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Article

Jun Zhong and Ruqi Ma

Jumping robots with coordinated multiple legs have been a hot research subject during the past years because of their excellent abilities in fast moving and…

Abstract

Purpose

Jumping robots with coordinated multiple legs have been a hot research subject during the past years because of their excellent abilities in fast moving and obstacle-climbing. However, dynamics of jumping process of these coordinated legged robots are complex because of collisions between coordinated legs and the ground. This paper aims to analyze features of jumping process and to present the kinematic and dynamic models of a novel sole-type quadruped jumping robot with variable coordinated joints.

Design/methodology/approach

A complete jumping period of is divided into several subphases according to contact status of different coordinated legs to the ground. Continuous dynamics and discrete dynamics are established in different subphases. Simulations are performed in MATLAB software and ADAMS environment.

Findings

Comparison between two-set simulated results acquired from ADAMS and MATLAB demonstrates the validity of kinematic and dynamic equations.

Originality/value

The established dynamics establish the foundation of further research in motion planning and controller design of coordinated multiple legs.

Details

Assembly Automation, vol. 40 no. 1
Type: Research Article
ISSN: 0144-5154

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Article

Jiehao Li, Junzheng Wang, Shoukun Wang, Hui Peng, Bomeng Wang, Wen Qi, Longbin Zhang and Hang Su

This paper aims on the trajectory tracking of the developed six wheel-legged robot with heavy load conditions under uncertain physical interaction. The accuracy of…

Abstract

Purpose

This paper aims on the trajectory tracking of the developed six wheel-legged robot with heavy load conditions under uncertain physical interaction. The accuracy of trajectory tracking and stable operation with heavy load are the main challenges of parallel mechanism for wheel-legged robots, especially in complex road conditions. To guarantee the tracking performance in an uncertain environment, the disturbances, including the internal friction, external environment interaction, should be considered in the practical robot system.

Design/methodology/approach

In this paper, a fuzzy approximation-based model predictive tracking scheme (FMPC) for reliable tracking control is developed to the six wheel-legged robot, in which the fuzzy logic approximation is applied to estimate the uncertain physical interaction and external dynamics of the robot system. Meanwhile, the advanced parallel mechanism of the electric six wheel-legged robot (BIT-NAZA) is presented.

Findings

Co-simulation and comparative experimental results using the BIT-NAZA robot derived from the developed hybrid control scheme indicate that the methodology can achieve satisfactory tracking performance in terms of accuracy and stability.

Originality/value

This research can provide theoretical and engineering guidance for lateral stability of intelligent robots under unknown disturbances and uncertain nonlinearities and facilitate the control performance of the mobile robots in a practical system.

Details

Assembly Automation, vol. 40 no. 5
Type: Research Article
ISSN: 0144-5154

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Article

M. Görner, T. Wimböck and G. Hirzinger

The purpose of this paper is to present and evaluate methods of control and gait generation for the DLR Crawler – a six‐legged walking robot prototype based on the fingers…

Abstract

Purpose

The purpose of this paper is to present and evaluate methods of control and gait generation for the DLR Crawler – a six‐legged walking robot prototype based on the fingers of the DLR Hand II.

Design/methodology/approach

Following the institutes philosophy, the DLR Crawler is a highly integrated mechatronic device. As in all DLR robots, joint torque sensing plays an important role to allow actively compliant interaction with the environment. To control the Crawler a joint compliance controller is implemented and two different methods of gait generation are in use. The first method, intended for moderately uneven terrain, employs scalable patterns of fixed coordination combined with a leg extension reflex. For the second method, used in rougher terrain, a set of rules found by biologists in stick insect studies is applied. Based on these rules gaits emerge according to a velocity command. These gaits are combined with several reflexes to a reactive walking algorithm.

Findings

The compliance controller together with the reactive gaits allows the robot to autonomously master uneven terrain and obstacles with height differences within the nominal walking height. Further, the controller reduces internal forces compared to pure joint position control. The sensitive joint torque sensors allow fast collision detection and reactions thereafter.

