OpenServo.com

andylippitt · Posted: Tue Jan 03, 2006 5:09 pm Post subject: Related Projects

floli mentioned these in another thread:
http://www.tribotix.com/Products/Robotis/Dynamixel/DynamixelIntro.htm

Colin MacKenzie is working on a servo:
http://www.colinmackenzie.net/

The Kondo ""Red Version"" has position feedback:
http://robosavvy.com/KHR1Info/2

Please add any you know of.

mpthompson · Joined: 02 Jan 2006 Posts: 650 Location: San Carlos, CA

I know of the following other than the ones Andy mentioned:

The AI Motor
http://www.megarobotics.com/ai_e01.htm

The I-Servo
http://www.i-servo.com/

-Mike

andylippitt · Posted: Tue Feb 07, 2006 5:12 am Post subject:

HiTEC's new servos that are shipping with the robonova support HMI (hitec multiprotocol) which as best I can tell (can't find any serious documentation) accepts either a standard pwm signal or a 2-way bus supporting a daisychained bus, current, voltage, and position feedback.

andylippitt · Posted: Tue Mar 14, 2006 4:14 pm Post subject:

First bit of info I've seen on HiTec HMI protocol:

http://www.robonova.de/store/down/download/files/anleitung_8498.pdf

Still only a bit. I don't really understand why it's such a big secret.

mpthompson · Joined: 02 Jan 2006 Posts: 650 Location: San Carlos, CA

The HiTech protocol looks a bit klunky. I guess the primary advantage is that it allows standard RC PWM controllers to continue to control the servo while still allowing some type of feedback with more advanced controllers.

If this catches on, it is something that the OpenServo should be able to support if we wish. However, the signal line would need to be routed to a different input on the MCU -- ideally one that can do PWM input without too much software overhead.

-Mike

andylippitt · Posted: Tue Mar 14, 2006 9:55 pm Post subject:

Perhaps that's why it's such a big secret. I we set about supporting another companies protocols, is this a copyright issue?

mpthompson · Joined: 02 Jan 2006 Posts: 650 Location: San Carlos, CA

In todays crazy world of copyright and patent litigation I suppose anything is possible, but I'm fairly certain using public information to reverse engineer a protocol to make a compatible device is still fair game. The major issue would be if there is a patent on using a special PWM pulse to trigger a feedback signal that can be read by a modified RC controller. I wouldn't be surprised if there is a patent on that to force competitors to come up with an alternate method.

In any case, I really like the TWI/I2C bus for sending commands and providing feedback. It's packet oriented and multiple devices can be connected to the same bus. Kinda perfect for what we are doing.

-Mike