Society A Publish/Subscribe Architecture for Behavior Based Control

Transcription

1 Society A Publish/Subscribe Architecture for Behavior Based Control CPE Senior Projects Hardware Component Lance Hutchinson Department of Computer Science and Engineering University of Nevada, Reno Submitted as part of the Project Design Document for Team One Sebastian Smith, Lance Hutchinson, Ben Damonte, and Jennifer Knowles April 2nd, 2006

2 Contents 1 Purpose 2 2 Introduction 2 3 Robot Computational Hardware Central Processing Unit Serial Communication Robot Sensor Hardware Sonar Arrays Laser Robot Embedded PC 6 6 Robot Actuator Hardware Gripper Motors Network Communication Hardware Wired Ethernet Hardware Wireless Ethernet Hardware Conclusion 9 List of Figures 1 Diagram of Pioneer 3 Robot, Side View Pioneer 3 Robots being assembled Pioneer 3 Expansion Board Pioneer 3 Side View Diagram of Pioneer 3 Serial Port Connectors Diagram of Pioneer 3 Sonar Array Photo of the Laser Enclosure on top of the Pioneer 3 Robot The Pioneer 3 s Gripper The Cisco/Linksys WRT54GL

3 1 Purpose This document is presented for the satisfaction of the hardware requirement portion of the course CPE 426 Senior Projects. This work applies to the project Society: A publish/subscribe architecture for behavior-based control and was compiled by Lance Hutchinson for satisfaction of the hardware component of the senior project necessary for completion of a degree in Computer and Information Engineering. 2 Introduction Society, the main component of this senior project, is an application program interface (API) for programming behavior networks. These behavior networks primarily run on one or more robots. A robot is simply a collection of sensors and actuators, together with the ability to communicate between these components. In order to properly implement and test the Society API, it was necessary to configure and modify robot hardware to meet the specifications of the Society project. These specifications are clearly outlined in the Engineering Specifications document. In short, it is necessary to have a robot that is capable of running a Linux operating system, communicating with its onboard sensors, controlling onboard actuators, and communicating with an IEEE g wireless network. This document outlines the specific hardware involved, namely the ActivMedia Pioneer 3DX robot, as well as the modifications made to the robot. 3 Robot Computational Hardware The Pioneer 3DX robot, produced by ActivMedia Robotics ( com), is the primary robot platform used for development of the Society project. A diagram of the Pioneer 3 is shown in figure 1 on page 3. The Pioneer 3 contains a microcontroller which manages all of the robot s sensors and actuators, as well as a complete PC, used to install a host operating system to execute program code. Below is a description of the primary computational hardware employed on this robot. 3.1 Central Processing Unit The basic hardware components of the robot are based around its MHz Renesas SH2 microprocessor. This processor is a 32-bit Reduced Instruction Set Computer (RISC) processor, and has access to 32 kilobytes of onboard RAM and 128 kilobytes of onboard FLASH memory. Interfaces to the microcontroller are provided through three PCI expansion ports as well as numerous onboard communication ports outlined below. In figure 3 on page 4 you can see one of the expansion boards, along with the system RAM and microcontroller s cooling fan. Figure 4 shows the input/output ports on the robot s side, as well as the sonar arrays on the front of the robot. Also visible is the power distribution board on the top of the robot, to which all the onboard sensor devices are connected for 5V or 12V DC power. 2

4 Figure 1: Diagram of Pioneer 3 Robot, Side View. Figure 2: Pioneer 3 Robots being assembled. 3

5 Figure 3: Pioneer 3 Expansion Board. Figure 4: Pioneer 3 Side View. 4

6 Figure 5: Diagram of Pioneer 3 Serial Port Connectors 3.2 Serial Communication The Pioneer 3 interfaces to devices through five Serial ports employing the RS-232 standard for serial communication. In addition to these five external serial ports, four sonar arrays are directly connected to interal serial ports. Two universal serial bus (USB) ports are also included for serial devices using the USB protocol. The serial ports and attached ribbon cables can be seen at the top of the photograph in figure 5 on page 5. 4 Robot Sensor Hardware 4.1 Sonar Arrays The robot comes with an integrated sonar array, providing full 360-degree acoustic ranging. Multiple sonar transducers are arranged around the robot. A diagram of the front sonar array is show in figure 6 on page Laser Attached to the top of the robot is a SICK model 200 Laser Measurement System (LMS). The laser has a 180-degree scan path and returns values measured in half-degree increments. The laser is accurate within 1cm to up to 30m. The laser has an approximate refresh rate of 60Hz. The laser has a longer range than the sonar arrays and is much more accurate, 5

7 Figure 6: Diagram of Pioneer 3 Sonar Array this making it desirable for obstacle avoidance and detection. You can see SICK 200 LMS in figure 7 on page 7. 5 Robot Embedded PC The Pioneer 3DX includes an integrated PC based off an EBX form-factor motherboard and Mobile Intel Pentium-III processor. The computer hardware includes ATA hard drive, 10/100 Base Ethernet, VGA monitor, PS/2 keyboard and mouse, and both PCMCIA and PC104/PC104+ style expansion card slots. This embedded PC communicates with the robot s microcontroller through an RS-232 serial port. Installed on this embedded PC is the Gentoo distribution of the GNU/Linux operating system. This OS provides us with access to the robot s microcontroller through the Player/Stage driver software sourceforge.net. 6 Robot Actuator Hardware 6.1 Gripper The Pioneer 3DX has a gripper mounted on the front, used for basic grabbing and manipulating of objects directly in front of the robot. It is an electrically controlled gripper, and can be seen in figure 8 on page 8. 6

8 Figure 7: Photo of the Laser Enclosure on top of the Pioneer 3 Robot. 7

9 6.2 Motors Figure 8: The Pioneer 3 s Gripper The robot contains 2 geared, brushed electric motors controlling two drive wheels. Wheel motor encoders provide accurate information about the linear distance travelled. 7 Network Communication Hardware 7.1 Wired Ethernet Hardware The Pioneer 3DX robot includes a wired ethernet port. For our application, we desired to have wireless communication available to communicate with the University s IEEE g wireless network. We are using the Pioneer s ethernet port to attach to a wireless access point, and thus do not have wired ethernet capability. 7.2 Wireless Ethernet Hardware For wireless connectivity, we modified the Pioneer 3 to attach to a Cisco/Linksys WRT54GL wireless router. We have installed OpenWRT firmware, a port of the linux kernel http: // on the routers and configured them to act as wireless bridges. Then we could connect the access point to the Pioneer 3 s wired ethernet port and the access point would connect us to the wireless network. An image of the Cisco/Linksys WRT54GL hardware is shown in figure 9 on page 9. 8

10 Figure 9: The Cisco/Linksys WRT54GL. 8 Conclusion This document has outlined the large hardware component necessary to make the Society senior project a success. From a microcontroller and serial ports, to knowledge of wired and wireless ethernet networks, a significant amount of hardware engineering knowledge and practice was necessary to assemble a robot platform appropriate for implementing a behavior network with society. 9