FEETECH Mini Servo FT1117M-FB with Position Feedback

FEETECH Mini Servo FT1117M-FB with Position Feedback - Pololu 3440

The mini servo FT1117M-FB from FEETECH features the same output spline as standard servos, making it compatible with standard-size servo horns. The pinion gear is plastic, but the rest of the gear train consists of all metal gears, allowing this servo to deliver the kind of speed and torque typically associated with larger servos.

This version of the FT1117M miniature servo from FEETECH is specially modified to provide access to the feedback potentiometer through a fourth (green) wire, allowing you to directly measure the position of the output. This extra information enables more complex robotics applications, such as determining when the servo has reached its target, detecting when the output is blocked, or implementing your own higher-level closed-loop position control.

The FT1117M-FB is a specially modified version of FEETECH’s FT1117M miniature-sized servo that provides access to the feedback potentiometer through a fourth (green) wire, which makes it possible to directly measure the output angle. With this extra information, you can determine when the servo has reached its target position (or detect if something is interfering with its ability to get there). This feedback also enables more complex closed-loop control of the servo from your main controller.

Like the FT1117M, the FT1117M-FB works with standard RC servo pulses, providing an operating angle of approximately 120° over a servo pulse range of 900 µs to 2100 µs. The feedback voltage varies linearly over this range by a couple of volts. As with most servos, the pulse range can be expanded to achieve an expanded operating angle, but the limits of this are not specified by FEETECH. (In our tests, we were able to get an expanded range of approximately 165° over a pulse range of 550 µs to 2400 µs, but as this is not part of FEETECH’s official specifications, it is possible different units will behave differently in this regard.)

The servo signal, power, and ground are provided through a 3-wire servo cable that is terminated with a standard JR-style connector, which is Futaba-compatible. The feedback is accessible through a separate green wire that is terminated like our female premium jumper wires and works with standard 0.1″ male header pins. These cables are approximately 7″ (18 cm) long

Key Specs: At 6 V: 0.11 sec/60°, 50 oz-in (3.5 kg-cm), 22 g.

FT1117 Mini Servo Dimensions:

• Size:  30 x 12 x 31.7 mm
• Weight: 22 g

FT1117M Mini Servo General specifications:

Note that, as with most hobby servos, stalling or back-driving this servo can damage it.

Documents:

• Datasheet for FT1117M-FB Mini Servo (pdf)