Game Development Reference
In-Depth Information
Table 8.1 Abilities of the users, seated posture, power grip.
Translation
Rotation
Work space
300 to 400mm
± 60 to ± 80
Motor resolution
109 µ m
0.01
Sensory resolution
0.1 to 24 µ m
-
Force
40N
2N · m
Motor resolution
0.4N
-
Sensory resolution
0.0006N
-
Motor Bandwidth
20 Hz
-
Sensory Bandwidth
30 Hz (kinaesthesia)-300 Hz (tactile)
-
Table 8.2 Abilities of the users, placed elbow posture, precision grip.
Translation
Rotation
Work space
150 to 250mm
±
45 to ± 75
Motor resolution
69 µ m
0.01
Sensory resolution
0.1 to 11.2 µ m
-
Force
10N
0.25N · m
Motor resolution
0.1N
-
Sensory resolution
0.0006N
-
Motor Bandwidth
25 Hz
-
Sensory Bandwidth
30 Hz (kinaesthesia)-300 Hz (tactile)
-
8.3.2 Modelling and dimensioning
8.3.2.1 Problem
The dimensioning of a force feedback interface and its optimisation are complex prob-
lems and the results obtained strongly depend on the weight accorded to each criterion
(Vertut & Liégeois, 1981; Hayward et al., 1994; Mathone & Roth, 1997). Generally,
the work space, force capacity, stiffness and apparent mass are the elements to be opti-
mised. The parameters to be optimised that are most frequently taken into account are
structure, geometry and size of the robot (which determine its work space) as well as
the performance of the motors and the reduction ratios introduced on different axes
(which determine its force capacity and its electric stiffness). Some parameters are dis-
creet (for example, the type of motors), while others are continuous (like length of
segments). Before carrying out this optimisation, it is necessary to be able to establish
the problem in mathematical form. For this, it is mainly necessary to be able to model
the behaviour of the robot (geometry, force, stiffness and dynamics).
8.3.2.2 Methods and tools
Modelling of the haptic interfaces : A force feedback interface is a robot operated by
a user. It consists of several interconnected mobile bodies connected by articulations,
which constitute an articulated mechanical chain connecting a fixed base to the robot
gripper grasped by the user. For its modelling, we use notations and tools developed