The requirement of ideal rolling without sideways slipping for wheels imposes nonholonomic (non-integrable) constraints on the motion of the wheels and consequently on the motion of wheeled mobile ...robots. From the control point of view, the dynamics of nonholonomic systems can be divided in two parts: external and internal dynamics. The dimension of the external dynamics of nonholonomic systems depends on the number of inputs to the system and the dimension of the internal dynamics depends on the number of independent nonholonomic constraints. For different motion control problems of nonholonomic systems, a smooth (model based) state feedback control law only deals with the system external dynamics; therefore, the system internal dynamics must be examined separately and its stability has to be analyzed and proved.
In this paper, the internal dynamics of a three-wheel mobile robot with front wheel steering and driving is investigated. In particular, its internal dynamics stability is analyzed for two different situations, when the mobile robot is moving and when it is stationary.
This paper presents model predictive control of an autonomous vehicle. Simulation and experimental results have been shown and compared with input-output linearization method. The results obtained ...show that the MPC is an efficient method that allows for accurate control and navigation of an autonomous vehicle. Model based predictive control is tested in simulations for motion on an inclined plane. This is done to prepare future work regarding the avoidance of the violation of the smoothness condition for exact linearization, while at the same time by modifying the input commands the geometric path planning results are conserved. The approach is presented for the wheel-ground slippage and tip-over avoidance of the three-wheeled vehicle for inclined plane motion. A complete three-dimensional dynamic model using Newtonian dynamics is also presented. Simulation results using a three-wheeled vehicle built in our laboratory illustrate the performance of the proposed controller.
The present and future importance of Li-Ion batteries is immeasurable; this is evidenced by the awarding of the Nobel Prize in chemistry in 2019, to the team of John Goodenough - director, M Stanley ...Whittingham and Akita Yashino, who developed the technology to make this type of rechargeable battery. Used at the beginning (1990-2000) in applications such as portable electronic equipments (mobile phones, laptops, electric tools, energy storage systems, etc.), these batteries are considered the most suitable battery for powering electric vehicles. Today the number of electric cars in the world has exceeded 4 million units and the future estimates are among the most optimistic. Recycling of Li-Ion batteries is mainly done in China and South Korea, countries that have a large share in their production, but things can change. Intense research for the recovery and reuse of useful metals contained in these batteries is carried out in many research laboratories. The paper presents the current state of the research undertaken for the recovery of the cathodic paste with high content of Cobalt of waste LIBs, by ultrasonography in lactic acid solution. The hydrometallurgical method uses a non-polluting organic (lactic) acid. The working technique, the results obtained and the investigations carried out on the recovered materials are presented (analysis of optical and electron microscopy, EDX, X-ray diffraction). The paper also includes data regarding the optimization of the separation process of the active cathode paste from the aluminium foil using the orthogonal central-compositional programming of the second order.
Lithium-ion batteries (LIBs) are use in electric devices such as phones, cameras, laptops, etc. and also for electric automotive propulsion. More consumption means more amount of scrap. The wastes of ...LIBs contain rare and high value metals: Co (32 $/kg), Li, Ni, Cu, Al. Many recycling processes were developed with the purpose of recovering metals contained in used batteries. This paper presents a method for separation active cathodic paste (containing LiCoO2 compound) from the aluminum cathode using a solution of lactic acid and an ultrasonic bath. Cathodic paste has been detached from aluminum foils and analyzed by scanning electron microscopy (SEM) and X-ray diffractometry. The effects of the lactic acid concentration and the power of ultrasonic bath on separation efficiency were investigated.
The topic of this paper focuses on the development of formation controller for multiple car-like mobile robots. The studied robot formation is constructed under Leader-Follower approach, so that the ...follower robots are able to keep constant desired distances and relative bearing angles with respect to the leader. Affected by the data transmission delay between the leader and follower robots, the formation performance is degraded, which may even lead to undesired collision of the followers. A PD-type controller is proposed to compensate the delay effect, which is proved to be stable and effective in formation keeping. Some initial studies on parameter selection were also carried out. Both simulations and hardware experiments support the implementation of this type of controller, which also showed the capability of dealing with variable time delays in the communication channel.
The objective of this paper is to present an approach for processing infrared images and accomplishing automatic detection and path tracking of moving subjects with fever. The detection is based on ...two main features: the distinction between the geometry of a human face and other objects in the field of view of the camera and the temperature of the radiating object. These features are used for tracking the identified persons with fever. The position of camera with respect to direction of motion the walkers appeared to be critical in this process. Infrared thermography is a remote sensing technique used to measure temperature based on emitted infrared radiation, in this case from people in crowded environments. This application may be used for fever screening in major public places such as airports and hospitals. For this study, we first look at human body and objects in a line of view with different temperatures that would be higher than the normal human body temperature (37.8C at morning and 38.3C at evening). As part of the experimental study, two humans with different body temperatures walking a path were subjected to automatic fever detection applied for tracking the detected human with fever. The algorithm consists of image processing to threshold objects based on the temperature and template matching used for fever detection in a dynamic human environment.
Mobile non-holonomic robot motion control with collision avoidance is investigated in this paper for the case of unknown concave obstacles locally sensed. Motion control achieves in this case a ...reactive motion using velocity potential fields approach in a modified, quasi-harmonic, solution. Analytical solutions and simulations show how the harmonic solution for collision avoidance with concave obstacles can be separated smoothly from a non-harmonic solution for positioning.
This paper analyzes several control schemes for single-file vehicle platoons. Extensive simulation studies have been conducted based on transfer function analysis to evaluate the performance of ...existing control schemes and to test the new control schemes suggested in this paper. Concepts of string stability are extended from 1D motion to 2D motion. Several interesting features have been identified. In particular, it was shown that the "path attenuation" effect, that allows an indefinite number of followers to achieve string stability behind a leader, is achievable for a planar trajectory.
The interaction between the human operator and a virtual environment can be significantly enhanced by a haptic interface. The implementation of a haptic interface requires to account for the dynamics ...characteristics of the interface components. In this paper, haptic interface development and testing are analyzed using hardware-in-the-loop experimental setups. Two setups are presented, 1DOF and 3DOF. The paper presents issues regarding HIL implementation of haptic interfaces using a nonlinear force feedback from a virtual environment. The results are relevant for the characterization of the performance and the limits of the haptic interface implementations.
Motion control of mobile robots, when autonomy is needed, requires the ability of operational space control. Exact input output linearization of the mobile robot dynamics facilitates the design of ...the operational space control but requires verification of sufficient smoothness condition. Torque saturation of actuators, slippage avoidance of the wheels with regard to the ground and tip-over of the overall mobile robot are to be avoided not only for satisfying the smoothness conditions, but also for keeping the ability to control the mobile robot in general. In this paper, predictive control is used for avoidance of the occurrence of these events by modifying the input commands such that the geometric path planning result is conserved and the smoothness condition for exact linearization is not violated. The performance of the input command (computed jerk) modification is verified by comparison with the corresponding output jerks of the mobile robot in operational space.
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