In this paper, we propose a new compact variable gravity compensation mechanism (CVGC). The CVGC can be used to generate gravity compensation torque by using the cam and lever mechanism and can also amplify the target gravity compensation torque by varying the pivot point of the lever. The feature of variable gravity compensation is very useful to the mobile platform, which needs to handle unstandardized tasks with a high variation of the workpiece weight. The proposed CVGC has many advantages. Most importantly, it is designed as a compact, independent one-piece structure and is lightweight, meaning it can easily be used as a mobile platform with a simple modification. The CVGC can also have a full range of compensation angle (360°), so it does not restrict any of the original workspaces of the target platform when it is installed. First, the mechanism concept and details are explained. Next, the mechanics of the prototype for force analysis are presented. Based on these mechanics and cam theory, the methodology of the cam profile design is presented. Finally, the performance of variable gravity compensation is verified through experiments that compare the designed and measured gravity compensation torque. The verification test shows adequate performance, as we had hoped, which shows potential for the development of the CVGC.

This paper presents design and force-tracking impedance control of 2-degree-of-freedom (DOF) wall-cleaning manipulator equipped with disturbance observer (DOB) and sliding mode control (SMC). In order to keep in contact with various shapes of walls, the proposed manipulator is designed to ensure 2-DOF motions of translation and tilting by using ball screws. The position-based force tracking impedance control (FTIC) is first adopted for the proposed manipulator not only to interact with walls in a desired dynamic behavior but also to maintain a constant contact force. Also, to improve the force tracking capability of proposed manipulator against different walls and brushes for manipulator, the FTIC is combined with the disturbance observer (DOB) and the sliding mode control (SMC). Extensive experiments prove that although different brushes used for manipulator rotate against varying shapes of walls, the proposed manipulator can keep a constant contact force within a bound of ± 4.5 N by virtue of the proposed FTIC equipped with the DOB and the SMC.

A new lizard-inspired robot is presented in this paper, which enables to maintain its moving direction by lateral body motions even during high-speed bipedal running. First, a dynamic model for lizard-inspired robot is derived to simulate the lateral body motion of real lizard. Based upon the simulation using dynamic model, the lizard-inspired robot is tactfully built so that its hind leg is optimally designed on a 4-bar mechanism and its body is simplified to consist of two body links and a tail connected by two revolute joints. The experiments verify that the proposed robot can maintain its moving direction via proper lateral motions during high-speed bipedal running similar to that of real lizard.

This paper presents a new mobile robotic platform (R-Mo) which can reduce unexpected variations in height as well as pitch angle of its main body while traversing rough terrains. As a measure for the smooth movement of mobile platform, the variations in height and pitch angle are chosen in this study. Then, the kinematic analysis on the Rocker-Bogie mechanism is carried out to investigate its variations in height and pitch angle on rough terrains. Based on this result, a new mobile platform is systematically designed by combining the Rocker-Bogie with the inverse four bar linkage. The extensive experiments are carried out by using the Rocker-Bogie mechanism and the proposed R-Mo against rough terrain, which validate that in comparison with the Rocker-Bogie mechanism, the average and maximum variations in height of proposed R-Mo are reduced by 12.72% and 5.96%, respectively, and the average and maximum variations in pitch angle of proposed R-Mo are considerably reduced by 65.87 % and 60.53 %, respectively.

This paper covers the energy-saving features of a robotics system by redundant actuation. By installing more actuators than the degrees of freedom, the actuating torques can be distributed This distribution can reduce the overall energy loss, which reduces the overall energy consumption. An experiment was conducted with a 2-DOF general manipulator and redundant actuated manipulator; these were made to follow a typical welding pathway used in an automotive factory. The results showed that the redundant manipulator saved up to 38% electrical energy for actuation compared to the general manipulator.

