On the Manipulability of the Center of Mass of Humanoid Robots: Application to Design

2010 ◽  
Author(s):  
Sebastien Cotton ◽  
Philippe Fraisse ◽  
Andrew P. Murray
Keyword(s):  
Humanoid Robot ◽  
Mechanical Design ◽  
Dynamic Balance ◽  
Center Of Mass ◽  
Humanoid Robots ◽  
Contact Forces ◽  
Joint Torque ◽  
Contact Points ◽  
Floating Base ◽  
Space Formulation

This paper proposes an analysis of the manipulability of the Center of Mass (CoM) of humanoid robots. Starting from the dynamic equations of humanoid robots, the operational space formulation is used to express the dynamics of humanoid robots at their CoM and under their specific characteristics: a free-floating base, forces at contact points, and dynamic balance constraints. After a review of the kinematic manipulability of the CoM, the concept of dynamic manipulability of the CoM is introduced. The latter represents the ability of a humanoid robot to generate a spatial motion under a stability criterion. The size and shape of the dynamic manipulability of the CoM are a function of the joint torque limitations, the contact forces and the zero moment point used as a stability criteria. Two calculations of the CoM dynamic manipulability are proposed, a fast ellipsoid approximation, and the exact polyhedron computation. A case study illustrates the proposed approach on the HOAP3 humanoid robot and its use for mechanical design optimization.

New 3-DOFs Hybrid Mechanism for Ankle and Wrist of Humanoid Robot: Modeling, Simulation, and Experiments

2011 ◽  
Vol 133 (2) ◽  
Author(s):  
Samer Alfayad ◽  
Fethi B. Ouezdou ◽  
Faycal Namoun
Keyword(s):  
Degrees Of Freedom ◽  
Humanoid Robot ◽  
Power Transmission ◽  
Mechanical Design ◽  
Humanoid Robots ◽  
Classical Solutions ◽  
Kinematic Modeling ◽  
New Class ◽  
Hybrid Mechanism ◽  
And Control

This paper deals with the design of a new class of hybrid mechanism dedicated to humanoid robotics application. Since the designing and control of humanoid robots are still open questions, we propose the use of a new class of mechanisms in order to face several challenges that are mainly the compactness and the high power to mass ratio. Human ankle and wrist joints can be considered more compact with the highest power capacity and the lowest weight. The very important role played by these joints during locomotion or manipulation tasks makes their design and control essential to achieve a robust full size humanoid robot. The analysis of all existing humanoid robots shows that classical solutions (serial or parallel) leading to bulky and heavy structures are usually used. To face these drawbacks and get a slender humanoid robot, a novel three degrees of freedom hybrid mechanism achieved with serial and parallel substructures with a minimal number of moving parts is proposed. This hybrid mechanism that is able to achieve pitch, yaw, and roll movements can be actuated either hydraulically or electrically. For the parallel submechanism, the power transmission is achieved, thanks to cables, which allow the alignment of actuators along the shin or the forearm main axes. Hence, the proposed solution fulfills the requirements induced by both geometrical, power transmission, and biomechanics (range of motion) constraints. All stages including kinematic modeling, mechanical design, and experimentation using the HYDROïD humanoid robot’s ankle mechanism are given in order to demonstrate the novelty and the efficiency of the proposed solution.

Optimization-Based Whole-Body Control of a Series Elastic Humanoid Robot

2016 ◽  
Vol 13 (01) ◽  
pp. 1550034 ◽  
Author(s):  
Michael A. Hopkins ◽  
Alexander Leonessa ◽  
Brian Y. Lattimer ◽  
Dennis W. Hong
Keyword(s):  
Inverse Dynamics ◽  
Contact Forces ◽  
Joint Torque ◽  
Whole Body ◽  
Quadratic Program ◽  
Successful Implementation ◽  
Control Approach ◽  
Floating Base ◽  
High Level ◽  
Series Elastic

