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The purpose of this paper is to introduce a quadruped robot strategy to avoid tipping down because of side impact disturbance and a control algorithm that guarantees the strategy can be controlled stably even in the presence of disturbances or model uncertainties.

A quadruped robot was developed. Trot gait is applied so the quadruped can be modelled as a compass biped model. The algorithm to find a correct stepping position after an impact was developed. A particle swarm optimization-based structure-specified mixed sensitivity (H₂/H_∞) robust is applied to reach the stepping position.

By measuring the angle and speed of the side tipping after an impact disturbance, a point location for the robot to step or the foothold recovery point (FRP) was successfully generated. The proposed particle swarm optimization-based structure-specified mixed sensitivity H₂/H_∞ robust control also successfully brought the legs to the desired point.

A traditional H_∞ controller synthesis usually results in a very high order of controller. This makes implementation on an embedded controller very difficult. The proposed controller is just a second-order controller but it can handle the uncertainties and disturbances that arise and guarantee that FRP can be reached.

The first contribution is the proposed low-order robust H₂/H_∞ controller so it is easy to be programmed on a small embedded system. The second is FRP, a stepping point for a quadruped robot after receiving side impact disturbance so the robot will not fall.

This paper aims to propose a novel balance-assistive control strategy for hip exoskeleton robot.

A hierarchical balance assistive controller based on the virtual stiffness model of extrapolated center of mass (XCoM) is proposed and tested by exoskeleton balance assistive control experiments.

Experiment results show that the proposed controller can accelerate the swing foot chasing XCoM and enlarge the margin of stability.

As a proof of concept, this paper shows the potential for exoskeleton to actively assist human regain balance in sagittal plane when human suffers from a forward or backward disturbing force.

A low-level controller is critical to the overall performance of multirotor unmanned aerial vehicles. The purpose of this paper is to propose a nonlinear low-level angular velocity controller for multirotor unmanned aerial vehicles in various operating conditions (e.g. different speed and different mode).

To tackle the above challenge, the authors have designed a nonlinear low-level controller taking the actuator dynamics into account. The authors first build the actuator subsystem by combining the actuator dynamics with the angular velocity dynamics model. Then, a recursive low-level controller is developed by designing a high-gain observer to estimate unmeasurable states. Furthermore, a detailed stability analysis is given with the Lyapunov theory.

Simulation tests and real-world flying experiments are provided to validate the proposed approach. In particular, we illustrate the performance of the proposed controller using violent random command test, attitude mode flight and high-speed flight of up to 18.7 m/s in real world. Compared with the classical method used in PX4 autopilot and the estimation-based incremental nonlinear dynamic inversion method, experimental results show that the proposed method can further reduce the control error.

Low-level control of multirotor UAVs is challenging due to the complex dynamic characteristics of UAVs and the diversity of tasks. Although some progress has been made, the performance of existing methods will deteriorate as operating conditions change due to the disregard for the electromechanical characteristics of the actuator.

To solve the low-level angular velocity control problem in various operating conditions of multirotor UAVs, this paper proposes a nonlinear low-level angular velocity controller which takes the actuator dynamics into account.

This study aims to establish a bio-inspired controller for realizing the bounding gait of a quadruped robot system presented in this paper.

The bio-inspired controller is divided into three levels to mimic the biological patterns of animals. First, the high-level sub-controller is equivalent to the cerebellum, which could plan and control the motion of animals. Second, the effect of the middle-level sub-controller corresponds to the central nervous system. The central pattern generators in the spine generate the stable and cyclic signals as the fundamental rhythm for periodic motion of the leg and spine joints. Third, the low-level sub-controller is equal to the end effector, which adopts the simple proportional-derivative (PD) control to realize the specific motion trajectory of the legs and spine.

Combined with the stability criterion presented previously and the delayed feedback control method, the bounding gait of the cheetah virtual prototype could be actuated and stabilized by the bio-inspired controller. Moreover, the bio-inspired controller is applied to realize the bounding gait of an SQBot, which is a quadruped robot with a spine joint. Meanwhile, the validity and practicability of the bio-inspired controller for the control of quadruped robot have been verified against different forward velocities.

The bio-inspired controller and bionic quadruped robot system are instructive for the designing and actuating of the real quadruped robot.

Industrial robots are extensively used in the robotic assembly of rigid objects, whereas the assembly of flexible objects using the same robot becomes cumbersome and challenging due to transient disturbance. The transient disturbance causes vibration in the flexible object during robotic manipulation and assembly. This is an important problem as the quick suppression of undesired vibrations reduces the cycle time and increases the efficiency of the assembly process. Thus, this study aims to propose a contactless robot vision-based real-time active vibration suppression approach to handle such a scenario.

