Predictive Dynamics: Lifting - Human Motion Simulation: Predictive Dynamics - page 193

Vision
vector

Hands parallel

Collision
avoidance

Hands normal
to box

FIGURE 8.6
Hand-orientation, vision, and collision-avoidance constraints.

initial and final static conditions are new constraints for the lifting problem.
These new constraints are depicted in Figure 8.6 and described as follows.

8.5.3.1 Vision
We shall enforce a vision constraint, which is to align the eye vector, r eye , with
the vision vector, r vision . The vision vector is aligned to the box center. The vision
vector is defined as a vector from the midpoint of the two eyes to the box center.
The eye vector is defined as a vector located at the midpoint of the eyes and nor-
mal to the forehead as shown in Figure 8.7 .

r eye r vision
k r eye kk r vision k

α # θ 5 arccos

# β

(8.20)

where α and β define the vision cone.

8.5.3.2 Hand distance and orientation
Hand distance during the lifting task is a constant defined by the box dimension.
Furthermore, the hand orientation is represented by two vectors: the hand normal
vector, r n , and the hand tangential vector, r t , as depicted in Figure 8.8 .
r n 3

r box 5 0

(8.21)

r t 3 r handle 5 0