As whole-body control approaches begin to enter the mainstream of humanoid robotics research, there is a real need to address the challenges and pitfalls encountered in hardware implementations. This paper presents an optimization-based whole-body control framework enabling compliant locomotion on THOR, a 34 degree of freedom humanoid featuring force-controllable series elastic actuators (SEAs). Given desired momentum rates of change, end-effector accelerations, and joint accelerations from a high-level locomotion controller, joint torque setpoints are computed using an efficient quadratic program (QP) formulation designed to solve the floating-base inverse dynamics (ID). Constraints on the centroidal dynamics, frictional contact forces, and joint position/torque limits ensure admissibility of the optimized joint setpoints. The control approach is supported by an electromechanical design that relies on custom linear SEAs and embedded joint controllers to accurately regulate the internal and external forces computed by the whole-body QP. Push recovery and walking tests conducted using the THOR humanoid validate the effectiveness of the proposed approach. In each case, balancing is achieved using a planning and control approach based on the time-varying divergent component of motion (DCM) implemented for the first time on hardware. We discuss practical considerations that led to the successful implementation of low-impedance whole-body control on our hardware system including the design of the robot’s high-level standing and stepping behaviors and low-level joint-space controllers. The paper concludes with an application of the presented approach for a humanoid firefighting demonstration onboard a decommissioned US Navy ship.

HOW TO COMPENSATE FOR THE DISTURBANCES THAT JEOPARDIZE DYNAMIC BALANCE OF A HUMANOID ROBOT?

2011 ◽  
Vol 08 (03) ◽  
pp. 533-578 ◽  
Author(s):  
BRANISLAV BOROVAC ◽  
MILUTIN NIKOLIĆ ◽  
MIRKO RAKOVIĆ
Keyword(s):  
Humanoid Robot ◽  
Dynamic Balance ◽  
Humanoid Robots ◽  
Control Synthesis ◽  
Common Environment ◽  
Near Future

It is expected that the humanoid robots of the near future will "live" and work in a common environment with humans, which imposes the requirement that their operative efficiency ought to be close to that of humans. The main prerequisite to achieve this is to ensure the robot's efficient motion, which is its ability to compensate for the ever-present disturbances. The work considers the different strategies of how to compensate for the large disturbances that jeopardize the robot's dynamic balance in a most direct way, as well as the requirements to be met in the control synthesis. The ways in which such compensation can be efficiently realized are proposed and then verified by simulation.

Heel-strike and toe-off motions optimization for humanoid robots equipped with active toe joints

Robotica ◽  
2018 ◽  
Vol 36 (6) ◽  
pp. 925-944 ◽  
Author(s):  
Majid Sadedel ◽  
Aghil Yousefi-Koma ◽  
Majid Khadiv ◽  
Faezeh Iranmanesh
Keyword(s):  
Energy Consumption ◽  
Friction Coefficient ◽  
Dynamic Model ◽  
Humanoid Robot ◽  
Optimization Procedure ◽  
Humanoid Robots ◽  
Joint Torque ◽  
Heel Strike ◽  
Walking Pattern ◽  
Goal Functions

SUMMARYIn this paper, a walking pattern optimization procedure is implemented to yield the optimal heel-strike and toe-off motions for different goal functions. To this end, first, a full dynamic model of a humanoid robot equipped with active toe joints is developed. This model consists of two parts: multi-body dynamics of the robot which is obtained by Lagrange and Kane methods and power transmission dynamic model which is developed using system identification approach. Then, a gait planning routine is presented and consistent parameters are specified. Several simulations and experimental tests are carried out on SURENA III humanoid robot which is designed and fabricated at the Center of Advanced Systems and Technologies located in the University of Tehran. Afterward, a genetic algorithm optimization is adopted to compute the optimal walking patterns for five different goal functions including energy consumption, stability margin, joint velocity, joint torque and required friction coefficient. Also, several parametric analyses are performed to characterize the effects of heel-strike and toe-off angle and toe link mass and length on these five goal functions. Finally, it is concluded that walking pattern without heel-strike and toe-off motions requires less friction coefficient than the pattern with heel-strike and toe-off motions. Also, heavier toe link lowers tip-over instability and slippage occurrence possibility, but requires more energy consumption and joint torque.

