The advent of endoscopic techniques had considerable influence on surgery in many clinical areas. This paper intends to describe an overview about robotics technologies facilitating endoscopic surgery. A major enhancement for endoscopic techniques is the introduction of robotic technology to design assisting devices for solo-surgery and manipulators for microsurgical instrumentation to provide the surgeon with ad-ditional degrees of freedom of instrumentation. In 1996 a first prototype of an endoscopic manipulator system, named ARTEMIS, could be used in experimental applications. Master slave systems consist of a user station (master) and an instrument station (slave) . The surgeon sits at a console which integrates endoscopic monitors, communication facilities and two master devices to control the slave arms which are mounted to the operating table. Systems developed by industry quickly gained the interest of the surgical community and are today employed at several specialised centers around the world in clinical use, mainly in the area of cardiac surgery. The combination of telecomunication technology with robotic instruments will open new frontiers, such as teleconsulting, teleassistance and telemanipulation. With the increasing complexity of endoscopic surgery in the various clinical specialties, such as general, cardiac or other fields of surgery, came the demand for more sophisticated instrumentation. Robotics was soon identified as a major pacemaker towards the technological future of minimally invasive surgery. The first steps in the use of robotics for increasing instrument functions were made in the area of endoscope guidance, where robotic instrument holders got used to direct the endoscope during the operation   . Robotic endoscope holders demonstrated to be efficient and safe in clinical use and are today accepted as assisting devices among endoscopic surgeons  . The field of robotics for enhancing surgical instrumentation did not emerge so fast as the former because of its technical complexity and safety concerns linked to the use of robotic devices for surgical operations.
The kip is a fundamental gymnastic movement performed on a variety of gymnastic apparatuses at all levels of competition. We analyze the kip with a multi-model approach consisting of a pendulum and 3-link model. Our simulations have shown that a variable length pendulum model is sufficient for modeling the dynamics of an expert gymnast's center-of-mass without considering the complex parameters of the 3-link model. The optimized pendulum model can generate kip pattern variations which yield a midpoint target region of success. We then evaluate these kip patterns based on the center-of-mass and 3-link system's total energy. Experimental data of both success and failure performances show that the novice raises his center-of-mass too high during the forward swing thus resulting in failure. Analysis of midpoint kip pattern variations also indicate that raising the center-of-mass at the end of the forward swing is a cause of failure.
It is an effective method to improve the controllability for a robot to construct it using the least number of DOF as possible. In this paper, a new lightweight walking robot is developed that uses a simple mechanism to move and work with high efficiency. This robot consists of two leg-bases with three legs each and walks by moving each leg-base alternately. These leg-bases are connected to each other through a 6-DOF mechanism. Thus, when the robot stands on three legs, or one leg-base is placed on the ground, the other leg-base can be used as a 6-DOF manipulator or active working platform. The output force, velocity, and movable range of various mechanisms for connecting the two leg-bases were analyzed using a new idea of comparison for its output characteristic. Good performance can be achieved with a serial-parallel hybrid mechanism consisting of three 6-DOF serial linked arms composed of two active and four passive joints positioned with radial symmetry about the center of each leg-base. Walking experiments with this robot that uses this mechanism as a leg-drive mechanism confirm that this mechanism has satisfactory performance despite having less DOF and can be used for 6-DOF motion base.
A real-time control method of an anthropomorphic robot which moves with its legs while doing a given task by its arm is proposed. The robot has two legs and one arm because the motion in sagittal plane is discussed; the unknown external force acts on the arm tip. The arm controls its tip by impedance control so that the tip can always follow the desired position or external force prescribed by the given task. The legs change two control modes according to the current arm tip position and external force: 1) When the external force is small or the arm tip moves in narrow space, the robot keeps double support state and controls its shoulder in order to keep the robot stable against the force and to make the arm easy to do the task. 2) If the large force acts or the arm tip must be moved in wide range, the robot steps in order to prevent it from tumbling, thus recovering the robot's stability and the arm tip's manipulability shifted in new double support state. Furthermore, the robot can cope with the sudden change in the external force and the moving direction of the arm tip. The effectiveness and usefulness of the proposed method are ascertained by computer simulation and experiment.
CPG (central pattern generator) and entrainment dynamics together form a promising framework for robust and adaptive behavior generation for a high degree of freedom system in unstructured environment. This paper investigates its possibility in the domain of biped robotic locomotion. We extend a previous work on 2D biped locomotion using neural oscillators to 3D, introducing many more degrees of freedom and complexity in control. While the complexity of the problem has been increased, we have simplified the internal neural mechanism compared to the original 2D work. Our fully dynamic 3D simulation experiments showed that our mechanism can generate 3D stable biped stepping motion as well as tolerance against external perturbations.
We are studying a leg-wheeled robot with the ability of going up and down stairs. We already developed a 'biped type leg-wheeled robot' which has ability to pass over stairs with short treads, but it could not negotiate the stairs fast. In this paper, in order to realize the fast negotiation of stairs, we propose a new dynamic trajectory planning method to make the staggering distance smaller and the landing stabler. We also propose a method to connect the dynamic trajectory control motion in statically unstable state and the structure changing motion in statically stable state. As the result, we realize the fast going up and down stairs by this robot successfully and confirm the effectiveness of our proposed method.