Transitioning capability and high payload capacity are problems for climbing robots. To increase the possible applications for climbing robots, these two abilities are required. We present a new climbing robotic platform named “Combot” to achieve both transitioning capability and high payload capacity. The robot is composed of three main modules with flexible magnetic treads, connecting links with torsion springs and torque-controlled motors, and an active tail at the end of the robot. The robot can perform internal and external transitions using compliant torques from the torsion springs and the active tail. The compliant torques are changed according to external structures; thus, a complex feedback controller is not required. The payload capacity of the robot is measured by 10 kg (1.56 times the robot mass) during flat surface vertical climbing. The robot is expected to be used to move heavy materials to high places in the ship building industry.

The ability to overcome rough terrain is a main issue of mobile robots. However, as the speed of a robot increases, stability becomes another issue because it is directly related to the mobility of the robot. Without stability, the robot is exposed to risks of overturn. Therefore, a mobile robot needs to be not only maneuverable but also stable. We present a new mobile platform named “Rocker-Pillar” which enables a robot to overcome rough terrains with stability. The robot is composed of two sets of caterpillar tracks, four wheels, and a pair of two linkages. The robot can travel a rugged terrain at a speed 50m/min while maintaining stability, and can overcome complex terrains such as holes, steps without frontal sides, and stairs. The robot can overcome a hole 1.5 times larger than the wheel diameter of the robot and a step without the frontal side that is 1.25 times higher than wheel diameter.

A kinematic optimization procedure for redundantly actuated parallel manipulator is developed to ensure the isotropic antagonistic stiffness in a workspace. The kinematic parameters of the mechanism are optimized to maximize and equal out antagonistic stiffness of the redundantly actuated manipulator when size and shape of the usable workspace are given but position in the entire workspace is not. The proposed procedure is verified with a 2-DOF planar manipulator by experiments. The experimental results show that the proposed procedure is useful for designing the redundantly actuated parallel manipulator with isotropic antagonistic stiffness in a predefined usable workspace as a design constraint.

In this paper, two torque assignment methods of the antagonistic stiffness for a 2-DOF planar parallel manipulator are presented and verified by experiments. The first method is equalizing the magnitude of the stiffness in all directions at a desired position. The second method is maximizing the active stiffness in one direction at a given path. A 2-DOF parallel mechanism with four actuators is used for verification tests, where the internal torque of the mechanism exists on the two dimensional null space. In the experiment, passive and active stiffness are tested when endowing the external force at the moving platform and compared with the estimated results.

This paper presents the controller synthesis for a fine actuation system of a 3-DOF micro parallel positioning platform. The platform is composed of a dual stage servo system for realizing both long stroke and high precision, simultaneously. Among the dual stage, the fine actuation system is more important as it guarantees high speed and accuracy. First, a physics-based model for the fine actuation system is developed through the constraint equations of the parallel mechanism and the dynamic equations of the fine actuation system. Several experiments have been conducted and unknown physical parameters such as the stiffness and the damping coefficients were estimated to precisely predict the dynamics of the fine actuation system. Equipped with the physics-based model, the PID-based controller, mixed-sensitivity H2and Hinfincontrollers were designed to accomplish both high accuracy and fast response of the micro positioning platform, respectively. The satisfactory performances of the synthesized controllers were successfully verified and compared with one another through extensive simulations and experiments.

Welding is very difficult and dangerous for manual welders. The double hull structures found in ships are very hazardous environments, and as such the shipbuilding industry demands a safer, autonomous system to perform the welding rather than deploy manual welders. This paper describes the design of a new mechanism, called the 'Rail Runner', which is able to autonomously travel within the double hull structure. The design of a 3P3R serial manipulator for welding is also described in this paper. As an application of the 'Rail Runner' mechanism, we combine the 'Rail Runner' platform and the 3P3R serial manipulator for autonomous welding. The mechanical system of this robot is composed of a six-axes (3P3R) manipulator for achieving the welding function and a six-axes mobile platform for traveling within the double hull structure. This robot is able to autonomously travel between longitudinal structures, with transverse direction, and is capable of welding in double hull structures. The 'Rail Runner' can raise the efficiency of the welding process, as compared to manual welders. This in turn raises the international competitiveness of the shipbuilding industry.

