Exploring rough terrains and hazardous areas is a challenging issue for mobile explorer robotic designs. Wheel or palette type robots are usually used for explorations on flat surfaces because of simplicity of their mechanical, electronic and software implementations. But these robots are not quite applicable on rough terrains. Legged style robots are used to cope with this challenges because of their climbing and movement capabilities. In this study, an eight legged explorer robot (ELER) was mechanically designed and implemented. ELER’s goal is to achieve to help search and rescue missions where natural disasters happen or general map exploring tasks. Eight legged design was selected to mimic the spider’s ability of advancing on nearly every terrain and overcoming surrounding obstacles. Multi legged robotic systems are hard to implement because of the mechanics, electronics and software concerns. Therefore, this study is a very good optimization problem and didactic process for the mechatronics projects. Intelligent servo motors were used to simplify the mechanical design and ease the power and signal cabling. These intelligent motors also provide sensory feedback such as voltage, current, power, torque, motor temperature values to the electronic control unit. 24 smart servo motors were used for the mechanical leg movements. There are 3 servo motor for each leg and the motors are placed in a way to imitate the real life spider. Using smart servos enables the cables to go through one servo to another, thus it makes cabling process and servo control from one link easy. HC-06 Bluetooth 2.0 module was used to communicate with the robot. Arduino Mega platform was used to control the mechanical system, the battery system and the Bluetooth communication control system. First, the mechanical body and the leg parts are designed using SolidWorks and kinematic analysis was performed in MATLAB Simulink. Then the parts are printed with using 3D printer. Parts and the motors were assembled together. The cabling between motors, motor controller interface, Arduino Mega, SD card module, LCD module, Bluetooth module and the battery were performed maintaining minimum amount of cables. Software was initially built for each components separately, then integrated in one robust software using Arduino C coding. PC serial channel is used for software uploading, testing and debugging purposes. The basic leg and robot movements are developed using this PC communication interface. For enabling mobile control, a human machine interface (HMI) was built on Android mobile phone by using “MIT App Inventor 2”. The robot three dimensional movement (x, y, z and rotational movements) can be controlled with touch buttons on the screen. Some basic initial robot poses, robot base vertical ascending and descending codes are loaded using simple known robotic patterns. The other complex movements are first build with position teaching with moving the legs like a puppet. Simple human robot cooperative interaction for movement teaching was resulted an easy and effective way of robot movement programming. It is seen that teaching method eases the software development and the result robotic movements are satisfactory. As a result, eight-legged explorer robot electronic control software and human-robot interface software were developed. A simplified mechanical robotic system, efficient electronic system and a control software were implemented successfully.
Anahtar Kelimeler: Explorer robots, Multi legged robot design, Human-robot interface, Smart Servo motor.
|
