Author name cluster

Maxime Chalon

Possible papers associated with this exact author name in Arrow. This page groups case-insensitive exact name matches and is not a full identity disambiguation profile.

12 papers

1 author row

IROS Conference 2017 Conference Paper

EKF-based in-hand object localization from joint position and torque measurements

Martin Pfanne
Maxime Chalon

The ability to manipulate objects is the primary purpose of any robotic hand. However, when executing a grasp, the object and fingers rarely move exactly as planned. These unobserved deviations in the pose of the object or the contact configuration can make it impossible to solve a given task. In this paper, we presents a new approach to estimate the state of the grasp using only position and torque measurements from the joints of the hand. Based on the popular extended Kalman filter framework, the algorithm estimates the pose of the manipulated object, as well as the contact forces and positions on the surface of the object. It is able to reliably detect new and the loss of contacts and to incorporate this information in the estimation filter. The validity of this new method is shown in different grasp and manipulation tasks using David, a humanoid platform of DLR.

Details

ICRA Conference 2014 Conference Paper

Experimental comparison of slip detection strategies by tactile sensing with the BioTac ® on the DLR hand arm system

Jens Reinecke
Alexander Dietrich
Florian Schmidt 0001
Maxime Chalon

Dexterous manipulation of everyday objects requires a precise tactile sense. Slip detection is mandatory to overcome uncertainty and compensate for external disturbances. We compare three different approaches for detecting slip. The methods are model-based slip detection via friction cones, vibration-based detection via bandpass filtering, and a common learning algorithm. They are implemented and tested on a tendon-driven two-finger setup equipped with two tactile BioTac® sensors. Several experiments are conducted to evaluate each approach. The characteristics of the methods are discussed and compared.

Details

ICRA Conference 2014 Conference Paper

Guiding effects and friction modeling for tendon driven systems

Jens Reinecke
Maxime Chalon
Werner Friedl
Markus Grebenstein

This paper discusses tendon friction effects regarding guiding and material selection. In order to extract valuable information for designers of tendon driven systems, several experiments are conducted to investigate e. g. the intrinsic friction or sliding effect. The results are used to build an experimental friction model and to derive a set of guidelines. The mechanical designer can use the proposed models to anticipate the friction for a given tendon path. Additionally, the guidelines help the mechanical designer to systematically verify the numerous constraints involved in the design process of a tendon driven system.

Details

IROS Conference 2013 Conference Paper

Online in-hand object localization

Maxime Chalon
Jens Reinecke
Martin Pfanne

Robotic hands are a key component of humanoids. Initially more fragile and larger than their human counterparts, the technology has evolved and the latest generation is close to the human hand in size and robustness. However, it is still disappointing to see how little robotic hands are able to do once the grasp is acquired due to the difficulty to obtain a reliable pose of the object within the palm. This paper presents a novel method based on a particle filter used to estimate online the object pose. It is shown that the method is robust, accurate and handles many realistic scenario without hand crafted rules. It combines an efficient collision checker with a few very simple ideas, that require only a basic knowledge of the geometry of the objects. It is shown, by experiments and simulations, that the algorithm is able to deal with inaccurate finger position measurements and can integrate tactile measurements. The method greatly enhances the performance of common manipulation operations, such as a pick and place tasks, and boosts the sensing capabilities of the robot.

Details

ICRA Conference 2011 Conference Paper

Dexhand: A Space qualified multi-fingered robotic hand

Maxime Chalon
Armin Wedler
Andreas Baumann
Wieland Bertleff
Alexander Beyer
Jörg Butterfaß
Markus Grebenstein
Robin Gruber

Despite the progress since the first attempts of mankind to explore space, it appears that sending man in space remains challenging. While robotic systems are not yet ready to replace human presence, they provide an excellent support for astronauts during maintenance and hazardous tasks. This paper presents the development of a space qualified multi-fingered robotic hand and highlights the most interesting challenges. The design concept, the mechanical structure, the electronics architecture and the control system are presented throughout this overview paper.

Details

IROS Conference 2011 Conference Paper

FAS A flexible Antagonistic spring element for a high performance over actuated hand

Werner Friedl
Maxime Chalon
Jens Reinecke
Markus Grebenstein

In robotic hands design tendon driven systems have been considered for years. The main advantage is a small end effector inertia e. g. a light, small hand with high dynamics due to remote actuators. To protect the actuators from impact in unknown environments a compliant mechanism can be used. It absorbs energy during an impact or saves energy to enhance the joint dynamics. In this paper an antagonistic tendon mechanism is presented. It fits 38 times in the DLR Hand Arm System forearm and enables is adapted to the different finger joints and different tendon lengths. A magnetic sensor was developed for the force measurement of the tendons. Finally, the calibration and the robustness are demonstrated through a set of experiments.

