Results 1 to 4 of 4

Thread: HELP legged robot torque math

  1. #1
    Join Date
    Dec 2018
    Location
    Baker, FL
    Posts
    9
    Images
    5
    Rep Power
    6

    Question HELP legged robot torque math

    I am trying to modify Ferret's Quad Torque spreadsheet to work with hex and octopods. The first problem I am running into when calculating N1 & N2. The numbers I am getting don't look right to me and I am not sure where my mistake is. If I understand the forces/math involved, for a hex N1=2*N2 and an octo should be N1=N2 since you have the same number of legs in contact with the ground on each side.

    I am hoping those of you with more experience can help me figure it out.

    Legged Robot Torques.zip

  2. #2
    Join Date
    Dec 2018
    Location
    Baker, FL
    Posts
    9
    Images
    5
    Rep Power
    6

    Re: HELP legged robot torque math

    I found one of the major errors in my N2 formula for the hex so now if my above logic is correct I'm within 0.5 (N2 high) for the hexapod and 1.96 (N1 high) for the octopod.

    Legged Robot Torques v2.zip
    Last edited by lutinplunder; 03-03-2020 at 08:07 PM.

  3. #3
    Join Date
    Dec 2018
    Location
    Baker, FL
    Posts
    9
    Images
    5
    Rep Power
    6

    Re: HELP legged robot torque math

    Solved the equation for the octopod, I needed to reconfigure equation to be 2*N1=2*N2. I had originally thought that simplifying to N1=N2 would work... odd.

  4. #4
    Join Date
    Dec 2018
    Location
    Baker, FL
    Posts
    9
    Images
    5
    Rep Power
    6

    Re: HELP legged robot torque math

    Still haven't figured out the Hexapod calculation for N2 Here's what I've got so far...

    Calculations extended from those found at the RobotShop website and based on Ferret's original Spreadsheet.

    Leg section masses are taken to be actuator weights plus leg weights
    N1,2: normal (reaction) forces
    L1,2,3,4,5: Lengths of leg sections and half body width
    W1,2,3,4: Weights of actuators at each joint
    M1,2,3,4: Weights of leg segments
    WBody: Weight acting at center of mass
    T1,2,3,4: Torques required at Tars/Tibia, Tibia/Femur, Femur/Coxa, Coxa/Body joints respectively. (+) is counter clockwise, (-) is clockwise

    Wbody = Wcomplete chassis
    WIncline = WTotal(Sin(incline angle))

    N1+2*N2=Wbody+(#LegsUp)(W1+W2+W3+W4+Wn+M1+M2+M3+M4+Mn)

    To simplify and reduce equation lengths;
    L1.cos(a)=A, L2.cos(b)=B, L3.cos(o)=C

    N2=2*(W1+M1)(A+2(B+C+L4+L5))+2*(W2+M2)(A+B+2(C+L4+ L5))+2*(W3+M3)(A+B+C+2(L4+L5))+2*(W4+M4)(A+B+C+L4+ 2 .L5)+(Wbody+(#LegsUp)(W1+Wn+M1+Mn))*(A+B+C+L4+L5)+ (W4+M4)(A+B+C+L4)+(W3+M3)(A+B+C)+(W2+M2)(A+B)+(W1+ M1) A/4(A+B+C+L4+L5)

Thread Information

Users Browsing this Thread

There are currently 2 users browsing this thread. (0 members and 2 guests)

Similar Threads

  1. Four legged or more Hardcore battles?
    By Protaygo in forum Mech Warfare
    Replies: 0
    Last Post: 02-28-2016, 02:03 PM
  2. Question(s) How does one set the torque of the servos for a moving robot
    By Aims Bot in forum Robotics General Discussion
    Replies: 7
    Last Post: 08-06-2014, 03:43 PM
  3. Question(s) Math.h lib with Bioloid CM-530 and C
    By MattD in forum Software and Programming
    Replies: 7
    Last Post: 03-06-2013, 12:15 PM
  4. Contest Entry 3 legged swashbot
    By crabfu in forum Project Showcase
    Replies: 139
    Last Post: 08-15-2009, 12:09 AM
  5. Three Legged Robot
    By Sienna in forum Project Showcase
    Replies: 5
    Last Post: 05-13-2008, 03:06 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •