Digital type disturbance compensation control of a floating underwater robot with 2 link manipulator

We have proposed continuous and discrete time resolved acceleration control methods for underwater vehicle-manipulator systems and the effectiveness of the control methods have been shown by experiments. In this paper, we propose a digital type disturbance compensation control method based on the RAC method considering singular configuration of manipulator. Experimental results show the effectiveness of the proposed method. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January 25–27, 2007     

Digital RAC for underwater vehicle-manipulator systems considering singular configuration

We have proposed continuous-time and discrete-time resolved acceleration control methods for underwater vehicle-manipulator systems and the effectiveness of the control methods has been shown by experiments. In this article, we propose a digital control method considering the singular configuration of manipulator. Experimental results show the effectiveness of the proposed method. This work was presented in part at the 10th International Symposium on Artificial Life and Robotics, Oita, Japan, February 4–6, 2005     

Nonlinear control with acceleration feedback for a two-link flexible robot

In this paper, a three-loop control strategy is applied to each link of a two-link flexible robot. In the first loop feedback linearization is applied to the rigid and motor dynamics. The second loop consists of a simple proportional-derivative (PD) control law for accurate rigid body angle tracking. The third loop uses endpoint accelearation feedback to account for flexure effects. The overall scheme is relatively simple in order to facilitate easy implementation; experimental results are provided to verify the effectiveness of the developed schemes.     

Experiences and results from designing and developing a 6 DoF underwater parallel robot

REMO I Robot is a novel application of a parallel structure as an underwater robot of 6 DoF. Compared to other underwater robots, navigation of REMO I Robot is performed by the capability of its parallel structure to modify its geometric structure (thruster and front ring) and to displace by itself. This kinematic property of the parallel platform allows vectorial formation of thrusting forces to take place. Remo I Robot has just one single thruster in its rear ring, therefore the vectorial navigation gives maneuverability, flexibility, and holonomic capabilities for its navigation and positioning. The latter is important for intervention and manipulation tasks. That is why it gives a solid alternative when compared to traditional submarine robots such as shown in the simulation results and experiments performed using a real prototype. In conclusion, this paper proposes a conceptual frame for the development of underwater parallel robots. Moreover, it also points out the experience acquired from the development of the underwater Remo I Robot.     

双关节机器人操作臂控制系统设计

本设计针对工业现场使用的双关节机器人,主要完成了硬件系统平台构建和软件系统的设计。应用单片机技术,设计一款主从操作的控制器,能够根据旋转编码器的控制指令精确的控制电机的速度、位置、正反转等物理量,从而满足机器人操作臂精确位置伺服驱动的要求。     

新型多旋翼作业型空中机器人自抗扰控制

针对输电线路树障清理作业任务对空中机器人平台稳定性、平动性和抗扰性的高要求,为克服传统平面配置多旋翼无人机姿态配合式位置移动的缺点,本文在全驱动多旋翼飞行器设计思想的启发下,提出并设计了一种无需姿态配合即可实现前后平移运动的非平面作业型多旋翼空中机器人.首先分别建立其姿态的运动学和动力学模型,然后采用自抗扰控制技术设计了该机器人的位置和姿态跟踪控制律.多组仿真和样机实验结果表明,本文所设计的非平面配置旋翼空中机器人在作业过程中的接触力扰动下具有良好稳定性、平动性和抗扰性.     

Rule-based supervisory control of a two-link flexible manipulator

In this paper, we propose a two level hierarchical control strategy to achieve accurate end-point position of a planar two-link flexible manipulator. The upper level consists of a feedforward rule-based supervisory controller that incorporates fuzzy logic, whereas the lower level consists of conventional controllers that combine shaft position-endpoint acceleration feedback for disturbance rejection properties and shaping of the (joint) actuator inputs to minimize the energy transferred to the flexible modes during commanded movements. The effectiveness of this hierarchical control strategy is verified by experimental results for various movements of the links, in various configurations. In particular, we illustrate how the hierarchical intelligent control strategy performs better than conventional control techniques for endpoint position control in the presence of flexure effects.     

