B. Verrelst - Academia.edu (original) (raw)

Papers by B. Verrelst

Research paper thumbnail of ANTY : The development of an intelligent huggable robot for hospitalized children

This paper reports on the concept for the development of an intelligent huggable robot named ANTY... more This paper reports on the concept for the development of an intelligent huggable robot named ANTY (Fig.1) that will interact with hospitalized children to distract and support them during their stay in hospital. This robot is subject of a multidisciplinary project covering research opportunities not only in mechanical design, vision, speech and AI, but also in sociology and psychology. The

Research paper thumbnail of Control of Pneumatic Artificial Muscles with Enhanced Speed Up Circuitry

The power to weight ratio of the actuators is an important design factor for running robots. Ther... more The power to weight ratio of the actuators is an important design factor for running robots. Therefore pleated pneumatic artificial muscles are optimal actuators. Obviously the weight of the pressure control valves has to be taken into consideration as well. For this application, standard pressure regulating valves are rather heavy and slow. An intelligent controlled number of fast switching on-off

Research paper thumbnail of Control architecture of LUCY, a Biped with Pneumatic Artiflcial Muscles

This paper describes the biped Lucy and it's control architecture that will be used. Lucy is actu... more This paper describes the biped Lucy and it's control architecture that will be used. Lucy is actuated by Pleated Pneumatic Artificial Muscles, which have a very high power to weight ratio and an inherent adaptable compliance. These characteristics will be used to let Lucy walk in a dynamically stable manner while exploiting the adaptable passive behaviour of these muscles. A quasi-static global control has been implemented while using adapted PID techniques for the local feedback joint control. These initial control techniques resulted in the first movements of Lucy. This paper will discuss a future control architecture of Lucy to induce faster and smoother motion. The proposed control scheme is a combination of a global trajectory planner and a local low-level joint controller. The trajectory planner generates motion patterns based on two specific concepts, being the use of objective locomotion parameters, and exploiting the natural upper body dynamics by manipulating the angular momentum equation. The low-level controller can be divided in four parts: a computed torque module, an inverse delta-p unit, a local PI controller and a bang-bang controller. In order to evaluate the proposed control structure a hybrid simulator was created. Both the pneumatics and mechanics are put together in this hybrid dynamic simulation.

Research paper thumbnail of Dynamic Control of a Bipedal Walking Robot actuated with Pneumatic Artificial Muscles

Proceedings of the 2005 IEEE International Conference on Robotics and Automation, 2005

Abstract—This paper reports on the control structure of the pneumatic biped Lucy. The robot is ac... more Abstract—This paper reports on the control structure of the pneumatic biped Lucy. The robot is actuated with pleated pneumatic artificial muscles, which have interesting characteristics that can be exploited for legged machines. They have a high power to weight ratio, an ...

Research paper thumbnail of A Control Strategy for a Dynamic Walking Biped with Articulated Legs

In this paper, a high-level real-time control strategy for a bipedal walking robot is presented. ... more In this paper, a high-level real-time control strategy for a bipedal walking robot is presented. The considered motion is a steady walking pattern with instantaneous double support phase. The presented algorithm introduces a number of objective locomotion parameters which char- acterize the steps, and at the same time controls the upper body motion. Polynomial trajectories are designed to be tracked by the different controllers of the leg links. These trajectories deal with the fact that the ankle torque is limited by the physical length of the foot. The motion of the upper body is quasi naturally steered by using the angular momentum equation in a convenient way. Only a small ankle torque has to be added to reach exactly the desired conditions for the upper body. Promising results of the simulations are shown.

Research paper thumbnail of Proxy-based Sliding Mode Control of a Planar Pneumatic Manipulator

The International Journal of Robotics Research, 2009

For a robotic system that shares its workspace with humans and physically interacts with them, sa... more For a robotic system that shares its workspace with humans and physically interacts with them, safety is of paramount importance. In order to build a safe system, safety has to be considered in both hardware and software (control). In this paper, we present the safe control of a two-degree-of-freedom planar manipulator actuated by Pleated Pneumatic Artificial Muscles. Owing to its low weight and inherent compliance, the system hardware has excellent safety characteristics. In traditional control methods, safety and good tracking are often impossible to combine. This is different in the case of Proxy-Based Sliding Mode Control (PSMC), a novel control method introduced by Kikuuwe and Fujimoto. PSMC combines responsive and accurate tracking during normal operation with smooth, slow and safe recovery from large position errors. It can also make the system behave compliantly to external disturbances. We present both task-and jointspace implementations of PSMC applied to the pneumatic manipulator, and compare their performance with PID control. Good tracking results are obtained, especially with the joint-space implementation. Safety is evaluated by means of the Head Injury Criterion and by the maximum interaction force in the case of collision. It is found that in spite of the hardware safety features, the system is unsafe when under PID control. PSMC, on the other hand, provides increased safety as well as good tracking.

