Here come the clones

[i-Bot]

Just saw this:
Specification is sort of weird. low voltages and torque in an RX package and interface ?

http://chigift.en.alibaba.com/product/320824401-200760136/2010_NEW_SR518_Robot_Servo.html

Anyone know any more ?

[billyzelsnack]

I figured that it would take at least another couple of years for this to start. I'm not sure this counts as a real start though. Low speed, low torque, and heavy for the low speed/weight. Seems like they are stuck in the RC world with those voltages. Form factor is interesting though.

I asked for a quote on 10 and 20. I'll post back when I get a response.

Here's the manufacturer..
http://www.springrc.cn/pro_list.asp?newsid=96

[i-Bot]

The SR402 are clones of the Hitec Robonova servos. Apparently with HMI and metal gears ( I sometimes wonder if metal means something else in China though).

Still on ebay they are under 20$ each inc shipping.

[billyzelsnack]

Sample price $49
10 for $430

When thrown into my servo torque to weight ratio chart it does not look too hot..
http://billyzelsnack-robotics.blogspot. ... atios.html

[limor]

I've been in touch with these guys for well over a year.
They weren't able to provide technical documentation for the RX compatible servos till recently and finally now there's something but in Chinese
Curious thing with the Chinese manual, there's half of it dedicated to what seems to be programming the servo firmware using eclipse. That is quite a unique way to say "we didn't copy the firmware from Robotis, we've open-source'ed it..".
I'm not convinced that they are the actual manufacturer (cloner) or a brand that markets some other factory's servos. Or maybe they make the hardware and someone else makes the software.. There's another company called http://robot.up-tech.com that seems more like the engineering company behind these servos. They were somehow involved in Robocup probably supplying the Chinese teams with equipment. They have a download page section with interesting things.
I was wondering when the Chinese will get into the business of hobby/research robotics and spice up this little market

Billy : great table!

[limor]

From UP-Tech's downloadable "CDS55XX Robot Servo Quick Start EN.pdf" comparing to AX12

3.1 CDS55xx special feature
1. Output torque can be limited and controlled by user
2. Acceleration and deceleration can be set by user to get smooth motion
3. The velocity can be feed back at “motor mode”
4. Intelligent I2T current limit enables user to control torque and load current
5. Refresh rate of feedback data can be up to 1KHz
6. available baud rate is 19200，57600，115200，250K，500K, 1M
7. Hardware temperature limit is 80° C, user can not exceed this limit
8. CDS55xx use the following 6 parameters to control PWM algorithm:
a) ACC Acceleration
b) DEC Deceleration
c) P_CW Coefficient of proportionality, CW
d) P_CCW Coefficient of proportionality, CCW
e) Dead_CW Dead band width, CW
f) Dead_CCW Dead band width, CCW
When AX12+ use other 6 parameters: CW Compliance Slope，CCW Compliance Slope，CW Compliance Margin，CCW Compliance Margin，Punch
9. Status LED is currently unavailable in CDS5500/5501.

[billyzelsnack]

The CDS5516 actually looks pretty interesting. Especially at 60% of AX-12 price. I do find it strange that they show numbers for 7.4V when the say it can go up to 14V. Maybe they start to get fragile at higher voltages.

[billyzelsnack]

Curious thing with the Chinese manual, there's half of it dedicated to what seems to be programming the servo firmware using eclipse. That is quite a unique way to say "we didn't copy the firmware from Robotis, we've open-source'ed it..".

I think this is more like the equivalent of programming a CM-5 to talk to the servo, but instead of a CM-5 you use your own AVR.

[siempre.aprendiendo]

I've been in touch with these guys for well over a year.
They weren't able to provide technical documentation for the RX compatible servos till recently and finally now there's something but in Chinese

Well, Google do a pretty good job translating it... (but no images)

[roo]

I've currently got an SR518 for evaluation, but I'm struggling to control it using an Ardiuno board so I can't say if it's any good or not!

[nsted]

I'm using the CDS5500 instead of ax-12, and I like them a lot...they're lower cost, use metal gears, have higher torque apparently, and are packaged in a standard servo case. You can get them from RobotShop.

http://www.robotshop.ca/uptech-cds-5500 ... tible.html

[limor]

Hi nsted and roo, please post any more information, pics, videos etc.

[roo]

i-Bot is helping me make the SR518 work; I don't have a decent RS485 solution at the moment so progress has stalled for now.

Stay tuned though, as a fix is on its way - full write-up and vids etc. to follow!

[UncleBob]

I wonder what protocol it uses. What kind of controller one can connect to. Finally can you program it and read the position like the dynamixel. Daisy chain?

[limor]

I wonder what protocol it uses. What kind of controller one can connect to. Finally can you program it and read the position like the dynamixel. Daisy chain?

Protocol: dynamixel like Robotis
controller: either Atmel based board (need that UART with 1mpbs at 0% error), or FTDI/Profilic/.. serial-usb that can handle 1mbps
program it: if they installed a bootloader. probably yes.
read position: yes (see previous posts on this thread)
daisy chain: yes