Precision Motion Capture Systems

Motion capture systems have found wide applications in computer-human interface devices. Augmented reality and virtual reality simulators are examples of high technology applications which have been continuously developing from the advent of high performance digital computers. A wide variety of simulators which need accurate measurement of object motion with acceptable computing lag, are being developed every year and surgical simulators which have had an enormous impact on training and evaluating surgery, are recently developed examples.a
Farand Systems has developed the precision motion capture technology using high speed image processing, magnetic field and INS devices both for surgical simulation and for human-machine interface systems.s

Basics of Operation

The system uses 3 or 4 high speed cameras which simultaneously capture images of the objects which are colour marked probes – in surgery simulators – or a number of bright marks – in head tracking systems.z
These images are processed by hardware using the FPGA technology which provides the least possible processing lag. 2D processed data of each camera is then sent to an ARM® microprocessor system which performs highly optimized 3D calculations and sends out position data via a LAN (or optionally USB) connection.z
Output data includes (X, Y, Z) coordinates of the probe(s) – or landmark(s) – plus (Ω, Φ, k) which represent Yaw, Pitch and Roll of the probe with respect to the 3D coordinate system of the motion capture system.z

Probes

In case of surgery simulators, usually needle shaped probes with painted tips are used, enabling the system to distinguish several probes simultaneously. Since such probes have no imaging feature to be used to measure the probe roll around its own axis a uniform magnetic field is produced around the operating region which is detected by the magnetic sensor embedded inside each probe. This way the probe roll is also measured.xc
In head tracking systems, 3 or more landmarks are used on the helmet. These can be infrared LEDs when the device is used in difficult lighting conditions. The landmarks are traced by the high speed cameras and both the position coordinates and Euler angles can be calculated without the need for applying a magnetic field.x

Applications

Surgical Simulators
Augmented Reality
Manipulators
Head Tracking Systems
Flight Simulators
HMI for 3D visualization & Design
In-lab positioning

Features

Precise position measurement, and accuracy better than %0.2
Precise angle measurement better than 1 deg.j
Real time operation
Very low system lag
USB, LAN and RS232 connectivity
Up to 3 color coded probes) 2 probes and one 1 gimbal)
Accurate optical design and positioning for the cameras