (like medical treatment transfer pump) in still have use, but to PTZ design, not be feasible choice normally.

BLDC electric machinery (also call electronic inverting or EC electric machinery) very agree with the closed circuit design that carries positional sensor, this kind of design also can be used at speed to control (graph 3) . Its rate is rapid and service life is long, enclose high power density at the same time.

Graph 3: BLDC electric machinery is the most commonly used in closed circuit configuration, in order to ensure fixed position precision and high speed are spent; Installation offers wants feedback to servo controller in the positional sensor on the axis. (picture origin: Analog Devices)

The electrify electricity that needs coil of pair of electric machinery stator to the control of BLDC electric machinery undertakes timing accurately. To raise function and precision, normally use closed circuit feedbacks. For this, can use coder to come inductive rotor position, at the same time induction coil electric current, in order to be used at carrying out magnetic field directional control (the design of FOC) (more sees later development about the introduction of FOC) .

The controller of TMC4671-LA polyphase servo of Trinamic / electric machinery driver is the IC that designs technically in the light of this task, it is strong link of BLDC electric machinery one kind embedded FOC is algorithmic (graph 4) .

Graph 4: The TMC4671-LA servo controller of Trinamic / electric machinery driver, be aimed at design of BLDC electric machinery technically, strong link embedded FOC is algorithmic. (picture origin: Analog Devices)

This parts of an apparatus also can be used at the electric machinery of other type, like electric machinery of permanent magnetism synchronism (PMSM) and two-phase pace take electric machinery, dc chance symphonious circle is sent move implement. Ask an attention, the distinction of BLDC electric machinery and PMSM is, former it is dc (DC) electric machinery, and PMSM is communication (AC) electric machinery. Accordingly, BLDC electric machinery is the dc electric machinery of inverting of a kind of electron, without physical commutator component; Contrary, PMSM is electric machinery of synchronism of a kind of communication, use permanent magnet offers necessary magnetic field drive.

TMC4671-LA uses basic SPI or as small as its controller undertakes UART interface communication. This parts of an apparatus realized the control function of all need and character in hardware respect, still have a mistake at the same time / breakdown state monitors a function. Its include converter of compositive type modulus (interpolation of interface of sensor of ADC) , position, position implement with other and necessary function, make its make the complete controller that applies to all sorts of servo application.

To answer pilot of BLDC electric machinery to challenge, sex of this one function is crucial, because these algorithm are very complex. Fortunately, complex details is in charge of completely handling by IC, so these detail won’t create a burden to designing small controller of engineer or system (graph 5) .

Graph 5: The many links function that TMC4671-LA is included and executes the BLDC that realizes complex, nicety to control functional place to need piece (be like FOC) , make design personnel and lead plane processor to need not execute this mission thereby. (picture origin: Analog Devices)

Its control loop frequency to be 100 KHz, the 20 KHz frequency that compares a lot of BLDC controller is 4 times taller, because this can bring crucial advantage, include faster stabilization period, faster to torque control command response, better position stability, and lower cross voltaic state risk. This kind of risk may damage electric machinery driver or electric machinery.

The pace takes the replacement scheme that electric machinery is BLDC electric machinery. This kind of electric machinery suits to be used at open loop fixed position or speed operation very much, can offer tall torque when low speed and moderate rate (graph 6) . Generally speaking, the pace that function comparatives compares petty gain of BLDC electric machinery into electric machinery, but the operation difficult problem that the pace must solve into electric machinery existence.

Graph 6: Compare with controller of BLDC electric machinery, the pace is mixed to electric machinery driver from lead plane into electric machinery controller the way of electric machinery is more direct. (picture origin: Analog Devices)

Look suddenly under, the signal method flow that the pace receives electric machinery controller compares controller of BLDC electric machinery it seems that a few simpler. Although the in some way is really such, but the demand that accurate and significant step must provide specific function to satisfy this electric machinery into electric machinery controller.

TMC5130A is a high-powered controller that has serial communication interface and driver IC, enter electric machinery design for two-phase pace only. This kind of IC aims to utmost ground decreases or remove relevant issue (graph 7) .

Graph 7: TMC5130A is a high-powered controller and driver IC, deploy serial communication interface, enter electric machinery design for two-phase pace only. (picture origin: Analog Devices)

The pace with the agile brae generator that this parts of an apparatus will use at looking mark locates automatically and advanced height enters electric machinery driver to be united in wedlock. Its still include in-house MOSFET, can provide the coil electricity that is as high as 2 A directly (peak value 2.5 A) , have 256 small steps / the resolution of whole situation.

