A Review of Active Mechanical Driving Principles of Spherical Robots <s> Summary and Conclusions <s> This paper deals with hopping motion analysis of spherical robot with a typical impact condition like 'superball'. A horizontal velocity of super ball after an impact depends on the angular velocity before the impact where it doesn't slip at the contact point. Our robot model consists of an elastic spherical shell with such an impact condition and of an internal rotary input. Assuming the perfectly elastic impact in a vertical direction, a feedback control strategy for generating the horizontal velocity after an impact by the rotary input during flying phase is derived. Simulation results show that some hopping motion is achieved by the proposed method. In addition, this paper shows the possibility and necessary condition that a climbing motion with impacts against two parallel vertical planes is achieved. <s> BIB001 </s> A Review of Active Mechanical Driving Principles of Spherical Robots <s> Summary and Conclusions <s> We describe circular/spherical robots for crawling and jumping. Locomotion over rough terrain has been achieved mainly by rigid body systems including crawlers and leg mechanisms. This paper presents an alternative method of moving over rough terrain, one that employs deformation. First, we describe the principle of crawling and jumping as performed through deformation of a robot body. Second, in a physical simulation, we investigate the feasibility of the approach. Next, we show experimentally that prototypes of a circular robot and a spherical robot can crawl and jump. <s> BIB002 </s> A Review of Active Mechanical Driving Principles of Spherical Robots <s> Summary and Conclusions <s> The authors have designed and constructed a new type of actuation for a spherical robot. The proposed actuation system consists of a large number of individually inflatable rubber bladders covering a sphere. Inflation of one or more of these bladders imparts a moment to the sphere and coordinated inflation results in a directed motion. Further, the authors introduce a scheme for steering the robot by correctly selecting the proper bladders to inflate so that motive force is developed in a specified direction. The control scheme utilizes a passively rolling inner vehicle with a directional, remotely positioned light source that causes valves housed within the sphere to inflate the designated bladders through optical commutation. <s> BIB003 </s> A Review of Active Mechanical Driving Principles of Spherical Robots <s> Summary and Conclusions <s> This paper presents investigations toward the development of an inflated deformable rolling rover. The proposed novel locomotion system could find potential future use, for example, in scouting and exploration missions. The manufacturing procedure used to fabricate a preliminary prototype is presented in this paper. The prototype consists of a rigid frame and four dielectric elastomer actuator (DEA) sectors, which give the prototype a spherical shape. Analytical models are proposed to predict the electromechanical behavior of the DEA sectors and to estimate their effect on the prototype's dynamics. These models are validated through an experimental procedure. <s> BIB004
Spherical robots have an abundant number of usages with an equal number of methods to control them. A brief table of taxonomy is shown in Table 1 . Most of the types of active drive designs are based on three main principles: offset of center of gravity (barycenter offset), outer-shell deformation, or conservation of angular momentum. Compared with the other methods, the designs based on barycenter offset tend to be the least complex and can be controlled relatively easily. Generally speaking, barycenter offset designs can be analyzed with a single model (Figure 3) . However, the power in these robots is limited because the center of gravity cannot be moved outside of the shell. Common types of barycenter offset designs include a single wheel model, car model, universal wheel model, and a pendulum model. These are the most commonplace of the designs with a large amount of research data available on them. Designs utilizing methods of conservation of angular momentum typically involve creating torque by manipulating a single axis or three axes of a CMG. Designs can either utilize the counter rotational force generated when spinning a CMG faster or slower (single-axis), or the precession torque created when rotating an already spinning CMG orthogonal to its axis of spin (triple-axis). The magnitude of torque generated in single axis designs is controlled by the amount of acceleration of the spinning CMG, whereas in triple axis designs, the precession torque is controlled by the angular velocity times the rotational acceleration. CMGs integrated into a spherical robot offer a way to solve the power constraints placed on spherical robots by barycenter-offset designs, but this method has its own unique set of hurdles to overcome. Shell transformation designs are a rather new concept and may be more difficult to design but can be maneuvered with an almost calculation-less control method. Groups have begun merging these three concepts together producing robots that have advantages over designs based on a single concept. Marriages of multiple principles, such as a pendulum type with a CMG bob, have proved to be noteworthy concepts. Future research on gyroscope-augmented designs may lead to technology that can be integrated into a fast, agile, holonomic spherical robot. BIB004 BIB003 BIB001 BIB002 