A disturbance observer-based-dynamic load-torque compensator for current-controlled DC-drives, as joint actuator of assistive exoskeletons, has been recently proposed. It has been shown that this compensator can effectively linearize and decouple the coupled nonlinear dynamics of the human-exoskeleton system, by more effectively compensating the associated nonlinear load-torques of the exoskeleton

Multi-motor driving servomechanisms are widely used in modern industry for high-performance applications involving synchronized control of position, speed, acceleration and deceleration. Several synchronous control schemes have been developed to achieve good speed or position tracking regardless of various uncertainties and load torque perturbations. However, these solutions have some disadvantages

In this paper, a novel range-based control algorithm for dual-stage nanopositioners is studied. Dual-stage nanopositioning systems have the powerful ability to achieve high-speed and long-range positioning by coupling a short-range, high-speed actuator with a long-range, low-speed actuator. One of the drawbacks of currently implemented control algorithms is that they tend to determine control allocation

In this paper, a flexure-based piezoelectric actuated microgripper is presented for high precision micro/nano manipulation tasks. A new design of microgripper based on a three-stage displacement amplification mechanism is utilized to magnify the piezoelectric actuator displacement. A bridge-type mechanism with a two-sided output port is serially connected with two consecutive lever mechanisms. The

A robotic system can consist of a single or multiple agents with a fixed or mobile base, with full or under-actuation, and possibly redundancy. Collision avoidance is a crucial task for any robotic system and is necessary to ensure safe operation. In this paper, we use a set-based approach to ensure collision avoidance as a high-priority task of a robotic system while simultaneously defining one or

This paper describes a research activity concerning the design and the development of an energy harvesting system integrated in a pneumatic spring for railway application to recover otherwise wasted energy sources from the train suspension vibration. The final scope of this research is to harvest energy and create a self-powered smart component capable of supplying useful information for the monitoring

Wheel-legged robots operating on the ground experience real-time interactions with the complex unknown terrain, which may lead to tilting of the whole body and instability if no regulated effort is made. Maintaining a horizontal posture of the whole body with changes in the terrain geometry via impedance control (IC) that is widely used in many fields is desirable to be realized. However, because the

Most of the existing (BLDCM) brushless dc motor drive systems are designed with the traditional drive scheme for long-time operation. For short-time and heavy-duty applications, there are problems of energy consumption, large volume, heavyweight and high-cost. In this paper, a new short-time high-overload BLDCM drive system based on "electronic flywheel" and time-division switching control is proposed

A vehicle-manipulator system (VMS) is a class of mobile robots characterised by their ability to carry or be a robotic arm and therefore also manipulate objects. The VMS class includes vehicles with a robotic manipulator, free-floating space robots, aerial manipulators and underwater vehicle-manipulator systems (UVMSs). All of these systems need a kinematic controller to solve the kinematic redundancy

Four-bar mechanisms have increased their use in current applications from industrial to rehabilitation systems. These applications become more demanding over time, and the control systems are required to provide them higher accuracy, lower energy consumption, and an extended lifetime, among other conflicting features. In addition to the previously mentioned demands, four-bar mechanisms have highly

This research focuses on the development of an electric bicycle robot which balances itself while moving at a constant forward speed. The bicycle robot is balanced by applying a pendulum mass moving together with heading steering to share the balancing load. The nonlinear dynamics model of a bicycle along with a pendulum is derived from the Euler-Lagrange equation of motion and nonholonomic constraints

In order to increase the mobility and dynamic agility of a two-wheeled self-balancing vehicle, a dynamic posture control strategy for the initial state transition is proposed in terms of a well-planned nonlinear reference trajectory. The dynamic trajectory planning for the underactuatedmobile inverted pendulum is conducted by solving a two-point boundary value problem with the constraint equation of

Position based visual servoing is a widely adopted tool in robotics and automation. While the extended Kalman filter (EKF) has been proposed as an effective technique for this, it requires accurate noise covariance matrices to render desirable performance. Although numerous techniques for updating or estimating the covariance matrices have been developed in the literature, many of these suffer from

