Posture Prediction and Optimization - Human Motion Simulation: Predictive Dynamics - page 61

FIGURE 3.10
Detailed 15-DOF kinematic model of the torso and arm.

3.11 A 15-DOF motion prediction
The current 15-DOF model provides a simple example of optimization-based
motion prediction. Although a higher-DOF model has the potential to improve
results, it is useful to discuss the current model as a starting point and basis for
comparison.

3.11.1 The 15-DOF DenavitHartenberg model
A 15-DOF kinematic chain for the upper torso and right arm was developed using
the DH method ( Figure 3.10 ). This model combines rotational and translational
DOFs to estimate human joint movements. The distances L i between joints define
the transformation matrices of Equation (2.49). These values are considered input
to the motion prediction routine. They can therefore be varied to correspond with
specific anthropometric data. For the purpose of testing, reasonable values of L i
are determined by inspection.
Since the discomfort objective depends on a neutral posture, this 15-DOF
model must have a defined neutral posture q

N

5 f q i

nDOF g . Currently,
the chosen neutral posture is a standing position with the arms at the sides.
The vector q

j 1 i

# #

N

is then defined as q 10 5 q 13 52 0, and q i 5 90 : 0 ; 90 : 0 for all

other i,1 i nDOF. Note that any q i is measured with respect to the posture

# #