基于强化学习的机械臂避碰研究

将强化学习引入机械臂的避碰问题研究,建立了平面三自由度机械臂的多Agent避碰系统,系统结合了最近障碍物信息和偏差角信息来产生控制指令.采用基于K-均值聚类的强化学习方法作为基本的控制策略,给出了系统算法的具体实施过程.通过仿真试验,证明了基于聚类划分的强化学习方法在机械臂避碰问题中的可行性和有效性.     

Control of a high precision macro-micro robotic manipulator system

A controller for macro-micro robotic manipulator system in which kinematically independent two robotic sub-systems work together to improve the accuracy of the motion is proposed. A nonlinear feedback linearization scheme is employed as basic architecture for the controller and additional formulations about the controller structure are made to assure the robustness of the overall control action and to restrict the motion of micro sub-system close to its nominal position without causing saturation of joints associated with micro-robot.     

空间机械臂模拟系统的设计与实现

针对某科技馆的一个科普展品,设计了一种空间机械臂模拟系统。首先对空间机械臂各部分的结构和传动机构进行了设计,利用D—H坐标法建立了机械臂的运动学模型,并进行了其运动学正、反解的求解。然后,构建了空间机械臂的伺服控制系统,开发了上位工控机和底层运动控制器的控制软件。最后,使用Quest3D虚拟现实软件制作了VR机械臂。机械臂模拟系统的工作情况表明,该系统可以满足科普展品的要求。     

一种车载式排爆机械手的机构设计

为提高排爆工作的安全性,本文研究设计了一种基于高压水射流技术的车载式排爆机械手。由于该机械手的排爆方式和行进机构特殊性,将机械手分成固定部分和活动部分来分别进行设计并采用电机作为驱动机构。在活动部分的设计中,通过仿生人的手臂关节确定了该部分的形状和尺寸,以便能灵活地完成对不同类型的爆炸物进行排除。本文用Solid Works三维软件建立了该机械手模型。同时还将活动部分中的小臂分为摆动和旋转两节,既增强了机械手的稳定性和灵活性,又降低了机械手的控制部分难度。通过计算得出了机械手的运动范围。     

基于最小疼痛感的机器人操作臂轨迹规划方法

针对机器人操作臂跟踪运动目标的问题,从仿生学的角度提出一种新的轨迹规划方法.将关节加速度的增量进行编码,同时将疼痛感作为优化指标,利用遗传算法在操作臂的关节空间进行轨迹优化,得到操作臂在跟踪运动目标过程中的具有较小疼痛感的轨迹.仿真试验结果表明,所提出的方法是可行的,可以规划出正确的跟踪轨迹,同时有效的减小了操作臂运动过程中的疼痛感.     

基于RBF的机械手无需模型自适应控制研究

针对机械手存在的扰动等未知模型,提出了基于RBF神经网络的自适应控制策略.采用RBF神经网络对机械手动力学模型在线自学习,并根据Lyapunov稳定性理论建立了网络权值自适应学习律,确保了网络逼近误差的收敛及系统的稳定.以平面转动双臂机械手轨迹跟踪为例进行仿真,结果表明该方法能够有效地补偿建模误差,实现了无需模型的机械手自适应控制,提高了系统的控制性能及对外部不确定扰动的鲁棒性,对实际工业机械手的自适应控制具有一定的可操作性.     

Gravity-balancing of spatial robotic manipulators

This paper describes the underlying theory of gravity balanced spatial robotic manipulators through a hybrid strategy which uses springs in addition to identification of the center of mass using auxiliary parallelograms. A significant contribution of this paper is to show that springs with fixed ends are sufficient to gravity balance a spatial mechanism if the hybrid method of gravity balancing is used where the center of mass is identified first through auxiliary parallelograms. Also, the system remains gravity balanced even if the orientation of the base is changed, i.e., the direction of the gravity is changed with respect to the base. Although the method can be applied to n link spatial serial manipulators, we apply the method for gravity compensation of two and three degrees-of-freedom (DOF) spatial manipulators. A prototype with the underlying principles of this paper was fabricated at the University of Delaware.     