But, TMC5130A surmounted fundamental condition to take function of electric machinery drive, because it solved a design,personnel uses a few challenges that face when type of this kind of electric machinery in the decision. Two the most apparent with the problem that deserves attention most it is electric machinery the noise that produces when the pace is entered, and electric machinery moves ” smooth sex ” . Although these is in below the environment such as industrial application,the likelihood is not a problem, but use in PTZ monitoring in may disturb, be just the opposite to what one wished even.

To the first challenge, TMC5130A carried out StealthChop, this is the wide modulation of arteries and veins that a proprietary is based on voltage (PWM) behead wave implement, can compare modulation electric current for nothing according to occupying (graph 8) . This function is aimed at in low speed undertook optimizing, can reduce noise considerably.

Graph 8: The StealthChop technology basis in TMC5130A occupies sky comparing to undertake modulation to voltaic drive, reduced a pace to enter the noise of electric machinery considerably. (picture origin: Analog Devices)

To the 2nd challenge, TMC5130A used SpreadCycle, technology of wave of behead of electric current of a kind of proprietary. This kind chased plan of wave of behead of periodic electric current drive to realize the slow attenuation with phasic drive, reduced electric energy loss and torsion wave motion thereby. This technology uses the electric machinery electric current that is based on magnetic hysteresis and mean square of target electric current type, produce the electric machinery electricity of sine wave, although be below high speed,also be such (graph 9) .

Graph 9: The SpreadCycle in TMC5130A chases periodic electric current MOSFET behead wave plan reduced electric energy loss and torsion wave motion. (picture origin: Analog Devices)

The other and distinctive function of TMC5130A includes his stall of StallGuard electric machinery detects and CoolStep trends gets used to voltaic drive oneself, among them latter was used former.

StallGuard is passed oppose electromotive force (EMF) offers the load that does not have sensor to detect, can stop electric machinery inside one synchronization, protect electric machinery driver and electric machinery thereby. Another advantage is, its sensitivity can be adjusted, in order to accord with applied requirement. CoolStep adjusts electric machinery electric current according to turning over the reading of electromotive force StallGuard. Below low laden circumstance, can reduce electric machinery electric current 75% , save electric energy thereby and decrease calorific.

In drive two two-phase pace enters electric machinery and not be when, TMC5072 provided a lot of same functions that support with TMC5130A place (graph 10) . This parts of an apparatus is OK the coil that drive becomes independent twice, the electric current of every coil is as high as 1.1 A (peak value 1.5 A) ; Two driver are OK also and collateral the job, offer 2.2 A for individual coil (peak value 3 A) electric current.

Graph 10: TMC5072 is the double drive version of TMC5130A; Two independent output are OK and collateral use. (picture origin: Analog Devices)

FOC alters an aspect

Still have the positional feedback that a problem is electric machinery. The pace does not need feedback into electric machinery, but often can add feedback in order to ensure high accuracy is controlled, and BLDC design needs feedback. Feedback uses coder commonly (be based on sensor of Huo Er effect or optical coder normally) will come true, but can suffer be confined to to replace rate and resolution, and the processing burden that increases to the system.

To BLDC electric machinery, still have option of another kind of control. Magnetic field is directional control (FOC) (also call vector to control (VC) ) , replace the issue that rate and resolution concern with feedback to solve only, and coder cost is designed with installation problem.

In short, FOC is a kind of electricity that is used at electric machinery adjusts plan, its use magnetic field direction and position of electric machinery rotor to undertake modulatory. FOC is based on ” simple ” observation result, namely action of two component of force is in on the rotor of electric machinery. A component of force, call direct component of force or ID, just pull along radial move; And another component of force, namely orthogonal component of force or IQ, it is to pass tangential pull move will bring to bear on torsion (graph 11) .

Graph 11: The principle of FOC inspiration is to observe rotor gets the action of two orthogonality force, one is the radial load on rotor axis, another is tangential force. (picture origin: Analog Devices) .

Ideal FOC offerred voltaic closed-loop control, the electricity that produces pure torsion to generate thereby (IQ) , and without ID of direct electric current. Next, adjust the intensity of drive electric current, make electric machinery provides target torsion amount. One of numerous character of FOC are, it can enhance power of have rendered great service to the greastest extent and reduce disengaged power to the greastest extent.

The electric machinery that FOC is a kind of high-energy effect controls a method. The job below the condition that this kind of method spends in trends of expensive electric machinery and high speed is good, and because its closed-loop control is characteristic, enhanced immanent safe function. The response of resistor type electric current of FOC use standard will measure the electricity that carries stator coil intensity and phasic, and the angle of rotor. Next, adjust measures rotor point of view magnetism axis to go up. The angle of rotor uses suddenly Er sensor or positional coder is measured reach, can know the magnetic field way of rotor so.

