Hi,
Yes, I’ve been thinking of something like that.
Actually, I did a little test and it seems like I can simply use standard servos instead! LOL I’ve some cheap MG996R laying around too, and I believe they can do the job very well. If not, I’ll go for the Hitec 645MG.
I just did a little test and I think the MG996R are going to work fine. I just have to make the mandibles again since the low profile servos I used had different dimensions.
everything does to start with…
Test and Test again. at first you thought the “retract servos” worked.!?
Hi Zenta,
I’m sorry to hear that you’ve burned out one servo. I hope the MG996R will do the job. Good luck with remaking the new mandibles.
Looking forward to see some pics… (hint hint 
)
Xan
Thanks Xan, you’ll have to wait for the pics…
Yesterday I made the new mandibles and I also needed to make a new head-plate today.
Late at night yesterday I replaced the mandible servos by simply soldering the existing wires directly to the servo printboard. For some reason the two MG996R servos had a little different board layout, and that combined with a very tired head and eyes 
I managed to solder the + and - wires wrong so they made a short circuit… 
So when I was going to do a little test, I very soon discovered that something was very very wrong. Lucky me I had connected a LiPo monitor beeper, and when turning on the power switch I heard several beeps. Very fast I turned it off again and suddenly I was very awake Knowing that my RC Lipo are capable of delivering over 125 amps continious made me a bit nervous…
Anyway, the end result was a defect switch regulator. And thats it! 
This weekend I’m probably going to mount the head on again and start working with a FSR sensor solution for the mandibles. And hopefully finish the calibration part…
So the lipo kicks back. you have a good relationship there. LOL
keep up the good work cant wait for more pic’s.
Hi,
As I mentioned I’ve been working with the mandibles and I had to do some modifications. The original low profile servos are replaced by standard size servos. Meaning that I had to make a new set of mandibles and also a new head-plate.
In this post I’ll explain how I’ve tried to solve the sensor part for the mandibles. I feel that pictures says more than 1000 words, so therefore I’ll post some pictures with a few comments.
This picture is a little overview of all parts I used for adding sensor to one mandible:
Custom made spacers:
This picture demonstrate how the spacers are going to be mounted to the servo:
And here is a picture of how the mandible are going to be mounted:
Another view:
I’m guessing you’ve already understood the simple principle here
As you can see I’ve also added a soft foamrubber(?) to the mandible to make the grip more solid.
great work. you did them quick. 
the idea is really good. hopefully this will work better for you.
the foam will really help. it will take the pressure off nicely!
really wish i had the chance to make custom parts… 
Hi Zenta,
First of all congratz with this awesome looking robot.
When going through the pictures I saw the one with the closeup of the ballbearing joint.
Do you connect the servo to the ballbearing through the servo backplate?
Jeroen
Thanks! Your reply to this post was even quicker!
Yeah, I hope this will work. I’ve only done some small tests with the FSR…
I think I’ll get a better result by using some large diameter FSR.
Hi Zenta,
Great work on your design! Smart solution with the Force sensor. Are you planning on using one or two of them? Did you already decide on going with analog or digital inputs?
The spacers look very professional! Did you made them at work? I wish I had more then just pc’s at work
Good job!
Xan
Hi Xan,
Thanks!
I’m hoping the design will do the job, I did some more testing and it seem to work very fine. The only thing I’m thinking of is to replace the FSR with a larger one.
I’m only planning to have sensor on one of the mandible, I think that is enough. And I’m gonna use analog A/D to measure the FSR on the BAP, only for the mandible though. For the leg I’m hoping to the same as you did. It is necessary to be able to adjust the mandible force. There is a bit difference in holding an egg or a can of coke or beer
I make most of my parts at work
Hi,
I didn’t finsihed the calibration part this weekend, but the new head and mandible with FSR sensor are done. So I grabbed my camera and took some pictures again.
The abdomen/tail part containing SSC32, BB2 with BAP28, 2x Turnigy switch regulators, power switch for electronic and servos and a switch for serial select between BAP and PC for SSC32. I’m using a 2S 800 mAh LiPo for electronics and a 2S 5100 mAh LiPo for servo powering. Both batteries are monitored by a little Maxtro Battery Monitor that gives you a loud beep when the LiPo’s needs to be charged/changed. I know that this could be solved by letting the BAP doing the monitor, but I wanted a solution that worked when I didn’t use the BAP (only SSC32). I’ve not mounted the RC receiver yet.
To guide all wires to the tail wasn’t an easy task… Total of 25 servos and 7 pair of sensor wires makes alot of spagetti!
Another view:
I’ve not mounted the lower and upper abdomen cover yet, but this picture gives you a little hint:
I made a stand, giving A-pod’s leg full freedom while testing and calibration:
A-pod on the stand:
Some pictures of A-pod:
Here are two pictures of A-pod together with Phoenix for comparing sizes (ah, I forgot to crop the picture…):
Comments are appreciated!
Looks great!
I can not wait to see it walk, although I am not sure I would want to run into it in the dark!
Kurt
Even more impressive. looks great in them animated stances. even comes with its own stand! 8)
likewise… cant wait for vid!! 
Thanks for your comments Kurt and Innerbreed!
I’m looking forward to the walking and moving part myself, but first I’ve to finish the calibration, then working on the code for control of the head, mandible and abdomen.
Take it you will be intergrating their movements into/with the gait.
These would look great in balance mode! definatly give it an organic look.
Yes, something like that! I’ve not everything crystalclear for the code yet. But I’ve figured out the kinematics for the head. I’m looking forward to it though (working with the code), I think its gonna be fun!
Hi Zenta,
I’m shocked again! Great work with the wiring! What do I say, great work on the whole hex!
I guess the green/black wires run to the pressure switches for the legs? Are you using switches or the same analog sensors as I did?
Do you think you can close the abdomen with all the wires?
I also like the upgraded CD-spindle stand
Xan