Analyzing and Reducing Energy Usage in a Humanoid Robot During Standing Up and Sitting Down Tasks

2016 ◽  
Vol 13 (04) ◽  
pp. 1650014 ◽  
Author(s):  
Ercan Elibol ◽  
Juan Calderon ◽  
Martin Llofriu ◽  
Wilfrido Moreno ◽  
Alfredo Weitzenfeld
Keyword(s):  
Humanoid Robot ◽  
Center Of Pressure ◽  
Center Of Mass ◽  
Electrical Power ◽  
Joint Torque ◽  
Q Learning ◽  
Current Usage ◽  
Standing Up ◽  
Joint Velocity ◽  
Joint Acceleration

The aim of this paper is to reduce the energy consumption of a humanoid by analyzing electrical power as input to the robot and mechanical power as output. The analysis considers motor dynamics during standing up and sitting down tasks. The motion tasks of the humanoid are described in terms of joint position, joint velocity, joint acceleration, joint torque, center of mass (CoM) and center of pressure (CoP). To reduce the complexity of the robot analysis, the humanoid is modeled as a planar robot with four links and three joints. The humanoid robot learns to reduce the overall motion torque by applying Q-Learning in a simulated model. The resulting motions are evaluated on a physical NAO humanoid robot during standing up and sitting down tasks and then contrasted to a pre-programmed task in the NAO. The stand up and sit down motions are analyzed for individual joint current usage, power demand, torque, angular velocity, acceleration, CoM and CoP locations. The overall result is improved energy efficiency between 25–30% when compared to the pre-programmed NAO stand up and sit down motion task.

Development of lightweight hydraulic cylinder for humanoid robots applications

2017 ◽  
Vol 232 (18) ◽  
pp. 3351-3364 ◽  
Author(s):  
M Elasswad ◽  
A Tayba ◽  
A Abdellatif ◽  
S Alfayad ◽  
K Khalil
Keyword(s):  
Humanoid Robot ◽  
Mechanical Design ◽  
Experimental Testing ◽  
Fiber Composite ◽  
Humanoid Robots ◽  
Hydraulic Cylinder ◽  
Hydraulic Actuator ◽  
Carbon Fiber Composite ◽  
Robotic Applications ◽  
Actuator Performance

This paper presents a lightly weighted hydraulic actuator that is designed mainly for robotic applications. This hydraulic cylinder will be used as the main actuator for the hydraulic humanoid robot HYDROïD. For implementation, the knee joint is taken as an example in order to execute the necessary steps to build the actuator from carbon fiber composite material. An optimization process is used to minimize the total weight of the actuator and satisfy its constraints. Meanwhile, the mechanical design with the integrated sensors is shown. In addition, results are discussed on the spot of the weight minimization and actuator performance. Finally, experimental testing is carried out to monitor the pressure and the position readings of the hydraulic cylinder.

scholarly journals Whole-Body Dynamic Analysis of Challenging Slackline Jumping

2020 ◽  
Vol 10 (3) ◽  
pp. 1094 ◽  
Author(s):  
Kevin Stein ◽  
Katja Mombaur
Keyword(s):  
Center Of Pressure ◽  
Center Of Mass ◽  
Contact Forces ◽  
Joint Torque ◽  
Whole Body ◽  
Reconstruction Method ◽  
Motion Reconstruction ◽  
Interaction Forces ◽  
Optimization Framework ◽  
Equations Of Motions

