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In this paper, we describe a gait generation method for the crawling motion of a legged robot using Normalized Energy Stability Margin (NESM). The crawling motion is a method of locomotion that, since the robot is very close to a state of falling, its leg and torso are grounded alternately in order to enable the robot to move with a low center of gravity. It has the benefit of decreasing the impact...
A key prerequisite for planning manipulation together with locomotion of humanoids in complex environments is to find a valid end-pose with a feasible stance location and a full-body configuration that is balanced and collision-free. Prior work based on the inverse dynamic reachability map assumed that the feet are placed next to each other around the stance location on a horizontal plane, and the...
The task of whole-body motion planning for humanoid robots is challenging due to its high-DOF nature, stability constraints, and the need for obstacle avoidance and movements that are efficient. Over the years, various approaches have been adopted to solve this problem such as bounding-box models and jacobian-based techniques. More commonly though, sampling-based algorithms are employed for this task...
In this work we present a novel and generic framework for reactive collision avoidance in bipedal locomotion, which is formulated as an optimization problem considering the constraints of collision avoidance as well as others (e.g. joint limits) to simultaneously satisfy both Cartesian and joint space objectives. To realize the reactive behaviors, several task space motions, such as the translational...
Passive walking model can make full use of the potential energy, which made it more efficient and more natural. So that it has become a hot spot in the current research. However, the condition of passive walking robot is heavily affected by its own structure and the external environment parameter, especially the slope angle which may result in a chaotic gait. In this paper, a control method capable...
Studies on power-assist robots are actively performed to assist human motion. Some of them are applied to assist the daily motion of physically weak persons such as elderly persons. Perception-assist was proposed to avoid an unexpected accident of users of the power-assist robot. In perception-assist, a virtual wall is sometimes used to avoid stumbling accident. In this paper, an effective shape of...
We present a simple walking prototype that is capable of demonstrating an efficient, near-collisionless gait down a ramp. This inertia-coupled rimless wheel is able to “walk” down a 3° incline, which corresponds to a cost of transport of approximately 0.05. This is the first device designed to demonstrate the concept of collisionless walking, where energy-loss due to foot/ground collisions is minimized...
The main advantage of multi-legged robots is the ability to traverse uneven terrain and to overcome obstacles that would impede the movement of a wheeled robot. Compliant joint drives can further improve the performance of legged robot systems by considerably reducing the problems associated with uneven or slippery footholds. Small changes of the foot position in uneven terrain are compensated by...
In grasping tasks carried out with humanoids, knowledge about the robot's reachable workspace is important. Without this knowledge, it might be necessary to repeatedly adapt the stance location and call an inverse kinematics solver before a valid robot configuration to reach a given grasping pose can be found. In this paper, we present an approach to select an optimal stance location in SE(2) for...
We present a new method for planning footstep placements for a robot walking on uneven terrain with obstacles, using a mixed-integer quadratically-constrained quadratic program (MIQCQP). Our approach is unique in that it handles obstacle avoidance, kinematic reachability, and rotation of footstep placements, which typically have required non-convex constraints, in a single mixed-integer optimization...
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...
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...
Multi-legged walking robots often make use of sophisticated control architectures to play their strengths in rough and unknown environments. The adaptability of these robots is an essential skill to achieve the maneuverability and autonomy needed in their application fields. In this work we present a reactive control approach for the hexapod LAURONV, which enables it to overcome large obstacles and...
The objective of this paper is to propose an approach for generating on-line walking patterns for a biped robot to navigate towards destination and reactively avoid obstacles. Kinect-based sensor system detects obstacles with velocity and dimension estimated for obstacle modeling. With identified obstacles, repulsion vectors of potential field given by obstacles modify walking path of a biped robot...
This paper presents an autonomous planning and control framework for humanoid robots to climb general ladder- and stair-like structures. The approach consists of two major components: 1) a multi-limbed locomotion planner that takes as input a ladder model and automatically generates a whole-body climbing trajectory that satisfies contact, collision, and torque limit constraints; 2) a compliance controller...
This paper proposes a humanoid dance motion generation system that deals with a huge variety of leg motions. While previous research only tackled on a few kinds of leg motions, original human dance leg motions contain various foot touch states such as slide, turn, and heel contact, as well as complex motions such as kick and twist. According to the dance literature, we found that there are seven major...
This paper deals with an optimal landing motion of a 4-link legged robot that minimizes the impact force at the contact point and the joint torques necessary during the motion. The cost function for optimization is given as the weighted sum of the one for impact force and the one for joint torques. While the configuration where the leg is bent is advantageous in reducing the impact force, the configuration...
This research aims to develop a novel foot sole mechanism which utilizes the jamming transition effect of granular material enclosed in an air tight bag, for use by bipedal robot walking on uneven ground. The mechanism is designed to make the foot sole be soft and compliant to adapt to the surface of an uneven terrain, and be stiff when the robot is in the support phase of the walking gait. The stiffness-variable...
Humanoid robots have abilities of stepping over or onto obstacles, which is different from wheeled robots. However it may be difficult to apply the ordinary motion planning methods such as Rapidly-exploring Random Trees (RRT) to humanoid robots directly. Because these kinds of methods only consider to circumvent obstacles and ignore the constraint of balance. Aiming at dealing with these problems...
Trotting on irregular terrain is a difficult task as undesirable impulse force by collision between robot foot and an obstacle makes the robot unstable. To cope with the problem, in this paper, variable impedance control algorithm changing leg impedance parameters according to the change of finite trot states is proposed. The state of quadruped trot is divided into five phases and the impedance parameters...
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