This paper presents a multiple humanoid cooperative control system(MHCCS) developed for the demonstration of heterogeneous humanoid collaborating to complete a mission consists of multiple humanoid tasks. MHCCS consists of CORBA based framework, humanoid control software, multiple humanoid cooperative control software, sensing software. Multiple humanoid cooperative control software consists of 3 layers: mission layer, task layer, action layer. User can design a task for humanoid by drawing a state diagram using developed graphical user interface, or edit XML-based command script directly. We defined action primitives suitable to abstract humanoid tasks by using state diagram, which is stored in a knowledge database for the future use. The developed MHCCS is successfully tested through the demonstration of a heterogeneous humanoid team cleaning the tables without confliction.

This paper concerns the singularity of the half parallel manipulator, a novel three degrees of freedom (DOFs) mechanism, with revolute actuators. The parallel manipulator, proposed previously, consists of a base plate, a movable platform, and three connecting legs. It has the advantages in terms of only single-DOF joints and high rotational capability. The parallel manipulator has wide application in the fields of industrial robots, simulators, parallel machine tools and any other manipulating devices that high rotational capability is required. The inverse kinematics problem and Jacobian matrices are recalled firstly. And then all possible singularities of the manipulator are analyzed in detail. The results of the paper are very useful for the apprehension and the application of the manipulator.

In this paper, a novel spatial three degree-of-freedom, that are two degrees of translational freedom and one degree of orientational freedom, parallel manipulator is proposed. The parallel manipulator consists of a base plate, a movable platform, and three non-identical connecting legs. The kinematics problems and velocity equation of the new parallel manipulator are given. Three kinds of singularities are presented. The parallel manipulator has wide application in the fields of industrial robots, motion simulators, and parallel kinematics machines.

This paper presents the Eclipse II, a new six-degrees-of-freedom parallel mechanism, which can be used as a basis for general motion simulators. The Eclipse II is capable of x, y, and z axes translations, and a, b, and c axes rotations. In particular, it has the advantage of enabling continuous 360/spl deg/ spinning of the platform. We first describe the computational procedures for the forward and inverse kinematics of the Eclipse II. Next, the complete singularity analysis is presented for the two cases of end-effector singularity and actuator singularity. Finally, two additional actuators are added to the original mechanism to eliminate both types of singularity within the workspace.

This paper presents the Eclipse-II, a new six degree-of-freedom parallel mechanism, which can be used as a basis for general motion simulators. The Eclipse-II is capable of s, p and z-axis translations and n, b and c-axis rotations. In particular, it has the advantage of enabling continuous 360-degree spinning of the platform. The computational procedures for forward and inverse kinematics of the Eclipse-II are described. The complete singularity analysis is presented for the two cases of end-effector singularity and actuator singularity. Two additional actuators are added to the original mechanism to eliminate both types of singularity within the workspace.

This paper describes the design, construction, and performance analysis of the Eclipse, a redundantly actuated six-degree-of-freedom parallel mechanism intended for rapid machining. The Eclipse is a compact mechanism capable of performing five-face machining in a single setup while retaining the advantages of high stiffness and high accuracy characteristic of parallel mechanisms. We compare numerical and algebraic algorithms for the forward and inverse kinematics of a class of the Eclipse and formalize the notion of machine tool workspace. We also develop a simple method for the first-order elasto-kinematic analysis of parallel mechanisms that is amenable to design iterations. A complete characterization of the singularities of the Eclipse is given, and redundant actuation is proposed as a solution. The Eclipse case study demonstrates how diverse analytical tools originally developed in a robotics context can be synthesized into a practical design methodology for parallel mechanisms.