Modelling the movement of a two-link manipulator

An algorithm for optimizing the control signal for simple movements of a two-link manipulator with four degrees of freedom is described. Based on the typical movement and functions of upper human extremities, the manipulator (so-called anthropomorphic manipulator) is composed of two links. The motion of the links is developed by four driving motors. The mathematic model is based of the Lagrange equations of the IInd king. The minimization of the time of movement with initial limitation of accuracy is obtained and the error of the final position is minimized without changing the time-optimal criterion. The relations connected with minimalization of both quality factors are considered. At the same time, the algorithm optimizes the torque distribution between the actuators which drive each link of manipulator. As well the manipulator as its activity are modelled on the digital computer. The results of the computer simulation of the algorithm, and the modelling of the time and accuracy optimal control, are presented.     

A design of digital adaptive control systems for space robot manipulators using a transpose of the generalized Jacobian matrix

We propose a digital control method for space robot manipulators using the transpose of the generalized Jacobian matrix. The method, however, is developed on the supposition that all the physical parameters of the robot manipulator are known. Therefore, if the end-effector of the manipulator captures an object whose mass is unknown, the stability of the control system cannot be maintained because the physical parameters are changed. This article presents the adaptive control version.This work was presented, in part, at the 9th International Symposium on Artificial Life and Robotics, Oita, Japan, January 28–30, 2004     

机械手臂的多模型预测控制

针对机械手臂的非线性特点,提出了基于隶属度函数的多模型预测控制方法。该方法首先根据机械手臂的特点,选择合适的调度变量,将机械手臂的工作空间划分为若干个工作子空间,在每个子空间内的平衡点处对机械手臂进行线性化处理,得到相应的线性子模型,从而得到机械手臂的多模型表示;其次针对每个线性子模型设计局部预测控制器,使其在相应的子空间内达到控制要求;最后选择梯形隶属度函数与局部预测控制器进行加权求和,获得全局多模型预测控制器,以对机械手臂进行控制。仿真结果表明,当机械手臂的工作条件在大范围内变化时,全局多模型预测控制器的控制性能远优于常规PD控制器,达到了预期的控制目的。     

Dynamic modelling and adaptive robust tracking control of a space robot with two-link flexible manipulators under unknown disturbances

In this paper, both the closed-form dynamics and adaptive robust tracking control of a space robot with two-link flexible manipulators under unknown disturbances are developed. The dynamic model of the system is described with assumed modes approach and Lagrangian method. The flexible manipulators are represented as Euler–Bernoulli beams. Based on singular perturbation technique, the displacements/joint angles and flexible modes are modelled as slow and fast variables, respectively. A sliding mode control is designed for trajectories tracking of the slow subsystem under unknown but bounded disturbances, and an adaptive sliding mode control is derived for slow subsystem under unknown slowly time-varying disturbances. An optimal linear quadratic regulator method is proposed for the fast subsystem to damp out the vibrations of the flexible manipulators. Theoretical analysis validates the stability of the proposed composite controller. Numerical simulation results demonstrate the performance of the closed-loop flexible space robot system.     

Methodology for the kinematical selection of a manipulator for a specified task

Manipulator design methodology is a recent and important issue in the robot design research area. Most importantly, to design a robot rationally, one must have a strong understanding of the design parameters of the manipulator, and of the characteristics of the robot relative to its kinematical and dynamical requirements. Development of a robot capable of fast movements or high payloads is progressed by the analysis of dynamic characteristics, DOF positioning, actuator selection, structure of links, and so on. This paper highlights the design of a robot manipulator scaled down from its final form, when it will passively be handled by a human for man-machine cooperation. The requirements of the system include its having 6-DOF and the capacity for a high payload in the condition of its maximum reach. The primary investigation factors are motion range, performance within the motion area, and reliability during the handling of heavy materials. Traditionally, the mechanical design of robots has been viewed as a problem of packaging motors and electronics into a reasonable structure. This process usually transpires with heavy reliance on designer experience. Not surprisingly, the traditional design process contains no formally defined rules for achieving desirable results, as there is little opportunity for quantitative feedback during the formative stages. This work primarily focuses on the selection of proper joint types and link lengths, considering a specific task type and motion requirements of the curtain wall installation process in the construction site based on the result of experiment of proto type system of this study.     

用固定单信标修正水下机器人导航误差

针对固定单信标情况下水下机器人纯距离导航非线性系统的能观性和稳定性,给出了理论分析和证明.在导航系统稳定性分析基础上,提出一种保证滤波器渐近稳定的新方法,并提出固定单信标情况下的保证导航系统能观的机器人机动方案和路径.最后,仿真实验结果表明了该方法的有效性.     

