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Legged robots are inevitably to interact with the environment while they are moving. This paper aims to properly handle these interactions. It works to actively control the joint torques of a hydraulic-actuated leg prototype and achieve compliant motion of the leg.

This work focuses on the modelling and controlling of a hydraulic-actuated robot leg prototype. First, the design and kinematics of the leg prototype is introduced. Then the linearlized model for the hydraulic actuator is built, and a model-based leg joint torque controller is presented. Furthermore, the virtual model controller is implemented on the prototype leg to achieve active compliance of the leg. Effectiveness of the controllers are validated through the experiments on the physical platform as well as the results from simulations.

The hydraulic joint torque controller presented in this paper shows good torque tracking performance. And the actively compliant leg successfully emulates the performance of virtual passive components under dynamic situations.

The main contribution of this paper is that it proposed a model-based active compliance controller for the hydraulic-actuated robot leg. It will be helpful for those robots that aim to achieve versatile and safe motions.

THE continuing development of aircraft operational concepts has in recent years resulted in the emergence of a variety of flight control functions which are essential to the safety of the aircraft and which moreover have to be performed automatically, the task being either too difficult for the human pilot, or at least so difficult as to command so much of his attention that his ability to carry out other functions is impaired. Among these functions may be instanced automatic landing, autostabilisation of V.T.O.L. aircraft in the hovering flight mode, the autostabilisation of an aircraft in some part of the flight regime in which its own natural stability is negative, and the autopiloting of aircraft operating at extremely low relative altitudes, to avoid collision with the terrain.

To develop structured guidelines for the synthesis of dynamic force simulators that are required for the testing of high speed aerospace actuators. To provide realistic and proven solutions at both test bench hardware and control design levels.

The state of the art in control design applied to load simulators in mainly based on complex controllers and does not take into account practical considerations. The objective of the present work is to provide generic preliminary design rules to ensure that the test bench architectures (frame, power transmission and control) and the components specifications are consistent with the targeted performance. Once selected the appropriate power transmission architecture, a linear approach is used as a foundation to generate design rules. Then, preliminary design is achieved thanks to the introduction, as early as possible, of the unavoidable technological defects.

A step‐by‐step methodology allows the designer to select the controller architecture and to specify components with special care to their consistency with the required dynamic performance. The linear then practical approach generates key rules that can be used in the very early phase of the test bench design.

Practical considerations on the components static and dynamic limitations are introduced progressively to make the natural test bench performance as consistent as possible with the performance requirements. Consequently, the controller becomes simpler to design and robust.

The purpose of this paper is to provide a new hydrostatic actuator controlled by a piezoelectric piston pump and to reveal its characteristics.

In this paper, a piezoelectric pump with passive poppet valves and hydraulic displacement amplifier is designed as a new control component in a hydrostatic actuator for high actuation capacity. A component-level mathematical model is established to describe the system characteristics. Simulation verification for cases under typical conditions is implemented to evaluate the delivery behavior of the pump and the carrying ability of the actuator.

By using the displacement amplifier and the passive distributing valves, simulation demonstrates that the pump can deliver flow rate up to 3 L/min, and the actuator controlled by this pump can push an object weighing approximately 50 kg. In addition, it is particularly important to decide a proper amplification ratio of the amplifier in the pump for better actuation performance.

The piezoelectric pump presented in this paper has its potential to light hydrostatic actuator. The model constructed in this paper is valid for characteristic analysis and performance evaluation of this pump and actuators.

The purpose of this paper is to present state-of-the-art approaches for precise operation of a robotic manipulator on a macro- to micro/nanoscale.

This paper first briefly discussed fundamental issues associated with precise operation of a robotic manipulator on a macro- to micro/nanoscale. Second, this paper described and compared the characteristics of basic components (i.e. mechanical parts, actuators, sensors and control algorithm) of the robotic manipulator. Specifically, commonly used mechanisms of the manipulator were classified and analyzed. In addition, intuitive meaning and applications of its actuator explained and compared in details. Moreover, related research studies on general control algorithm and visual control that are used in a robotic manipulator to achieve precise operation have also been discussed.