Originality/value

This paper introduces a six‐legged walking robot test bed with comprehensive force‐torque sensing capability. Joint compliance controllers are implemented and successfully combined with reactive gait algorithms. For the second gait algorithm inspired by Cruse's rules, which were identified for forward walking stick insects, an implementation has been found for the DLR Crawler that gives the robot full omnidirectional mobility.

Details

Industrial Robot: An International Journal, vol. 36 no. 4
Type: Research Article
ISSN: 0143-991X

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Article

Kazuo Hirai

Honda revealed a humanoid robot with two legs and two arms in December of 1996. The robot walks not only forward and backward but also diagonally either to the right or…

Abstract

Honda revealed a humanoid robot with two legs and two arms in December of 1996. The robot walks not only forward and backward but also diagonally either to the right or left and turns in any direction as well. The robot can also steadily walk up and down a staircase without missing a step and push a cart with coordinated movement of its legs and arms. This robot with its innovative posture stability control can keep its balance against such unexpected disturbances as irregularities and unevenness on the floor surface. The paper introduces an outline of the structure and joints of the robot along with the development history. The basic principle of the robot’s posture recovery control is also briefly explained.

Details

Industrial Robot: An International Journal, vol. 26 no. 4
Type: Research Article
ISSN: 0143-991X

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Article

William A. Lewinger and Roger D. Quinn

Biological systems such as insects have often been used as a source of inspiration when developing walking robots. Insects' ability to nimbly navigate uneven terrain, and…

Abstract

Purpose

Biological systems such as insects have often been used as a source of inspiration when developing walking robots. Insects' ability to nimbly navigate uneven terrain, and their observed behavioral complexity have been a beacon for engineers who have used behavioral data and hypothesized control systems to develop some remarkably agile robots. The purpose of this paper is to show how it is possible to implement models of relatively recent discoveries of the stick insect's local control system (its thoracic ganglia) for hexapod robot controllers.

Design/methodology/approach

Walking control based on a model of the stick insect's thoracic ganglia, and not just observed insect behavior, has now been implemented in a complete hexapod able to walk, perform goal‐seeking behavior, and obstacle surmounting behavior, such as searching and elevator reflexes. Descending modulation of leg controllers is also incorporated via a head module that modifies leg controller parameters to accomplish turning in a role similar to the insect's brain and subesophageal ganglion.

Findings

While many of these features have been previously demonstrated in robotic subsystems, such as single‐ and two‐legged test platforms, this is the first time that the neurobiological methods of control have been implemented in a complete, autonomous walking hexapod.

Originality/value

The methods introduced here have minimal computation complexity and can be implemented on small robots with low‐capability microcontrollers. This paper discusses the implementation of the biologically grounded insect control methods and descending modulation of those methods, and demonstrates the performance of the robot for navigating obstacles and performing phototaxis.

Details

Industrial Robot: An International Journal, vol. 38 no. 3
Type: Research Article
ISSN: 0143-991X

Keywords

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Article

Servet Soyguder and Hasan Alli

This paper seeks to develop a novel legged robot.

Abstract

Purpose

This paper seeks to develop a novel legged robot.

Design/methodology/approach

First, the paper models the legged robot using 3D computer model by intelligent inspiration of biological principles. Then, based on this model, it develops the prototype of the legged robot.

Findings

A novel motion mechanism is used and only two actuators are used for driving the system.

Originality/value

The modelled legged robot is original in terms of the developed motion mechanism.

Details

Industrial Robot: An International Journal, vol. 34 no. 5
Type: Research Article
ISSN: 0143-991X

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Article

Edgar A. Martínez-García, Luz Abril Torres-Méndez and Mohan Rajesh Elara

The purpose of this paper is to establish analytical and numerical solutions of a navigational law to estimate displacements of hyper-static multi-legged mobile robots

Abstract

Purpose

The purpose of this paper is to establish analytical and numerical solutions of a navigational law to estimate displacements of hyper-static multi-legged mobile robots, which combines: monocular vision (optical flow of regional invariants) and legs dynamics.

Design/methodology/approach

In this study the authors propose a Euler-Lagrange equation that control legs’ joints to control robot's displacements. Robot's rotation and translational velocities are feedback by motion features of visual invariant descriptors. A general analytical solution of a derivative navigation law is proposed for hyper-static robots. The feedback is formulated with the local speed rate obtained from optical flow of visual regional invariants. The proposed formulation includes a data association algorithm aimed to correlate visual invariant descriptors detected in sequential images through monocular vision. The navigation law is constrained by a set of three kinematic equilibrium conditions for navigational scenarios: constant acceleration, constant velocity, and instantaneous acceleration.

