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In this paper, the effect of adding sliding mode methodology to the kinematic control of robot manipulators with damped least square (DLS) Jacobian inverse is studied. The proposed controller is experimentally tested on a 6 degree of freedom (DoF) robotic manipulator. Three different types of end-effector path are considered for which the controller performance is evaluated. The results show that...
For the characteristic of compact structure, low inertia, high rigidness and accuracy, parallel mechanisms are worthwhile to be popularized in the field of agricultural robotization, especially in situations that require precise movement in limited space. Focusing on the harvesting task of strawberries in ridge culture, a 4-PPPR robot manipulator with three translational DOF and one rotational DOF...
Learning by observation is a useful goal for humanoid robots that strive for human-like motion. Over time the movements and actions of these robots are likely to require modification for different scenarios and environments. Therefore being able to `teach' the robot new tasks and motions without tedious programming is highly useful. The operational space formulation is a highly elegant robot manipulator...
This paper suggests a novel reaction force control in a robot manipulator by position feedback that is motivated by the analysis of human musculoskeletal system. First, we suggest an analogy between a muscle force characteristic and two-degree-of-freedom control input structure so that the complicated human muscle structure can be reflected in robot manipulator control. In order to clarify functions...
An adaptive multi-dimensional compliance model reference controller was implemented in real-time on a 4 degrees of freedom (DOF) of the humanoid Bristol-Elumotion-Robotic-Torso II (BERT II) arm in Cartesian space. The robot manipulator has been controlled in such a way as to follow the compliant passive behaviour of a reference mass-spring-damper system model subject to externally sensed forces/torques...
This paper gives an overview of a series of the authors' researches on the passivity-based visual motion observer and its applications to a variety of control and estimation problems. After providing notations and preliminaries, we introduce the visual motion observer which is a mechanism to estimate the target object's motion in 3D space from vision data. We next build a visual motion observer-based...
According to the apple's growth distribution space and ecological characteristics, we developed a five-DOF articulated robot manipulator (including robot arm and its end-effector), which had redundancy to avoid obstacles and had metamorphic mechanism to reach targets flexibly. The real-time image is acquired from a camera with the installation method of Eye-in-hand and the apple's position will be...
This paper suggests a novel reaction force control in a robot manipulator by position feedback, motivated by the analysis of human musculoskeletal system. First, we suggest an analogy between a muscle force characteristic and two-degree-of-freedom control input structure so that the complicated human muscle structure can be reflected in robot manipulator control: reaction force generated by the viscoelasticity...
Dynamic gain scheduling (DGS) is applied to control the end-effector of a robot manipulator mounted on a satellite. DGS is a novel control approach which exploits the availability of a linearized model at each operating point rather than using a complete nonlinear model. This practical study shows the feasibility of the DGS approach for a satellite system in three different simulated scenarios. In...
Studies of human manipulation strategies suggest that pre-grasp object manipulation, such as rotation or sliding of the object to be grasped, can improve task performance by increasing both the task success rate and the quality of load-supporting postures. In previous demonstrations, pre-grasp object rotation by a robot manipulator was limited to manually-programmed actions. We present a method for...
It is interesting to observe from human visually guided tasks that visual feedback is not used for the entire movement, but only at end phases when our hand is near the target. We are able to move our hand from an initial position that is not within our field of view and transit smoothly and easily into visual feedback when the target is near. Inspired by this natural action, this paper presents a...
Behaviors in human reaching movement suggest that certain visually guided tasks consist of an initial movement without visual feedback, and a fine movement with visual feedback when our hand is near the target. Inspired by this phenomenon, we propose a new setpoint controller that only requires vision feedback when the end effector is near a desired position. The proposed controller consists of a...
A novel geometric algorithm is proposed that assures a smooth path around the obstacle by generating a virtual sphere around it. The spherical virtual sphere algorithm (SVSA) makes the end-effector (the outermost tip of a closed gripper and hence, considered a point object) of the robot manipulator navigate along the orthodrome, the shortest path connecting the end-points of the obstacle avoidance...
This paper reveals the advantage of the biarticular muscle which has been said to play an important role in human's motion control and applies it to the robot manipulator control. Biarticular muscle changes the energy flow in muscles resulting in efficient motion and help stabilizing the posture of the human body. These advantages are analyzed and reflected to the control of a robot manipulator. In...
In this paper, a position based impedance controller (i.e. admittance controller) is designed by utilizing measurements of a force/torque sensor, which is mounted at the robot's base. In contrast to conventional force/torque sensing at the end-effector, placing the sensor at the base allows to implement a compliant behavior of the robot not only with respect to forces acting on the end-effector but...
The article shows the design and implementation of an artificial vision system capable to obtain in real time the position of an object (working piece or an end-effector of a robot manipulator) within an enclosed environment like a manufacturing cell using graphical symbols "wall marks" recognition to obtain location. The system comprises a digital camera with pan-tilte movements attached...
We have investigated the deformation of a soft fingertip when it slides. This process was first simulated using the non-linear Finite Element Analysis (FEA) method. Based on the results of this simulation, we designed experiments to observe the sliding and object grasping of a soft fingertip, in which a 3-DOF (degree of freedom) micro force/moment sensor was embedded. With this sensor, forces and...
The accurate and unambiguous description of motion patterns is essential for the type synthesis of robot manipulators, including serial and parallel ones. This paper employs the concept of the GF (Generalized Function) set to achieve a systematic classification of motion patterns. Simple robot structures are illustrated for each motion pattern. The results shown in this paper clarify the classification...
This paper addresses two problems in visually-controlled robots. The first consists of positioning the end-effector of a robot manipulator on a plane of interest by using a monocular vision system. The problem amounts to estimating the transformation between the coordinates of an image point and its three-dimensional location supposing that only the camera intrinsic parameters are known. The second...
In this paper, a region reaching controller with motion constraints is proposed for robot manipulator. In this control concept, the desired objective can be specified as a region instead of a point. In addition, physical constraints can be imposed on the robot motion by defining an additional region for the robot. For example, a region for the boundary of the end effector to avoid singular points...
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