The modification is clearly visible due to the number of wires that come out from the servos, namely that the wires are directly connected to the potentiometer output reading pins inside of the servos.                                   (a)                                                                        (b) Fig. 3.4 Hexapod robot OSCAR-2. (a) Experimental robot OSCAR-2 setup - from above; (b) Robot OSCAR-2 in movement.  Fig. 3.5 Pressure sensors type FSR-400. The most right one in the figure is used by OSCAR 2.  Another difference to OSCAR-1 is that OSCAR-2 has pressure sensors on its feet (Figure 3.5) instead of the binary contact sensors, so a variable pressure on the robot’s feet can be sensed.  Furthermore, OSCAR 2 has an accelerometer sensor used to sense the accelera-tion and inclination of the robot.  By experiments with OSCAR-2, National Instruments hardware [Nat06] and software was used for acquisition and pre-processing of the signals (currents from servos, feet pressure, inclination values), their graphical representation, and data logging.  Fig. 3.6 Modified HiTec HS-645 servo with wires for current and position feedback Other important characteristic for robot OSCAR-2 is that in order to simulate a faulty situation of the robot’s legs by anomaly detection experiments, there have been modifications introduced to some of the robot’s legs for those particular ex-periments. Such experimental leg modification is shown in (Figure 3.7).  Fig. 3.7 Modification by leg of robot OSCAR-2, in order to allow simulated leg failure The presented modification allows the robot’s leg to intentionally malfunction (the inserted pins drop off) after some time of robot walking. 3.2.2.3   Hexapod Robot Demonstrator – OSCAR - 3 OSCAR-3 is similar to OSCAR-1 and OSCAR-2 in its principal construction. The difference to OSCAR-1 and OSCAR-2 is that the 18 modified HiTec HS-645 ser-vos have additional internal electronic printed board circuits that provide servo current feedback through an I2C bus back to the computing unit. Robot OSCAR-3 doesn’t have a microcontroller onboard, but instead it is connected to a PC via a USB cable. It uses the “Generic robot architecture” [Gen08] concept in order to provide a better software driver access to the robot’s sensors and actuators, and therefore easier control and actuation of the robot.   Fig. 3.8 Hexapod robot OSCAR-3. 3.2.2.4   Hexapod Robot Demonstrator – OSCAR - X The new prototype of the OSCAR robot generation, called OSCAR-X (Figure 3.9), is built to provide a better robot research test-bed for testing the biologically in-spired algorithms. In comparison to its predecessors, the OSCAR-X features a completely new design and was rebuilt from scratch.    New features of the robot include: -  Robot leg amputation mechanism: R-LEGAM [Jak09]; -  Light weight glass-fiber body; -  Robot legs spatially distributed in a circle with 60 degrees between each two neighboring legs; -  Greater payload capabilities (sensors, batteries, camera, etc.) for the scientific measurements and experiments; - Stronger digital RX-64 servos with digital feedback for their real time posi-tions, torque levels, current levels, temperatures, etc. - Powerful Lithium-polymer batteries for the servos and electronics; - Weight of the body including the batteries is 7,5 kg; - Improved foot design for better detection of the ground, complete with binary contact sensors; - Powerful embedded system - Gumstix®  “Verdex board” [GUM09] running embedded Linux; - Usage of the “Generic robotic architecture” [Gen08] concept, to provide bet-ter software driver access to the robot’s sensors and actuators and therefore easier control and actuation of the robot; - Orientation sensor; - Wireless camera and an additional camera servo. Fig. 3.9 (a) Hexapod robot OSCAR-X in development stage; (b) OSCAR-X in nature; (c) Front view of robot OSCAR-X with onboard camera and additional ultrasonic sensors; (d) 多足步行混合机器人英文文献和中文翻译(2):http://www.youerw.com/fanyi/lunwen_31396.html