Remarkable achievements in dexterous mechanical design, excellent actuators, accurate perception, optimized control algorithms, etc., have been made in precise operations of a robotic manipulator. Precise operation is critical for dealing with objects which need to be manufactured, modified and assembled. The operational accuracy is directly affected by the performance of mechanical design, actuators, sensors and control algorithms. Therefore, this paper provides a categorization showing the fundamental concepts and applications of these characteristics.

This paper presents a categorization of the mechanical design, actuators, sensors and control algorithms of robotic manipulators in the macro- to micro/nanofield for precise operation.

BEFORE BEING SELECTED as the design authority and manufacturer of the Concorde units, Dowty Boulton Paul had obtained considerable experience of electrically signalled control systems on the Tay Viscount aircraft in 1957, this being possibly the first aircraft to be controlled by a fly‐by‐wire system. In addition, multiplex actuator packs controlled by electric signals and operating on a majority voting system were tested in investigating their possibilities for fly‐by‐wire systems. The work on advanced designs of multiplex electro‐hydraulic actuator packs progressed in parallel with the Concorde unit design and at the present moment 15 actuators in three packs are being simultaneously tested in an endurance rig which is scheduled to run for 12,000hr. In addition three quadruplex packs are installed in a Hunter Mk. 12 aircraft at RAE Farnborough for flight trials.

The purpose of this review paper is to address the substantial challenges of the outdated exoskeletons used for rehabilitation and further study the current advancements in this field. The shortcomings and technological developments in sensing the input signals to enable the desired motions, actuation, control and training methods are explained for further improvements in exoskeleton research.

Search platforms such as Web of Science, IEEE, Scopus and PubMed were used to collect the literature. The total number of recent articles referred to in this review paper with relevant keywords is filtered to 143.

Exoskeletons are getting smarter often with the integration of various modern tools to enhance the effectiveness of rehabilitation. The recent applications of bio signal sensing for rehabilitation to perform user-desired actions promote the development of independent exoskeleton systems. The modern concepts of artificial intelligence and machine learning enable the implementation of brain–computer interfacing (BCI) and hybrid BCIs in exoskeletons. Likewise, novel actuation techniques are necessary to overcome the significant challenges seen in conventional exoskeletons, such as the high-power requirements, poor back drivability, bulkiness and low energy efficiency. Implementation of suitable controller algorithms facilitates the instantaneous correction of actuation signals for all joints to obtain the desired motion. Furthermore, applying the traditional rehabilitation training methods is monotonous and exhausting for the user and the trainer. The incorporation of games, virtual reality (VR) and augmented reality (AR) technologies in exoskeletons has made rehabilitation training far more effective in recent times. The combination of electroencephalogram and electromyography-based hybrid BCI is desirable for signal sensing and controlling the exoskeletons based on user intentions. The challenges faced with actuation can be resolved by developing advanced power sources with minimal size and weight, easy portability, lower cost and good energy storage capacity. Implementation of novel smart materials enables a colossal scope for actuation in future exoskeleton developments. Improved versions of sliding mode control reported in the literature are suitable for robust control of nonlinear exoskeleton models. Optimizing the controller parameters with the help of evolutionary algorithms is also an effective method for exoskeleton control. The experiments using VR/AR and games for rehabilitation training yielded promising results as the performance of patients improved substantially.

Robotic exoskeleton-based rehabilitation will help to reduce the fatigue of physiotherapists. Repeated and intention-based exercise will improve the recovery of the affected part at a faster pace. Improved rehabilitation training methods like VR/AR-based technologies help in motivating the subject.

The paper describes the recent methods for signal sensing, actuation, control and rehabilitation training approaches used in developing exoskeletons. All these areas are key elements in an exoskeleton where the review papers are published very limitedly. Therefore, this paper will stand as a guide for the researchers working in this domain.

Built as an integral component) Frames, stringers and stressed skin with integrally machined skin/stringer panels above the wing cut‐out. Entire shell pressurized, from front pressure bulkhead 2 to rear pressure bulkhead 33, at rear engine‐mounting, except for wing cut‐out and main and nose undercarriage bays