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Thread: Meet CLYDE

  1. #11
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    Re: Meet CLYDE

    Thanks for the kind words. DB, I made those feet myself. The bottom section is zinc-coated steel channel. The battery holder section is .050 aluminum, bent by my buddy Milt. He also bent the camera box to my specs. Then I drilled everything with 1/2" holes to lighten it. The camera box will get some 1/4" channels milled out later this week. Video to be posted as soon as I get him wired up.

  2. #12
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    Re: Meet CLYDE

    Shameless bump for recent video!
    "If A is a success in life, then A equals x plus y plus z. Work is x; y is play; and z is keeping your mouth shut."
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  3. #13
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    Unhappy 90% complete

    I have two 7.2V 1200mAh NiCad packs. One is connected to VS1 directly feeding 4 Hitec HSR5990TG servos. The other is run into a MPI 6V regulator which is bypassed at <6.3V incoming,from here into VS2 running 5 Hitec HSC645MG servos. VS1 and VS2 are electrically isolated via removal of jumpers. VL is also on its own fresh 9V alkaline supply and also unjumpered. I am controlling the SSC-32 with bluesmIRf modem which runs fine and stays connected to my laptop and the Visual Sequencer at all times, which is verified by the SSC-32 blinking when sent commands.

    Problem is, I can hold a pose or run a sequence ok very shortly, lets say 3-5min. Then suddenly, either VS1 or VS2 will dump and that bank of servos will go limp. Upon checking the packs, VS1 pack reads 6.4V and VS2 reads 5.6V

    I was expecting more running time than this. Am I crossing a minumum threshold to cause this? I am not sure if moving all servos at once could be causing this either. Could I be pulling too many amps? I have no idea how to check this. I still have a 5v 1A camera and two 3.6V 1.5A motors to add to this mix. I have tried swapping these old packs for some brand new 7.2 NiMH 3600mAh packs to no avail. One pack even read 7.4V after going slack!

    Many people have built LM Scouts using 12 5990tgs before, so where am I going wrong? Please help, my participation in RoboGames is riding on this!



  4. #14
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    Re: Meet CLYDE

    Are any of the servos getting hot? You should check your current with an Ammeter. I believe the 5990 servos can pull 5A each stalled. I'm not sure about the 645's. I think you are pulling a heck of a lot more current than you are expecting.

    You could conceivably be pulling 20A with the servos. 1200mA / 20 A = .06 = 3.6 minutes battery life. Plus NiCAD's suck. Are you competing this weekend? Are those standard size RC batteries?
    "If A is a success in life, then A equals x plus y plus z. Work is x; y is play; and z is keeping your mouth shut."
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  5. #15
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    Re: Meet CLYDE

    OK...two things that I have heared of people doing, but am not doing currently, though plan to implement in the future.

    1) Run a voltage divider off of your battery. Even if it is just connected to an empty terminal block, you can use that to check the status of your batteries. That way you won't get caught out starting a match with a dead battery.

    2) Run an amp meter between your battteries and your servos. that way you can check the current draw at different points along the way. I am currently running NiCads, and yes...they stink...long recharge times / short battery life. I think I am running the higher capacity NiMh RC car batteries about 4 times the capacity of what you are running...Both of my bots (quads) get about 15 minutes run time. I think you may find that you are just drawing too much current.

    DB
    Last edited by darkback2; 06-10-2009 at 11:07 AM.

  6. #16
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    Re: Meet CLYDE

    Your two NiMH batteries should be in parallel, not isolated. I don't see a point in isolating them. The faster you're discharging your batteries, the less effective they will be, so double those batteries up in parallel to share that discharge load.

    Ditch the NiCad entirely, I'm going to inject a strong opinion here but there is zero point in using NiCads when NiMH are so cheap and widely available. Weight to power is much lower so you're just cripping your robot.

  7. #17
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    Re: Meet CLYDE

    Quote Originally Posted by Tyberius View Post
    Weight to power is much lower so you're just cripping your robot.
    I keep hearing that, but these NiMH packs(Tenergy 7.2V SC3600 Titanium) are almost twice the weight of my my old 7.2V sub-c Nicads. So, the nicads are going in recycle bin, I'm going to heavier wire straight from the pack to my controller, eliminating on/off switches and unneccessary connectors, and speading the load parallel to the controller. BTW, the purpose was to provide the 645's with 6v regulated, as that is their max voltage. According to Jim at Lynxmotion they can take 7.2V in short doses (3-5 min) Getting rid of the regulator should unchoke the amp flow too, I think.

  8. #18
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    Re: Meet CLYDE

    Quote Originally Posted by mannyr7 View Post
    I keep hearing that, but these NiMH packs(Tenergy 7.2V SC3600 Titanium) are almost twice the weight of my my old 7.2V sub-c Nicads. So, the nicads are going in recycle bin, I'm going to heavier wire straight from the pack to my controller, eliminating on/off switches and unneccessary connectors, and speading the load parallel to the controller. BTW, the purpose was to provide the 645's with 6v regulated, as that is their max voltage. According to Jim at Lynxmotion they can take 7.2V in short doses (3-5 min) Getting rid of the regulator should unchoke the amp flow too, I think.
    You said your old NiCD were 1200mAh... these are 3600... big difference, you're adding a lot of capacity, that's gonna weigh a bunch. A 1200mAh NiMH would weigh less than a 1200mAh niCD.

    -Fergs

  9. #19
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    Re: Meet CLYDE

    You're getting 3x the power for 2x the weight? Seems like a reasonably good trade. But if you go with even denser LiPoly, you should double that again.
    I Void Warranties´┐Ż

  10. #20
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    Re: Meet CLYDE

    Ok, running 1 new NiMH pack straight to the ssc-32, VS1=VS2. I saw better performance, the 645's took the extra voltage like champs. Still, after a couple minutes, (five max. I guess, wasn't counting) a lone knee servo (5990TG) stopped responding. Still no overheating from any servos, that's good! Shouldn't this pack be enough to run this mix of 9 servos for at least 15 minutes?

    I see, apples to apples.
    So, replacing my current setup for two 7.4 LiPo's is there any danger of the servos drawing two much current? I've generally heard negative for rough and tumble robotics use. What are the pitfalls in LiPo shopping?
    Last edited by mannyr7; 06-10-2009 at 04:03 PM. Reason: Additional thought

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