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Applying humanoid robots in disaster sites requires strong locomotion abilities due to the cluttered and unstructured environment. Besides bipedal walking, it is beneficial to provide functionality to locomote on four limbs, and to control the transitions between bipedal and quadrupedal locomotion. In this paper, we propose a planning algorithm for bipedal and quadrupedal locomotion with intermediate...
In situations where humanoid robots with constrained posture walk through a narrow space (e.g. manufacturing plants and kitchens), shuffling motions that are stepless and possess wide foot supporting area are effective. One of the difficulties of humanoid's shuffle translations is the load distribution between both feet. If sole loads are not distributed appropriately, the humanoid robot cannot maintain...
Inspired by geckos, we built a new configuration for climbing robot, the GPL model with one passive waist and four active axil legs. In this paper, further research was made to analysis its motion. We found the anomalies line between supporting feet and its effect on robot motion. A step further, the principia of configuration design and gait planning were proposed based on dynamic analysis. The prototype...
Search and rescue (SAR) missions are being carried out by several types of robots. They include ground, marine and air vehicles depending on the terrain and mission to be tackled. A particular niche for SAR activities are shallow waters. They present high difficultly for conventional ground or marine robots because of the mix of water and ground. Such an environment is difficult to be accessed for...
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...
Bipedal walking is a complex and dynamic whole-body motion with balance constraints. Due to the inherently unstable inverted pendulum-like dynamics of walking, the design of robust walking controllers proved to be particularly challenging. While a controller could potentially be learned with a robot in the loop, the destructive nature of losing balance and the impracticality of a high number of repetitions...
Although in recent years several studies aimed at the navigation of robots in cluttered environments, just a few have addressed the problem of robots navigating while moving a large or heavy object. This is especially useful when transporting loads with variable weights and shapes without having to change the robot hardware. On one hand, a major advantage of using a humanoid robot to move an object...
Roll-over geometry, a leading design objective for passive prosthetic feet, does not provide enough information to find the lower leg segment orientation in the laboratory reference frame. The physical behavior of a prosthetic foot adds a constraint which makes finding this orientation possible. A novel optimization parameter for prosthetic feet that incorporates both the roll-over geometry and the...
This paper describes the initial design, control system development and preliminary testing of a robotic gait training device which aims to help teach and/or improve the gait patterns of children affected by cerebral palsy (CP). An H-frame, timing-belt driven, 2 degree-of-freedom stage has been designed and built to guide a child's leg through a gait pattern during over-ground training. The end-effector...
Assisted gait monitoring can benefit from the measurement of feet positions and orientations. Thus, in this paper, rollator type walkers are equipped with one active depth sensor for gait assessment. Also, a real-time feet positions and orientations algorithm is proposed and a gait assessment method is provided for clinical evaluation purposes. Results using the proposed algorithm are compared with...
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...
This paper proposes a method for human activity classification in home based monitoring. The proposed approach is based on minimum jerk (MinJerk), a primary model for smooth path planning employed by human motor control in upper-extremity motion. Based on new evidences that show common control strategies in lower and upper extremity, MinJerk is adapted in our study to estimate the foot motion with...
Gait planning is an important part of robotics research, and turning gait is an important and useful walking gait of a hexapod robot. But researches on turning gait of hexapod robots are limited. This paper presents the structure of a hydraulic hexapod walking robot. The coordinate of the leg is defined, and the positive and inverse kinematic equation of the leg is established. Foot trajectory based...
We propose a push-recovery strategy to stabilize the robot under unmodelled, large external forces. The strategy integrates Center-Of-Gravity (COG) angular momentum regulator, COG state estimator, and stepping control, which online modifies the trajectories of the COG and the swing leg. Using the centroidal-moment-pivot criterion, the COG angular momentum regulator controls the dynamics of the COG...
We investigate the design of periodic gaits that will also function well in the presence of modestly uneven terrain. We use parameter optimization and, inspired by recent work of Dai and Tedrake, augment a cost function with terms that account for perturbations arising from a finite set of terrain height changes. Trajectory and control deviations are related to a nominal periodic orbit via a mechanical...
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...
Biped walking control based on simplified models relies much on online feedback stabilizers to compensate the zero-moment point (ZMP) error which partially comes from the model inconsistency of pattern generation. Inspired by the fact that human improves the performance by practicing a task for multiple times, this paper presents an online learning control framework for improving the robustness during...
Quadruped locomotion offers significant advantages over wheeled locomotion for small mobile robots operating in challenging terrain. Central pattern generators (CPGs), as found in the neural circuitry of many animals, may be used to generate joint trajectories for quadruped robots. However, basic CPG-based trajectories do not explicitly consider ground contact constraints, a particular concern during...
This paper presents a trajectory generator for humanoid robots that can simultaneously consider 3D position tracking of the center-of-mass (COM), reactive stepping (foot positions are non-constant), zero-moment-point (ZMP) constraints as well as position constraints.
Many control policies developed for legged robots are based on control of an underlying, simplified version of the dynamics of the robot. A good example is the Linear Inverted Pendulum Model (LIPM) which has become the standard control template for ZMP-based rigid robots. For compliant robots, this reduced order model is naturally the Spring-Loaded Inverted Pendulum (SLIP), which has proven to have...
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