Details

IROS Conference 2011 Conference Paper

Impedance control of a non-linearly coupled tendon driven thumb

Maxime Chalon
Werner Friedl
Jens Reinecke
Thomas Wimböck
Alin Albu-Schäffer

A large workspace and proper force capabilities of a robotic thumb can be obtained using a tensegrity structure for the actuation, similar to the human thumb base muscles. Using nonlinear stiffness elements and an antagonistic architecture, the joint stiffness can be adjusted by variation of the tendon pre-tension. However, the highly nonlinear actuation creates new control challenges and in particular the nonlinear tendon kinematics must be accounted for. Despite the challenges, the nonlinear structure is required to achieve the desired torques. In this paper, the dynamic equations of a tendon driven thumb are established. An efficient formulation is proposed to generate the pretension forces in order to preserve the torques and approximate the stiffness matrix. A cascaded structure is used for the controller. The equations for the inner tendon force control loop and the outer impedance control loop are presented. Because of the absence of link side position sensors, an iterative estimation algorithm is proposed and implemented in real-time. It is shown that, using the mechanical joint flexibility, the controller impedance gain can be adjusted to improve the steady-state effective impedance. The search algorithm robustness is evaluated through a set of simulations. Finally, experimental results and equivalent simulations demonstrate the effectiveness of our controller.

Details

ICRA Conference 2011 Conference Paper

The DLR hand arm system

Markus Grebenstein
Alin Albu-Schäffer
Thomas Bahls
Maxime Chalon
Oliver Eiberger
Werner Friedl
Robin Gruber
Sami Haddadin

An anthropomorphic hand arm system using variable stiffness actuation has been developed at DLR. It is aimed to reach its human archetype regarding size, weight and performance. The main focus of our development is put on robustness, dynamic performance and dexterity. Therefore, a paradigm change from impedance controlled, but mechanically stiff joints to robots using intrinsic variable compliance joints is carried out.

Details

ICRA Conference 2010 Conference Paper

Bidirectional antagonistic variable stiffness actuation: Analysis, design & Implementation

Florian Petit
Maxime Chalon
Werner Friedl
Markus Grebenstein
Alin Albu-Schäffer
Gerhard Hirzinger

The variable stiffness actuation concept is considered to provide a human-friendly robot technology. This paper examines a joint concept called the bidirectional antagonistic joint which is a extension of antagonistic joints. A new operating mode called the helping mode is introduced, which increases the joint load range. Although the joint can not be pretensioned in the helping mode, it is shown that a stiffness variation is possible, assuming a suitable torque-stiffness characteristic of the elastic elements. A methodology to design such characteristics is presented along with several example cases interpreted in a torque-stiffness plot. Furthermore, a stiffness adaptation control scheme which ensures mechanism safety is described. Finally, the design methodology and the control are evaluated on an implementation of a bidirectional antagonistic joint.

Details

ICRA Conference 2010 Conference Paper

Dynamic modelling and control of variable stiffness actuators

Alin Albu-Schäffer
Sebastian Wolf 0001
Oliver Eiberger
Sami Haddadin
Florian Petit
Maxime Chalon

After briefly summarizing the mechanical design of the two joint prototypes for the new DLR variable compliance arm, the paper exemplifies the dynamic modelling of one of the prototypes and proposes a generic variable stiffness joint model for nonlinear control design. Based on this model, the design of a simple, gain scheduled state feedback controller for active vibration damping of the mechanically very weakly damped joint is presented. Moreover, the computation of the motor reference values out of the desired stiffness and position is addressed. Finally, simulation and experimental results validate the proposed methods.

Details

IROS Conference 2010 Conference Paper

The thumb: guidelines for a robotic design

Maxime Chalon
Markus Grebenstein
Thomas Wimböck
Gerhard Hirzinger

The impressive manipulation capabilities of the human hand are undoubtedly related to the thumb opposition. Such a versatility is highly desirable in the context of humanoid robots, in particular when performing object manipulation. Biomechanical data, surgery procedures and rehabilitation surveys represent an excellent base from which a robotic design can be inferred. This knowledge must be understood to identify the properties required for manipulation skills, and especially, to obtain a holistic view of the thumb functionality. Several designs have been realized, that concentrated on biomimetism or on classical mechanism designs. Therefore, it is currently difficult for designers to obtain a clear overview of the properties required for a functional robot thumb. In the present case, a robotic hand with size, forces, velocity and shape comparable to the human ones, is envisioned. Unlike most of robotic designs-where the fingers are modular and the thumb is simply a finger placed in opposition-the thumb benefits from an intensive functional analysis. This paper gathers anatomy, surgery and rehabilitation data and identifies the properties required for human like manipulation. Based on this synergy, guidelines are presented that are fused and applied to the hand design of the Integrated Hand arm project of DLR.

Details

ICRA Conference 2010 Conference Paper

Torque and workspace analysis for flexible tendon driven mechanisms

Maxime Chalon
Thomas Wimböck
Gerhard Hirzinger

Tendon driven mechanisms have been considered in robotic design for several decades. They provide lightweight end effectors with high dynamics. Using remote actuators it is possible to free more space for mechanics or electronics. Nevertheless, lightweight mechanism are fragile and unfortunately their control software can not protect them during the very first instant of an impact. Compliant mechanisms address this issue, providing a mechanical low pass filter, increasing the time available before the controller reacts. Using adjustable stiffness elements and an antagonistic architecture, the joint stiffness can be adjusted by variation of the tendon pre-tension. In this paper, the fundamental equations of m antagonistic tendon driven mechanisms are reviewed. Due to limited tendon forces the maximum torque and the maximum acheivable stiffness are dependent. This implies, that not only the torque workspace, or the stiffness workspace must be considered but also their interactions. Since the results are of high dimensionality, quality measures are necessary to provide a synthetic view. Two quality measures, similar to those used in grasp planning, are presented. They both provide the designer with a more precise insight into the mechanism.

Details