A New hybrid cylinder/wire drive parallel arm (simply called“hybrid arm”) for manipulating heavy materials in construction and ship building works is proposed. The total number of cylinder and wire is fixed to seven based on the force closure principle, and the kinematics and statics are formulated for hybrid arms with arbitrary combination of cylinders and wires. Various hybrid arms with different combination of cylinders and wires are compared with the conventional Stewart platform and a multi wire drive mechanism, evaluating their workspace with orientation. The workspace is determined under the constraints on the interference between the links and the limitation of the cylinder force and wire tension. As a result, the most suitable hybrid arm for heavy material handling is the mechanism with three cylinders, four wires, and one connecting rod between the cylinders and the end plate. Furthermore, this hybrid arm is modified into the mechanism with variable length rod for the application of manipulating a precasting concrete board with the size of 3×6×0.2 [m] and the weight of 10 [t], which is used in automatic building construction systems; the prototype of this arm is designed and developed.
In general, lightness is important in the legged locomotion robot from the point of the consumption energy. As a result, it is thought that the legged locomotion robot is a low rigidity multi link system. This thesis describes the vibration control of the robot which became a low rigidity because of lightening. When the robot swings the leg, the robot becomes a low gidity series multi link system. Therefore, because the landingposition and posture become irregular by the vibration of the leg when high-speed walking, walking of the robot becomes unstable. Then, filter inclusion LQ servo which did an intuitive adjustment with the actual thing easily as the composition was coparatively easy in the technique of the vibration control was applied to this robot. Moreover, the vibration by the backlash of the machine was suppressed by feedback the velocity of the motor directly to the torque command. As a result, the vibration of the swing leg was able to be suppressed and control at high speed. The robot walked about 1.4 [km] per hour on a floor
A prismatic-jointed leg mechanism is developed for walking robots. The leg, constructed by combining a pair of parallel links, has two degrees of freedom in the sagital plane; a translational motion at the knee joint, and a rotational motion at the ankle joint. By using the leg, it is possible to control a robot based upon a simple control algorithm, walking at various vertical height of its center of gravity. In order for the simplicity of the control, all motors for driving the joints are attached at the trunk of the walking robot so as to reduce the mass of the leg. Moreover, the top link of the leg is mechanically constrained to be parallel to the bottom link so as to fix the orientation of the trunk of the robot while walking. Experimental walking results by using a biped robot, constructed with the developed leg, are shown for verification of the leg mechanism.
This paper discusses an algorithm for achieving an equilibrium grasp for a pyramidal-like object placed on a horizontal table under the gravitational field. Assuming that the contact friction is small enough to ensure that any direct grasp surely fails in achieving an equilibrium one, we first show that there exists an algorithm for achieving an equilibrium grasp by using two fingers. After showing the two-fingers-algorithm easily fails in keeping an equilibrium grasp for a horizontal disturbance, we propose the three-fingers-algorithm. We define the concept of gravitationally stable equilibrium, where a gravitational force always pulls the object back to an equilibrium state. We also discuss the finger placement enabling the grasp to keep the stability. Finally, we validate the idea experimentally by using a slightly modified version of the three-fingers-algorithm.
Hyper-redundant robot arms have a very large degrees of kinematic redundancy, thus possess the unconventional features such as ability to enter a narrow space while avoiding obstacles. In this paper, a time-optimal path-tracking control scheme with considering the actuation characteristics of actuators was introduced for the Moray arm, a slider-installed hyperredundant robot arm. Therein, the used actuators were assumed to be the commonly-used DC motors and the maximum heat generated by DC motor was considered as the limit actuation characteristics of actuator. The time-optimal trajectories for tracking the path in posture space were generated with subjection of the limit-heat characteristics. Computer simulations were also performed to show that, 1) the proposed control scheme considering the limit-heat characteristics makes all output of actuators within the heat bounds and all outputs are still under the maximum power curve, 2) the required output of actuators is continuous and no pulse torques are generated, in comparison with the traditional time-optimal control schemes subjected to torques and/or velocities.
A control method to reduce the oscillations of a robot manipulator with elastic joints and non-backdrivable gear trains is proposed. The examined robot manipulator will be used as an arm for robots which work in the human living fields. Such a manipulator should be carefully designed from the safety point of view. Focusing on the interaction force between a human and a manipulator, there are two important aspects to gain the safety. When the manipulator contacts slowly with a human, the elasticity of the joints and the body will play an important role to prevent any injury. On the other hand, if the manipulator collides against a human with rather high speed, the kinetic energy will be the main index to measure the expected damage. The authors will point out that the effective manipulator mechanisms used where a human is in the robot's working space is one with high-gear-ratio gear trains (as a result of non-Backdrivable) and elastic joints. However, the elastic joints cause oscillations. The main purpose of this paper to propose a new method to reduce such an oscillation. This method is discussed based on the stability analysis with Lyapunov's theorem. The simulation and experimental results are also given to show the effectiveness of the method.
ODV9 is a newly designed nonholonomic omni-directional vehicle (ODV) to be used as a general platform for mobile robots. Omni-Directional mobility is a desirable property for such platform because indoor mobile robots are often requested to move in a narrow space. Furthermore, compared with other ODVs, the advantages of ODV9 are not limited to the simplicity of its mechanism. Benefiting from being able to use a normal type wheel equipped with a tire, e.g. air tire, ODV9 is capable of moving on somewhat bumpy surfaces. ODV9 has four wheel modules, with each wheel module incorporating one motor, one steering brake, and one normal type wheel equipped with a rubber tire. In this paper, the mechanism, the kinematics, the running modes are stated first. Next, we discuss an effective controller to stabilize the intrinsic instability of the wheel module if the steering brake is open. Finally, the characteristics of the steering wheel getting over a small step are examined through numerical simulations and experiments.