Reachable workspace determination for a spatial hyper-redundant manipulator formed by several parallel manipulators

Solving the reachable workspaces of spatial hyper-redundant manipulators (SHRMs) formed by serially connected parallel manipulators is an important and challenging work. This study addresses the issue on reachable workspaces and establishes a novel CAD-VBbased workspace determination system for determining the reachable workspaces of SHRMs. The reachable workspace determination of a novel (3-RPS)+(3-SPR)+(3-RPS) SHRM, a triple delta-type SHRM, and a novel (3-RRS)+(3-SPR)+(3-RRS) SHRM shows the generality and effectiveness of the proposed approach. The system proposed in this study can contribute to reachable workspace analysis for SHRMs.

     

Implementation of robust adaptive control for robotic manipulator using TMS320C30

A new adaptive digital control scheme for the robotic manipulator is proposed in this paper. Digital signal processors are used in implementing real time adaptive control algorithms to provide an enhanced motion for robotic manipulators. In the proposed scheme, adaptation laws are derived from the improved Lyapunov second stability analysis based on the adaptive model reference control theory. The adaptive controller consists of the adaptive feedforward and feedback controller and PI type time-varying control elements. The control scheme is simple in structure, fast in computation, and suitable for implementation of real-time control. Moreover, this scheme does not require an accurate dynamic modeling, nor values of manipulator parameters and payload. Performance of the adaptive controller is illustrated by simulation and experimental results for a SCARA robot.     

气动平衡助力机械手的原理及应用

本文从机械构造,结构细节及气动控制原理等多方面详细介绍了气动平衡助力机械手,并阐述了其在工业自动化领域中的广泛应用.     

Design of a slider-crank leg mechanism for mobile hopping robotic platforms

Legged locomotion has been widely researched due to its effectiveness in overcoming uneven terrains. Due to previous efforts there has been much progress in achieving dynamic gait stability and as the next step, mimicking the high speed and efficiency observed in animals has become a research interest. The main barrier in developing such a robotic platform is the limitation in the power efficiency of the actuator: the use of pneumatic actuators produce sufficient power but are heavy and big; electronic motors can be compact but are disadvantageous in producing sudden impact from stall which is required for high speed legged locomotion. As a new attempt in this paper we suggest a new leg design for a mobile robot which uses the slider-crank mechanism to convert the continuous motor rotation into piston motion which is used to impact the ground. We believe this new mechanism will have advantage over conventional leg mechanism designs using electronic motors since it uses the continuous motion of the motor instead of sudden rotation movements from stall state which is not ideal to draw out maximum working condition from an electronic motor. In order to control impact timing from the periodic motion of the piston a mechanical passive clutch trigger mechanism was developed. Dynamic analysis was performed to determine the optimal position for the mechanical switch position of the clutch trigger mechanism, and the results were verified through simulation and experiment. Development of a legged locomotion with two degrees of freedom, slider-crank mechanism for impact and additional actuation for swing motion, is proposed for future work.     

Dynamic characteristics of piezoelectric six-dimensional heavy force/moment sensor for large-load robotic manipulator

This paper presents research on dynamic characteristics of a piezoelectric six-dimensional heavy force/moment sensor for a large-load robotic manipulator. The theory on dynamic characteristics of the sensor structure is analyzed, and a mathematical model of the sensor dynamics, decoupled into separate vibration modes, is provided. This model is complemented by dynamic mode analysis of the sensor by finite-element modeling (FEM; ANSYS software). A dynamic calibration experiment is designed, and methods and principles for measurements and data analysis are provided. The characteristic dynamic vibration modes of the piezoelectric force/moment sensor are extracted by analyzing experimental data, yielding amplitude frequency and phase frequency curves of the transfer function linking the excitation loads with the output signals of the transducer. The results of the dynamic calibration experiment demonstrate the good dynamic characteristics of the piezoelectric six-dimensional heavy force/moment sensor. The natural frequencies in the three force directions are high, with values close 2000 Hz. This demonstrates the applicability of the presented six-dimensional heavy force/moment sensor to large industrial robotic manipulators.     

空间弹性并联机器人KED建模

本文首次用有限元方法建立了一种空间６自由度并联机器人的弹性动力学模型,文中根据并联机器人的结构特点,设其平台为刚性体,各条腿为弹性体,再根据平台与腿部的运动协调方程推导出它的ＫＥＤ方程,已知机器人的刚体运动规律,由此方程可以求出其平台以及腿部各关节的弹性运动规律,最后给出了数值例。     

管内异物抓取机械手机构参数优化设计

考虑抓取机械手工作于狭小圆形管道内与工作对象的分布特点两方面因素,管内异物抓取机械手采用三自由度关节型机械手的机构型式.以机械手的工作空间主截面最大与杆件长度尺寸之和最小为优化目标,建立了综合优化目标函数,得到机械手的结构参数优化解,为机械手的结构设计及运动学与动力学分析提供了基础参数.同时对所得优化结果做了进一步分析,为机械手的机构参数的修改与调整提供了可靠的理论依据.     