Modern industrial production requires fast and automated quality control using state-of-the-art surface metrology sensors embedded in fast high-precision measuring machines. In order to achieve both fast and precise positioning, active control systems with model-based compensation of dynamic positioning errors due to increased acceleration forces can be applied. However, these active control systems

Characterized by high power-to-weight ratio, modularity and energy efficiency, electro-hydrostatic actuators (EHAs) have been successfully applied to aircrafts and submarines, where high precision and repeatability are in high demand. The position tracking performance, however, can be inevitably affected by parametric uncertainties and uncertain nonlinearities. Model inaccuracy or system variations

Brake-by-wire (BBW) systems are electronically regulated actuators, which are capable of producing a desired braking torque to the vehicle's wheel. This paper focuses on the motor-type electro-hydraulic brake (EHB) system: an electric motor driven rotational-to-linear reducing mechanism that directly pushes the master cylinder to generate hydraulic pressure. A simple and practicable controller is developed

By employing a couple of columnar magnets with a specific arrangement, a negative stiffness magnetic spring (NSMS) is designed, modelled and then experimentally validated in this paper. Such a magnetic spring with negative stiffness can be used for a semi-active seat suspension to achieve vibration reduction on vehicle drivers. Extensive simulation analysis and experimental validation based on static

Owing to numerous advantages to patients, percutaneous intervention has become a popular research topic in recent decades. To improve trajectory following accuracy, many robotic steering systems have been developed using various advanced control algorithms. To overcome the complicated modeling procedures, this study proposed a three-dimensional (3D) feedback control method based on fuzzy logic for

In this paper we present a spherical soft robotic arm made from fabric. The inflatable arm has a small mass and is pneumatically actuated. A configuration is employed with only three actuators controlling the two rotational degrees of freedom of a spherical joint. This differs from the commonly employed antagonistic pairs, including four actuators for two degrees of freedom. The fabrication procedure

In desert zones, a continuous cleaning activity of photovoltaic panels in solar plants is required since the deposition of both airborne dust and sand after a storm can reduce their efficiency up to 80%. Manual cleaning of the photovoltaic panels in dry areas is costly, cannot make use of water and workers must be employed several times in a month, often under extreme environmental conditions. For

This paper presents a trajectory optimization framework for planning dynamic legged locomotion based on a robot’s centroidal momentum (CM), which is the aggregation of all the links’ momenta at the robot’s Center of Mass (CoM). This new framework is built around CM dynamic model driven by Ground Reaction Forces (GRFs) parameterized with Bézier polynomials. Due to the simple form of CM dynamics, the

The magnetic fluid deformable mirror (MFDM) is a new type of wavefront corrector which has advantages compared to conventional wavefront correctors, such as higher stroke and lower fabrication cost. In this paper, a Youla (Q) parameterized adaptive regulation approach is proposed for the MFDM to correct both random and deterministic dynamic aberrations based on the dynamic model of the MFDM. The parameter

The mechanical dynamics of modern machines very often depend on the angular position of the driven axis. To obtain optimal control, such applications typically require an advanced control structure such as an adaptive controller. Moreover, the variation in the dynamics like changing inertia, load torque, and viscous friction limits the performance and reduces the energy efficiency. Energy savings can

This paper proposed a multi-loop modulation method (MMM; 3M) on the servo drives applied for the lower limb rehabilitation exoskeleton (LLRE). This proposed 3M included the current, speed and position 3-loop with the auto-tuning, inertia identifier and external load torque observer. The controller gains by searching the optimal bandwidth and by identifying the inertia of the LLRE system were derived

Parallel mechanisms are used increasingly often as modular subsystem units in various robots and man-machine interfaces for their superior stiffness, payload-to-weight ratio and dynamic properties. This leads to series-parallel hybrid robotic systems which utilize closed loop linkages and parallel kinematic machines as an abstraction of a certain kinematic joint. This paper presents a survey of recently

In the face of magnetic bearing rotor system multivariable, nonlinear, strong coupling control problems, a novel control decoupling method based on inverse system state feedback decoupling theory for the five degree of freedom of active magnetic bearing is presented. It solved the problem of ignoring the limitation of control parameters in conventional control methods. In this paper, the rigid body

