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United Nations’ World Population Ageing Report states that falls are one of the most common problems in the elderly around the world. Falls are a leading cause of morbidity and mortality among mature adults, and the second leading cause of accidental or unintentional injury/death after road traffic injuries. The rates are higher in hospitalized patients and nursing home residents. Major contributing reasons for falling are loss of footing or traction, balance problem in carpets and rugs, reduced muscle strength, poor vision, mobility/gait, cognitive impairment: in other words lack of balance. Balance can be improved by the practice of yoga which helps to balance both body and mind through a series of physical postures called asanas, breathing control and meditation. Elders, especially women, are often unable to practice yoga regularly, largely brought on by a feeling of discomfort at having to do so in full public view, preferring instead to have private sessions at home, and at leisure. A computer-assisted self-learning system can be developed to help such elders, though improper training and the postures associated with it may harm the body’s muscles and ligaments. To have a flawless system it is essential to classify asanas, and identify the one the practitioner is currently practicing, following which the system can offer the guidance necessary. The purpose of this paper is to propose a posture recognition system, especially of sitting and standing postures. Asanas are chiefly classified into two: sitting and standing postures. This study helps to decide the values of the parameters for classification, which involve the hip and joint angles.

To model human bodies, skeleton parts such as head, neck (which are responsible for head movements), arms, hands (to decide on hand postures), and legs and feet (for standing posture identification) have been modeled and stored as a vector. Each feature is defined as a set of movable joints. Every interaction among the skeleton joints defines an action. Human skeletal information may be represented as a hierarchy of joints, in a parent–child relationship. So that whenever there is a change in joint its corresponding parent joint may also be altered.

The findings have to do with analyzing the reasons for falls in the elderly and their need for yoga as a precautionary measure. As yoga is ideally suited to self-assisted learning, it is feasible to design a system that assists people who do not wish to practice yoga in public. However, asanas are to be classified prior to doing so. In this paper, the authors have designed a posture identification framework comprising the sitting and standing postures that are fundamental to all yoga asanas, using joint angle measurements. Having fixed joint angle values is not possible, given the variations in angle values among the participants. Consequently, such parameters as the hip joint and knee angles are to be specified in range for a classification of asanas.

This work identifies the angle limits of standing and sitting postures so as to design a self-assisting system for yoga. Yoga asanas are classified and tested to enable their accurate identification. Extensive testing with older people is needed to assess the system.

The increase in the population of the elderly, coupled with their need for medical care, is a major concern worldwide. As older people are reluctant to practice yoga in public, it is anticipated that the proposed system will motivate them to do so at their convenience, and in the seclusion of their homes.

As older people are reluctant to adapt as well as practice yoga in public view, the proposal motivates and helps them to carry out yoga practices at their convenience.

This paper fulfills the initial study on the need and feasibility of creating a self-assisted yoga learning system. To identify postures and classify them joint angles are used; their range of motion has been calculated in order to set them as parameters of classification.

In traditional calibration methods of kinematics parameters of industrial robots, dozens of model parameters are identified together based on an optimization procedure. Due to different contributions of model parameter errors to the tool center point positioning error of industrial robots, obtaining good results for all model parameters is very difficult. Therefore, the purpose of this paper is to propose a sequential calibration method specifically for transmission ratio parameters, which includes reduction ratios and coupling ratios of industrial robot joints.

The ABB IRB 1410 industrial robot is considered as an example in this study. The transmission ratios for each joint of the robot are identified using the spatial circle fitting method based on spatial vectors, which fit the center and radius of joint rotation with the least squares optimization algorithm. In addition, a method based on the Rodrigues’ formula is designed and presented for identifying the actual coupling ratio of the robot. Subsequently, an experiment is carried out to verify the proposed sequential calibration method of transmission ratios.

In this experiment, the actual positions of the linkages before and after joint rotations are measured by a laser tracker. Accurate results of the reduction ratios and the coupling ratios are calculated, and the results are verified experimentally. The results show that by calibrating the reduction ratios and coupling ratios of the ABB robot, the rotation angle errors of the robot joints can be reduced.

The authors propose a sequential calibration method for transmission ratio parameters, including reduction ratios and coupling ratios of industrial robot joints. An experiment is carried out to verify this proposed sequential calibration method. This study may be beneficial for calibrating the kinematic parameters of industrial robots and improving their positioning accuracy.

This paper aims to present an iterative path-following method with joint limits to solve the problem of large computation cost, movement exceeding joint limits and poor path-following accuracy for the path planning of hyper-redundant snake-like manipulator.

When a desired path is given, new configuration of the snake-like manipulator is obtained through a geometrical approach, then the joints are repositioned through iterations until all the rotation angles satisfy the imposed joint limits. Finally, a new arrangement is obtained through the analytic solution of the inverse kinematics of hyper-redundant manipulator. Finally, simulations and experiments are carried out to analyze the performance of the proposed path-following method.

