Turning Your Factory into a Metrology Lab
With the exception of iGPS, all mainstream large volume metrology systems today place the “sensing” technology within or near the source instrument itself.
Laser trackers, photogrammetry, optical CMM’s all use either active or passive targets placed on the points of interest and subsequently measure these targets from one or more source instruments. iGPS however does not measure from/at the transmitters but instead reconstructs position information by timing data received at each of the sensors.
This architecture creates many strengths for the iGPS system including;
- a discrete modular design,
- simultaneous “multi-sensor” capability
- accurate measurement of high-speed moving sensors
- native dynamic reference capability
- automatic target acquisition,
- choice of application software packages
- real time network health monitoring, and
- a measurement resolution/accuracy that does not degrade with distance
As a network system, iGPS hardware can be deployed in a modular fashion starting with a single application and growing with each new installation. Any number of applications can be served within a single iGPS calibrated space even in situations requiring completely different requirements.
New systems deployed within line of sight and range of other iGPS networks can leverage/share the existing iGPS infrastructure creating the potential to reduce significantly the cost of new applications. If configured to do so, new systems will also extend and strengthen the measurement volume of adjacent cells.
Multi-Sensor and Multi-User
A single iGPS network can measure 100’s of sensors at the same instant in time. This eliminates uncertainty introduced by measuring parts at different times since parts can move due to external forces, changing ambient temperatures (CTE effects), or instrument alignment errors (leapfrog effects). Simultaneous measurement also allows users to quickly inspect a large number of points/features on a single part either by tooling the points directly (snapshot) or deploying multiple probe devices for parallel measurement processes.
When configured to run in client server mode, multiple 3rd party software applications can simultaneously interface to an iGPS server each running concurrent inspection plans. This means that cycle times can be reduced within the same measuring volume by using multiple probes to inspect a single part, or by running multiple independent processes simultaneously on different parts – all leveraging the same iGPS network.
Dynamic Measurement and Dynamic Reference
In addition to static sensor measurement, the iGPS system is also capable of tracking and measuring sensors moving at speeds up to 25m/s. This allows static, quasi-static, and full motion point (3DOF) and frame (6DOF) tracking throughout the measurement volume.
The multi sensor, multi frame architecture of iGPS allows the system to report points or object positions relative to other objects. In a normal use model the reference system is static (i.e. fixed coordinate system), an alignment is performed transforming from an instrument coordinate system to a part/aircraft coordinate system, and all subsequent measurements are reported relative to the static fitted alignment. If however the configured reference frame moves, proportional error is introduced into the measurement. Using a dynamic reference frame, the iGPS system can be configured so that measurement observations (whether frame or point positions) are reported relative to a moving object and in a time synchronized fashion. During a simple inspection process, this has the advantage of allowing the part to move during the measurement process without impacting its inspection results. For a more complicated adaptive assembly process, part positions can be reported relative to any other coordinate frame (delta from nominal) providing critical data for adapting the assembly process to “as-built” or “off-nominal” interface geometries.
Automatic Target Acquisition and Fully Automated Measurement
The iGPS system uses sensor technology that automatically locks onto any visible transmitter. Sensors will automatically re-acquire occluded transmitters within 1-3 seconds making the system resilient to moving people and objects within the measurement volume. Unlike vision-based systems where blocked sensors must re-emerge within the field of view of the tracking camera, the iGPS autolock capability extends anywhere within the iGPS measurement volume where two or more transmitters are visible.
By directly instrumenting parts or tools with iGPS sensors, fully automated inspection plans can be created and run. Measuring points, tracking parts, and/or providing live position feedback information for other metrology enabled processes/systems can all be done autonomously without requiring operator intervention.
In addition to highly integrated custom applications/GUI’s developed by our integration partners, the iGPS system is also designed to work seamlessly with leading 3rd party software products like Spatial Analyzer, CMM-Manager. This flexibility allows customers to leverage existing training and take advantage of the many capabilities these software tools offer including CAD importers, 3D graphics environments, feature based inspection, scripted measurement plans, and custom reporting.
Real Time Health Monitoring
By continuously measuring static sensors, the iGPS system is able to determine and report the health status of the reference network and the transmitter constellation. This provides live feedback to an operator or control station on equipment status, measurement accuracy, and overall system performance.
Scalable Volumes with Uniform Accuracy
A single iGPS transmitter has a range of 40-60m depending on ambient light conditions. Adding additional transmitters to the network scales the measurement volume and allows any size object to be measured.
Following design principles for triangulation based networks, very large calibrated volumes of space can be configured within which the systems measurement uncertainly is uniform. This makes iGPS an ideal tool for measuring large objects, such as aircraft, using a single metrology system and without having to do multiple setups.