Digital control of space robot manipulators with velocity type joint controller using transpose of generalized Jacobian matrix

For free floating space robots having manipulators, we have proposed a discrete-time tracking control method using the transpose of Generalized Jacobian Matrix (GJM). Control inputs of the control method are joint torques of the manipulator. In this paper, the control method is augmented for angular velocity inputs of the joints. Computer simulations have shown the effectiveness of the augmented method. This work was presented in part and awarded as Best Paper Award at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

双连杆刚柔机械臂无残余振动位置控制

针对双连杆刚柔机械臂,提出一种基于轨迹规划的无残余振动位置控制方法,在将机械臂的末端执行器从任意初始位置移动到目标位置的同时,确保系统没有残余振动产生.首先,建立系统的动力学模型,并通过分析该模型得到系统的状态约束方程.其次,基于状态约束方程,运用双向轨迹规划方法规划一条系统前向轨迹和一条系统反向轨迹.然后,利用时间倒转方法及基于遗传算法的轨迹优化方法对两条轨迹进行拼合,得到一条从系统初始状态到目标状态的期望轨迹.最后,设计轨迹跟踪控制器使系统沿期望轨迹到达目标状态,实现系统的无残余振动位置控制目标.仿真结果验证了本文所提方法的有效性.     

Cooperative manipulation of a floating object by some space robots: application of a tracking control method using the transpose of the generalized Jacobian matrix

In future space missions, it is considered that many tasks will be achieved by cooperative motions of space robots. For free-floating space robots with manipulators, we have proposed a digital tracking control method using the transpose of the generalized Jacobian matrix (GJM). In this paper, the tracking control method using the transpose of the GJM is applied to cooperative manipulations of a floating object by space robots. Simulation results show the effectiveness of the control method. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January 25–27, 2007     

3D Surface-Tracking with a robot manipulator

This paper presents incremental research in Surface Tracking with a robot manipulator. Surface tracking is an important operation in self-teaching and exploratory tasks in unknown environments, and to cope with inaccurate workspace and environment modeling. The paper addresses the problem of 3D Surface-Tracking in contact, where the main concern is the angle formed between the end-effector and the surface. This study constitutes a first approach to the more general and important problem of surface following in contact. The new contribution is the 3D tracking operation based on a new alignment control algorithm using real-time contact force feedback. Simulations, and experimental results using the PUMA 560 manipulator demonstrate the feasibility of the proposed algorithm. This paper also presents a method for tool-tip contact frame calibration using forces/moments data.     

Nonlinear robust adaptive Cartesian impedance control of UAVs equipped with a robot manipulator

In this paper, a new nonlinear robust adaptive impedance controller is addressed for Unmanned Aerial Vehicles (UAVs) equipped with a robot manipulator that physically interacts with environment. A UAV equipped with a robot manipulator is a novel system that can perform different tasks instead of human being in dangerous and/or inaccessible environments. The objective of the proposed robust adaptive controller is control of the UAV and its robotic manipulator’s end-effector impedance in Cartesian space in order to have a stable physical interaction with environment. The proposed controller is robust against parametric uncertainties in the nonlinear dynamics model of the UAV and the robot manipulator. Moreover, the controller has robustness against the bounded force sensor inaccuracies and bounded unstructured modeling (nonparametric) uncertainties and/or disturbances in the system. Tracking performance and stability of the system are proved via Lyapunov stability theorem. Using simulations on a quadrotor UAV equipped with a three-DOF robot manipulator, the effectiveness of the proposed robust adaptive impedance controller is investigated in the presence of the force sensor error, and parametric and non-parametric uncertainties.     

A novel path planning and control framework for passive resistance therapy with a robot manipulator

In this article, we present a paradigm for safe path generation and control for a robotic manipulator such that it provides programmable passive resistance therapy to patients with deficits in the upper extremities. When the patient applies an interaction force at the robot's end-effector, a dynamic path generator time parameterises any therapist-specified contour in the robot's workspace–thus, the robot mimics the dynamics of a passive impedance whose anisotropy vector can be continuously reconfigured. The proposed algorithm is easily implementable because it is robust to uncertainty in the robot dynamics. Moreover, the proposed strategy also guarantees user safety by maintaining the net flow of energy during the human robot interaction from the user towards the manipulator.