A robot-assisted camera calibration method is developed to determine the extrinsic camera parameters with respect to the robot position. Thereafter, an innovative robot vision method is proposed to identify a flexible beam grasped by the robot gripper using a virtual marker and obtain the dimension, tip deflection as well as velocity of the same. To model the dynamic behaviour of the flexible beam, finite element method (FEM) is used. The measured dimensions, tip deflection and velocity of a flexible beam are fed to the FEM model to predict the maximum deflection. The difference between the maximum deflection and static deflection of the beam is used to compute the maximum error. Subsequently, the maximum error is used in the proposed predictive maximum error-based second-stage controller to send the control signal for vibration suppression. The control signal in form of trajectory is communicated to the industrial robot controller that accommodates various types of delays present in the system.

The effectiveness and robustness of the proposed controller have been validated using simulation and experimental implementation on an Asea Brown Boveri make IRB 1410 industrial robot with a standard low frame rate camera sensor. In this experiment, two metallic flexible beams of different dimensions with the same material properties have been considered. The robot vision method measures the dimension within an acceptable error limit i.e. ±3%. The controller can suppress vibration amplitude up to approximately 97% in an average time of 4.2 s and reduces the stability time up to approximately 93% while comparing with control and without control suppression time. The vibration suppression performance is also compared with the results of classical control method and some recent results available in literature.

The important contributions of the current work are the following: an innovative robot-assisted camera calibration method is proposed to determine the extrinsic camera parameters that eliminate the need for any reference such as a checkerboard, robotic assembly, vibration suppression, second-stage controller, camera calibration, flexible beam and robot vision; an approach for robot vision method is developed to identify the object using a virtual marker and measure its dimension grasped by the robot gripper accommodating perspective view; the developed robot vision-based controller works along with FEM model of the flexible beam to predict the tip position and helps in handling different dimensions and material types; an approach has been proposed to handle different types of delays that are part of implementation for effective suppression of vibration; proposed method uses a low frame rate and low-cost camera for the second-stage controller and the controller does not interfere with the internal controller of the industrial robot.

The research goal was to trace behavioural patterns of management accountants, comprising activities and courses of action, in order to enhance understanding of the management accounting profession.

Protoscripts were derived, using interview techniques and a research method called “interpretive interactionism”. These protoscripts depict observable, recurrent activities and patterns of interaction characteristic for a group of persons, and can be used in various types of situations.

The paper describes the procedure and outcome of the collection of behavioural protoscripts used by management accountants and controllers, as well as their possible ordering.

The findings enlarge understanding of the controller profession, but are limited solely to controller activities. The protoscripts collected are stereotypical, at least for the controllers interviewed. Of course, all human experience is interpretation and it should be acknowledged that interpretations are never complete.

The control mechanisms and instruments that emerge in an organisation are the result of several interrelated factors and processes. Of special interest here is the behaviour of management accountants and controllers in shaping, maintaining and exerting control. Behavioural protoscripts can show how management accountants give contents to their role and structure their daily work.

Scripted behaviour of management accountants has received little prior research attention, especially in combination with the research method of interpretive interactionism.

Industrial robots are extensively deployed to perform repetitive and simple tasks at high speed to reduce production time and improve productivity. In most cases, a compliant gripper is used for assembly tasks such as peg-in-hole assembly. A compliant mechanism in the gripper introduces flexibility that may cause oscillation in the grasped object. Such a flexible gripper–object system can be considered as an under-actuated object held by the gripper and the oscillations can be attributed to transient disturbance of the robot itself. The commercially available robots do not have a control mechanism to reduce such induced vibration. Thus, this paper aims to propose a contactless vision-based approach for vibration suppression which uses a predictive vibrational amplitude error-based second-stage controller.

The proposed predictive vibrational amplitude error-based second-stage controller is a real-time vibration control strategy that uses predicted error to estimate the second-stage controller output. Based on controller output, input trajectories were estimated for the internal controller of the robot. The control strategy efficiently handles the system delay to execute the control input trajectories when the oscillating object is at an extreme position.

The present controller works along with the internal controller of the robot without any interruption to suppress the residual vibration of the object. To demonstrate the robustness of the proposed controller, experimental implementation on Asea Brown Boveri make industrial robot (IRB) 1410 robot with a low frame rate camera has been carried out. In this experiment, two objects have been considered that have a low (<2.38 Hz) and high (>2.38 Hz) natural frequency. The proposed controller can suppress 95% of vibration amplitude in less than 3 s and reduce the stability time by 90% for a peg-in-hole assembly task.

