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Uneven terrain walking is one of the important premises for biped robots to serve people. However, it is one of the key challenges for biped robots walking on a slope. In this paper, a universal method to generate patterns for biped robot walking on a three-dimensional (3D) slope is proposed. Different from most researches, which only focused on the specific walking directions on a slope as across...
To improve the efficiency of multi legged climbing robot, a dynamic climbing gait is proposed for a gecko inspired mechanism with a pendular waist and linear legs (GPL). Then, a mathematical model is built and the kinetics of the climbing gait is illustrated. Trajectory of the waist, identical to centroid of the GPL model, is also discussed in this paper. The forces at the feet of GPL are calculated,...
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...
We propose a new biped locomotion planning method that optimizes locomotion speed subject to friction constraints. For this purpose we use approximate models of required coefficient of friction (RCOF) as a function of gait. The methodology is inspired by findings in human gait analysis, where subjects have been shown to adapt spatial and temporal variables of gait in order to reduce RCOF in slippery...
A motion design for humanoid robots to satisfy dynamical constraints on the external forces even at the kinematic exceptions such as singular configurations and joint angle limits is proposed. It enables robots to mimic natural, comfortable and lively human motions, which leverage the limit of kinematics, based on a robust numerical solver of the prioritized inverse kinematics. The idea of prioritization...
This paper proposes a new generic strategy to investigate the dynamic limits of the humanoid robot HRP-2 based on whole body optimal control optimization. In this study we exploit the intuitive access to complex motion characteristics, given by optimal control, to effectively resolve a major technical coupling effect, namely between the ankle elasticity and the stabilizing algorithms. Control efforts...
This paper presents an approach to shank-foot trajectory control using computed-torque control method. The aim is to provide rehabilitative measures to help patients with lower limb disorders improve their mobility performance. This measure is achieved by designing a desired trajectory to be followed by the shank-foot model for the rehabilitative purpose. The shank-foot model is designed to depict...
Human movement, as for example human gait, can be considered as an optimal realization of some given task. If the optimization criteria for different types of gait were known, this knowledge could help to improve robot motion generation and control, also for complex walking motions on slopes or stairs. Unfortunately, in general the criteria for which the naturally performed human motion is optimal,...
In this paper, a method for a biped to quickly change its running direction is proposed. To change the running direction of the biped robot, a rotation of the body is needed. When the robot rotates its body during a support phase, however, there may be a few limitations such as the workspace of hardware and the time. To overcome these limitations, the running direction of the biped robot is changed...
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...
Due to the high complexity of the humanoid body, and its inherently unstable inverted pendulum-like dynamics, the development of a robust and versatile walking controller proves to be a difficult task. Using machine learning algorithms with hardware in the loop is a promising way of achieving balanced and dynamic gaits. In this work, we propose an online learning technique that learns how to step...
It is in general complex to consider the complete robot dynamics when planning trajectories for bipedal locomotion. We present an approach to trajectory planning, with the classical Linear Inverted Pendulum Model (LIPM), that takes explicit consideration of the unstable dynamics. We derive a relationship between initial state and the control input that ensures the overall system dynamics will converge...
Biped Robots are a class of legged robots, which should work in various environments such as flat or uneven terrain. To walk on different surfaces, it should be adaptable to the variations on the ground with a flexibility in foot movement to maintain its stability. Zero Moment Point (ZMP) is a technique used to ensure dynamic stability. ZMP should be within the support polygon for a robot to be stable...
Lizards with a thin and flexible body can easily pass through a narrow path. Their sprawled gait increases their stability and allows them to overcome obstacles and rough terrain. Therefore, lizard bio-mimetic robots are suitable for reconnaissance and detection. The dynamic modeling of a lizard was carried out by weighing each link of a lizard and constructing its 3D shape using micro-CT scanning...
This paper considers the problem of planning the motion of a humanoid robot that must execute a manipulation task, possibly requiring stepping, in environments cluttered by obstacles. The proposed method explores the submanifold of the configuration space that is admissible with respect to the assigned task and at the same time satisfies other constraints, including humanoid equilibrium. The exploration...
This paper presents a biped locomotion control to step sideways based on the framework of the dynamics morphing. Since the proposed controller does not require detailed referential motion trajectories, it enables a robot to walk sideways at arbitrary velocity given at random timing. Sideward locomotion is realized by alternating the velocity following control and the self-excited oscillating control...
This paper works with the concept of Divergent Component of Motion (DCM), also called ‘(instantaneous) Capture Point’. We present two real-time DCM trajectory generators for uneven (three-dimensional) ground surfaces, which lead to continuous leg (and corresponding ground reaction) force profiles and facilitate the use of toe-off motion during double support. Thus, the resulting DCM trajectories are...
Balance strategies range from continuous postural adjustments to discrete changes in contacts: their simultaneous execution is required to maintain postural stability while considering the engaged walking activity. In order to compute optimal time, duration and position of footsteps along with the center of mass trajectory of a humanoid, a novel mixed-integer model of the system is presented. The...
Biped walking is sensitive to large perturbation because of the limited foothold and unstable nature. This paper proposed a strategy of dynamic updating the footstep for humanoid robots to recover their balance from an unexpected perturbation with one step. The proposed strategy consists of a desired footstep calculator and a swing leg controller. The desired footstep calculator consists of three...
The ability to avoid collisions is crucial for locomotion in cluttered environments. It is not enough to plan collision-free movements in advance when the environment is dynamic and not precisely known. We developed a new method which generates locally optimized trajectories online during the feedback control in order to dynamically avoid obstacles. This method successfully combines a local potential...
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