Findings

The proposed data association method concerns local motions of multiple invariants (enhanced MSER) by minimizing the norm of multidimensional optical flow feature vectors. Kinematic measurements are used as observable arguments in the general dynamic control equation; while the legs joints dynamics model is used to formulate the controllable arguments.

Originality/value

The given analysis does not combine sensor data of any kind, but only monocular passive vision. The approach automatically detects environmental invariant descriptors with an enhanced version of the MSER method. Only optical flow vectors and robot's multi-leg dynamics are used to formulate descriptive rotational and translational motions for self-positioning.

Details

International Journal of Intelligent Unmanned Systems, vol. 2 no. 2
Type: Research Article
ISSN: 2049-6427

Keywords

Content available
Article

Yitao Pan, Yuan Chen and Lin Li

The purpose of this paper is to propose a two-degrees-of-freedom wire-driven 4SPS/U rigid‒flexible parallel trunk joint mechanism based on spring, in order to improve the…

Abstract

Purpose

The purpose of this paper is to propose a two-degrees-of-freedom wire-driven 4SPS/U rigid‒flexible parallel trunk joint mechanism based on spring, in order to improve the robot’s athletic ability, load capacity and rigidity, and to ensure the coordination of multi-modal motion.

Design/methodology/approach

First, based on the rotation transformation matrix and closed-loop constraint equation of the parallel trunk joint mechanism, the mathematical model of its inverse position solution is constructed. Then, the Jacobian matrix of velocity and acceleration is derived by time derivative method. On this basis, the stiffness matrix of the parallel trunk joint mechanism is derived on the basis of the principle of virtual work and combined with the deformation effect of the rope driving pair and the spring elastic restraint pair. Then, the eigenvalue distribution of the stiffness matrix and the global stiffness performance index are used as the stiffness evaluation index of the mechanism. In addition, the performance index of athletic dexterity is analyzed. Finally, the distribution map of kinematic dexterity and stiffness is drawn in the workspace by numerical simulation, and the influence of the introduced spring on the stiffness distribution of the parallel trunk joint mechanism is compared and analyzed. It is concluded that the stiffness in the specific direction of the parallel trunk joint mechanism can be improved, and the stiffness distribution can be improved by adjusting the spring elastic structure parameters of the rope-driven branch chain.

Findings

Studies have shown that the wire-driven 4SPS/U rigid‒flexible parallel trunk joint mechanism based on spring has a great kinematic dexterity, load-carrying capacity and stiffness performance.

Research limitations/implications

The soft-mixed structure is not mature, and there are few new materials for the soft-mixed mixture; the rope and the rigid structure are driven together with a large amount of friction and hindrance factors, etc.

Practical implications

It ensures that the multi-motion mode hexapod mobile robot can meet the requirement of sufficient different stiffness for different motion postures through the parallel trunk joint mechanism, and it ensures that the multi-motion mode hexapod mobile robot in multi-motion mode can meet the performance requirement of global stiffness change at different pose points of different motion postures through the parallel trunk joint mechanism.

Social implications

The trunk structure is a very critical mechanism for animals. Animals in the movement to achieve smooth climbing, overturning and other different postures, such as centipede, starfish, giant salamander and other multi-legged animals, not only rely on the unique leg mechanism, but also must have a unique trunk joint mechanism. Based on the cooperation of these two mechanisms, the animal can achieve a stable, flexible and flexible variety of motion characteristics. Therefore, the trunk joint mechanism has an important significance for the coordinated movement of the whole body of the multi-sport mode mobile robot (Huang Hu-lin, 2016).

Originality/value

In this paper, based on the idea of combining rigid parallel mechanism with wire-driven mechanism, a trunk mechanism is designed, which is composed of four spring-based wire-driven 4SPS/U rigid‒flexible parallel trunk joint mechanism in series. Its spring-based wire-driven 4SPS/U rigid‒flexible parallel trunk joint mechanism can make the multi-motion mode mobile robot have better load capacity, mobility and stiffness performance (Qi-zhi et al., 2018; Cong-hao et al., 2018), thus improving the environmental adaptability and reliability of the multi-motion mode mobile robot.

