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| Figure 1. Prismatic Joint Type. |
This joint type can be used in the biomechanical editor to create a musculo-skeletal
model. The prismatic joint is much like the Hinge, since two axes, one fixed in each of the two
constrained bodies, are forced to coincide. However, in this case the bodies are allowed to move
along the axis, not to rotate. Like a hinge, a prismatic joint removes five degrees of freedom from
the relative motion of the attached bodies, leaving only one. The relative orientation of the bodies
is maintained by the joint, which is imagined as a bar with a prismatic section sliding inside a
block with a prismatic hole.
For this joint, a line l0 fixed in body b0 is coincident with a line l1 fixed on body b1 and the
rotation of b1 about l0 is fixed. However, the origin of l1 is not fixed on l0, which allows sliding
along the common axis but no rotation about it. For convenience, the origin of l0 is called the
position of the joint and the common axis of the two lines is the axis of the joint.
This joint type has two constraints, a min and max value. These values determine how far the body can
move along the positive direction of the axis and the negative direction of the axis. These values also determine the
size of the bar that is drawn in the editor.
The prismatic joint also contains a built in motor. You must enable the motor before it can be used. Once you do then
you can control it by setting a velocity for the motor. This can be accomplished using either a
motor velocity stimulus
or direct neural control of the
motor velocity.
General Properties
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| Figure 2. The properties of the prismatic joint. |
To see a description of the properties common to all bodies follow
this link
Hinge Properties
These properties are specific to Prismatic only.
Constraint
The maximum positive or negative velocity that the motor can use to move this part
Default value: 100 m/s
Acceptable range:
The maximum amount a body can move in the positive direction along the axis
Default value: 40 cm
Acceptable range: 0 - infinity
The minimum amount a body can move in the negative direction along the axis.
Default value: -40 cm
Acceptable range: 0 - (-infinity)
Part Properties
Determines whether the motor is on or not. If the motor is on then it will not allow movements until either a neural input or a stimulus tells it
to move by setting its velocity. See how to add a motor velocity stimulus
here, and how to move a motor using a neural network
here.
Default value: False
Acceptable range: True/False
The maximum torque that this motor can apply to obtain a desired velocity of movement
Default value: 100 Nm
Acceptable range: Any value greater than 0.
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