46 PRZEGLĄD ELEKTROTECHNICZNY, ISSN 0033-2097, R. 92 NR 4/2016 Diana OLEJNIK, Tomasz CHADY, Paweł Karol FRANKOWSKI Department of Electrical and Computer Engineering, West Pomeranian University of Technology, Szczecin doi:10.15199/48.2016.04.12 Climbing Quadruped Robot for Nondestructive Testing Abstract. This paper presents design, construction and control of a quadruped robot, capable to maneuver on vertical surfaces. A nondestructive system integrated with the robot enables location and tracking of rebars in concrete structures. This paper illustrates robot manipulation in the kinematic approach and practical application of the platform dedicated for nondestructive testing. Streszczenie. W artykule przedstawiono projekt, budowę oraz sterowanie czworonożnym robotem, zdolnym manewrować na powierzchniach pionowych. Nieniszczący system zintegrowany z robotem umożliwia lokalizację i śledzenie prętów w konstrukcjach betonowych. W artykule przedstawiono manipulację robotem w podejściu kinematycznym oraz praktyczne zastosowanie platformy dedykowanej do badań nieniszczących. (Czworonożny robot wspinający się przeznaczony do badań nieniszczących). Keywords: non-destructive testing, reinforced concrete structures, quadruped robot, vacuum technology. Słowa kluczowe: badania nieniszczące, struktury zbrojonego betonu, czworonożny robot, technologia próżniowa. Introduction The purpose of this paper is to present the design, construction and control of the quadruped robot, capable of maneuvering even on vertical surfaces of reinforced concrete structures. The non-destructive system integrated with the robot enables the location and tracking of the rebars in concrete structures. The robot's ability of climbing is assured by the high quality vacuum system. The prototype of the measurement platform is equipped with the ejector pumps and suction cups, which make robot adhesion dependent on the surface roughness. This paper discusses briefly theoretical aspects of robotic manipulation. Also, computer simulations of the robot representation in a reference configuration are presented. In the last section potential of the robot platform for application in non-destructive testing is described. Structure and Control The project of a quadruped robot was prepared using the Autodesk Inventor Professional, 3D design software. Every moving element and actuator can be modelled in a CAD project, thereby the precise designing of the mounting parts and printing them using a 3D printer is possible (Fig. 1, 2). Printed parts are made of thermoplastic polymer Acrylonitrile Butadiene Styrene (ABS) with the print temperature in the range of 210-240ºC. Fig.1. Autodesk Inventor - design software Fig.2. 3D printing using UP Plus 2 To make climbing possible it is necessary to use light and strong actuators. Due to this aspect, the vacuum technique is used. The decentralized system assumes application of four ejector pumps (one per leg) equipped with the suction cups. High friction of the rubber material allows the suction cups to withstand forces, even at rapid accelerations in horizontal directions. Lifting force vertical to the surface is equal to 168 N and lifting force parallel to the surface is 225 N, at vacuum level of 60 kPa. Multistage ejector technology ensures small size of vacuum pumps with higher efficiency than the conventional technology. The pumps can operate within the feed pressure range of 0.4 to 0.6 MPa. Compressed air flow control is performed by the pneumatic electro-valves [1]. Applied solenoid valves operate on 5/2 function. The robot is driven by a Raspberry PI B+ - single-board computer. Motions of the robot legs are carried out by eight digital servos, two per leg. The required number of degrees of freedom is ensured by a 3D printed spherical bearing. Torque of the coreless motor servo is equal to 1,37 Nm, which is highly efficient. The servos are connected to a pulse-width modulation (PWM) driver. A position of electro-valves and servomechanisms are controlled by the Raspberry Pi board. Fig.3. 3D visualization and photography of the Climbing Robot An operating system - Raspbian, is based on the Debian/GNU Linux optimized for the Raspberry Pi hardware. This environment provides a complete graphical user interface and a console mode. Robot programming was done using Python 2 language. Additionally, for calculation and plotting Numpy and Matplotlib packages were utilized. The implemented software allows both manual and automatic robot control through a wireless communication. A major function of the software is the ability to record the measurements for a further analysis. To improve a user control system, three methods of communication with the robot were prepared. The simplest one is based on remote desktop using Virtual Network Computing software and hand control via console mode.