Characterization of a multi-chip microelectrofluidic bench for modular fluidic and electric interconnections

We present the design, fabrication, and characterization of a multi-chip microelectrofluidic bench, achieving both fluidic and electric interconnections with simple and low pressure-loss interconnections. The microelectrofluidic bench provides easy alignment of fluidic interconnection using microfabricated annular fluidic connectors; also provides simple electric interconnection using isotropic conductive adhesives at room temperature. Thus, the present microelectrofluidic bench provides a modular concept for fluidic and electric interconnection. In experimental study, we characterize pressure losses, electric resistances loss, and pressure stability of the interconnection. The average pressure drop per each fluidic contact is measured 0.12 ± 0.19 kPa at the DI water flow rate from 10 to 100 μl min⁻¹. The electric resistance per each electric contact is measured as 0.64 ± 0.29 Ω. The fluidic interconnection endures maximum pressure of 115 ± 11 kPa. The present microelectrofluidic bench, therefore, offers a simple and low pressure-loss electrofluidic modular interconnection for electrofluidic multi-chip microsystems.     

Application of the general elimination method in robot kinematics

A general method for solving the robot inverse kinematics problem is presented. The method is based upon the general elimination method to obtain the equivalent system of equations which are triangularized and the solutions of the inverse kinematics problem can be solved by backsubstitutions.     

On rotation representations in computational robot kinematics

Various methods of implementing forward and inverse kinematics of six-axes industrial robots are analyzed in this paper from the viewpoint of numerical conditioning and convergence speed both close to a solution and away from it. Computational complexities are derived in terms of the number of arithmetic operations and comparisons are made by observing the actual CPU time consumption. The formulations presented make use of different sets of invariants describing the orientation of the gripper. It is shown that, in inverse kinematics, there is a tradeoff between numerical stability and computational speed.An abridged version of this paper was presented in the 1992 IEEE International Conference on Robotics and Automation, 1992 [1].     

The kinematics of modular spatial hyper-redundant manipulators formed from RPS-type limbs

This study addresses the kinematics, including position, velocity and acceleration analyses, of a modular spatial hyper-redundant manipulator built with a variable number of serially connected identical mechanical modules with autonomous motions. First, the kinematics of the base module, a three-legged in-parallel manipulator, is formulated using the theory of screws. After that, the results thus obtained, are applied recursively for accomplishing the kinematic analyses of the hyper-redundant manipulator at hand. A numerical exampled is included.     

Symbolic modeling of robot kinematics and dynamics

As a component of advanced manufacturing technology, this report presents applications of FORM to solve symbolically a class of usual robotic problems. One advantage of this symbolic manipulation code is to perform, even on PCs, the manipulation of giant formulae. Though the code has a low built-in knowledge, but handles indices, vectors, matrices, traces, tensors, as well as factorial and delta functions, it can be directly ported on a large variety of computers such as Alliant, Appolo, Atari ST, Gould (NP1 and 9080), MacIntosh, PCs, SUN and VAX (VMS and Ultrix). The symbolic programs given in this paper perform on PCs the kinematics and dynamics analysis of simple robots via the free version 1.0 of FORM. This approach shows us a way to develop at low cost many useful robotic packages for education as well as Research & Development purposes.     

Analytic generation of workspace using the robot kinematics

When designing workplaces, controls should be placed within the reach of an operator's arm or foot for guaranteeing effective performance. In designing a workplace which must cater to a wide range of operator size, it might be sufficient to plan only for the ‘average person’. Static arm reach measurements which are taken in conventional, standardized positions provide necessary information, but they cannot be applied to dynamic situations directly. To obtain reach envelope or workspace of the human body not by direct measurement but by analytic generation, data on range of joint motion(ROM) are required as an input. The purposes of this research are to measure the range of motion of two degrees of freedom for Korean young males, and to propose an approximate algorithm to generate the workspace of the human body including foot and trunk motion, in which joint mobility of two degrees of freedom motion are considered. The robot kinematics was employed to represent the human body as a multi-link system.     

