Zenta's review of the Lynxmotion A-Pod

Lynxmotion Legged Robots
1

Hi,

A couple of months ago I got the A-Pod clone from Lynxmotion. :smiley:
Sadly I don’t have much free time for robotics and therefore it took me almost 2 months assembling the robot. But yesterday I was more or less finished with everything.

I tried to follow the assembly guide from a-z. After carefully removing each PVC part from the panel I cleaned them with a mix of alcohol, water and soap. I didn’t add the leg sensor switch. The kit came with REC-01 rubber caps but I liked REC-02 better, they gave a tighter fit.

When assembling the body I did some modifications. Made a similar battery holder like I did on the original A-Pod, for easy battery replacement. Since I’m using a LiPo battery I’ve added a couple of UBEC regulators and a main power fuse.

I also mounted the SSC-32 with the DB9 plug pointing to the abdomen (tail). This was more logic for easier serial connection while calibrating the servos. I’m using two power switches, one main switch and one for servo power. Using the two outer holes for mounting the switches makes it possible to use the serial connector on the SSC-32 board.

When assembling the head I added the FSR sensor to the left gripper (as described in the tutorial). There is one detail in the assembly guide I didn’t understand though; step 7, I didn’t find any plastic spacer. Instead I used a modified part of the Nylon Snap Rivets. I also placed a small pad of soft rubber in the gap between the servo and the gripper just beside the FSR sensor. The soft pad work like a spring making sure the gripper releases the pressure to the sensor. You can barely see the pad in this picture:

Ok, that’s about all I’ve to say when it comes to the mechanical part. Next step; the software.

One detail that is relatively different between the original A-Pod and this one is the coxa. I didn’t realize how much this detail affected the overall performance until I had it on my desk. On the Lynxmotion version the horizontal coxa length is 55mm vs 42mm on the original. I remember other members on this forum pointed this out but I could not imagine the result of this. Anyway, I entered the new leg dimensions into my PEP sheet and found some new values for the init positions that gave a better result. You’ll find the new values in the config file.

Since I reversed the SSC-32 board I added a #ifdef ApodSSCRev. I did use some other pins for the head. You might need to change this to make it fit your own configuration.

[code];[SSC PIN NUMBERS]
#ifdef ApodSSCRev
cAbdomPanPin con P30 ;Abdomen Panorate (tail side to side)
cAbdomTiltPin con P31 ;Abdomen Tilt (tail up and down)

cHeadRotPin con P0 ;Head Rotate
cHeadPanPin con P2 ;Head Panorate (side to side)
cHeadTiltPin con P17 ;Head Tilt (up and down)

cMandRightPin con P1;Right Mandible
cMandLeftPin con P16;Left Mandible

cLFCoxaPin con P3 ;Front Left leg Hip Horizontal
cLFFemurPin con P4 ;Front Left leg Hip Vertical
cLFTibiaPin con P5 ;Front Left leg Knee

cLMCoxaPin con P6 ;Middle Left leg Hip Horizontal
cLMFemurPin con P7 ;Middle Left leg Hip Vertical
cLMTibiaPin con P8 ;Middle Left leg Knee

cLRCoxaPin con P9 ;Rear Left leg Hip Horizontal
cLRFemurPin con P10 ;Rear Left leg Hip Vertical
cLRTibiaPin con P11 ;Rear Left leg Knee

cRFCoxaPin con P18 ;Front Right leg Hip Horizontal
cRFFemurPin con P19 ;Front Right leg Hip Vertical
cRFTibiaPin con P20 ;Front Right leg Knee

cRMCoxaPin con P21 ;Middle Right leg Hip Horizontal
cRMFemurPin con P22 ;Middle Right leg Hip Vertical
cRMTibiaPin con P23 ;Middle Right leg Knee

cRRCoxaPin con P24 ;Rear Right leg Hip Horizontal
cRRFemurPin con P25 ;Rear Right leg Hip Vertical
cRRTibiaPin con P26 ;Rear Right leg Knee
#else[/code]

If you are using the same pin configuration as shown in the assembly guide you simply comment this line in the config file: ApodSSCRev con 1

I did also some other minor changes to the config file like setting the mechanical limit to 100 deg for the femurs. I’ve not measured the other, I believe they are about the same as the original. New updated files:
APod_PS2.zip (26.8 KB)

I think I’ll never be satisfied with the PS2 remote though… So I might put in a XBee module soon.