However, reach from FOC observation arrives as a result form complete electric machinery to dominate program, still need an endless and extremely complex course. FOC needs to know parameter of a few static states, the measure that includes electric machinery magnetic pole to be opposite, coder pulse number that every turn, coder is mixed at the direction of rotor magnetism axis relatively the computation direction of coder, and a few dynamic parameter, be like phase current and rotor direction.

In addition, the scale of the two PI controller that is used at phase current closed-loop control and integral (P and I) the adjustment of parameter depends on the electric parameter of electric machinery. These parameter include resistor, inductance, electric machinery turn over electromotive force constant (the torsion that also is electric machinery is invariable) and power source voltage.

The freedom that designing the challenge that personnel faces when applying FOC is all parameter is spent very tall. Although the flow chart of FOC even source code is obtained very easily, but what implementation FOC place needs is actual ” but consign ” code is complex and accurate. Include a variety of coordinate shift among them, if carat overcomes commutation, handkerchief,go against carat to overcome commutation (end is multiplication of a group of matrix) , still include concentrated repetition computation and operation. There is the tutorial of a lot of FOC on the net, from form of qualitative not in the proper way / easy to read and understand tutorial arrives complex mathematical tutorial; The norms book of TMC4671 uprights at among, be worth to look.

Try to realize FOC through firmware, need many CPU computation faculty and resource, choose processor to be able to be restricted somewhat to designing staff accordingly. However, TMC4671 of have the aid of, design personnel is OK from more extensive microprocessor undertake choosing in controller of low even Duan Wei, still can avoid to suspend the encode issue such as processing and direct memory visit at the same time. What what need is to pass its SPI only (or UART) communication port and TMC4671 join, because process designing and software are designed,already simplified to need initialization and setting target parameter only.

Do not forget driver

Although a few electric machinery control IC (if be used at the pace to enter the TMC5130A of electric machinery and TMC5072) compositive the function of driver of electric machinery grid that drive electric current is 2 A about, but other IC (if be used at the TMC4671-LA of BLDC electric machinery) not. To these circumstances, half bridge of such as TMC6100-LA-T the parts of an apparatus such as IC increased grid drive this kind of needs capability (graph 12) . Driver of grid of half bridge MOSFET uses this three-layer the QFN of 7 Mm of 7 × is enclosed, provide the drive electricity that is as high as 1.5 A, suit drive to handle the exterior MOSFET that is as high as electric current of 100 A coil.

Graph 12: Half bridge of TMC6100-LA-T IC offers grid drive the drive electric current that is as high as 1.5 A, suit drive to handle the exterior MOSFET that is as high as electric current of 100 A coil. (picture origin: Analog Devices) .

TMC6100-LA-T has pair of drive electric current to have software pilot function, can make be optimized inside the system to its setting. This parts of an apparatus still includes programmable safety function, detect like short circuit and overheat threshold value; Collocation is used at diagnostic SPI interface, support dovish and reliable design.

Appear on the market to quicken a product further time, convenient optimize parameter and fine tuning driver, trinamic offerred TMC6100-EVAL general evaluate board (graph 13) . Should evaluate board convenient undertake hardware is handled, and match the user evaluates software tool friendlily. This system divides composition by 3: A motherboard, the connector that contains feature of a few tests together board TMC6100-EVAL, adscititious controller of a TMC4671-EVAL FOC.

Graph 13: TMC6100-EVAL is general evaluate board the driver parameter that can simplify to need to match electric machinery and laden circumstance to undertake is optimized and driver fine tuning. (picture origin: Analog Devices)

Summary

Use at monitoring and the video that how prevent to photograph resembling a head is a kind of powerful tool, can decrease to give a demand and relevant the sources of energy to use personally. This kind is photographed use PoE power supply normally like the head, and the PTZ control of drive of electric machinery of have the aid of will enhance a function, but function of this kind of control is very complex. The place before be like is narrated, control an all sorts of needed functions through integrated and efficient electric machinery, use grid driver according to need, the IC of Trinamic is those who be used at PTZ to not have brush and the pace offers smooth and accurate motion and fixed position into dc machine.

Trinamic offerred comprehensive solution for the engineer, can accelerate what efficient, accurate electric machinery controls a system to carry out, in order to satisfy applied requirement. These products settled the challenge of hardware respect, reduced the complexity of integral design and software to the greastest extent thereby.

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