Simulation results show that the average computation time is 0.1 ms per step for a hyper-redundant manipulator with 12 degrees of freedom, and the deviation in tip position can be kept below 0.02 mm. Experiments show that all the rotation angles are within joint limits.

Currently , the manipulator is working in open-loop, the elasticity of the driving cable will cause positioning error. In future, close-loop control based on real-time attitude detection will be used in in combination with the path-following method to achieve high-precision trajectory tracking.

Through a series of iterative processes, the proposed method can make the manipulator approach the desired path as much as possible within the joint constraints with high precision and less computation time.

For the climbing rod object with large diameter variation and the need of obstacle crossing, this paper aims to propose a new embracing-type climbing robot named as EVOC-I robot.

The design philosophy and structural scheme are introduced. The kinematic analysis of embracing and telescoping mechanisms is carried out to provide the theoretical foundation for the effective climbing of the robot. Based on the prototype robot, three preliminary experiments are carried out to verify the effectiveness of the designed robot.

The theoretical and experimental analyses have verified the reasonability and effectiveness of the proposed robot design.

As the preliminary study, the prototype still need a lot of improvement. The experimental verification is also limited. Future work will focus on improving the design and increasing the theoretical analysis, especially increasing experimental study and designing the next generation of the rod climbing robot.

The designed climbing robot can be used for climbing the rod with variation diameter and flange obstacle, especially the lightening rod in the transformer substation.

The paper designs a new climbing robot that integrates the ability of large variation diameter adaptation and obstacle crossing.

Articulated robots are widely used in industrial applications owing to their high repeatability accuracy. In terms of new applications such as robot-based inspection systems, the limitation is a lack of pose accuracy. Mostly, robot calibration approaches are used for the improvement of the pose accuracy. Such approaches however require a profound understanding of the determining effects. This paper aims to provide a non-destructive analysis method for the identification and characterisation of non-geometric accuracy effects in relation to the kinematic structure for the purpose of an accuracy enhancement.

The analysis is realised by a non-destructive method for rotational, uncoupled robot axes with the use of a 3D lasertracker. For each robot axis, the lasertracker position data for multiple reflectors are merged with the joint angles given by the robot controller. Based on this, the joint characteristics are determined. Furthermore, the influence of the kinematic structure is investigated.

This paper analyses the influence of the kinematic structure and non-geometric effects on the pose accuracy of standard articulated robots. The provided method is shown for two different industrial robots and presented effects incorporate tilting of the robot, torsional joint stiffness, hysteresis, influence of counter balance systems, as well as wear and damage.

Based on these results, an improved robot model for a better match between the mathematical description and the real robot system can be achieved by characterising non-geometric effects. In addition, wear and damages can be identified without a disassembly of the system.

The presented method for the analysis of non-geometric effects can be used in general for rotational, uncoupled robot axes. Furthermore, the investigated accuracy influencing effects can be taken into account to realise high-accuracy applications.

In large equipment and highly complex confined workspaces, the maintenance is usually carried out by snake-arm robots with equal cross-sections. However, the equal cross-sectional design results in the snake arm suffering from stress concentration and restricted working space. The purpose of this paper is to design a variable cross-section elephant trunk robot (ETR) that can address these shortcomings through bionic principles.

This paper proposes a cable-driven ETR to explore the advantages and inspiration of variable cross-section features for hyper-redundant robot design. For the kinematic characteristics, the influence of the variable cross-section design on the maximum joint angle of the ETR is analysed using the control variables method and the structural parameters are selected. Based on the biological inspiration of the whole elephant trunk following the movement of the trunk tip, a trajectory-tracking algorithm is designed to solve the inverse kinematics of the ETR.

Simulation and test results show the unique advantages of the proposed variable cross-section ETR in kinematics and forces, which can reduce stress concentrations and increase the flexibility of movement.

This paper presents a design method for a variable cross-section ETR for confined working spaces, analyses the kinematic characteristics and develops a targeted trajectory control algorithm.

This study aims to propose a novel method based on model learning with sparsity inducing norms for estimating dynamic gravity terms of the serial manipulators. This method is realized by operating the robot, acquiring data and filtering the features in signal acquisition to adapt to the dynamic gravity parameters.

The core principle of the method is to analyze the dictionary composition of the basis function of the model based on the dynamic equation and the Jacobian matrix of an arm. According to the structure of the basis function and the sparsity of the features, combined with joint-angle and driving-torque data acquisition, the effective features of dynamic gravity parameters are screened out using L1-norm optimization and learning algorithms.

