Fathi Ben Ouezdou

Design and development of the biped prototype ROBIAN

In order to study the human being locomotion system, a multi-degrees of freedom (DOFs) biped prototype equipped with flexible feet, which is named ROBIAN, is developed. In this paper, the conceptual design of the biped prototype ROBIAN is discussed. The features of ROBIAN include: (1) parallel mechanism at the hip and the ankle, (2) modular design, and (3) 1-DOF active/passive joint between the heel and the toe. ROBIAN has 18-DOFs in total: 6-DOFs for each leg, 1-DOF passive or active joint for each foot and 4-DOFs for the upper limb. One of the major application of ROBIAN is the efficient development of a real testbed of active/passive prosthesis for the disabled.

Lightweight high performance integrated actuator for humanoid robotic applications: Modeling, design & realization

Actuation of robotic systems is still an open question and represents a big challenge. Demanding performances including high power to mass ratio, capability of producing high power at low speed within a small-occupied volume are some of the key issues that required careful consideration. These criteria aimed to increase autonomy of humanoid robots. In this paper, a novel hydrostatic transmission actuator is proposed. The proposed actuator is controlled by displacement and has capacities for energy storage. This leads to an optimal solution in terms of power consumption. First, the proposed hydrostatic actuation principle is explained. A simplified hydraulic scheme to illustrate the energy storage capability is then provided. A mathematical model of the proposed solution is detailed showing our ability to access to the payload “jerk”. The built prototype is presented and its properties are outlined. Finally, a prototype of the actuator and the preliminary results of the actuator performance are presented, demonstrating the novelty of our solution.

Design of a 3 DOFs parallel actuated mechanism for a biped hip joint

This paper deals with a novel approach to carry out the design of 3 DOF actuated joints for humanoid robots. Instead of common serial mechanism, a more robust parallel mechanism was developed. This kind of structure allows the terminal body to move within a cone from the nominal position and permits unlimited rotation about the cone pointing axis. Simulations were conduced to validate the kinematic model and optimize the design. Experimental prototype was developed to perform realistic tests on the control of this kind of mechanism.

Comparison of several kinds of feet for humanoid robot

This paper describes our research efforts aimed in the analysis of the humanoid robot feet role during walking gait. To improve the humanoid robot walking performances, a dynamic simulation using ADAMS software is carried out. To analyze the foot model effects virtual locomotion system has been built. Four foot models are compared through two criteria: the total energy consumption and the normal contact force component. These models are plate, flexible, active and hybrid flexible active feet parts. Simulation results show the relative effects of the flexibility and the introduction of the active joint at the toes level. The results prove the efficiency of the flexible active foot model

Dynamic simulation of a humanoid robot with four DOFs torso

In this paper, we present the 3D dynamic simulation of walking gait of biped Robian II virtual manikin. The biped has 16 degrees of freedom (DOFs). Initially, a biomimetic approach is used to model a humanoid biped having 25-DOFs based on common European male (75 kg, 1.78 m). Using human being motion recording, foot/ground contact model and inverse kinematics, a 3D dynamic simulation of this humanoid is carried out. Scale factorization is used in order to reach Robian II weight and height. A 3D dynamic simulation of the Robian size humanoid gives the effort wrench exerted by the torso on the lower limbs. An analysis of the six components of this wrench shows the existence of two coupling relations. A study of four DOFs mechanisms based on the general state equation formalism leads us to an interesting result. Indeed, four DOFs are necessary and sufficient to emulate the dynamic effects. A RPPP mechanism is presented in order to replace Robians upper part. Results of 3D simulation of the 16-DOFs resulting biped are presented. The ZMP control algorithm is used to ensure dynamic stability of the biped during walking gait.

A new control strategy for ROBIAN biped robot inspired from human walking

In this paper, we show that a biped robot can walk dynamically using a simple control technique inspired from human locomotion. We introduce four critical angles that affect robot speed and step length. Our control approach consists in tuning the PID parameters of each joint for increasing stability of the walk. This method could be easily implemented in real time because it needs acceptable calculation time. We validated the control approach to a dynamic simulation of our 14DOF biped called ROBIAN. A comparison with human walking is presented and discussed. We prove that we can maintain robot stability and walk cyclepsilas repetition without referencing a predefined trajectory or detecting the center of pressure. Results show that the walk of the biped is very similar to human one. A power consumption analysis confirms that our approach could be implemented on the real robot ROBIAN.