Off-line nominal path generation of 6-DoF robotic manipulator for edge finishing and inspection processes

Due to some special properties, alloy cast iron HTCuCrSn-250 is widely used to manufacture the cylinder block of the diesel engines. However, the additional alloying elements aggravated tool wear which is significantly affected by cutting parameters during machining process. In this paper, tool wear in face milling of alloy cast iron under constant material removal volume (MRV) condition was investigated. First, the relationship between tool flank wear (VB) and MRV was determined. Secondly, the wear morphology and mechanism were analyzed and a predicted model between cutting parameters and tool wear was proposed. Finally, the optimization was taken, and three groups of optimal parameters were obtained. This research illustrated that different combinations of cutting parameters result in different wear morphology and the main wear mechanisms are diffusion and oxidation. This research also indicated the two parameters, axial depth of cut and the radial depth of cut, which have significant impact on the tool wear. Meanwhile, a model between VB and the cutting parameters under the constant MRV condition during milling HTCuCrSn-250 was proposed.     

Trajectory tracking of a spatial flexible link manipulator using an inverse dynamics method

Discussed in this paper is the problem of trajectory tracking of a spatial flexible link manipulator. To solve this problem, an inverse dynamics method is proposed, based on which computed joint torques can be determined and used to drive the endpoint of a spatial flexible link manipulator to follow its given trajectory.     

Optimal load of robotic manipulator with joint elasticity using accuracy and actuator constraints

A computational technique for obtaining the maximum load-carrying capacity for a robotic manipulator with joint elasticity, subject to accuracy and actuator constraints, is described. Full load motions and increased productivity are linked in the industrial applications of many robotic manipulators; the maximum load carrying capacity which can be achieved by a manipulator during a given trajectory is limited by a number of factors. The dynamic properties of a manipulator, its actuator limitations, and joint elasticity (transmissions, reducers, and servo drive system) are probably the most important factors. This paper presents a strategy for determining dynamic load carrying capacity (DLCC), subject to both accuracy and actuator constraints, where a series of cubical bounds centred at the desired trajectory is used in the end-effector oscillation constraint while a typical d.c. motor speed-torque characteristics curve is used in the actuator constraint. The technique which considers the full nonlinear manipulator dynamics, actuator constraints, and accuracy constraints permits the manipulator user to specify the trajectory completely. Finally, a numerical example involving a two-link manipulator with joint flexibility using this method is presented and the results are discussed.     

空间对接缓冲试验台对接环重力平衡技术

在空间对接机构地面缓冲实验平台上,为了模拟空间失重状态,研制了一种高精度、高响应速度的主动对接环重力平衡装置.介绍了对接环重力平衡装置的机构原理.对对接过程随动装置的随动性对系统的干扰进行了详细分析.进行了重力平衡器相关实验,从实验数据和理论分析可以得出:所设计的重力平衡装置完全满足对摩擦阻力和惯性阻力设计指标的要求,重力平衡达到1.1%的精度.     

基于欠驱动机构的水下作业机械手仿真研究

建立了机械手的三维模型,对机械手运动学和动力学性能进行了仿真研究,分析了运动部件之间的相对关系,完成了机械手抓取不同目标物时的运动学、动力学仿真;机械手采用液压驱动方式,驱动力大、结构简单;机械手有3个手指,采用4个驱动元件实现对机械手11个自由度的驱动,3个手指之间的相对位置可根据抓取目标物的形状而改变,抓取物体时具有形状自适应能力.     

一种新型的空间3-■并联机构的运动仿真

对一种新型的3-RR(RR)R4自由度空间并联机器人进行了位置反解分析,建立机构输入运动副与工作点解析关系,在此基础上,利用Matlab软件构建机构的实体模型,模拟机构的实际运动,并利用微分法做出的机构的速度曲线、加速度曲线与影响系数法求出的速度曲线、加速度曲线进行分析比较.验证了影响系数法对少自由度并联机器人求解的正确性,同时也说明利用该仿真模型能够正确模拟机构的运动特性,为并联机构的优化设计提供依据.