The theoretical analysis revealed that training data obtained based on joint angles and driving torques could rapidly update dynamic gravity parameters. The simulation experiment was carried out by using the publicly available robot model and compared with the previous disassembly method to evaluate the feasibility and performance. The real 7-degree of freedom (DOF) industrial manipulator was used to further discuss the effects of the feature selection. The results show that this estimation method can be fully operational and efficient in industrial applications.

This approach is applicable to most serial robots with multi-DOF and the dynamic gravity parameters of the robot are estimated through learning and optimization. The method does not require prior knowledge of the robot arm structure and only requires joint-angle and driving-torque data acquisition under low-speed motion. Furthermore, as it is a data-driven-based method, it can be applied to gravity parameters updating.

Different from previous general robot dynamic modelling methods, the sparsity of the analytical form of dynamic equations was exploited and model learning was formulated as a convex optimization problem to achieve effective gravity parameters screening. The novelty of this estimation approach is that the method does not only require any prior knowledge but also does not require a specifically designed trajectory. Thus, this method can avoid the laborious work of parameter calibration and the induced modelling errors. By using a data-driven learning approach, the new parameter updating process can be completed conveniently when the robot carries additional mass or the end-effector changes for different tasks.

This paper aims to introduce a new design concept for robotic manipulator driven by the special two degrees of freedom (DOF) joints. Joint as a basic but essential component of the robotic manipulator is analysed emphatically.

The proposed robotic manipulator consists of several two-DOF joints and a rotary joint. Each of the two-DOF joints consists of a cylinder pairs driven by two DC motors and a universal joint (U-joint). Both kinematics of the robotic manipulator and the two-DOF joint are analysed. The influence to output ability of the joint in terms of the scale effect of the inclined plane is analysed in ADAMS simulation software. The contrast between the general and the proposed two-DOF joint is also studied. Finally, a physical prototype of the two-DOF joint is developed for experiments.

The kinematic analysis indicates that the joint can achieve omnidirectional deflection motion at a range of ±50° and the robotic manipulator can reach a similar workspace in comparison to the general robotic manipulator. Based on the kinematic analysis, two special motion modes are proposed to endow the two-DOF joint with better motion capabilities. The contrast simulation results between the general and the proposed two-DOF joints suggest that the proposed joint can perform better in the output ability. The experimental results verify the kinematic analysis and motion ability of the proposed two-DOF joint.

A new design concept of a robotic manipulator has been presented and verified. The complete kinematic analysis of a special two-DOF joint and a seven-DOF robotic manipulator have been resolved and verified. Compared with the general two-DOF joint, the proposed two-DOF joint can perform better in output ability.

To study fracture characteristics of jointed rock masses under blasting load, the RFPA2D analysis software for dynamic fracture of rocks based on the finite element method and statistical damage theory was used.

On this basis, this research simulated the fracture process of rock masses in blasting with different joint geometrical characteristics and mainly analysed the influences of distance from joints to blasting holes, the length of joints, the number of joints and joint angle on fracture of rock masses.

The calculation results show that with the constant increase of the distance from joints to blasting holes, the influences of joints on blasting effects of rock masses gradually reduced. Rock masses with long joints experienced more serious damages than those with short joints. Damages obviously increased with the changing from rock masses without joints to rock masses with joints, and when there were three joints, the further increase of the number of joints had unobvious changes on blasting effects of rock masses. Joints showed significant guidance effect on the propagation of cracks in blasting: promoting propagation of main vertical cracks deflecting to the ends of joints.

The research results are expected to provide some theoretical bases in practical application of engineering blasting.

The purpose of this paper is to present the design and implementation of a zero‐initial‐velocity self‐motion scheme on a six degrees of freedom (six‐DOF) planar robot manipulator.

In view of the existence of physical limits in an actual robot manipulator, both joint‐angle limits and joint‐velocity limits are initially incorporated into the proposed self‐motion scheme for practical purposes. The proposed self‐motion scheme is then reformulated as a quadratic program (QP) and resolved at the joint‐velocity level. By combining the zero‐initial‐velocity constraint, the resultant QP can prevent the occurrence of a large initial joint velocity. Finally, based on the conversion technique of QP to a linear variational inequality, a numerical computing algorithm is presented to solve the QP and the corresponding self‐motion scheme.

The proposed zero‐initial‐velocity self‐motion scheme eliminates the phenomenon of the abrupt and drastic increase in joint velocity at the beginning of the self‐motion task execution. Simulative and experimental results based on a practical six‐DOF planar robot manipulator further verify the realizability, effectiveness and accuracy of the proposed self‐motion scheme. Based on the simulative results, the joint angle and the joint velocity meet the joint physical constraints.

The paper provides effective methods for handling the physical limits, the design of zero‐initial velocity, and the conversion from joint angle and joint velocity to motor‐driving pulses. Thus, the effective and safe self‐motion control of a manipulator is realized.

The paper describes the design and implementation of a zero‐initial‐velocity self‐motion scheme.