Telescopic Legs Research Articles

A new method for measuring a large set of poses with a single telescoping ballbar

Abstract This paper presents a novel method of measuring a set of more than fifty poses under static conditions, using a single telescoping ballbar and two fixtures, each bearing three equally spaced magnetic cups. The position accuracy of the device is in the ±0.003 mm range, making it suitable for measuring the pose accuracy and repeatability of industrial robots and even calibrating them. The proposed method is an extension of a known approach using a hexapod (a Stewart-Gough platform) comprising telescoping ballbar legs and provides an original solution to the constraint imposed by the limited measurement range of current telescoping ballbars, namely an innovative hexapod geometry capable of assembly in 144 different configurations. An additional advantage of the method is that the pose of one fixture with respect to the other can be obtained for each of these configurations by solving a cascade of three quadratic equations using the six hexapod leg lengths as input. The application of the device and method to measuring numerous poses of an ABB IRB 120 industrial robot is presented.

High-speed dynamic gait generation for limit cycle walkers based on forward-tilting impact posture

This paper proposes a novel method for generating a dynamic gait based on anterior-posterior asymmetric impact posture tilting the robot’s center of mass forwards. The primary purpose of this method is to make the impact posture become asymmetrical by actuating the robot’s telescopic legs to easily overcome the potential barrier at mid-stance, accordingly restoring the mechanical energy. First, we introduce a planar rimless wheel model with telescopic legs, and investigate the validity of the stance-leg extension control. The basic properties and efficiency of the generated gait are also numerically analyzed. Second, we extend the method to a planar telescopic-legged biped model, and investigate the validity through numerical simulations. We also discuss the role of asymmetric shape of human foot through efficiency analysis from the point of view of the brake effect, taking the ankle-joint actuation into account.

1A2-P01 脚伸縮型受動歩行規範2足ロボットの段差歩行(受動歩行ロボット(2))

This paper tries to make a 2D biped with active telescopic legs and passive hip joint walk over a step-floor. By choosing a suitable fixed actuation pattern, the biped can walk through small up and down steps of 4.5[mm] without any change of actuation. This indicates a range of mechanical convergence ability of passive walk. For a larger variation of the floor height, stroke increase and timing delay of telescopic leg actuation is introduced. Using these techniques, the trial manufactured human-sized biped can walk stably through up and down steps of 52.5[mm].

Research on hydraulic-powered roof supports test problems

The load-bearing characters of hydraulic-powered roof support with dual telescopic legs were analyzed. With a specific type hydraulic-powered roof support with dual telescopic legs for research object, the inside load test problems in factories was analyzed, and the correct test methods were given, which can enhance the test efficiency and make the factories away from the error design of hydraulic-powered roof supports and legs.

TELESCOPIC LINKAGES AND A TOPOLOGICAL APPROACH TO PHASE TRANSITIONS

AbstractA topological approach to the theory of equilibrium phase transitions in statistical physics is based on the topological hypothesis, which claims that phase transitions are due to changes of the topology of suitable submanifolds in the configuration space. In this paper we examine in detail the antiferromagnetic mean-field XY model and study the topology of the subenergy manifolds. The latter can be interpreted mechanically as the configuration space of a linkage with one telescopic leg. We use methods of Morse theory to describe explicitly the Betti numbers of this configuration space. We apply these results to the antiferromagnetic mean-field XY model and compute the exponential growth rate of the total Betti number. Previous authors studied the Euler characteristic rather than the total Betti number. We show that in the presence of an external magnetic field the model undergoes a single ‘total Betti number phase transition’.

Experimental Study of Dynamic Bipedal Walking Based on the Principle of Parametric Excitation with Counterweights

This paper reports some interesting results from our experimental study of parametrically excited dynamic bipedal walking. We describe the details of the walking machine that has telescopic legs, semicircular feet, free hip joint and counterweights. The walker can sustain stable dynamic walking on level ground based on mechanical energy restoration in accordance with the principle of parametric excitation utilizing the effects of semicircular feet and counterweights. Results of numerical analysis on the effect of the counterweights on the gait efficiency are also described.

