Snake Aerial Manipulators: A Review <s> 3) ESTIMATION OF INERTIAL PARAMETERS AND CENTERS OF MASS OR GRAVITY <s> Active center of gravity (C.G.) control is a key technology of vehicle management system, which has been extensively used in various types of aircraft. With active C.G. control system, aircraft may deviate from its known dynamics due to the C.G. offset, thus bringing new problems to the existing flight control system. A new design approach of the attitude control system of aircraft with C.G. variations is proposed in this paper. <s> BIB001 </s> Snake Aerial Manipulators: A Review <s> 3) ESTIMATION OF INERTIAL PARAMETERS AND CENTERS OF MASS OR GRAVITY <s> Changing the position of the Center of Gravity (CoG) for an aerial vehicle is a challenging part in navigation, and control of such vehicles. In this paper, an all-accelerometers-based inertial measurement unit is presented, with a proposed method for on-line estimation of the position of the CoG. The accelerometers' readings are used to find and correct the vehicle's angular velocity and acceleration using an Extended Kalman Filter. Next, the accelerometers' readings along with the estimated angular velocity and acceleration are used in an identification scheme to estimate the position of the CoG and the vehicle's linear acceleration. The estimated position of the CoG and motion measurements can then be used to update the control rules to achieve better trim conditions for the air vehicle. <s> BIB002 </s> Snake Aerial Manipulators: A Review <s> 3) ESTIMATION OF INERTIAL PARAMETERS AND CENTERS OF MASS OR GRAVITY <s> Inertial sensor arrays present the possibility of improved and extended sensing capabilities as compared to customary inertial sensor setups. Inertial sensor arrays have been studied since the 1960s and have recently received a renewed interest, mainly thanks to the ubiquitous micro-electromechanical (MEMS) inertial sensors. However, the number of variants and features of inertial sensor arrays and their disparate applications makes the literature spread out. Therefore, in this paper we provide a brief summary and literature review on the topic of inertial sensor arrays. Publications are categorized and presented in a structured way; references to +300 publications are provide. Finally, an outlook on the main research challenges and opportunities related to inertial sensor arrays is given. <s> BIB003 </s> Snake Aerial Manipulators: A Review <s> 3) ESTIMATION OF INERTIAL PARAMETERS AND CENTERS OF MASS OR GRAVITY <s> In this paper we present a concept of a multirotor unmanned aerial vehicle (UAV) capable of horizontally moving without tilting the vehicle body. The concept is based on the moving mass control, which we have recently proposed for roll and pitch control of a large multirotor UAV with internal combustion engines (ICEs). The vehicle is comprised of four ICEs with rotors tilted towards the body center and four moving masses, each placed in a motor arm. We give a complete 6 degrees of freedom (DOF) mathematical model in the form of nonlinear differential equations, which we linearize to obtain transfer functions. The models are used to design a control system comprised of state space controllers for roll/pitch stabilization and PID controllers for height, yaw and velocity control. The concept is verified in the Gazebo simulator and experimentally on a 2DOF laboratory gimbal. <s> BIB004 </s> Snake Aerial Manipulators: A Review <s> 3) ESTIMATION OF INERTIAL PARAMETERS AND CENTERS OF MASS OR GRAVITY <s> External wrench estimation is very helpful for aerial exploration and manipulation tasks. During the exploration, there might be unseen obstacles to cause dangerous collisions. The estimation of the external force and torque is also beneficial in aerial manipulation tasks. In this paper, we present a framework of estimating the external wrench for the aerial multilink robot based on the onboard inertial measurement unit (IMU) sensors, joints state and robot dynamic models. Compared to the conventional multirotor robot, the center of mass (CoM) is always changing when the robot transforms. The sensor could not be attached to CoM to observe the acceleration data. Consequently, we present a novel method by applying a distributed IMU system to estimate the CoM linear and angular accelerations for the external wrench estimation. With the help of the robot model, the position of the contact point could be estimated, which is useful in exploring tasks to safely interact with the physical world. We design the contact-aided navigation strategy and computationally efficient motion primitives library to help our robot react to the unexpected collision. We experimentally validate our framework with a two-dimensional multilink aerial robot to show the results of external wrench estimator and its further applications2.2Experiment video: https://youtu.be/R-WDReLnWWI <s> BIB005 </s> Snake Aerial Manipulators: A Review <s> 3) ESTIMATION OF INERTIAL PARAMETERS AND CENTERS OF MASS OR GRAVITY <s> We present a novel pose and posture estimation framework of aerial skeleton system for outdoor flying. To exploit redundant/independent sensing while rendering the system “modular”, we attach an IMU (inertial measurement unit) sensor and a GNSS (global navigation satellite system) module on each link and perform SE(3)-motion EKF (extended Kalman filtering). We then apply the kinematic constraints of the aerial skeleton system to these EKF estimates of all the links through SCKF (smoothly constrained Kalman filtering), thereby, enforcing the kinematic coherency of the skeleton system and, consequently, significantly enhancing the estimation accuracy and the control performance/stability of the aerial skeleton system. A semi-distributed version of the obtained estimation framework is also presented to address the issue of scalability. The theory is then verified/demonstrated with real outdoor flying experiments and simulation studies of a three-link aerial skeleton system. <s> BIB006 </s> Snake Aerial Manipulators: A Review <s> 3) ESTIMATION OF INERTIAL PARAMETERS AND CENTERS OF MASS OR GRAVITY <s> Transformable multi-links aerial robots have great potentials in application relying on the transformable features to change its shape during the flight. Compared to traditional quadrotor robots, t... <s> BIB007
As these parameters are geometrically dependant on the aircraft shape, some algorithms for their calculation are described in BIB002 BIB003 BIB001 BIB004 BIB005 BIB006 BIB007 , these algorithms involve calculating the inertial variations on each UAV and / or intermediate points of design, and transferring this data to a processing center, where the equivalent inertial point and centers of flight are calculated. This computationally implies the sending of simultaneous sensor data and also sending by wire or wireless protocols ensuring the correct transfer of data (for example the checksum protocol in the more basic level of verification).