It is well-known that helicopters descending fast may enter the so-called Vortex Ring State (VRS), a region in the velocity space where the blade’s lift differs significantly from regular regions and high amplitude fluctuations are often present. These fluctuations may lead to instability and, therefore, this region is avoided, typically by increasing the horizontal speed. This paper researches this

The precise manipulation of fluid through pumping systems has been the technological challenge in microfluidic applications. The biomedical applications call for precise and accurate delivery of fluid through miniaturized pumping systems. This paper presents a novel valveless micropump for biomedical applications operated by the Amplified Piezo Actuator. Integrating the disposable chamber and reusable

This paper proposes a detection method to identify the drill bit position during assisted bone drilling. A platform has been developed to support the surgeon in the planning of the drilling path. Albeit constrained along a fixed trajectory, the advancement of the drilling tool is manual, in order to preserve the natural haptic perception of the surgeon, who remains in charge of modulating the drilling

Pump-controlled actuators generally use single-rod cylinders in order to provide high output forces and reduce the installation space. According to the working principle of such systems, there are four possible circuit configurations, corresponding to four operational quadrants. This paper presents the design and experimental validation of a robust, fixed-gain, linear position controller for a newly

The recent developments in micro/nano-positioning technologies have highlighted the demand for compact large range three-degrees-of-freedom (3-DOF) XYΘ mechanisms for applications such as sample positioning in nanoimprint lithography, scanning probe microscopy, precision machining, and many more. However, this type of mechanisms suffers from a large footprint, sensing difficulties, and low motion accuracy

The Dahl friction model is a simple dynamic model for friction obtained by adding dynamics to the stress strain curve. The model captures many aspects of friction and has been used for simulation for a long time. A drawback with the model is that it does not display the stick-slip effect. The LuGre friction model extends the Dahl model to capture the stick-slip motion but is does not capture the fact

In the study we propose and examine a novel concept, eMR-TMD as we call it, replacing a standard tuned mass damper (TMD) by an electrical harmonic oscillator (RLC circuit). The concept employs an electromagnetic energy harvester (EEH) to extract energy from vibrations, an RLC circuit in which serial resonance phenomenon occurs and a magnetorheological (MR) damper. The approach does not require modifications

This paper presents the design and implementation of a Tactile/Force sensor which has been used on a 3-DOF decoupled parallel mechanism for Human-Robot Interaction purposes.The sensor, called HexaTactile, is a soft tactile sensor array based on six MEMS barometers, where each of them is covered by a silicone layer in the form of an incomplete pyramid. HexaTactile consists of six soft and highly sensitive

In the field of wearable robots, actuator efficiency and user safety are frequently addressed by intentionally adding compliance to the actuation unit. However, the implications compliance has on the actuator’s overall performance in different conditions and activities are not fully understood, largely due to single task-focused experimental evaluations of these devices. To overcome this, our paper

This study presents the design and system integration of the 13-degree-of-freedom legged platform, GAZELLE. The goal of this research is to develop a fast and reliable biped platform for walking experiments. Rapid leg movement can increase robustness in walking stability. During external push or walking on uneven ground, fast leg movement can realize an abrupt change on the landing position. GAZELLE

Hydraulically actuated manipulators are commonly used for material handling or at construction sites due to the high power density of hydraulic systems. Dig assistance systems or payload monitoring systems for excavators become more common to increase the efficiency and productivity. In this paper, a novel approach for estimating the dynamic parameters of a payload (including the mass) attached to

We address in this paper the problem of planning motion of free floating robot with state constraints. Due to the conservation of angular and linear momentum during the in-air motion, the problem is two-fold: one needs to design, in addition to the in-air motion, the initial impulse that imparts the robot with the appropriate momentum to perform a desired motion. The existence of state constraints

The nano scale motions of piezoelectric actuated nano-positioning systems are very sensitive to operating tasks, external disturbances, as well as variations of system dynamics. In this paper, a data-driven Iterative Feedback Tuning (IFT) based Active Disturbance Rejection Control (ADRC) approach is developed to optimize the control performance by conducting controller parameter tuning iteratively

