# Fault Diagnosis of a Reconfigurable Crawling-Rolling Robot Based on Support Vector Machines
## 2 Scorpio Robot: System Overview  
The experiments presented in this paper involve fault diagnostics using SVM. They were performed on Scorpio, a rolling-crawling reconfigurable urban reconnaissance robot. With the increasing number of unique robotic applications in urban reconnaissance missions, a robot that can reconfigure itself to multiple morphologies and realize an extended set of locomotion modes is highly desired. To this end, we looked to nature to extract biological principles that would enable a robot to assume multiple morphologies and significantly extend its locomotion capabilities beyond conventional means. In this work, we develop a novel class of bio-inspired, self-reconfigurable robot deriving inspiration from _Cebrennus rechenbergi_, a species of a huntsman spider. The design is validated in realizing rolling-crawling-climbing locomotion [18; 19; 20; 21]. This spider is found in the desert Erg Chebbi, in southeastern Morocco. This spider can crawl in any direction, like any other spider. In addition to this, when threatened, it can also roll in different directions. This is one of the few species that can roll by creating rapid flip-flop movements using its legs. An interesting characteristic of this spider is that it does not require a slippery or sloped surface to begin the rolling motion. Instead, it can transform itself into a rolling position on level ground and start rolling using its flip-flop movements. Discovery of this spider has also inspired a group of other researchers to develop robotic platforms based on the _Cebrennus rechenbergi_ spider [22]. An extended set of locomotion and behavioral gaits has been synthesized from an exhaustive study of gaits in _Cebrennus Rechenbergi_ spiders. Modeling, simulation, and synthesis were accomplished with real hardware. Our fault diagnostics experiments included nine distinct locomotion gaits, including forward, backward, right-turn, left-turn, curve-left, curve-right, shift-right, shift-left, and rolling locomotion modes. The outer body of the robot is made from Polylactic acid (PLA) plastic used in three-dimensional (3D) printing. The robot has four legs, with each leg containing three servo motors, which provide it with three degrees of freedom to realize crawling and rolling motions. To reduce the weight and size of the robot, a motor with a dimension of 21.5 mm \(\times\) 11.5 mm \(\times\) 21.5 mm and weight of 11.5 g is chosen. In total, the robot consists of 12 JR ES376 servo motors, each requiring a voltage of 4.8 V. A Polulu Maestro servo controller is used to interface the 12 servo motors via a microcontroller, which provides the user with an option to control the motors. Figure 1 presents the Computer Aided Design (CAD) model of our Scorpio robot with actuator details. In addition to the actuators that enable robot locomotion, the platform is also equipped with an IMU sensor and a central microcontroller. The IMU sensor used is a Pololu MinIMU-9 v3 (which contains an L3 GD20H 3-axis gyro), a LSM303D three-axis accelerometer, and a three-axis magnetometer. The IMU sensor provides the rotational and translational data so that the robot can enable the user to detect any anomalies in robot locomotion gait. The specific IMU sensor was chosen due to the smaller footprint and size constraints of the Scorpio platform. An Arduino pro-mini based on ATmega328, which requires about 5 to 12 V, is used as the central microcontroller. The hardware specifications of our Scorpio robot are detailed in Table 1.  
The IMU sensor constantly communicates with the accelerometer and the gyroscope via update messages to the Arduino pro mini microcontroller. The Arduino controller delivers the output control commands to the servo controller through a serial communication protocol. The Pololu Maestro servo controller can control up to 18 servo motors. The robot can be operated by a wireless device equipped with an onboard Bluefruit EZ-Link transceiver. The overall system architecture of the Scorpio robot is shown in Figure 2.