Human-like motion based on a geometrical inverse kinematics and energetic optimization

For humanoid robotics the cooperation with human beings makes human like behavior indispensable. The robots of our days have to feature human like form and structure. But, more importantly its ways of motion and reactions should be like that expected with human. In this paper, we propose an algorithm for solving the human arm inverse kinematics problem (position and orientation). The proposed method eliminates the singular configurations faced in the classical inverse kinematics methods. Our algorithm is based on the choice of a special reference frames in the workspace of the different parts of human arm. The geometrical projection in local frames gives the aimed results. The proposed redundancy resolution criterion for 7ddl human like arm is obtained through an energetic optimization. The proposed algorithm could be used for humanoid robots arm, in upper limb prosthesis application, as well as in computer animations. It gives the solution for the inverse kinematics of the arm. Simulation results within ADAMS software are presented. Our study takes the result of a detailed grasping research which gives an associated object reference frame indicating the way to grasp the object.

Three DOF hybrid mechanism for humanoid robotic application: Modeling, design and realization

This paper deals with a research work aimed to develop a new three degrees of freedom (DOF) mechanism for humanoid robots. The main idea is to build hybrid (3DOF) mechanism, which avoids the drawbacks of the serial and parallel mechanisms. The new solution has to merge the advantages of both classical (serial and parallel) structures in order to achieve optimal performances. The proposed mechanism can be used as a solution for several modules in humanoid robot. The hip mechanism is taken as an example to illustrate the contribution of this paper. To evaluate the performances of the system, simulation of this new mechanism is carried out with Adams software. Geometrical and Kinematic models are developed and included in the simulation tool. Based on biomechanical data, analysis of the new kinematic structure is carried out. The design of the proposed solution is then described. Finally the first prototype developed for the HYDROi¿D robots hip is presented. This mechanism is a part of an International patent accepted at INPI- France.

New three DOF ankle mechanism for humanoid robotic application: Modeling, design and realization

Designing and control of biped robot are still open questions. Design of ankle joint which is considered one of the more compact with high power capacity and low weight is a big challenge. The very important role played by this joint during walking, makes its design and control the first step of having a robust walking biped. In this paper, a novel three dof hybrid mechanisms has been proposed. This mechanism is actuated hydraulically and uses cable technology for power transmission. The proposed solution fulfils the requirements induced by both geometrical and biomechanical constraints. At first, the geometrical and kinematics properties of the proposed solution have been developed. A simulation tool has been built using ADAMS software and used to carry out early design dimensioning of the several components. Singularity study is detailed showing the advantage of this new solution. Control method has been proposed and tested. Finally manufactured prototype of this solution is presented with preliminary results showing the performances of the mechanism. This mechanism is a part of an International patent accepted at INPI- France.

General method for kinematic synthesis of manipulators with task specifications

This paper deals with the kinematic synthesis of manipulators. A new method based on distributed solving is used to determine the dimensional parameters of a general manipulator which is able to reach a set of given tasks specified by orientation and position. First, a general Distributed Solving Method (DSM) is presented in three steps: the problem statement, the objective functions formulations and the minimum parameters values determination. Then, this method is applied to solve the synthesis of the Denavit and Hartenberg set of parameters of a manipulator with a given kinematic structure. In this case, the kind and the number of joints are specified and a set of constraints are included such as joint limits, range of dimensional parameters and geometrical obstacles avoidance. We show that if the Denavit and Hartenberg parameters (DH) are known, the synthesis problem is reduced to an inverse kinematic problem. We show also how the problem of robot base placement can be solved by the same method. A general algorithm is given for solving the synthesis problem for all kind of manipulators. The main contribution of this paper is a general method for kinematic synthesis of all kind of manipulators and some examples are presented for a six degrees of freedom manipulator in cluttered environment.