A technique to identify feedthrough coupling in an unstable one degree-of-freedom electrostatic bearing is described. The feedthrough is caused by the simultaneous use of electrodes for differential capacitive sensing and electrostatic actuation. Cancellation of the feedthrough over a broad frequency band is necessary for the system to be practically stabilizable. A feedforward filter based on open-loop

Transverse ricochetal brachiation is a sophisticated locomotion style that mimics athletes swinging their bodies with their hands on a ledge in order to propel themselves for a leap to a target ledge. This paper describes the development of a transverse ricochetal brachiation robot (TRBR) and outlines motion control strategies for active flight body posture compensation. The crucial design parameters

Energy harvesting by using functional materials in suspension systems bear potential to win-back certain (even if low) amounts of vibrational energy, otherwise dissipated via the conventional (passive) dampers. Piezoelectric (PE) ceramics are functional materials that can be used for transforming mechanical energy into electrical and vice versa. In this paper, we study the capabilities and efficiency

Soft robots and manipulators with inflatable links possess inherent safety characteristics that make them a very interesting choice for tasks requiring human-robot interaction. However, they may face important challenges in their performance due to low structural stiffness. Accurate positioning of the end effector may prove a difficult task due to limitations in gravity compensation, or due to the

This paper presents an approach to mobile robot 6D localization based on a 3D laser scanner in GPS-denied scenarios. Commonly, 6D localization using laser scanners is performed with the use of extraction and association of the features or by comparison of the whole scans (very often off-line) using the ICP algorithm or its modifications. However, in some unstructured non-urbanized rough terrain environments

Based on the multiple wedge effects, magnetically manipulated petal-shaped capsule robots (PCRs) using circle-based profiles have achieved an advantageous comprehensive driving performance, which lies in acquiring the high fluid dynamic pressure to ensure the good self-centering ability inside the pipe, the fast steady swimming speed and the low fluid resistance torsion moment. Nevertheless, the limited

Active magnetic bearing (AMB) supported rotor systems require advanced control strategies to meet the increased performance requirements of more and more demanding applications. To meet the particular requirements for the performance under changing dynamics, an adaptive control structure is a task worth pursuing. This paper studies adaptive multi-input multi-output (MIMO) pole placement applied to

This paper presents the design, analysis, and control of a novel compact, large range 1-DOF micro manipulation mechanism. Leaf flexures were incorporated into a modular multilayer design configuration to achieve large range motion with a high natural frequency. The modular design of the proposed mechanism makes it usable as a building block to construct higher DOF-mechanisms. Computational analysis

In bone surgery, drilling of bone without causing severe damage to tissue is a critical procedure. Particularly for skull, spine, and special kinds of orthopedic surgeries, the process of bone drilling requires high accuracy and precision since excessive drill protrusion can cause damage to nerves, blood vessels, and nearby organs. To enhance safety of drilling, a new breakthrough detection technique

This paper presents comprehensive investigations on a new multi-pole multi-layer magnetorheological (MR) brake. This unique design features MR working gaps set between two-layer individual coils. Independent current supply was proposed to generate more flexible braking torque and lower power consumption. In this article, an exploded-view drawing of the proposed MR brake was presented, and theoretical

Hydro viscous clutch (HVC) is a power transmission unit which relies on shear stress of fluid to transmit driving torque. The conventional pressure control system suffers from high minimum operating pressure problem. This makes the HVC has a large drag torque and greatly limits the usage flexibility. In this article, a valve-and-pump compounded pressure control (VCPC) system is proposed for the hydro

In order to improve the performance of a magnetically levitated (maglev) axial flow blood pump, three-dimensional (3-D) finite element analysis (FEA) was used to optimize the design of a hybrid magnetic bearing (HMB). Radial, axial, and current stiffness of multiple design variations of the HMB were calculated using a 3-D FEA package and verified by experimental results. As compared with the original

In most Atomic Force Microscopes (AFM), a piezoelectric tube scanner is used to position the sample underneath the measurement probe. Oscillations stemming from the weakly damped resonances of the tube scanner are a major source of image distortion, putting a limitation on the achievable imaging speed. This paper demonstrates active damping of these oscillations in multiple scanning axes without the