matlab - Modeling a floor/ground for a walking robot in Simulink -

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i'm trying create simple model of body later controlled. however, running trouble when i'm connecting both legs body.

what have done have built model starting left foot, attached world frame, , torso. ended duplicating 1 of legs , attached again the world frame , torso, closing "loop". however, following error message when trying run simulation.

'untitled/right leg/hip/revolute joint' has degenerate mass distribution on follower side.

i have feeling has fact both legs attached torso and world frame.

if let legs dangle torso attaching torso world frame directly, works. need legs attached "ground/floor"

what correct way model can later actuate joints?

block diagram of bipedal system

visualisation of bipedal system

i believe need 3 connections between robot , floor:

  1. a contact force between left foot , floor

  2. a contact force between right foot , floor

  3. a virtual connection lets specify initial height of torso above floor.

the virtual connection specify initial height above floor done 6-dof joint. doesn't constrain anything, lets specify initial position, orientations, , velocity of torso.

the contact force can done hard stop, recommend @ library on matlab central file exchange:

https://www.mathworks.com/matlabcentral/fileexchange/47417-simscape-multibody-contact-forces-library

this allow model contact between feet , floor, friction enable robot walk. force need face plane contact force.

give try , see think.

--steve


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