多智能体的机器人逆运动学算法研究

提出了一种基于多智能体的逆运动学算法,算法采用多个关节智能体协同进行串行和并行运算求解,适用于绝大多数关节机器人,不受关节形状和关节数目的限制。     

Effects of military load carriage on kinematics of gait

Manual load carriage is a universal activity and an inevitable part of the daily schedule of a soldier. Indian Infantry soldiers carry loads on the waist, back, shoulders and in the hands for a marching order. There is no reported study on the effects of load on gait in this population. It is important to evaluate their kinematic responses to existing load carriage operations and to provide guidelines towards the future design of heavy military backpacks (BPs) for optimising soldiers' performance. Kinematic changes of gait parameters in healthy male infantry soldiers whilst carrying no load (NL) and military loads of 4.2–17.5 kg (6.5–27.2% body weight) were investigated. All comparisons were conducted at a self-selected speed. Soldier characteristics were: mean (SD) age 23.3 (2.6) years; height 172.0 (3.8) cm; weight 64.3 (7.4) kg. Walk trials were collected using a 3-D Motion Analysis System. Results were subjected to one-way ANOVA followed by Dunnett post hoc test. There were increases in step length, stride length, cadence and midstance with the addition of a load compared to NL. These findings were resultant of an adaptive phenomenon within the individual to counterbalance load effect along with changes in speed. Ankle and hip ranges of motion (ROM) were significant. The ankle was more dorsiflexed, the knee and hip were more flexed during foot strike and helped in absorption of the load. The trunk showed more forward leaning with the addition of a load to adjust the centre of mass of the body and BP system back to the NL condition. Significant increases in ankle and hip ROM and trunk forward inclination (≥10°) with lighter loads, such as a BP (10.7 kg), BP with rifle (14.9 kg) and BP with a light machine gun (17.5 kg), may cause joint injuries. It is concluded that the existing BP needs design improvisation specifically for use in low intensity conflict environments.

Statement of Relevance:The present study evaluates spatial, temporal and angular changes at trunk and limb joints during military load carriage of relatively lighter magnitude. Studies on similar aspects on the specific population are limited. These data can be used for optimising load carriage and designing ensembles, especially a heavy BP, for military operations.     

Inverse kinematics of spherical wrist robot arms: Analysis and simulation

The spherical wrist robot arm is the most common type of industrial robot. This paper presents an efficient analytical computation procedure of its inverse kinematics. It is based on the decomposition of the inverse kinematic problem to two less complex problems; one concerns the robot arm basic structure and the other concerns its hand. The proposed computation procedure is used to obtain the inverse kinematic position models of two robot arms: one contains only revolute joints and the other contains both revolute and prismatic joints. The 1st and 2nd time derivatives of the obtained models give more accurate inverse kinematic velocity and acceleration models than numerical differentiation. These models are verified by simulation for two different trajectories. The obtained results demonstrate the effect of the proposed procedure on reducing the necessary computation time compared to other computation techniques.     

Neural networks and the inverse kinematics problem

Inverse kinematics is a fundamental problem in robotics. Past solutions for this problem have been realized through the use of various algebraic or algorithmic procedures. In this paper the use of feedforward neural networks to solve the inverse kinematics problem is examined for three different cases. A closed kinematic linkage is used for mapping input joint angles to output joint angles. A three-degree-of-freedom manipulator in 3D space is used to test mappings from both cartesian and spherical coordinates to manipulator joint coordinates. A majority of the results have average errors which fall below 1% of the robot workspace. The accuracy indicates that neural networks are an alternate method for performing the inverse kinematics estimation, thus introducing the fault-tolerant and high-speed advantages of neural networks to the inverse kinematics problem.This paper also shows the use of a new technique which reduces neural network mapping errors with the use of error compensation networks. The results of the work are put in perspective with a survey of current applications of neural networks in robotics.     

6R关节型机器人运动学建模

为满足新开发的多机器人实验系统编程需要,研究了6R机器人运动学逆解问题.推导了代数逆解结果,并研究了将其用于实际控制系统时,逆解的漏解、增根和多解问题.与传统方法比较,采用了便于程序模块化的坐标系设置方式,在需要经常更换作业工具的多机器人系统中更为适用.推导过程只需2次矩阵逆乘,步骤简单.基于VC++和OpenGL技术编制了系统程序,检验了方法的有效性.以其中一个位姿为例,对比几何方法得出的结果,验证了算法的正确性.研究的结果适用于MOTOMAN-UP6和PUMA560等相似构型的所有机器人.     

Improving the panconnectedness property of locally twisted cubes

The n-dimensional locally twisted cube LTQ_n is a promising alternative to the hypercube because of its great properties. Not only is LTQ_n n-connected, but also meshes, torus, and edge-disjoint Hamiltonian cycles can embed in it. Ma and Xu [Panconnectivity of locally twisted cubes, Appl. Math. Lett. 19 (2006), pp. 681–685] investigated the panconnectivity of LTQ_n for flexible routing. In this paper, we combine panconnectivity with Hamiltonian connectedness to define Hamiltonian r-panconnectedness: a graph G of m vertices, m≥3, is Hamiltonian r-panconnected if for any three distinct vertices x, y, and z of G there exists a Hamiltonian path P of G such that P(1)=x, P(l+1)=y, and P(m)=z for every r≤l≤m?1?r, where P(i) denotes the ith vertex of P for 1≤i≤m. Then, we show that LTQ_n is Hamiltonian n-panconnected for n≥5. This property admits the path embedding via an intermediate node at any prescribed position, and our result achieves an improvement over that of Ma and Xu.     

