Tarsus Model

Cassie Kinematic Model

Rigid Bodies on Cassie

--- Pelvis --- Yaw --- Hip --- Thigh --- Knee --- Shin --- Tarsus --- Toe ---
--- Knee Spring --- Heel Spring --- Toe Output Crank --- Plantar Rod --- Achilles Rod ---

Motors in Cassie

--- Abduction/Yaw Motors --- Hip/Knee Motors --- Toe Motor ---

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Tarsus

Body Properties:

m = 0.782 kg

    |  1125 | -2878 |   -63 |                   
J = | -2878 | 23138 |    36 | kg.mm^2
    |   -63 |    36 | 23947 |

COM = [ 110.5 | -30.6 | -1.3 ] mm

Connects to --> Toe Crank

     | 1 | 0 | 0 |    58 |                   
H1 = | 0 | 1 | 0 |   -34 |
     | 0 | 0 | 1 | 22.75 |                  
     | 0 | 0 | 0 |     1 |

Connects to --> Heel Spring Base

H2 Euler Angles = [ 155.8 | 0.315 | 4.47 ] deg, ZYX
H2 Offset = [ -12.69 | -30.59 | 0.92 ] mm
k = 2000 N-m/rad

Connects to --> Toe

     | 1 | 0 | 0 | 408 |                   
H3 = | 0 | 1 | 0 | -40 |
     | 0 | 0 | 1 |   0 |                  
     | 0 | 0 | 0 |   1 |

Tarsus is 13 degrees from parallel to the thigh for an undeflected heel spring. Spring deflection adds to this constant offset.

R1 is driven by Toe Motor.