Robotik platformlar için USB tabanlı gerçek zamanlı bir iletişim altyapısı

A typical robot operates by carrying out a sequence of tasks, usually consistingof acquisition of sensory data, interpretation of sensory inputs for makingdecisions, and application of commands on appropriate actuators. Since this cycleinvolves transmission of data among electro-mechanical components of therobot, high quality communication is a fundamental requirement. Besides beingreliable, robust, extensible, and efficient, a high quality communication infrastructureshould satisfy all additional communication requirements that are specific tothe robot it is used within. To give an example, for a rapid moving autonomousrobot with a reactive controller which is intended to be used in time critical situations,a real-time communication infrastructure which guarantees demandedresponse times is required.The Universal Robot Bus (URB) is a distributed communication frameworkbased on the widely used I2C standard, intended to be used specifically withinrapid autonomous robots. Real-time operation guarantees are provided by definingupper bounds in response times. URB facilitates exchange of informationbetween a central controller and distributed sensory and actuator units. Adoptionof a centralized topology by connecting distributed units directly to a centralcontroller creates a bottleneck around the central unit, causing problems in scalability,noise and cabling. In order to overcome this problem, URB is physicallyrealized such that gateways (bridges) are incorporated between the central anddistributed units which offload the work of the central unit and master the underlyingI2C bus. Connection between the central unit and the gateway, the uplinkchannel, can be established using any high bandwidth communication alternativewhich successfully satisfies communication requirements of the system.The main contribution of this thesis is the design and implementation of the URB uplink channel using the well known Universal Serial Bus (USB) protocol.Although true real-time operation is not feasible with USB due to its pollingmechanism, USB frame scheduling of 1ms is acceptable for our application domain.In this thesis, hardware components used in the USB uplink implementationas well as our software implementation are covered in detail. These detailsinclude the firmware running on the gateway, a Linux based device driver and aclient control software that uses a USB library running on central controller, andfinally sub-protocols between the application-driver and driver-firmware layers.The thesis also includes our experiments to estimate the performance of the USBuplink in terms of its roundtrip latency, bandwidth, scalability, robustness, andreliability. Finally, this thesis also serves as a reference on distributed systems,device driver development, Linux kernel programming, communication protocols,USB and its usage in real-time applications.