This topic is about using the (currently) under development OpenServo V4 to power poppy.
The intention is to offer a much lower cost servo, so that not only does the cost reduce of making poppy, it simplifies poppy by only using a single type of servo.
This servo is USB controlled and uses 2.43mA (vs 100mA for MX-28 / 64) when not moving and has the possibility to drop down to 100nA when in standby to preserve the battery.
A later version may well use USB 3.1 which allows 12v at 5A down the USB cable so only one cable would then be required. But we have to wait for the standards board co confirm the new specification in July.
It is likely to be exactly 153% of the size of a MX-28 servo and initial indications are it will be between 40 & 50 Kg/cm of torque. (i.e. print poppy at 153% scale and just add these new servos, so poppy would now be 128.5 cm tall).
This means that if you print out a version of poppy with only MX28 servos at 153%, you are all ready to go (though the internals of the head will also expand); BUT, ideally the horn size would remain the same, but we may simply scale that up to, it depends on how difficult it is to scale poppy.
Further, this servo has a JTAG debug port and open source RTOS on it so people can expand it and add their own routines, as well as it has a 3D accelerometer, current sensor, temperature sensor, can detect if the motor power is lost and in ASCII mode can be controlled simply via any program (even a terminal emulator) and looks like a standard serial port over USB (i.e. a CDC device) and has been tested on OSX, Linux and Windows.
We are looking at a binary mode where a user can use LIBUSB and Python (as an example) to control the servos and react to various thresholds, for example if the servos detect a freefall or sudden knock, it can interrupt the host and interact in whatever manner is required.
We have built the initial prototypes, and are looking at build the new scaled up prototype that I have mentioned above.
Here is a link http://www.openservo.com/forums/viewtopic.php?t=925&postdays=0&postorder=asc&start=180&sid=61c923ed2426c4dfa844de43901b65035 this shows a prototype before we move to the new case design.
The price is going to be much cheaper than a MX-64 or 28 and runs at 11.1v (i.e. 3S LiPO battery)
I do not have the skills to modify poppy to meet these needs, and may well need to assistance in this area.