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Our aim is to develop an algebraic approach to estimate human posture in the sagittal plane using Inertial Measurement Unit (IMU) providing accelerations and angular velocities. For this purpose, we address the issue of the estimation of the amplitude, frequency and phase of a biased and noisy sum of three sinusoidal waveform signals on a moving time horizon. The length of the time window being small,...
In this research, an approach to optimize motions for a humanoids is presented. Rapidly-exploring Random Tree(RRT) were used to plan an initial suboptimal motion. A reinforcement learning was then implemented to optimize the trajectories with respect to energy consumption, similarity to a human's natural motion and, physical limits. Energy cost was estimated by joint torque from a dynamic model, and...
Although the problem of dynamic locomotion in very rough terrain is critical to the advancement of various areas in robotics and health devices, little progress has been made on generalizing gait behavior with arbitrary paths. Here, we report that perturbation theory, a set of approximation schemes that has roots in celestial mechanics and nonlinear dynamical systems, can be adapted to predict the...
This paper presents a low-cost automated system that is able to apply a 5-degree-of-freedom (DOF) force on a human fingertip with high precision. It is designed to be used as a calibration platform for the previous proposed fingernail imaging system, and as a haptic system. The system is composed of two Novint Falcon devices linked by two universal joints and a rigid bar to provide 5-DOF motion and...
The Lower-limb Power Assisted Robot is a typical exoskeleton power assistance device, which is worn on the user's lower extremities. It can help the elderly and the infirm walk independently. According to the characteristics of human lower extremity joints, a robot with four-bar knee joint whose pelvis and knee joint are driven by the motor-driven screw-nut body is designed. Employing the Denanit-Hartenberg...
In this work, we present an approach to fuse video with orientation data obtained from extended inertial sensors to improve and stabilize full-body human motion capture. Even though video data is a strong cue for motion analysis, tracking artifacts occur frequently due to ambiguities in the images, rapid motions, occlusions or noise. As a complementary data source, inertial sensors allow for drift-free...
This paper introduces a kinematically constrained closed loop inverse kinematics algorithm for motion control of robots or other articulated rigid body systems. The proposed strategy utilizes gradients of collision and joint limit potential functions to arrive at an appropriate weighting matrix to penalize and dampen motion approaching constraint surfaces. The method is particularly suitable for self...
This work presents an approach for the modeling and numerical optimization of ball joints within a Marker-less Motion Capture (MoCap) framework. In skeleton based approaches, kinematic chains are commonly used to model 1 DoF revolute joints. A 3 DoF joint (e.g. a shoulder or hip) is consequently modeled by concatenating three consecutive 1 DoF revolute joints. Obviously such a representation is not...
This paper presents a new technique for estimating the center of mass of articulated rigid body systems. This estimation technique uses the statically equivalent serial chain, a serial chain representation of any multilink branched chain whose end-effector locates directly the center of mass. This technique works based on a knowledge of only the kinematic architecture of the system and does not require...
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