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By Amon Tunwannarux And Supanunt Tunwannarux
THE RESCUE ROBOT HARDWARE CONCEPT
As mentioned in the introduction, this robot is developed to solve the problem of the previous version CEO Mission I robot to have the better victim access ability. In Fig.1, the CEO Mission II is showing how to use the multi-joint mechanical arm to explore the vital signs of a victim in the box which locate in the upstairs. It is faster and easier to sense the vital signs.
Our main design concept is using the simple method but highly effective and reliable. The block diagram of the rescue robot system is shown in Fig. 2. The robotic system design is separated to two parts of functions; those are the controlling and monitoring. All of controlling commands are sent from operator’s computer to robot via Wi-Fi 802.11b. The controlling commands compose of the locomotion control, robot’s device on-off and multi-joint mechanical arm control. While all signals from robot sensors are monitored and sent via Wi-Fi 802.11b. In order to monitor audio and video in real time, another transmitter is required via Wi-Fi 802.11g. So we can get the 30 frames/sec. video rate for 324×248 resolution size. A wireless router 802.11 b/g is used at operator side for communication between operator and robot.
Because controlling function and monitoring function are devided as shown, so hardware on robot is quite simple as shown in Fig. 3. Three CPUs are used separately for each function. They communicate with each other via serial port pin. The CPU1, 40pins, MCS51, is assigned for all data sensing collection such as, 5 distance sensors, left/Right flipper angles, infrared temperature sensor, 2 voltages of batteries, and compass/pitch/roll angle of robot body. The CPU3, 20 pins, MCS51, is used only for counting encoder pulse of left/right robot wheel. All of collecting data is wirelessly sent to the operator side via serial to Wi-Fi module 802.11b. In addition, the CPU1 also handle 4 key pads and 16 x 2 characters LCD display. The display is very useful for robot sensors testing without wireless communication. The CPU2, 40 pins, MCS51, is set up for all equipment control, left/right flipper control and multi-joint mechanical arm control. Because of having 5 PWM signals of servos in mechanical arm and 2 PWM signals of speed control modules in locomotion, a special servo controller CPU is required.
ROBOT MECHANICAL PART
The rescue robot is tracked wheel vehicle. They are relatively lightweight (about 30 kg.) and have a small footprint (approximately 50cm. x 60cm.) They are quite active and fast in unstructured environments and they also perform well on uneven terrain. This hold for tracked vehicles in general ,which can also be seen by their popularity in the RoboCup rescue league, for example in the robots of Team Freiburg, Robhaz, Casualty, IRL and IUB
The track wheel robots which mentioned above are variety designs. Each design has different good points. In this robot, the tracks which use for the locomotion are double tracks (wheel track and flipper track). They are very useful for climbing over the pile of collapse.
A. Body and locomotion driving system
The 3.5 mm. thick aluminum sheet is folded to be the base frame. The locomotion driving system (all motors and gear sets) and the batteries are placed in this frame in order to have the low level center of gravity. Two 24V DC motors are used for driving two front wheels separately. The track driving system with two shafts in same rotating center is designed in order to drive wheel track and flipper track together.
B. Flipper driving system
These flippers are created in order to raise robot body up for better climbing. All driving mechanic are designed to locate at the shaft of front wheel so most of robot weight tends to be at the front. This is very important for climbing up the stairs. Another two 24V DC motors and transmission chains are required for flippers driving as shown in Fig 5.
C. Multi-joint mechanical arm
The mechanical arm does credit to the rescue robot. It helps the robot to explore in many ways such as, from high level, going to narrow space and able to get vital signs of victims easier and faster.
Because the pay load at the tip of arm is small and the arm structure weight is not much, servo motor with gear set still can regulate the joint angle quite well. Resistor potentiometer is installed for each joint angle feedback.
D. Tip of the mechanical arm
This part is the place to install many sensors which are used for searching vital sign of the victims such as an IR temperature sensor, a voice sensor, a distance sensor, and two CCD cameras. It also handles a laser pointer for pointing the measuring location.
About the Author: Amon Tunwannarux and Supanunt Tunwannarux
The University of the Thai Chamber of Commerce(UTCC)
Source:
isnare.com
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