Table of Contents
Advertisement
How the Polaris Vicra System Works
3.5
Polaris Vicra System Tools
Do not use a wireless tool whose design does not conform to the Polaris Vicra System's unique geometry
constraints. When a Polaris Vicra System attempts to track more than one wireless tool in the measurement
volume, these unique geometry constraints ensure that they are distinguishable from each other. Reliance on
Warning!
data produced by two indistinguishable tools can lead to inaccurate conclusions. If your application involves
personal safety, these inaccurate conclusions increase the possibility of personal injury.
Tools used with the Polaris Vicra System are wireless, and incorporate either active or passive
markers. The system can track up to six tools at a time. The Position Sensor tracks tools based on
marker geometry, which is specified in the tool definition file for each tool. A tool definition file
must be loaded before the Polaris Vicra System can track its associated tool. For more information
on tool definition files, see
Tools are available from NDI for use with the Polaris Vicra System. Contact NDI for more details.
Tool Characteristics
Tools used with the Polaris Vicra System have the following characteristics:
•
A 5DOF (five degrees of freedom) tool has between three and six markers. All the markers
on a 5DOF tool are collinear. The Polaris Vicra System will report the 3D position and 2D
orientation of a 5DOF tool.
•
A 6DOF (six degrees of freedom) tool has between three and six markers that are not
collinear. The Polaris Vicra System will report the 3D position and 3D orientation of a
6DOF tool.
•
The geometry of each tool must follow the unique geometry constraints. Tools must have
different marker geometries from one another, so the Position Sensor can distinguish
between them. A marker geometry that is the mirror image of another tool's marker
geometry is not considered unique. For more details on unique geometry constraints and
marker geometry, see the "Polaris Tool Design Guide".
•
A multi-faced tool (which is also 6DOF) can have up to six faces, totalling a maximum of
20 markers. Each face on a tool is treated as a separate rigid body which complies with the
following constraints:
•
It has a maximum of eight markers
•
It complies with the unique geometry constraints
•
It has a different marker geometry from the other faces on the tool.
•
Each tool has its own local coordinate system This is defined during the tool
characterization process, and is often dependent on the tool's intended use.
Multi-Faced Tool Tracking
When the Polaris Vicra System is tracking a multi-faced tool, it tracks only one face at a time. The
face being tracked is returned with reply option 0x0002 of the BX and TX commands, and is
reported in NDI ToolBox (see the online help in NDI ToolBox for more details).
30
"Tool Definition File" on page
31.
Polaris Vicra User Guide - Revision 2
Advertisement
Table of Contents
