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Many wearable robots are not fully capable of fitting the motion of the wearer, owing to their limited degrees-of-freedom (DOF). This limitation disturbs motions such as corner curving, which are required in daily life. In this study, the effect of the DOF restriction on the corner curving motion was observed and analyzed. The gait motions, when curving a round corner with and without the restriction...
This paper presents the gait design and comparison study of a quadruped robot. The main contributions of this paper are: (i) Explore the modularized system design of an 8 degree-of-freedom quadruped robot with a power management system. (ii) Propose a gait design method based on drive function. (iii) Propose another gait design method based on foot trajectory. (iv) The simulation of the walk and trot...
In this paper, we presented a low cost assistive device of an exoskeleton robot, to assist the lower limb muscle by following the gait pattern generation. The paper presents the technique how to duplicate the natural gait motion pattern based robotic platform from the neutral person motion as data pattern generation, to control the positioning of foot trajectory by following the data pattern generation...
The lift-and-carry of non-rigid objects is challenging for both people and bipedal robots. Examples include lifting and carrying jugs, jerry cans or bags that are respectively filled with water, gasoline or sand. Carrying such objects often makes it difficult to walk due to the shifting center-of-mass. As such, tripping and falling are risks. Such lift-and-carry is a common material handling task...
Heel-toe walking can increase the stride length within the same joint limit of the robot. This paper proposes a method to compute the foot angle for heel-toe walking. In heel-toe walking, the value of the foot angle influences the movement of the legs, so it is proposed to select the foot angle to minimize the movement of the legs. The changes in stride and movement of leg with or without the heel-toe...
In this paper, we show an underactuated bipedal walker can travel on steep slope by bending its stance knee when the swing foot hits on the ground. First, we introduce an underactuated bipedal model with knees which can be controlled knee angles by applying the control input. Second, we consider an input-output linearization formula with three desired time trajectory functions and output-following...
Although three segmented mechanical leg is similar to animal limb morphology, it is difficult to solve inverse kinematic and dynamic equations due to the redundant degrees of freedom. Therefore, simple and efficient motion control cannot be achieved. Based on a structure of goat's hindlimb, the work in this paper aims at studying the movement mechanism to remove redundant degrees of freedom in three...
Generating gait trajectories is an important step in biped motion control. So, in this paper, a neuro fuzzy (ANFIS)-based gait trajectory generator for a normal walking of a biped robot during the single support phase is developed. Since human sensorimotor controls are done in an optimal way following the principle of optimality, gait trajectories data of human subjects of different hip heights, and...
This paper presents a study on overground non-pathological gait, focusing on hip and knee joint trajectories in sagittal plane. The objects of study are some characteristic points of the joint curves (including the extrema) and their relation to gait parameters, namely normalized walking speed, cadence and normalized step length. The main objective is to predict the spatio-temporal values of these...
This paper presents a systematic methodology utilizing multi-domain hybrid system models and optimization based controllers to achieve human-like multi-contact prosthetic walking experimentally on a custom-built prosthesis: AMPRO. Inspired by previous work that realized multi-contact locomotion on a bipedal robot AMBER2, a hybrid system based optimization problem is proposed leveraging the framework...
This work presents a method for deriving a gain scheduled balance controller to stabilize the gate of a three legged under-actuated robotic platform called THALeR (Tri-Pedal Hyper Altitudinal Legged Robot). The scheduler adapts the controller gains in real time based upon the system's instantaneous potential energy in order to create a smooth, stable gait. The final controller is simulated with white...
Patients affected by spinal cord injury cannot usually regain unassisted walking. This is why several research groups and companies have developed exoskeletons which enable these people to regain mobility in a standing position. The simplest joint configuration for exoskeletons is to actuate the knees and the hips in the sagittal plane. The ankles and feet are then unactuated and their range of motion...
The variable spring-loaded inverted pendulum (V-SLIP) model captures characteristic properties of the hip or COM motion in human locomotion. A control strategy consists of a leg stiffness controller and a foot placement controller is proposed for a biped walker. Some restrictions are considered in the control strategy, e.g. the friction and the ability of the actuator. A novel trajectory function...
Functional locomotion requires continuous modulation of coordination within and between legs to flexibly accommodate demands of real-word environments. In this context, dynamic movement primitives (DMP) is a powerful tool for motion planning based on demonstrations, being used as a compact policy representation well-suited for robot learning. In this work, we study on-line adaptation of robot biped...
A technique to achieve stable walking of a biped robot on an uneven terrain is proposed in this paper. A biped structure with a flexible foot will be able to navigate uneven terrain more effectively than the same with a flat foot. The criterion used for stable walking is Zero moment point (ZMP). The geometric center of the support polygon formed by the flexible foot is taken for dynamically planning...
This paper presents a lower limb rehabilitation robot based on free gait and virtual reality, which is intended to improve therapeutic efficacy. With the help of the robot, patients with motor disabilities can walk with free gait in a virtual environment and choose between passive and active training modes. So the impaired limbs can get appropriate exercise in all clinical stages and the motivation...
This paper presents a method of designing a natural human-like walking pattern for a bipedal humanoid robot. Motivated by biomechanical studies on human walking, we model the walking pattern with continuous and differentiable mathematical functions. For stable walking of the robot, we design a pattern generator based on the ZMP (Zero-Moment Point) criterion. The proposed walking pattern involves three-dimensional...
This paper presents new methods to control humanoid turns while running, through the use of a 3D-SLIP template model with steering control. The work builds on a previous controller for straight-ahead running and describes the new methods that enable online humanoid steering for different speeds and turn rates. As opposed to previous research which has studied 3D-SLIP steering with a monopod model,...
This work analyses the obstacle crossing during gait and compares the behavior of humans with a robot model. The aim of the study is to compare the obstacle crossing task between human subjects, performing the task both with vision and blindfolded, and ZMP biped robots. It was hypothesized that the trajectories of the hip joint and the foot of the blindfolded subjects would resemble those of the robot...
The Segmented Spring-Loaded Inverted Pendulum model is analysed, and it is shown that it exhibits walking gait. We propose a control architecture that exploits control of the knee stiffness to provide robustness of the system with respect to changes in gait. This controller is extended for a realistic bipedal robot model that uses variable stiffness actuators to control the knee stiffness. The variable...
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