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This paper addresses the design of instrumented single joint and multi-joints active orthoses for musculoskeletal and neuromuscular disorder exploration and functional rehabilitation. The use of these multi-contact exoskeletons, operating a selective limb joint mobilization, allows the measurement and the control of physiological parameters (instantaneous helical axis (IHA) motion, joint motion and...
Impedance control has been widely developed in the robotic exoskeleton field for human performance assistance and enhancement. However, the determination of desired impedance parameters that dominates the characteristics of interaction force and motion control is not straightforward since these parameters depend not only on the physical properties of the wearer but also on the speed region during...
In this paper, we propose and analyze a Regenerative Magnetorheological Actuator (RMRA) for gait assistance in knee joint. The actuator has motor and magnetorheological (MR) brake parts working in parallel, and can harvest energy through regenerative braking. This novel design provides multiple functions with good energy efficiency. The design of the RMRA is first introduced, and its multiple functions...
Compliant-motion control implementation on a humanoid robot with electrohydraulic joints is presented. Characterization results are shown, leading to a dynamic model used in feedback. A Natural Admittance Controller is designed, and its performance is demonstrated in demanding manipulation tasks, including dual-arm palmar manipulation of an egg and dual-arm valve turning.
Series elastic actuation (SEA) has been widely used for output force/torque regulation, however, the nonlinearity introduced by its torsion spring hysteresis will greatly affect the quality of feedback control. Thus an experimental procedure is conducted for the modeling and identification of spring hysteresis effect, based on which a compensated control scheme is given. Experiment results show that...
Manipulators with flexible joints are widely used as the space manipulators, whereas the elasticity of flexible joint leads to poor dynamic performance. To solve the influence of elasticity, the paper is to establish the model of flexible joint, identify the parameters, and design the controller. The off-line methods are applied to identify the current coefficient and the parameters of flexible joint...
Two-Step Test is now widely used to evaluate the locomotion ability of human in Japanese biomechanical clinical hospitals. It is a test in which Two-Step Value is calculated by dividing a subject's height by the maximum distance of his/her two steps of walking. The test was developed by Hirano and Muranaga in 2003 to conveniently predict human's walking ability and is shown to have high relations...
The traditional six-dimensional force/torque sensor calibration method requires a lot of precision loading force and can only be off-line calibration. In this paper, to solve the problem, an online calibration and decoupling method based on the shape from motion combined with complex algorithm is proposed. It does not require accurate and redundant loading force information, and have better noise...
Human robot cooperation is a challenging task of future generation home robots and is relevant also for industrial applications, where robots are supposed to act together with humans in non-structured environments. The paper focuses on on-line adaptation of robot trajectories, where robots and humans are autonomous agents coupled only through the manipulated object. Within the proposed approach, the...
This paper proposes an algorithm that estimates a reaction torque loading the grasping jaws of wire-actuated robotic forceps and compensates for subsequent wire elongation. The algorithm is constructed by the combination of the Reaction Force Observer (RFOB) and an optimization problem based on a gradient descent method. The conventional RFOB is used to estimate an external torque that includes not...
As a driving source of a robot arm in order to achieve a smooth movement at high power and with a minimal size, a series elastic drive system added with another actuator is used in this research. A series elastic mechanism using a torsion bar and a high reduction actuator drives the arm, and the added low reduction actuator reduces the vibration characteristics of the arm according to the response...
Several passive joints are usually needed in surgical robots to decrease the difficulty in doctors' operating, which can be manually rotated without motor pushing. When stopped at a specified position, passive joints should be locked until operation ends, and keep bearing torques. This paper is aimed to design a locking method used in minimally invasive surgical robot. Firstly choose the locking type...
In this paper, the estimation of the grasping torque of robotic forceps without the use of a force/torque sensor is discussed. To estimate the grasping torque when the robotic forceps driven by a rotary motor with a reduction gear grasps an object, a novel robust reaction torque observer is proposed. The robust reaction torque observer is developed according to the following steps. First, cancellation...
A physical assistant robot is useful for elderly and disabled people, as well as workers in certain industries, as it enhances their locomotive capabilities. However, risk assessment has identified some unique risks such as wounding of the skin and fall because of the use of such physical assistant robots. Among these potential risks, falls can be particularly severe. This study focuses on the effect...
In grasping, one fundamental question is to ask how well a grasp can resist external disturbance. Canonically, the solution of this question lies in calculating the set of wrenches that can be generated by the grasp assuming some limitation of the hand and measurement of the extreme point in some direction of that set. Using wrenches comes with two issues: the dependency on the choice of the origin...
A new control strategy for redundant robot motion control is proposed in this paper. In this strategy, the robot manipulator can track different trajectory precisely submitting to a multi-level constraints model. The significant physical quantity, namely, torque of the motor, is considered in this multi-level constraints model. Besides, to track the different path effectively, a control law has been...
In this paper, a Genetic Algorithm is used to solve for the optimization problem of a quadruped rover, which is developed based on a two-dimensional model of a domestic cat. The rover's gait, pose and control parameters are optimized for two separate objectives. First, the energy consumption through applied joint torque is minimized for fixed thrust speeds. Secondly, the rover's thrust speed is maximized...
We have developed the robotic vehicle on water that moves by the rider's balance. Previously, due to the lack of stability of the vehicle, balancing skill was required for the rider. In general, the center of buoyancy of the floating body influences on the stability. Therefore, in this paper, the floating vehicle was modeled and the appropriate body shape and size that improves the stability was simulated...
For an Unmanned Surface Vehicle (USV) system, it is difficult to obtain a precise system model. This is mainly because the USV system is, 1) of extensively complicated and thus presents huge nonlinearities, and 2) easily to be influenced by extensive hydrodynamics. In this paper, our main motivation is to construct a quasi-Linear Parameter Varying (qLPV) dynamical model for a water-jet propulsion...
Ensuring the motion stability and improving the mobility are crucial for wheeled ground vehicles (WGVs) to complete their missions, e.g., outdoor inspections and explorations. However, wheel slip may deteriorate the mobility performance and safety, particularly on unknown low-adhesive ground. In this research, a novel methodology to detect the adhesion stability using a force transmitting factor is...
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