伸縮脚を用いた衝突姿勢の非対称化に基づく高速動的歩容生成

伸縮脚を用いた衝突姿勢の非対称化に基づく高速動的歩容生成

Kinematic-Dimensional Analysis of Parallel Robot Used for Orientation

In the paper a very simple parallel robot intended for some celestial orientation applications (satellite dishes, sun trackers, cameras, telescopes etc.) is proposed. After describing the mechanism and its kinematics, the workspace and the presence of the singularities are studied. The dimensional optimization to maximize the workspace is described, taking into account the constraints due to telescopic leg lengths and transmission angles.

Stable running of a planar underactuated biped robot

SUMMARYThis paper investigates the stable-running problem of a planar underactuated biped robot, which has two springy telescopic legs and one actuated joint in the hip. After modeling the robot as a hybrid system with multiple continuous state spaces, a natural passive limit cycle, which preserves the system energy at touchdown, is found using the method of Poincaré shooting. It is then checked that the passive limit cycle is not stable. To stabilize the passive limit cycle, an event-based feedback control law is proposed, and also to enlarge the basin of attraction, an additive passivity-based control term is introduced only in the stance phase. The validity of our control strategies is illustrated by a series of numerical simulations.

Homology of planar telescopic linkages

We study topology of configuration spaces of planar linkages having one leg of variable length. Such telescopic legs are common in modern robotics where they are used for shock absorbtion and serve a variety of other purposes. Using a Morse theoretic technique, we compute explicitly, in terms of the metric data, the Betti numbers of configuration spaces of these mechanisms.

2A2-F07 半円足を利用した衝突姿勢の非対称化による動的歩容生成

The authors have proposed a novel gait generation method based on asymmetrization of impact posture using the model of rimless wheel with telescopic legs. In this paper, we attach semicircular feet to this model, and investigate what effect the foot shape had on the gait efficiency. We can expect that the gait efficiency is improved by the geometric and physical effects of feet, and that the excessive speed-up in our previous model is suppressed by the braking effect. In addition, we mathematically investigate the geometric action of the toe support phase on the impact posture, and examine the effect through numerical simulations.

Energy-Efficient and High-Speed Dynamic Biped Locomotion Based on Principle of Parametric Excitation

We clarified that the common necessary condition for generating a dynamic gait results from the requirement to restore mechanical energy through studies on passive dynamic walking mechanisms. This paper proposes a novel method of generating a dynamic gait that can be found in the mechanism of a swing inspired by the principle of parametric excitation using telescopic leg actuation. We first introduce a simple underactuated biped model with telescopic legs and semicircular feet and propose a law to control the telescopic leg motion. We found that a high-speed dynamic bipedal gait can easily be generated by only pumping the swing leg mass. We then conducted parametric studies by adjusting the control and physical parameters and determined how well the basic gait performed by introducing some performance indexes. Improvements in energy efficiency by using an elastic-element effect were also numerically investigated. Further, we theoretically proved that semicircular feet have a mechanism that decreases the energy dissipated by heel-strike collisions. We provide insights throughout this paper into how zero-moment-point-free robots can generate a novel biped gait.

1P1-B14 パラメータ励振原理に基づく2脚動歩行の実験的検証(受動歩行ロボット)

This paper reports some interesting results on our experimental case study of parametrically excited dynamic bipedal walking. We describe the detailed specifications of the final walking machine that has telescopic legs, semicircular feet, free hip-joint, and counterweights. The walker finally succeeded in sustaining stable dynamic walking on level ground in accordance with the principle of parametric excitation utilizing the effects of semicircular feet and counterweights. We also conducted numerical analysis to examine the change of gait descriptors with respect to the physical parameters, and the results show that the counterweights are effective for improvement of the gait efficiency.

伸縮脚と円弧足を有する２足歩行システムのＧｅｏｍｅｔｒｉｃ Ｔｒａｃｋｉｎｇ制御と安定解析―円弧足半径と安定性の関係に関する考察

伸縮脚と円弧足を有する２足歩行システムのＧｅｏｍｅｔｒｉｃ Ｔｒａｃｋｉｎｇ制御と安定解析―円弧足半径と安定性の関係に関する考察

1P1-F02 膝関節駆動によるパラメータ励振に基づく2脚歩容生成(受動歩行ロボット・メカトロニクス)

The restoration of mechanical energy lost during the collision between a leg and the ground is requisite for a steady and continuous gait. One principle to do this is the parametric excitation. Recently, Asano et a!. applied this principle to a biped robot with telescopic legs, and succeeded in generating a sustainable biped gait in a computer simulation. In this paper, we deal with a model of a biped robot that has semicircular feet and actuated knees. Though this robot has no actuator at the hip, knee actuators can sustain gait by parametric excitation. We first verify that an actuated knee can cause parametric excitation and then show by computer simulation that the proposed biped robot can walk continuously with actuated knees only.