The present vibration control strategy uses a camera with a low frame rate (25 fps) and the delays are handled intelligently to favour suppression of high-frequency vibration. The mathematical model and the second-stage controller implemented suppress vibration without modifying the robot dynamical model and the internal controller.

The purpose of this paper is to describe a two‐level hierarchical control strategy for electrical energy transfers in multisource renewable energy systems. The aim of the control design is to perform the energy transfers, according to the sources power variations and the load characteristics.

The controller determines the operating mode of the multisource renewable energy system and the power ratio provided by each source to satisfy the load demand. The study is based on an accurate model of the DC/DC converters coupled on the DC bus. The performance of the controller is compared with the usual method based on the measurements of the system variables with sensors (solar radiation, shaft speed, voltages, and currents).

The proposed method does not need extra sensors to measure the available power for each source.

The method is developed for an hybrid system with two sources (photovoltaic and lead‐acid battery bank) and specific zero voltage switch full‐bridge isolated buck DC/DC power converters but can easily extended to more sources and other classes of DC/DC converters.

The method is assessed through computer simulations using a simple comprehensive model. An experimental device is also developed by the GREAH Research Group of University Le Havre (France). The GREAH also participates to a technologic centre with similar topology on the site of Fecamp (France).

The proposed autonomous control schema is suitable to control hybrid systems with several energy sources in remote areas.

The main contributions of this work are first to introduce a two stages controller and second to use the duty cycle value of the power converters as decision criteria to switch off/on the sources.

This paper aims to present an approach for the simulation of a heterogeneous robotic cell. The simulation enables the cell’s developers to conveniently compare the performance of alternative cell configurations. The approach combines the use of multiple available simulation tools, with a custom holonic cell controller. This overcomes the limitation of currently available robot simulation packages by allowing integration of multiple simulation tools including multiple vendor simulation packages.

A feeding cell was developed as a case study representing a typical robotic application. The case study would compare two configurations of the cell, namely, eye-in-hand vision and fixed-camera vision. The authors developed the physical cell in parallel with the simulated cell to validate its performance. Then they used simulation to scale the models (by adding subsystems) and shortlist suitable cell configurations based on initial capital investment and throughput rate per unit cost. The feeding cell consisted of a six-degree of freedom industrial robot (KUKA KR16), two smart cameras (Cognex ism-1100 and DVT Legend 500), an industrial PC (Beckhoff) and custom reconfigurable singulation units.

The approach presented here allows the combination of dissimilar simulation models constructed for the above mentioned case study. Experiments showed the model developed in this approach could reasonably predict various eye-in-hand and fixed-camera systems’ performance. Combining the holonic controller with the simulation allows developers to easily compare the performance of a variety of configurations. The use of a common communication platform allowed the communication between multiple simulation packages, allowing multi-vendor simulation, thereby overcoming current limitation in simulation software.

The case study developed here is considered a typical feeding and assembly application. This is however very different from other robotic applications which should be explored in separate case studies. Simulation packages with the same communication interface as the physical resource can be integrated. If the communication interface is not available, other means of simulation can be used. The case study findings are limited to the specific products being used and their simulation packages. However, these are indicative of typical industry technologies available. Only real-time simulations were considered.

This simulation-based approach allows designers to quickly quantify the performance of alternative system configurations (eye-in-hand or fixed camera in this case) and scale, thereby enabling them to better optimize robotic cell designs. In addition, the holonic control system’s modular control interface allows for the development of the higher-level controller without hardware and easy replacement of the lower level components with other hardware or simulation models.

The combination of a holonic control system with a simulation to replace hardware is shown to be a useful tool. The inherent modularity of holonic control systems allows that multiple simulation components be connected, thereby overcoming the limitation of vendor-specific simulation packages.

Increases in air traffic and air traffic controller workload lead to a need to provide assistance to the air traffic controller. Proposes and validates a new organization of air traffic control, which allows air traffic controllers to remain active in the control and supervisory loop of the process, in order to maintain the present traffic safety level and to improve the global system performances. Consists of decomposing the problem according to the two levels of the air traffic control organization. Directs the first step towards a horizontal cooperation that consists of a dynamic allocation of the tactical level control tasks between human air traffic controllers and an assistance tool. Presents the dynamic task allocation principles, and describes the experimental platform for task allocation in air traffic control. Describes the experimental protocol used for the experiments with qualified controllers and presents the first results. They show the real help a dynamic task allocation provides to the air traffic controllers.