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Continuous monitoring, accuracy of evaluation, and proper analysis of human gait characteristics have presented the importance not only in clinical studies, but also in the field of sports, rehabilitation, training, and robotics research. Human knee joint plays an important role in balancing and stabilizing human body while walking. So it is obvious to observe knee joint movement characteristics as...
The performance of feedforward controllers is known to be subject to the accuracy of the mathematical models used for controlled objects. To obtain an accurate mathematical model for a single-link flexible manipulator, we perform nonlinear modeling based on large-deflection theory. A feedforward vibration control technique is applied to the resulting mathematical model in which we consider point-to-point...
In the present work, a method based on belief space planning, assuming maximum likelihood of the observations, is applied to the planning of manipulation for an underwater robotic arm. The manipulator is rigidly connected to a floating platform, such as a ROV (Remotely Operated Vehicle) or an AUV (Autonomous Underwater Vehicle). The arm and platform motions are statistically independent from the motion...
This paper considers the position tracking control problem of uncertain flexible joint robot system with input time-delay. A new approach is proposed by using prediction scheme and dynamic surface control method. All the signals of the considered system are guaranteed semi-globally uniformly ultimately bounded. Moreover, the tracking error can be tuned as small as possible. A simulation example is...
Mobile manipulators are robots able to accomplish complicated missions, requiring the conjunction of the mobility and the manipulation. This paper is centred on the study of the movement of a single-armed wheeled vehicle. The mobile robot provides mobility to the robotic arm, and adds more degrees of freedom. Manipulation tasks might be, thus, performed in a large workspace. Human can often be replaced...
In this paper, a hexapod robot that consists of its body and six legs is considered. The leg mechanism is a 1-UP&2-UPS (U-universal joint, P-prismatic joint and S-spherical joint) parallel mechanism with three degree-of-freedoms (DOFs). A comparative investigation of tracking control methods in the hexapod robot with parallel legs is presented. The methods include standard PID control, position-velocity...
This paper provides a novel method towards imparting agility to the anguilliform robotic fish. The anguilliform robotic fishes are idealized to the real fishes using a series of N connected links to be closely approximated to their biological counterparts. To generate robot motion, torque are applied to the N-1 joints connecting any two consecutive links. There is high amount of interest among researchers...
This paper presents algorithms for optimal selection of needle grasp, for autonomous robotic execution of the minimally invasive surgical suturing task. In order to minimize the tissue trauma during the suturing motion, the best practices of needle path planning that are used by surgeons are applied for autonomous robotic surgical suturing tasks. Once an optimal needle trajectory in a well-defined...
In this work, we propose a constraint-based algorithm for combined trajectory generation and kinematic control for robotic manipulators. The main feature of the algorithm is to ease robot programming, shifting from an imperative paradigm, in which task constraints are semantically and uniquely mapped into a suitable end-effector velocity profile, towards a declarative motion programming, where such...
Selective tasks such as harvesting or spraying of single crops are a promising research topic in agricultural automation. Inspired by industrial production, an obvious approach is to use robot manipulators in greenhouses and orchards. To exploit the potential of redundant manipulators in particular, advanced motion planning algorithms are needed. While harvesting, a new trajectory for every fruit...
Due to excellent dynamic properties and high precision, parallel manipulators are particularly suited for high-speed and high-accuracy object handling. For this reason, the design process of parallel manipulators is usually supposed to optimize the manipulators' dexterity or structural stiffness. Accordingly, this research intends to analyze the effects of changing actuator and frame-configurations...
It is well known that anthropomorphic manipulators, such as the PA-10, are intolerant to a single locked joint failure of the elbow. This is because the elbow is the only joint that can change the distance between the spherical shoulder joint and the spherical wrist. In this work, it is shown how such arms can be made significantly more fault tolerant by a minor modification to the kinematic structure...
A failsafe control strategy is presented for online safety certification of robot movements in a collaborative workspace with humans. This approach plans, predicts and uses formal guarantees on reachable sets of a robot arm and a human obstacle to verify the safety and feasibility of a trajectory in real time. The robots considered are serial link robots under Computed Torque schemes of control. We...
In this paper, we propose a novel design of compliant safe joint, which has flexibility when the work load exceeds a predefined threshold. The compliance is generated by a spring. We design a special transmission mechanism to convert axial motion into circumferential motion such that the linear compliance can be converted into circular one. When the end-effector of a surgical robot actuated by the...
The snakeboard is a well-studied example for mechanical systems analysis, largely because of its simultaneous richness in behavior and simplicity in design. However, few snakeboard models incorporate dissipative friction in the traveling direction and skidding as a violation of the rigid nonholonomic constraints. In this paper we investigate these effects on trajectory planning by evaluating a previously...
Having human-like motions will make humanoid robots more predictable and safer for the people around them. An effective way to realize this would be to use human motions as reference. Due to different kinematic and dynamic properties between humans and humanoid robots, however, a human motion could be physically infeasible for a robot and cause the robot to fall over. Therefore, it is necessary to...
This paper addresses the issue of workspace trajectory tracking control of flexible robot manipulators. A control strategy integrated with computed-torque-like control scheme, link vibration suppressing control scheme, and learning control scheme is proposed. Dynamics of a virtual rigid robot and vision feedback are used to construct the computed torque like controller. The learning controller is...
This work presents a method for assisting people in getting out of chairs with a dynamically stable mobile robot. A user study is described in which force profiles and joint trajectories were recorded for a human-human sit-to-stand experiment. These data were used to develop an impedance-based controller designed to allow the ballbot to help people out of chairs. The control strategy is experimentally...
An increasing number of robotic systems are using compliant actuators in which springs are placed in series with the actuator. The need for identification procedures tailored to these systems is consequently rising. When measurements of both the link side and the motor side of the spring are available the dynamic parameters can be identified independent of the spring model. The excitation of the identification...
This paper discusses a dynamic nonprehensile manipulation by using a vibrating plate. The manipulation method, where two DOF (degrees of freedom) motion of an object on the plate surface is controlled by a single active joint, is proposed. For the plate vibration mechanism, we newly introduce an active-passive hybrid joint whose two axes are arranged in nonparallel to each other. This mechanism features...
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