Type type servo yang ada dan fakta faktanya .......

[jstnt]

Mungkin dengan ini dapat membantu sedikit tentang servo. Servo secara umum kita mengenal digital dan analog servo. Tapi berdasarkan motor penggeraknya dapat digolongkan menjadi :
1. brushed motor servo
2. Tripole motor servo
3. Coreless motor servo
4. Brushless motor servo

Untuk saat ini yang banyak digunakan adalah coreless servo karena dianggap lebih reliable dan tahan lama, tapi berdasarkan penelitian yang kebetulan saya baca disebutkan kelebihan dari coreless servo adalah akurasi yang lebih baik dan kecepatan servo, jika dilihat perbandingannya tenyata coreless servo lebih efisien hanya 3 % saja dan inipun mengorbankan kemampuan servo karena torsi yang dihasilkan tidak sebesar brushed dan tripole motor servo dan coreless servo tidak tahan panas, karena itulah sekarang muncul brushless motor servo yang saat ini hanya merk futaba saja. Berikut paparan hasil penelitian yang dilakukan pada coreless servo

Coreless Servos
By James Goss

We have heard a lot lately about coreless servos and I thought you might enjoy reading a few facts about them. The coreless servo gets its name because of the dc motor used to drive the gears, it is a coreless dc motor. If you look at the diagram below for the standard motor you can see that it has an iron core that the armature windings are wound on. This core is used because it concentrates the magnetic field generated by the armature windings and prevents the magnetic energy from wondering off. The core does a good job, but it adds a lot of weight to the motor. The coreless motor gets its name because it has no steel core. This allows the armature windings to move at a faster rate because the armature now has less mass to move around. Also while using a core type armature a loss of efficiency occurs in the steel core. This loss is around 3% and is known as eddy current loss. They occur because any time you have a conductor in the presents of a magnetic field with relative motion between them, a current will be generated in the conductor, this is basic generation action. The core is a conductor so it has this unwanted eddy current that lowers the efficiency of the motor. The eddy currents energy is dissipated in the form of heat that adds to the total heat produced by the motor. This is another advantage for the coreless motor; to produce its torque the motor uses more of the power supply energy to develop rotational forces instead of heat.

Instead of being supported by an iron core, the windings are held together in a rigid structure by a thermosetting plastic. Another advantage of the coreless motor is that it can be made smaller and lighter than the conventional dc motor. I think the only disadvantage of the coreless motors is its thermal stability. In the core type motor the big steel core acts as a heat sink for removing heat from the armature windings, with the coreless motor it has no core to help it stay cool. So if the armature windings draw too much current they will quickly over heat. The heat will breakdown the adhesives holding the windings together and the armature will come apart. I know some manufactures such as GWS has went in and installed heat sinks to the motor and brought the heat sink out to the surface of the case where they furnish another large heat sink that you clamp over the servo case. So just remember that coreless servos can't withstand heat like the conventional servos can.

If you look at the diagram for the coreless motor you will see that the armature windings rotate around the magnet instead of rotating inside the magnet as they do in the older servo. This allows the armature to really accelerate fast and likewise it can stop fast as well. This helps give your servo arm a nice crisp and clean stop and go action. When you move your control stick on your transmitter and come to a stop, the motor can stop on a dime so to speak. This will be one of the first things you will notice about a coreless servo, it is fast. The coreless motor in our servos are driven be mosfet transistors that are high speed to turn on and off. More than likely they are in an H-bridge arrangement to obtain forward and reverse capability. The coreless servos do cost more but I think they are worth it if you are building that favorite plane you have always wanted to build.

Jika dibaca dari hasil paparan diatas dapat dilihat brushed, tripole motor, dan brushless motor servo lebih tahan banting dibanding coreless servo, tp tingkat akurasinya lebih baik daripada brushed dan tripole motor servo. Mungkin kadang terjadi kemacetan gerak servo pada saat main rc, jika menggunakan coreless servo mungkin hal ini terjadi karena panas. Mungkin jika kita memakai coreless servo sebaiknya dicari yang sanggup menahan load yang besar sehingga jika kita cuma perlu load kurang dari kemampuan servo maka servo akan lebih ringan kerjanya dan akan lebih dingin.

Banyak sekali kata mungkinnya hehehe, artikel ini kebetulan saya baca selagi browsing cuma berniat membagi informasi kepada rekan rekan semuanya. Jika ingin membaca langsung coba klik http://www.fortunecity.com/meltingpot/palau/4/id223.htm

Ada tambahan rekan rekan?

[christoffel]

sedikit tambahan bang ...
motor 3 pole dan coreless itu juga termasuk brushed motor.
yg belum ada diatas adalah motor DC 5 pole.
kalo di Futaba klasifikasinya :
- 3 pole
- 5 pole
- coreless
- brushless

5 pole lebih kuat dan lebih presisi daripada 3 pole.
coreless, cuman menang di akselerasi, karena rotornya lebih ringan dan lengan torsi lebih panjang.
brushless bebas perawatan karena nggak pake brush.