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We present a novel optimization-based motion planning algorithm for high degree-of-freedom (DOF) robots. Our approach combines a multi-contact dynamics formulation with optimization-based planning to compute collision-free, smooth and dynamically stable trajectories. Our formulation is general and can handle multiple simultaneous contacts and non-planar surfaces. We highlight the performance of our...
Iterative learning control(ILC) is used to track the trajectory of repetitive motion, especially for industrial robot. The proposed control scheme is based upon the feedback of tracking error and corresponding change rate, which construct a switching surface, with the use of a proportional structure, for which it is called sliding mode-like P-type ILC. In addition, an adaptive item was added to not...
Decreasing balance ability in older adults increases the risk of falls. According to the literature, two balance strategies are revealed, ankle strategy and hip strategy. The aim of this paper is to study the postural stability of the one leg stance on the frontal plane and verify the strategy used in older adults. A hypothesis about two different patterns in hip strategy is made and experiments were...
The MIT Cheetah demonstrated a stable 6 m/s trot gait in the sagittal plane utilizing the self-stable characteristics of locomotion. This paper presents a numerical analysis of the behavior of a quadruped robot model with the proposed controller. We first demonstrate the existence of periodic trot gaits at various speeds and examine local orbital stability of each trajectory using Poincar`e map analysis...
Minimally invasive surgery can involve navigating inside small cavities or reaching around sensitive tissues. Robotic instruments based on concentric tube technology are well suited to these tasks since they are slender and can be designed to take on shapes of high and varying curvature along their length. One limitation of these robots, however, is that elastic instabilities can arise when rotating...
The Spring-Loaded Inverted Pendulum (SLIP) is a widely used model for the description of humans and animals running motion. The SLIP model is, however, sensitive to impact angle for various terrain heights. One known method for increasing the model's robustness to terrain changes is the Swing Leg Retraction (SLR) method. Despite its popularity, an analytic formulation of this method has yet been provided...
Bio-inspired by moth or humming-birds, several micro air vehicles (MAV) have recently been developed. In these systems, the motion of the lifting surface is complex and modeled by flapping motion-controlled soft wings. The synchronization of the actuated periodic flapping motion of the wings and that of passive twisting degrees of freedom (dof) allows producing hovering flight. Depending on the feature...
This work introduces a novel balance monitoring strategy for humanoid robots. The proposed method addresses the problem of ensuring the balance maintenance of a humanoid robot, through the online monitoring of its state of balance by means of a Lyapunov (energy) function. The proposed method involves the use of dynamical models accounting for both the link and motor states. Energy limits corresponding...
Concentric-tube manipulators could experience a snapping-through motion that negatively impacts their smooth operation. This may limit their adoption in the operating room, despite their advantage of enabling dexterity within a highly confined space. In this paper, we demonstrate through the kinematics of concentric-tube robots, how this adverse effect of torsion could be reduced or potentially eliminated...
Iterative learning control can be applied to systems that repeat the same task over a finite duration with resetting to the starting location once each one is complete. The novel feature is the use of information from previous executions of the task in order to update the control signal applied during the next one and thereby sequentially improve performance. Linear iterative learning control laws...
This paper proposes a robust control scheme based on a disturbance observer (DOB) for flexible joint robots. In this paper, the DOB is applied only on the motor-side dynamics of the robot, and the uncertainties on the motor-side are successfully eliminated. It is shown that, to guarantee the stability, the estimated motor-side position should be fed back into the controller, which is different from...
A repairable system model which is consisted of two redundant robots and one safety unit is established in this paper. We are devoted to discussing the unique existence of the solution and the stability of the studied system by analyzing the spectrum distribution of the system operator in detail. Thus we can obtain stability analysis of the studied repairable system. Finally, some reliability indices...
A novel actuator is presented that merges traditional electromechanical motors and multistable composite structures. Previously, it has been shown that these structures are able to arrange themselves in multiple stable configurations corresponding to local minima of their strain energy. When coupled with an electromechanical motor as proposed in this article, the resulting actuator shows significant...
This paper presents a new non Parallel Distributed Compensation (non-PDC) controllers design based on line-Integral Lyapunov functions for continuous-time Takagi-Sugeno (T-S) fuzzy models. The previous works are mainly based on a BMI formulation (LMI for first and second order systems only). In this paper, we show that using a property on dual system, it can be possible to formulate the design of...
In practice, robot systems are usually required to hold uncertain load whose mass may change around a certain value. In this paper, the stability of the conventional model-based Computed-Torque Control(CTC) scheme for delta robots with uncertain load is investigated. Moreover a compensation control scheme is proposed to enhance the robustness of the conventional CTC scheme. The overall control is...
In this paper, taking the advantages of the simplicity of PD control and the high tracking performance of SMC and avoiding the drawbacks of both control methods, a new hybrid PD-SMC tracking control is proposed for trajectory tracking control of a serial robot by applying the hybridization concept. The unique features of the proposed hybrid control law are the model-free nonlinear feedback control...
This paper is concerned with the control problem for a class of discrete-time fuzzy Markov jump systems (MJSs). Unlike the common assumption in the existing literature, the antecedent parts of fuzzy rules are mode-dependent, i.e., the premise variables and/or their fuzzy partitions can be different in different modes. Based on a fuzzy-basis-dependent and mode-dependent Lyapunov function, the existence...
This study investigates the consensus control problem of linear multi-agent systems with input time delay. By exploring the certain features of Laplacian matrix, we transform the consensus problem into an asymptotic stability problem. The key element in our work is introducing the semi-discretization method to identify the optimal consensus control conditions and develops a mapping of the system response...
In this paper, we present a system that enables humanoid robots to imitate complex whole-body motions of humans in real time. In our approach, we use a compact human model and consider the positions of the endeffectors as well as the center of mass as the most important aspects to imitate. Our system actively balances the center of mass over the support polygon to avoid falls of the robot, which would...
The balance control of humanoid robots against external perturbations is a fundamental prerequisite for operating in unstructured environments where physical interaction may unexpectedly occur. These balancing actions can be very demanding in terms of power and torque requirements for ankle joints especially after strong and sudden impacts. In this work, an optimal control problem is formulated for...
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