In caging, an object is geometrically confined by position-controlled robots and never escapes from the constraint. Caging has some advantages over conventional grasping, and its applications have been performed not only in 2D but also in 3D scenes with various actual robots. However, the conditions of complete caging are not always satisfied due to limited robot configuration. This paper studies partial caging, in which an object is incompletely confined by robots or obstacles and is able to escape from the constraint. As an example of partial caging, a circular object moving in the planar hand is considered. We investigate an effect of arrangement of its fingertips, which prevents the object from escaping outside through the gap between the fingertips. Some simulation results show differences of difficulty of escaping for the object according to width of the gap and angle of the fingers. In addition, ease of entering the hand through the gap of the fingers is also evaluated. From these two scores on partial caging, we define an ability index for the hand, which represents the hand can easily capture an object and confine it without any finger motion.

Graspless manipulation is easily interfered by external disturbances because the manipulated object is not completely held by a robot hand and supported by an environment such as a floor. Thus it is important to ensure the manipulation is executed robustly against some disturbances. In our works, a rigid-body-based analysis of indeterminate contact forces for quasi-static graspless manipulation has been proposed, and also joint torque optimization for robotic hands. The joint torques of the robot is determined in consideration of some robustness of manipulation against disturbances, which include changes or estimation errors of friction. In the analysis of contact forces in quasi-statics, a kinematic constraint on static friction is considered to exclude infeasible sets of frictional force, with considering treatment of kinetic friction. Additionally, new objective functions for computing optimal joint torques in both static and quasi-static graspless manipulation are proposed. Some numerical samples of both applications are shown to verify our proposed methods.

In this paper, we propose a robot programming method for industrial manipulators. It enables novice human operators to teach "good" robot motions in a short period of time. First in this method, a human operator makes a robot manipulator sweep a volume by its bodies. The manipulator is equipped with a force sensor on its wrist and damping-controlled; the operator can move it freely by grasping its end-effector. The swept volume stands for a part of the manipulator's free space, because the manipulator has passed through the volume without collisions. Next, the obtained swept volume is used by a motion planner to generate a well-optimized path of the manipulator automatically. Finally, the planned motion is executed by the manipulator. Even non-skilled operators can generate robot motions with short cycle time by doing the above procedure. The effectiveness of our method is successfully demonstrated in teaching experiments for a comparison with other conventional methods.

In this paper, three-dimensional caging by a multifingered hand (3D multifingered caging) is studied. Caging is a method of object constraining in which robot bodies surround an object and make it inescapable from the ldquocagerdquo composed of the robot bodies. In 3D multifingered caging, position-controlled robot hands can constrain objects and transport them, and force control is not necessary. Furthermore, even a robot hand with low degrees of freedom can constrain an object to manipulate. We show some examples of 3D multifingered caging. Then, we derive sufficient conditions for caging objects, and propose a method to plan configurations of a robot hand for caging with the sufficient conditions.

In this paper, we analyze indeterminate contact forces in robotic grasping and contact tasks. Previous studies by Omata and Nagata showed that there is a constraint on static friction forces, which is derived from contact kinematics, in rigid-body power grasps. The set of possible contact forces can be calculated using the constraint. This approach can be applied to not only mechanical analysis of power grasps but also that of other robotic contact tasks. However, there are some cases where Omata and Nagata’s formulation generates paradoxical results on contact forces. In this paper, we investigate this problem and propose a modified method to calculate the set of possible indeterminate contact forces. We also study how to reduce the computation.

This paper presents manipulation of small electronic parts whose size is submillimeter order or smaller. For assembly of small parts which are components of electronic devices, we need two key technologies: accurate position control and force control in handling them. In this paper, we utilize a four-degree-of-freedom assembly robot with a camera for position control. This vision-based assembly system gives us positioning accuracy of micrometer order. We also control the pressing load of the robot in pick-and-place of small objects indirectly with mechanical springs and a displacement sensor by changing resilience force of springs actively. We execute some experiments to handle small electronic parts using above-mentioned active force control and vision-based position control.

In this paper, the robustness of graspless manipulation (or nonprehensile manipulation) is investigated. We derive some new constraints for static frictional forces in graspless manipulation, which gives us more accurate evaluation of the robustness of graspless manipulation than previous studies. We also present a procedure to calculate a measure of the robustness based on linear programming. Numerical examples are shown to prove that our new method works well even when previous methods make an inappropriate evaluation