Vertical hopping control of elastic one-legged robot with two actuated arms

A new model of elastic one-legged hopping robot is proposed. The hopping robot is constructed by two actuated arms and an elastic passive telescopic leg. Motion control of the one-legged robot such as stance balance, lift-off and hopping stably depends on the dynamics coupling of the system. The mechanism model of the robot and the variable constraints property of it are analyzed. It is shown that the robot is a nonholonomic system, which is second order in stance phase, first order in flight phase. A motion control algorithm is proposed for hopping control in vertical direction based on nonlinear transformation of inputs for this kind of underactuted nonholonomic dynamic system. The whole state variables are controlled by considering the orientation of the leg, the vibration of the linear spring, and the momentum of the robot system in horizontal direction. Some simulations test the feasibility of the control method numerically. The research results are helpful for investigating the techniques to save energy of the elastic underactuated mechanical system by utilizing the vibration of compliant components, thus the research can be used for reference in designing other new elastic underactuated mechanical systems and their application in space field.

A Computational Mechatronics Approach for the Analysis, Synthesis and Design of a Simple Active Biped Robot: Theory and Experiments

Biped walking is a quite complex process that has been mastered only by human beings. Transferring this skill to a robot requires implementing advanced techniques in every aspect. To this end, a computational mechatronics platform was integrated to run the scheme for the analysis, synthesis and design to achieve planar biped walking. The result is an advanced computational tool that integrates advanced modeling and control as well as path planning techniques along with hardware-in-the-loop for perhaps the simplest biped robot. An experimental underactuated three-degree-of-freedom (two active and one passive) active biped robot yields encouraging results; that is, achieving biped walking with this simple device requires adding a telescopic support leg. Considering a more complete dynamic model to take into account frictional and contact forces.

Self-stabilizing somersaults

We investigate the open-loop stability of a planar biped robot performing a periodic motion of forward somersaults with alternating single-leg contacts. The robot has a trunk and two actuated telescopic legs with point feet which are coupled to the trunk by actuated hinges. There is compliance and damping in the hip and in the legs. The concept of open-loop control implies that all actuators of the system receive predetermined inputs that are never altered by any feedback interference. Only with the right choice of model parameters and actuator inputs is it possible to create such self-stabilizing motions exploiting the natural stability properties of the system. These unknowns have been determined using special-purpose stability-optimization methods. The resulting motion is not only stable, but also a more efficient form of forward motion than running for the investigated robot.

A study of the impact of machine tool structure on machining processes

This paper deals with parallel kinematics machine (PKM) applications for high speed machining. PKM behaviour is anisotropic, so structural deflection due to cutting loads generates different defects in the machined part, according to tool position and orientation in the workspace. The aim of the present study is the definition of a mechanical workspace where the part is machined to a specified quality level. Models of the machine tool structure, the load generated by the cutting phenomena and the machined surface are used to determine this workspace and are applied to a tricept structure with telescopic legs for grooving and drilling operations. A simulation shows that leg deflection gives rise to defects of the machined entity which are evaluated with respect to tool position and orientation. Finally, a mechanical workspace is defined for a drilling process using a tricept structure machine tool.

パラメータ励振に基づく伸縮脚ロボットの動的歩行制御

It is clarified throughout studies of passive dynamic walking mechanisms that the common necessary condition for dynamic gait generation comes from the requirement on mechanical energy restoration. Until now we have treated only rotational joints of the robot, whereas in this paper we considers a novel dynamic gait generation method based on mechanical energy restoration by parametric excitation phenomenon using telescopic leg actuation. We first introduce a simple biped walking model and a control law for telescopic leg motion, and analyze the typical walking pattern with respect to the change of control and physical parameters by numerical simulations. We then numerically analyze the energy efficiency in the presence of an elastic element by introducing criterions, and show that suitable adjustment of mechanical impedance dramatically increases the energy efficiency. Further, some extensions of the mechanism and control applications are investigated.