Research On The Mine Detecting Serpentine Tracked Robot And Its Key Technologies

With the development of technology, the search and rescue work in the disasters willnot only depend on human beings. The search and rescue robot prevents the injury of therescue people. The study of search and rescue robot that can replace human beings andgo to the disaster places possessing very important realistic meaning. Due to the limitedlevel of technology, the robot cannot finish the entire job by itself. The strategy of mainlydepending on remote control and partly depending on self-guidance is preferred. Underthis strategy, the operator can help the robot to finish the complex and difficult tasks. Andthe robot has some low-level autonomy. First, a serpentine tracked robot for underminesearching was develped. Then some key technologies for realizing its low-levelautonomy were studied. The first was obstacle detecting and self-motion detecting basedon the ultrasonic sensor and onocular vision. The second was location of serpentinetracked robot and the last was the control method and strategy.Facing the highly unstructured environment after disasters, this thesis designed aserpentine tracked robot. This robot is omni tracked and has strong ability to adapt theenvironment. It can keep work and even roll over which would definitely happen whileworking. The robot has four segments. The joint between two segments has yawing andpitching degrees. The design makes the robot have strong motion capability and canclimb high obstacles.This robot is equipped with ultrasonic distance sensors, the visionsensor, attitude sensor, hall sensors and other sensors. The navigation of robot can bebased on these sensors. Considering the structure of the robot, we constructed thedistributed control system based on the CANOpen bus. The MicroCANOpen nodes fordealing with the sensor information were developed and these two nodes were fixed inthe head segment and the tail segment. A monocular system for vision navigation wasdeveloped and studied. The wireless communication nodes and relay nodes based on thetechnology of Zigbee were developed. These nodes can keep reliable communicationwhile the distance is far or there are obstacles. A framework and architecture for controlsystem were also designed. This framework realizes seamless integration of sensor,model, plan, decision and motion. The sensor system for undermine environment wasdeveloped. The system can detect CH4, CO, temperature, dampness and other necessaryenvironment parameters. The high unstructured and unpredictable environment makessome motion of the robot very complex. To design the motions fast and to test thesemotions, a simulation system was set up. By the simulation on this system, we can getthe behavioral characteristics and result rapidly. And the result can offer reference andgist the remote control of the robot. The robot was proven to have good searching ability by experiments.Because of the limition of structure, the monocular vision system was equipted. Thevision sensor provides the richest information about the environment. The visioninformation is indispensable for navigation. Because the environment of rescue is oftendark, the vision sensor is a CCD camera with infrared vision. To resolve the problem ofbig noises in the infrared vision, the preprocessing algorithms based on the Contourlettransformation was studied. This algorithm has good results for image denoising andlight balance. A method of motion estimation based on the hypothesis of flat ground offront downward region is suggested. The method estimates the robot motion by pickingup the strong corners in the region and calculates the optical flow. And this methodprovides another information for location By analyzing the divergent of optical flow,obstacles in the vision can be detected. The obstacles diagram can be set up which willhelp the robot’s strategy of obstacle avoiding.Location is the base of robot navigation. The strap down inertial navigation system(SINS) is set up which can be attitude reference in short time. The stable movementmodel for serpentine tracked robot is set up. A linearization method of track curvatureand deviating angle is suggested based on the analysis of turning modes. Odometer forserpentine tracked robot is proposed based on the previous study. The Kalman filter forinformation fusion between the odometer and SINS is set up. And the UKF for theinformation fusion between the odometer and vision information is proposed too. Thesestudies realize the location of the robot.System level objective autonomy is the base of task level objective autonomy. It isthe necessary condition of partly autonomous navigation. The motions of the robot arerelatively independent function models to get to these targets. The typical motion forserpentine tracked robot is studied. A fuzzy controller for turning direction motion is setup. The wall follow motion and the obstacle avoiding motion are realized. In addition,the simulations or experiments about these typical motions are done.The experimentsystem for the search and rescue robot in coalmine was set up. The search and rescueexperiment in fields were done and this experiment verified the integral performance. Allof the experiments show that the serpentine tracked robot has the special advantage insearch and rescue jobs and verify the methods and algorithms in this thesis.