The field of research of this paper combines Human Computer Interface, gesture recognition and fingertips tracking. Most gesture recognition algorithms processing color images are unable to locate folded fingers hidden inside hand contour. With use of hand landmarks detection and localization algorithm, processing directional images, the fingertips are tracked whether they are risen or folded inside the hand contour. The capabilities of the method, repeatibility and accuracy, are tested with use of 3 gestures that are recorded on the USB camera. Fingertips are tracked in gestures presenting a linear movement of an open hand, finger folding into fist and clenched fist movement. In conclusion, a discussion of accuracy in application to HCI is presented.

The paper describes a prototype operator panel, which was designed to operate with the S7-200 family of Programmable Logic Controllers (PLC-s) from Siemens. Most of the functionality of the operator panel was implemented in a computer program, which runs on a PC-class computer. The program communicates with a PLC through its communication port configured in the Freeport mode. Two kinds of interface between the PC, and the PLC are supported: wired, and wireless. For wired connection a standard PC/PPI cable supplied by Siemens is used. For wireless connection two communication modules were designed, which operate in the free 433 MHz band. The operator panel program is intuitive, and easy to use. States of PLC inputs and outputs are presented using graphical objects. It is possible to modify states of the outputs, and monitor and edit any variable in the M and V memory in the PLC. The application supports also alarming. The program can be run on any computer with the MS Windows operating system installed. This makes the solution very cost-effective. Providing both wired and wireless communication radically increases flexibility of the proposed solution. The panel can be quickly mounted in areas, where pulling new cables is inconvenient, difficult or expensive.