# Transfer Function

I would like to know what are the values ​​and parameters of the Motor ST1 and HT1 to deduce the transfer function to simulate it and study on matlab.
here are the parameters:

• Moment of inertia
• Coefficient of friction
• Electromotive force
• Torque constant
• Electrical resistance
• Electric inductance
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@badreddine Welcome to the RobotShop Community.

If you can provide us with your RobotShop invoice number, we have some of the information (though not all) we can send via email.

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hello,
Here is a copy of my invoice

thanks

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Appreciated. The specs for the HT1 coreless DC motor available from the manufacturer are below. These are the motor alone, without gearbox (1:320 ratio) or electronics.

Motor Constants :

• Terminal resistance: 3 Ohms
• Terminal inductance: 0.65 milli Henry
• Torque constant: 5.12 mNm/A
• Speed constant: 1833.3 rpm/V
• Mechanical Time constant: 15.1ms
• Rotor inertia: 1.32gcm^2

Motor curve:

The general specs for the entire servo motor:

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it’s very kind of you, this is interesting information, but I also want to give me information about ST1…

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We only saw the HT1 as part of your order? The ST1 uses a different motor (cored) with very different properties.

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The servomotor HT1 constitute a DC Motor and a sensor, so I want to know

• The type of sensor is whether an optical or magnetic sensor.

• The resolution of the encoder: it is the number of points or the number of impulses per turn (example: Np = 16 points / turn).

• Angular precision: this is the angle between each pulse that the encoder can measure or we can say the smallest variation in angle Delta θ.

• The frequency of the square signal delivered by the encoder in Hz.

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The type of sensor is whether an optical or magnetic sensor.

360° magnetic absolute encoder.

The resolution of the encoder: it is the number of points or the number of impulses per turn (example: Np = 16 points / turn).

12 Bit. There are no pulses or wave form - it has a serial interface. Users cannot communicate with the encoder directly.

Angular precision: this is the angle between each pulse that the encoder can measure or we can say the smallest variation in angle Delta θ.

Being 12 bit, the encoder can theoretically measure 4096 distinct positions over 360°, therefore the smallest angle would be 0.088°. However, given that there is some play in the gears, the actual angle is closer to 1.1°.

The frequency of the square signal delivered by the encoder in Hz.

There is no square signal from the encoder. The encoder chip reads the magnetic field in order to calculate the angle and sends this value via serial to the microcontroller, which in turn can calculate the speed etc. This is different than an optical encoder or a magnetic encoder you might find at the rear of a geared DC motor.

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