Some new pictures I took an hour ago:

Can you see the difference in the next two pictures? :wink:

If I ever get time for it I’ll try to make a body cover of 3mm ABS or something…

And finally some members of my robot family. Others are dead (RIP Felix and Oxyopus) and some are not finished or a very different breed… :laughing:

Next on my to do list: MorpHex MK2…

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The last photo has to be my favorite - it’s the Zenta robot family! :smiley:

3

Very cool post. The pic of your robot family is awesome.

4

Looks great. I like the tail cover!

Not satisfied with the PS2 :open_mouth: :laughing:

Kurt

5

Good to see you have returned, and with some very stunning photos too. Just what i like to see.
Nice little review zenta. Interesting to hear what one thinks, especially from its creator. :wink:

Yes more updates on morphex would be awesome. Love that little guy.
You should return to the store you brought the globe from and exclaim to the shop assistant that their products are transforming on their own and you want a refund. Lol

no 'in all honestly only one word needs to be used next to your name. Awesome.

6

Very nice
It is very close to the original as i can see…

Now you need my mini in the last picture… LOLOOOLLOOOLL

http://farm9.staticflickr.com/8437/7988109640_22c6e30fbf_m.jpg

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Thanks guys! :smiley:
I hope this thread can be used to help out customers who are trying this kit. After a second thought I might increase the default body height (triangle) for avoiding the leg lifting issue while turing that has been mentioned before. Also some adjustments to the leg-anticrash function might be required. I’ll update the files later when I’ve got time to play more with it. I’ll probably use Github too.

Well, I’m sorry for my absence from this forum. As usual its the lack of free time that stops me… :unamused:

Glad you liked my little family. Hopefully there will be more.

8

physically, it looks the same, but what about the program? whether using PS2 some features of deductible?

I see the video youtube.com/watch?v=wYoFcPcypoQ

very different, are LM a-pod can walk while moving her head?
and some other features like in this video
youtube.com/watch?v=GDaNkff5Yyg

9

Kåre(Zenta) can better answer this than I can. But the 2nd video is one of his own videos, on his original A-Pod. The software is very similar between the two robots, except I believe he made a few changes to the configuration information as the leg segment lengths are not identical.

However He does not often use the PS2 to control his robots. Instead he uses the DIY remote control, which he later than modified the original joysticks that were on it to add another pot at the top of the joysticks. I believe you can see it in the thread:
viewtopic.php?f=21&t=5447&start=214

In addition to having additional controls over the PS2, the joysticks on our DIY remotes have a much better resolution than the ones on the PS2. There is lots of details in several threads.

Kurt

10

Hi,

Like Kurt said it is the same program with different configuration more suitable the LM A-Pod. But the control file is a little different due to PS2 vs DIY remote functionality. If the PS2 had the same precision the control part would be even more equal. While walking they are equally, they both can do a body X rotation (and head up/down) while walking (right stick up/down). The main difference are in the body rotation section.

11

hi,
ok thanks for respon guys, :smiley:
soo control robots better use DIY remote control,
why LM not sell remote control as made kurte hehehe

12

Hi Kåre,

I’d go with a real R/C control link! Find one made for a Heli, more flexible.
Get 7 or more channels. I like the Futaba although Spektrum and HiTec are popular. One can get a Turnigy quite cheap as well.

Alan KM6VV

13

Yes the Turnigy / Imax / Eurgle 9x, is a great radio.
Just be nice to hook it up to an Arduino and SSC for a hex or quad.
I brought several receivers and they have all been bind to the 9x, so I’m ready. :wink:

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Yep, the Turnigy could turn out to be an interesting RC to use here. However as to not completely hijack this thread, I continued that discussion over on a new thread: viewtopic.php?f=21&t=8459

Kurt

15

More on topic:

I wish that the Lynxmotion/Robotshop people would update the code pointed to by the tutorial with the updated code that Kåre (Zenta) posted in this thread. It has things like correct lengths of different components and the like. Also it has code in it to help keep the legs from running into each other when walking or turning. That way whoever receives this kit for Christmas won’t run into the same issues.

They may first wish to first review it and see if for example if it made sense to update the tutorial to use the orientation that he used to mount the SSC-32 or not and if so make sure the defaults work well on their stock robots…

And would love to see a video.

Thanks,
Kurt

16

Nice robots Zenta! Mind me asking what the name of the red one in the last picture is? Im planning on making a robot too, and id like it to look similar to that. and what material is the red made from? lexan? Thanks, and cool bots!

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Thanks! The red one is the Lynxmotion Phoenix. I’m not sure if the red color version is available any more…

18

Thanks! and im not planning on buying a ready made set anyways. Im making my own design, and i just wondering if the red is made from lexan or from anodized aluminum?

19

Ok, its aluminium.

20

Cool man thanks! If i have any questions while building the robot, you dont mind if i ask you for some help right?