Articulated robot

About: Articulated robot is a research topic. Over the lifetime, 4364 publications have been published within this topic receiving 52442 citations.

Practical bipedal walking control on uneven terrain using surface learning and push recovery

Abstract: Bipedal walking in human environments is made difficult by the unevenness of the terrain and by external disturbances. Most approaches to bipedal walking in such environments either rely upon a precise model of the surface or special hardware designed for uneven terrain. In this paper, we present an alternative approach to stabilize the walking of an inexpensive, commercially-available, position-controlled humanoid robot in difficult environments. We use electrically compliant swing foot dynamics and onboard sensors to estimate the inclination of the local surface, and use a online learning algorithm to learn an adaptive surface model. Perturbations due to external disturbances or model errors are rejected by a hierarchical push recovery controller, which modulates three biomechanically motivated push recovery controllers according to the current estimated state. We use a physically realistic simulation with an articulated robot model and reinforcement learning algorithm to train the push recovery controller, and implement the learned controller on a commercial DARwIn-OP small humanoid robot. Experimental results show that this combined approach enables the robot to walk over unknown, uneven surfaces without falling down.

Gait Planning of Quadruped Walking and Climbing Robot for Locomotion in 3D Environment

Abstract: One of the traditional problems in the walking and climbing robot moving in the 3D environment is how to negotiate the boundary of two plain surfaces such as corners, which may be convex or concave. In this paper a practical gait planning algorithm in the transition region of the boundary is proposed in terms of a geometrical view. The trajectory of the body is derived from the geometrical analysis of the relationship between the robot and the environment. And the position of each foot is determined by using parameters associated with the hip and the ankle of the robot. In each case of concave or convex boundaries, the trajectory that the robot moves along is determined in advance and the foot positions of the robot associated with the trajectory are computed, accordingly. The usefulness of the proposed method is confirmed through simulations and demonstrations with a walking and climbing robot.

Motion Planning In Phase Space For Intelligent Robot Arm Control

Abstract: Abstruct- This paper presents new robot aim1 planiiiiig and control schemes compatible with sensing based planning and control. These developiiieiits are a central component of robot arm coiitrol intelligence. The sclieines iise pliase space (velocity versus position) representation of robot arm motion in tlie task space, and apply time and energy optimization tecliiiiqiics to deteriiiiuc non-time based trajectories for giveii geometric path in tlie task space. A new pliasc space crror defiiiitioii aiid coiripiitatioii liavc been introtliiced aiid combined witli kiiowii nonlinear fcetlback control law, whicli linearizes and decoiiples the control in tlie task space. Tlic! system stability lias been proveii. Tlie new phase space plaiiiiiiig aiid coiitrol schemes were experiiiieiitally iiiipleiiieiited and tested on the 3-DOF positioii coiitrol of a PUMA 560 robot arm with very good results. I. INTRODIICTION

Distributed-Torque-Based Independent Joint Tracking Control of a Redundantly Actuated Parallel Robot With Two Higher Kinematic Pairs

Abstract: A redundantly actuated parallel robot of the 6RSS mechanism involving two point-contact higher kinematic pairs (HKPs) has been developed for the evaluation of food texture changes during the process of mastication. To accomplish this, a fundamental capability of reproducing complex mandibular motions of human subjects in a biomimetic manner is required. In this paper, first, the mechanism and experimental setup of the robot are described, followed by five performance criteria proposed for the torque distribution across the robot. Second, the distributed torque is employed as a feedforward to enhance the independent joint control for the tracking of the mandibular movement. The frictional effects are compensated for to further improve the tracking accuracy. Finally, experiments are carried out to evaluate and compare the proposed control algorithms with the robot being commanded to reproduce a real human mandibular motion in free chewing, chewing a silicone gel, and chewing a wooden stick. The results illustrate that the robot is able to emulate complex mandibular motions, the distributed-torque-based joint control significantly enhances the motion tracking accuracy, and the friction compensation can further improve the motion tracking performance.

A novel continuum-style robot with multilayer compliant modules

Abstract: This paper introduces a novel continuum-style robot that integrates multiple layers of compliant modules. Its essential features lie in that its bending is not based on natural compliance of a continuous backbone element or soft skeletal elements but instead is based on the compliance of each structured planar module. This structure provides several important advantages. First, it demonstrates a large linear bending motion, whilst avoiding joint friction. Second, its contraction and bending motion are decoupled. Third, it possesses ideal back-drivability and a low hysteresis. We further provide an analytical method to study the compliance characteristics of the planar module and derive the statics and kinematics of the robot. The paper provides an overview of experiments validating the design and analysis.