Details

International Journal of Structural Integrity, vol. 10 no. 6
Type: Research Article
ISSN: 1757-9864

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Article

Michał R. Nowicki, Dominik Belter, Aleksander Kostusiak, Petr Cížek, Jan Faigl and Piotr Skrzypczyński

This paper aims to evaluate four different simultaneous localization and mapping (SLAM) systems in the context of localization of multi-legged walking robots equipped with…

Abstract

Purpose

This paper aims to evaluate four different simultaneous localization and mapping (SLAM) systems in the context of localization of multi-legged walking robots equipped with compact RGB-D sensors. This paper identifies problems related to in-motion data acquisition in a legged robot and evaluates the particular building blocks and concepts applied in contemporary SLAM systems against these problems. The SLAM systems are evaluated on two independent experimental set-ups, applying a well-established methodology and performance metrics.

Design/methodology/approach

Four feature-based SLAM architectures are evaluated with respect to their suitability for localization of multi-legged walking robots. The evaluation methodology is based on the computation of the absolute trajectory error (ATE) and relative pose error (RPE), which are performance metrics well-established in the robotics community. Four sequences of RGB-D frames acquired in two independent experiments using two different six-legged walking robots are used in the evaluation process.

Findings

The experiments revealed that the predominant problem characteristics of the legged robots as platforms for SLAM are the abrupt and unpredictable sensor motions, as well as oscillations and vibrations, which corrupt the images captured in-motion. The tested adaptive gait allowed the evaluated SLAM systems to reconstruct proper trajectories. The bundle adjustment-based SLAM systems produced best results, thanks to the use of a map, which enables to establish a large number of constraints for the estimated trajectory.

Research limitations/implications

The evaluation was performed using indoor mockups of terrain. Experiments in more natural and challenging environments are envisioned as part of future research.

Practical implications

The lack of accurate self-localization methods is considered as one of the most important limitations of walking robots. Thus, the evaluation of the state-of-the-art SLAM methods on legged platforms may be useful for all researchers working on walking robots’ autonomy and their use in various applications, such as search, security, agriculture and mining.

Originality/value

The main contribution lies in the integration of the state-of-the-art SLAM methods on walking robots and their thorough experimental evaluation using a well-established methodology. Moreover, a SLAM system designed especially for RGB-D sensors and real-world applications is presented in details.

Details

Industrial Robot: An International Journal, vol. 44 no. 4
Type: Research Article
ISSN: 0143-991X

Keywords

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Article

Luca Bruzzone and Pietro Fanghella

The aim of the research is the development of a small-scale ground mobile robot for surveillance and inspection; the main design goals are mobility in indoor environments…

Abstract

Purpose

The aim of the research is the development of a small-scale ground mobile robot for surveillance and inspection; the main design goals are mobility in indoor environments with step climbing ability, pivoting around a vertical axis and without oscillations for stable vision, mobility in unstructured environments, low mechanical and control complexity.

Design/methodology/approach

The proposed hybrid leg-wheel robot is characterized by a main body equipped with two actuated wheels and two praying Mantis rotating legs; a rear frame with two idle wheels is connected to the main body by a vertical revolute joint for steering; a second revolute joint allows the rear axle to roll. The geometrical synthesis of the robot has been performed using a nondimensional approach for generality's sake.

Findings

The experimental campaign on the first prototype confirms the fulfilment of the design objectives; the robot can efficiently walk in unstructured environments realizing a mixed wheeled-legged locomotion.

Practical implications

Thanks to the operative flexibility of Mantis in indoor and outdoor environments, the range of potential applications is wide: surveillance, inspection, monitoring of dangerous locations, intervention in case of terroristic attacks, military tasks.

Originality/value

Different from other robots of similar size, Mantis combines high speed and energetic efficiency, stable vision, capability of climbing over high steps, obstacles and unevenness.

Details

Industrial Robot: An International Journal, vol. 41 no. 1
Type: Research Article
ISSN: 0143-991X

Keywords

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