Simulation

The Simulation options let you customize analysis and interpolation for Ergonomics at Work.

This page discusses:

Analyses

Update Ergonomic Analyses in Simulation

Verify to obtain manikin analysis namely, Postural score, RULA, Vision window and, Biomechanics analysis, to update for every time step during simulation. Cancel the selection then the respective analysis deactivates. Example, segment colors for Postural score, RULA, vision window updates, and others at the start of a simulation, even if activated for static analysis.

By default, this check box is cleared.

Interpolation

Linear Interpolation

The Manual Swivel Angle option is the swivel angle between any two postures. This computes manually taking into account the current and next posture as defined in the human task or activity. Selecting the Auto Swivel Angle, the system automatically computes the swivel angle.

Analytical IK for human limbs: The arms and legs of the manikin model as 7 DOF linkages. Each linkage has seven degrees of freedom (DOFs): three in the base joint (for example upper arm), and two in the mid (lower arm) and end joints (wrist) for which an analytical solution proposes. The analytical IK can resolve for 6 DOF in 3D space. But number of DOFs is one more than the constraints imposed by the condition that wrist can reach a 3D location and orientation. The extra (redundant) DOF models as the swivel angle. The swivel angle parametrizes rotation of a mid joint around the axis joining the base segment of the limb to the end segment. This capability helps make the results of IK resolution look more natural by controlling the elbow position. Apart from this, linear interpolation ensures IK repeatability; that is, the solution does not depend on the initial condition or starting position of the arm.

By default, the Manual Swivel Angle is selected.

GOTO Activity

Use postures from Motion Capture for GOTO activity

When selecting any human task that has GOTO activity and run the simulation. This provides walking postures in that simulation bases from a motion capture, which is, recordings of humans during a walk. This creates more natural postures during the walk simulation thus bringing the digital human model closer to the real world.

This table provides a comparison between the STM times, current GOTO activity times and, the GOTO activity time if based on Motion Capture postures. This compares with the STM time for having more than 3-5 steps and does not have any skidding or sliding.

Steps in Walk (paces used in GOTO activity)STM specified time (sec)GOTO time (speed base)Motion Capture based on GOTO time
1-2 steps (2P)1.080.360.4 - 0.6
1-2 steps sideways (3p)1.620.451.4
3-5 steps (4p)2.161.051.6
6-9 steps (7p)3.782.94.0
10-13 steps (11p)5.945.35.2
14-17 steps ---
18-22 steps (21p)11.3410.5810.5
23-28 steps ---
29-34 steps (33p)17.8517.917.9

By default, the Use Postures from Motion Capture for GOTO Activity is not selected.