Parallel VLSI architectures for real-time kinematics of redundant robots

We describe new architectures for the efficient computation of redundant manipulator kinematics (direct and inverse). By calculating the core of the problem in hardware, we can make full use of the redundancy by implementing more complex self-motion algorithms. A key component of our architecture is the calculation in the VLSI hardware of the Singular Value Decomposition of the manipulator Jacobian. Recent advances in VLSI have allowed the mapping of complex algorithms to hardware using systolic arrays with advanced computer arithmetic algorithms, such as the coordinate rotation (CORDIC) algorithms. We use CORDIC arithmetic in the novel design of our special-purpose VLSI array, which is used in computation of the Direct Kinematics Solution (DKS), the manipulator Jacobian, as well as the Jacobian Pseudoinverse. Application-specific (subtask-dependent) portions of the inverse kinematics are handled in parallel by a DSP processor which interfaces with the custom hardware and the host machine. The architecture and algorithm development is valid for general redundant manipulators and a wide range of processors currently available and under development commercially.     

Adaptive task-space regulation of rigid-link flexible-joint robots with uncertain kinematics

In this paper, an adaptive control scheme is proposed for the regulation problem of rigid-link flexible-joint (RLFJ) robots with uncertain kinematics. Existing research works in literature on RLFJ robot control assume exact knowledge of the kinematics of robot, and no result that can deal with kinematics uncertainty in RLFJ robot has been proposed so far. This paper presents the first study addressing this problem. The adaptive control scheme proposed can deal with the kinematics uncertainty and uncertainties in both link and actuator dynamics of the RLFJ robot system. A nonlinear observer is designed to avoid the use of acceleration due to the fourth-order overall dynamics. Asymptotic stability of the closed-loop system is shown and sufficient conditions are presented to guarantee the stability. Simulation results are provided to illustrate the effectiveness of the proposed control method.     

Overview of damped least-squares methods for inverse kinematics of robot manipulators

In this paper, we present a tutorial report of the literature on the damped-least squares method which has been used for computing velocity inverse kinematics of robotic manipulators. This is a local optimization method that can prevent infeasible joint velocities near singular configurations by using a damping factor to control the norm of the joint velocity vector. However, the exactness of the inverse kinematic solution has to be sacrificed in order to achieve feasibility.The damping factor is an important parameter in this technique since it determines the trade-off between the accuracy and feasibility of the inverse kinematic solution. Various methods that have been proposed to compute an appropriate damping factor are described.Redundant manipulators, possessing extra degrees of freedom, afford more choice of inverse kinematic solutions than do non-redundant ones. The damped least-squares method has been used in conjunction with redundancy resolution schemes to compute feasible joint velocities for redundant arms while performing an additional subtask. We outline the different techniques that have been proposed to achieve this objective. In addition, we introduce an iterative method to compute the optimal damping factor for one of the redundancy resolution techniques.     

超冗余度桁架机械臂的容错逆运动学仿真

超冗余度桁架机械臂路径规划中的逆运动学解算为一非线性优化问题,桁架机械臂冗余度高,容错性好,由于传统方法速度和收敛性较慢,冗余性和容错性未能得到很好的利用.为解决此问题,引入收敛速度较快的对偶内点法,针对问题规模较大占用内存多的特点,设计了一种基于稀疏矩阵向量相乘的减小内存方案.搭建了仿真平台,进行了三组正常和故障状态逆向运动学仿真解算,结果表明:该方法收敛性好,解算迅速,在故障状态下的逆运动学解算也较为理想,适用于进一步实际应用.     

Adaptive inverse dynamics control of robots with uncertain kinematics and dynamics

It has been about two decades since the first globally convergent adaptive tracking controller was derived for robots with dynamic uncertainties. However, not until recently has the problem of concurrent adaptation to both the kinematic and dynamic uncertainties found its solution. This adaptive controller belongs to passivity-based control. Though passivity-based controllers have many attractive properties, in general, they are not able to guarantee the uniform performance of the robot over the entire workspace. Even in the ideal case of perfect knowledge of the manipulator parameters, the closed-loop system remains nonlinear and coupled. Thus the closed-loop tracking performance is difficult to quantify, while the inverse dynamics controllers can overcome these deficiencies. Therefore, in this work, we will develop a new adaptive Jacobian tracking controller based on the inverse manipulator dynamics. Using the Lyapunov approach, we have proved that the end-effector motion tracking errors converge asymptotically to zero. Simulation results are presented to show the performance of the proposed controller.