Concluding Remarks - Human Motion Simulation: Predictive Dynamics - page 238

Here are some examples of cases where PD has been effectively used to pre-
dict cause and effect and to provide valuable insight into the design and perfor-
mance of equipment.

￿ Design of a new steering wheel for a vehicle. The torque needed to
accomplish a specific performance response is specified, and the PD
formulation can be used to simulate how various humans will perform the
turn. Furthermore, specific avatars can be chosen to emulate a specific
targeted population in terms of anthropometry and strength.
￿ Design of new levers in construction equipment. Predictive dynamics is used
to simulate force reactions at both hands and postural motion as the operator
attempts to exert a certain force on the joystick control.

￿ Simulation of stability while a person is wearing loads. Predictive dynamics

can be used to test the design of equipment that may restrict a person's range
of motion or may add a balanced or unbalanced load, changing their stability.
In PD, the notion of stability was effectively assessed using the ZMP approach
and was then dynamically adapted.

10.2.6 Egress/ingress
Entering and exiting a vehicle, a building, or any other constrained space has
been a challenge to analyze for many years. Consider, for example, a new vehicle
that has its interior ergonomically designed for maximum comfort, but may be
difficult to ingress. The door opens, but the constrained access requires the occu-
pant to assume quite uncomfortable postures, particularly in a dynamic manner,
where the body weight is sustained by the arms holding onto the vehicle's struc-
ture. This swing motion needed to enter the vehicle will result in significant stress
on some joints. This is particularly true in large equipment used for farming, mili-
tary operations, construction, etc.
Predictive dynamics allows for simulating these conditions and trying various
body sizes, weights, and strength capabilities while considering the geometric
design of the vehicle. Several simulations can be done to assess the various diffi-
culties, change the design, and rerun the simulation until a set of solutions is
deemed acceptable.

10.2.7 Unsafe situations
In many situations, humans are sent into harm's way to test a prototype. PD can
be used to mitigate the risk of testing unsafe designs or situations. Consider an
amusement park ride that requires occupants of various anthropometries, weights,
ages, and strengths to be subjected to strenuous dynamics. The prototypes of these
rides typically take several iterations with complete fabrication, using significant
time and resources. They are typically tested with dummies representing humans
until the ride is deemed safe for a first human attempt. There are many other