Planetary Gearhead Motor Servo Project Update!

If you want ugly, just look at the crusty crawlers… :laughing: :laughing: :laughing: :stuck_out_tongue:

Ok,

The first image is the lexan bracket to allow the PC board a place to mount with an SES bolt hole pattern on the tab for versatile mounting. Just a concept. I know the tab my be a little long… :laughing:

http://img234.imageshack.us/img234/8567/lexanbracketlt1.png

The next image is an aluminum bracket design that basically has an additional side with SES bolt holes for mounting anything SES. Jim has stated earlier he would prefer avoiding another bracket due to cost. In any case, it does not hurt to investigate the potential need. Another rough draft to discuss.

http://img234.imageshack.us/img234/8440/motormountseshm5.png

The second aluminum bracket seems to be more appropriate IMO mainly becuase its versitile and as you said can mount anykind of SES bracket as well as a motor. I think this would be a great addition to the SES brackets becuase it isnt a bracket for a specific use. It can be used in other situations. Cudos to you! 8)

Maybe I missed something in the drawings or your notes but how is this supposed to be mounted?

Other than that it looks quite sturdy and compact.

There would be a SES hole pattern in the bottom of the U section, as there is in Jim’s design. Since I was only thinking about how to get heat out of the motor and the servo board FETs, I didn’t get around to putting those holes in. This was a straw-man concept drawing that I had made to see if I could get a dialog started - it was never intended to be a final solution, just a rock target.

Now that I have a handle on the servo board requirements, I have been hoping that I could get real dimensions on Jim’s brackets and maybe come up with a solution that he likes better. I made a request for the dimensions, but so far I have gotten no response.

Cliff

Thats cause the weekend’s Jim’s day off :stuck_out_tongue: :wink:

Joe A,

I don’t know how to break this to you, but nobody that runs their own business, gets the weekend off. :open_mouth:

Cliff

:open_mouth: :open_mouth: :cry:

Jim does, and it’s never been a problem.

By the way, I saw your design on open servo and it looks very cool. Is the dimension of the PC board accurate? I have no idea what the true size of the board is.

I understand it’s a first crack, but once Jim gets you the dimensions of some of the SES brackets, you might want to try to design a one piece bracket and scratch the screw hardware. The screws would only add to the cost and inventory. My design is made to be symmetrical, you can mount the motor left or right using one bracket, and the SES bolt holes are symmetrical as well, allowing flexible mounting. The 90 deg side(s) of the bracket can be used for mounting to other SES brackets or the PC board or a heat sink; simple yet flexible.

http://img452.imageshack.us/img452/5386/ses2ic1.gif

Lynxmotion has a section where you can download SES models rather than wait for Jim to give you dimensions. I’m not sure what formats your software can handle but many of the brackets are in .3dm format. Go here: lynxmotion.com/ViewPage.aspx … e=sesmodel

I honestly think you did a real good job designing that bracket! :smiley:

Thanks Joe! :smiley:

I try to design it to provide multiple possibilities; that’s what Jim is going to want in any design. The goal right now is to allow mounting of both the motor and PC board close together and provide adequate heat dissipation as well.

I think if you could solder the board on directly to the bracket it could be used as one big heatsink. 8)

It’s not quite that simple. First, solder will not stick to aluminum very well. The board would have to be bolted to the bracket with no shorts to the underside also. The heat sink is another question to consider. A small heat sink for the FETs would need to be used.

This Gear Head Servo will have continues motion right? Also, when do you think they will be up for sale?

The gear head servo is limited to the pots rotational limits, so it will not be able to continuously rotate. If an encoder is used, you can get continuous rotation for linear movement applications such as moving a base on a track as an example. That’s about all I know about this.

however using an encoder will eliminate the ability to use it for position feedback to the openservo board, leaving you with just a dc gear motor having a fancy bracket and encoder on it.

you could replace the pot with a multi-turn pot and get 10 full rotations instead of 3/4 of a rotation, which is basically what I suggested for the power servo box in Georgerodr’s other thread about moving the L6 arm on a platform. The rotational axis relative to the mounting plane is different however.

How does the servos in the machines at our work do this? they look like stepper motors but they are servos. Don’t they have some sort of built in encoder? They are extreamly accurate, and they can also go to any location on the board the size of .5mm in micro seconds.

All encoders are not created equal. The most common is the quadrature encoder, it has two outputs that are 90° out of phase. This way you can tell the speed and direction of the shaft movement. This is an incremental encoder. However some encoders have an extra output that can be used as an index. This can provide a way to make the encoder act like an absolute encoder. The really high end robotics like you are describing have absolute encoders. This means the encoder has a unique address for each position in the 360° of rotation at whatever resolution is needed.

Ok so bottom line, can I use this Gear Head servo or not. I need a servo with torque and precision that can have continuous motion and can be controlled with the SSC-32 and the RIOS software. 10 full rotations Eddie are not going to be enough the way I want to mount the servo.

Short answer: No, you can’t