Maintaining balance on a slackline is a challenging task in itself. Walking on a high line, jumping and performing twists or somersaults seems nearly impossible. Contact forces are essential to understanding how humans maintain balance in such challenging situations, but they cannot always be measured directly. Therefore, we propose a contact model for slackline balancing that includes the interaction forces and torques as well as the position of the Center of Pressure. We apply this model within an optimization framework to perform a fully dynamic motion reconstruction of a jump with a rotation of approximately 180 ° . Newton’s equations of motions are implemented as constraints to the optimization, hence the optimized motion is physically feasible. We show that a conventional kinematic analysis results in dynamic inconsistencies. The advantage of our method becomes apparent during the flight phase of the motion and when comparing the center of mass and angular momentum dynamics. With our motion reconstruction method all momentum is conserved, whereas the conventional analysis shows momentum changes of up to 30%. Furthermore, we get additional and reliable information on the interaction forces and the joint torque that allow us to further analyze slackline balancing strategies.

A novel approach for humanoid push recovery using stereopsis

Robotica ◽  
2013 ◽  
Vol 32 (3) ◽  
pp. 413-431 ◽  
Author(s):  
Mohammad-Ali Nikouei Mahani ◽  
Shahram Jafari ◽  
Hadi Rahmatkhah
Keyword(s):  
Mathematical Model ◽  
Humanoid Robot ◽  
Center Of Mass ◽  
Humanoid Robots ◽  
Critical Issue ◽  
Acceleration Sensor ◽  
Deviation Angle ◽  
Push Recovery ◽  
Novel Approach ◽  
Angle Stable

SUMMARYPush recovery is one of the most challenging problems for the current humanoid robots. The importance of push recovery can be well observed in the real environment. The critical issue for a humanoid is to maintain and recover its balance against any disturbances. In this research a new stereovision approach is proposed to estimate the robot deviation angle and consequently, the movement of center of mass of the robot is calculated. Then, two novel strategies have been devised to recover the balance of the humanoid which are called “knee strategy” and “knee-hip strategy.” Also, a mathematical model validates the efficiency of the proposed strategies as demonstrated in the paper. Experiments have been conducted on a humanoid robot and demonstrate that the predicted robot deviation angle, using stereovision technique, converges to the actual deviation angle. Stable regions of proposed strategies illustrate that the humanoid can recover its stability in a robust manner. Vision-based estimation also shows a higher correlation to actual deviation angle and a lower fluctuation compared with the output of the acceleration sensor.

scholarly journals Sliding Balance Control of a Point-Foot Biped Robot Based on a Dual-Objective Convergent Equation

2021 ◽  
Vol 11 (9) ◽  
pp. 4016
Author(s):  
Yizhou Lu ◽  
Junyao Gao ◽  
Xuanyang Shi ◽  
Dingkui Tian ◽  
Yi Liu
Keyword(s):  
Balance Control ◽  
Center Of Mass ◽  
Biped Robot ◽  
Optimization Method ◽  
Contact Forces ◽  
Joint Torque ◽  
Whole Body ◽  
Physical Constraints ◽  
Equilibrium Control ◽  
Control Framework

The point-foot biped robot is highly adaptable to and can move rapidly on complex, non-structural and non-continuous terrain, as demonstrated in many studies. However, few studies have investigated balance control methods for point-foot sliding on low-friction terrain. This article presents a control framework based on the dual-objective convergence method and whole-body control for the point-foot biped robot to stabilize its posture balance in sliding. In this control framework, a dual-objective convergence equation is used to construct the posture stability criterion and the corresponding equilibrium control task, which are simultaneously converged. Control tasks are then carried out through the whole-body control framework, which adopts an optimization method to calculate the viable joint torque under the physical constraints of dynamics, friction and contact forces. In addition, this article extends the proposed approach to balance control in standing recovery. Finally, the capabilities of the proposed controller are verified in simulations in which a 26.9-kg three-link point-foot biped robot (1) slides over a 10∘ trapezoidal terrain, (2) slides on terrain with a sinusoidal friction coefficient between 0.05 and 0.25 and (3) stands and recovers from a center-of-mass offset of 0.02 m.

Sign in / Sign up

Export Citation Format

Share Document