Gait Programming for Multi-Legged Robot Climbing on Walls and Ceilings

Wall-climbing gait programming is one of the basic issues for the multi-legged robot working on vertical walls and ceilings. In this paper, the authors propose geometric measurements related to support patterns to describe the overturn-resistance capability for multi-legged robots climbing on vertical walls and on ceilings. Employing optimization approaches, optimal regular periodic wall gaits are computed for a six-legged robot climbing vertically or horizontally, and optimal ceiling gaits are also obtained. Comparisons are made for crab-type and insect-type leg-stroke layouts.

A New Method for Overconstraint Analysis Based on Kinematic Compatibility of Single-Opened-Chains

A new method for analyzing overconstrained mechanisms is presented in this paper according to the kinematic compatibility criterion of single-opened-chains (SOCs). This criterion states that: if for any value of an active input, two SOCs have die same distances and angles between two ending axes of each SOC, and the difference of axis-lengths corresponding to each hand-side for two SOCs is kept constant, then the two SOCs can be combined together as one closure loop which is an overconstrained mechanism. This method is simple with four clear targets. It is quite different from other methods because the input-output relationships of variables can be obtained during overconstraint analysis. In order to find overconstrained mechanisms, we can begin with parts of compatibility conditions to obtain some kinematic relationships, so that the input-output law and the overconstraint conditions satisfying all compatibility relationships could be given. As examples, the 4R overconstrained mechanisms and a 4R2P overconstrained mechanism are proved using this method.

Theory and Method of Dynamic Modeling for Multilayer Vibration Isolation System

The multilayer vibration isolation system has been widely applied to isolate vibration in dynamic devices of ships, high-speed vehicles forging hammer and precise instruments. The paper is based on the coordinate transformation of space general motion for mass blocks (rigid bodies) and Lagrangian equation of multilayer vibration isolation system. It gives a strict mathematical derivation on the differential equation of the motion for the system with six degrees of freedom of relative motion between mass blocks (including base). The equations are different from the same kind of equations in the reference literatures. It can be used in the floating raft of ships in order to isolates vibration and decrease noise, also used in design calculation of the multilayer vibration isolation for dynamic machines and precise instruments on the dry land.

Active Vibration Control for the Closed Loop Flexible Mechanisms Combined the Feedback and Feed-Forward Strategy: Part 2 — Control Design and Simulation

On the basis of the complex mode theory and the equations of motion of the flexible mechanisms developed in part 1, a hybrid independent modal controller is presented, which is composed of state feedback and disturbance feed-forward control laws. As an illustrative example, the strategy is used to control the elastic vibration response of a four-bar linkage mechanism. The imitative computational result shows that the vibration is efficiently suppressed.

SDAMP: Software for the Design and Analysis of Mechanical Presses

In this paper we introduce the MATLAB-based SDAMP (pronounced stamp) software for the analysis and synthesis of several mechanical press linkages. These linkages include the slider-crank and the four six-bar mechanisms formed by attaching a drag-link, crank-rocker, crank-shaper or Whitworth mechanism to a slider-crank. SDAMP performs four basic tasks: guided layout, kinematic analysis, mechanism refine and kinematic synthesis. Guided layout leads the user through joint selection to ensure a functioning mechanism. Kinematic analysis displays the position, velocity, acceleration and jerk of the sliding output versus the rotation of the input link. Mechanism refine allows the user to vary the geometry of an existing mechanism towards the goal of achieving a desired kinematic analysis. Lastly, kinematic synthesis determines the set of defect-free slider-cranks capable of achieving four precision points. All of these capabilities are integrated through a host of GUI driven MATLAB files in SDAMP.

Analytic Geometric Design of Spatial R-R Robot Manipulators

This paper studies the geometric design of spatial two degrees of freedom, open loop robot manipulators with revolute joints that perform tasks, which require the positioning of the end-effector in three spatial locations. This research is important in situations where a robotic manipulator or mechanism with a small number of joint degrees of freedom is designed to perform higher degree of freedom end-effector tasks. The loop-closure geometric equations provide eighteen design equations in eighteen unknowns. Polynomial Elimination techniques are used to solve these equations and obtain the manipulator Denavit and Hartenberg parameters. A sixth order polynomial is obtained in one of the design parameters. Only two of the six roots of the polynomial are real and they correspond to two different robot manipulators that can reach the desired end-effector poses.

Configuration Estimation of Gough-Stewart Platforms Using Extended Kalman Filtering

This paper develops extended Kalman filtering algorithms for a generic Gough-Stewart platform assuming realistically available sensors such as length sensors, rate gyroscopes, and accelerometers. The basic idea is to extend existing methods for satellite attitude estimation. The nondeterministic methods are meant to be a practical alternative to existing iterative, deterministic methods for real-time estimation of platform configuration.

A Method for Representing the Configuration, and Analyzing the Motion of Complex Cable-Pulley Systems

In this paper a systematic way of representing complex cable-pulley mechanism configurations and a method to analyze and synthesize the motion of these cable-pulley devices is presented. The cable-pulley system model that is being considered is composed of three basic elements which are pulleys, blocks, and cables. A configuration table is used to identify the constraint equations by systematically defining the connections between the cables, pulleys, and blocks. The basic strategy is to use the constraint equations to generate the relationship between each variable and a subset of the variables identified as the inputs. The number of input variables is equal to the total number of variables minus the number of independent constraints. This choosing of the set of inputs is done in conjunction with a row reduction process on the system of constraint equations which identifies the number of inputs and ultimately generates the relationships of each variable to the input(s). Examples are given to illustrate the procedure.

Workspace Generation As a Diffusion Process

In this paper we show that the workspace of a highly articulated manipulator can be found by solving a partial differential equation. This diffusion-type equation describes the evolution of the workspace density function depending on manipulator length and kinematic properties. The support of the workspace density function is the workspace of the manipulator. The PDE governing workspace density evolution is solvable in closed form using the Fourier transform on the group of rigid-body motions. We present numerical results that use this technique.

Assembly Configurations of Spatial RRRCC, RRCRC, RRRRCR, and RRRRRRR Mechanisms

This paper examines the problem of finding the assembly configurations, also called circuits, of spatial single-loop single-DOF mechanisms with five or more links. The RRRCC, RRCRC, RRRRCR, and RRRRRRR mechanisms are covered, along with all variations in which a revolute (R) joint is replaced by a prismatic (P) joint. A numerical method is given to find the ACs, and is illustrated with several examples.