Research paper thumbnail of Treadmill walking of the pneumatic biped Lucy: Walking at different speeds and step-lengths

International Applied Mechanics, 2008

Actuators with adaptable compliance are gaining interest in the field of legged robotics due to t... more Actuators with adaptable compliance are gaining interest in the field of legged robotics due to their capability to store motion energy and to exploit the natural dynamics of the system to reduce energy consumption while walking and running. To perform research on compliant actuators we have built the planar biped Lucy. The robot has six actuated joints, the ankle, knee and hip of both legs with each joint powered by two pleated pneumatic artificial muscles in an antagonistic setup. This makes it possible to control both the torque and the stiffness of the joint. Such compliant actuators are used in passive walkers to overcome friction when walking over level ground and to improve stability. Typically, this kind of robots is only designed to walk with a constant walking speed and step-length, determined by the mechanical design of the mechanism and the properties of the ground. In this paper, we show that by an appropriate control, the robot Lucy is able to walk at different speeds and step-lengths and that adding and releasing weights does not affect the stability of the robot. To perform these experiments, an automated treadmill was built Keywords: bipedal walking robot, pneumatic artificial muscle 1. Introduction. Bipedal robots are gaining interest because of their potential for higher mobility than that of wheeled vehicles. Although for an outsider in the field walking is very obvious, the fastest robot at the moment is Asimo with a top running speed of 6 km/h. A study on humanoid robots performed by FZI [1] forecasts that it will take about 10-20 years before bipeds can even with humans. The best-known humanoid robots are Asimo [2], Qrio [3], and HRP-2 [4], all actuated by classical electric drives. Nowadays, research is performed to develop soft or compliant actuators and implement them in bipeds. A study of the control system of robots in which soft actuators were used can be found in [5] for a sagittal hopping robot, [6, 7] for a 3D hopping robot, and [8] for a walking biped. Other publications can be noted, in which the problems of control of similar systems are considered. Main reason is to reduce the energy consumption of those robots by exploiting the natural dynamics of the system. The "Passive walkers" do not even need actuation at all to walk down a sloped surface or only use a limited amount of actuation when walking over level ground just enough to overcome friction. Examples are the Cornell biped, the Delft biped Denise, and MIT robot Toddler . Unfortunately, they are of little practical use. They have difficulties to start, cannot change their speed, and cannot stop, contrary to a completely actuated robot. Adding control while exploiting the natural dynamics of the system will be probably the optimal. The way we want to find this optimal is by using actuators with controllable compliance just like humans do.

Research paper thumbnail of MACCEPA, The mechanically adjustable compliance and controllable equilibrium position actuator: A 3DOF joint with two independent compliances

International Applied Mechanics, 2007

In this paper a novel rotational actuator with adaptable compliance is presented. First the impor... more In this paper a novel rotational actuator with adaptable compliance is presented. First the importance of adaptable compliance for bipedal walking is explained, and then a number of comparable designs are given with their possible drawbacks.

Research paper thumbnail of Concept of combining adaptable passive behaviour with an active control structure using Pleated Pneumatic Artificial Muscles for the bipedal robot LUCY

Proceedings of the …, 2003

Research paper thumbnail of The Pneumatic Biped ?Lucy? Actuated with Pleated Pneumatic Artificial Muscles

Autonomous Robots, 2005

Abstract. This paper reports on the bipedal robot Lucy which is actuated by pleated pneumatic art... more Abstract. This paper reports on the bipedal robot Lucy which is actuated by pleated pneumatic artificial muscles. This novel actuator is very suitable to be used in machines which move by means of legs. Besides its high power to weight ratio the actuator has an adaptable ...

Research paper thumbnail of Development of a compliance controller to reduce energy consumption for bipedal robots

Autonomous Robots, 2008

... The biped Lucy, powered by pleated pneumatic artificial mus-cles, has been built and controll... more ... The biped Lucy, powered by pleated pneumatic artificial mus-cles, has been built and controlled and is able to walk up to a speed of 0.15 m/s. The pressures inside the muscles are controlled by a joint trajectory tracking controller to track the desired joint trajectories calculated ...

Research paper thumbnail of The Development of the Eye-Systemfor the Intelligent Huggable Robot ANTY

Abstract: Thepur poseof this studyis to design and develop an anthropomorphic based eye-system, u... more Abstract: Thepur poseof this studyis to design and develop an anthropomorphic based eye-system, used in the intelligent huggable robot ANTY. The intelligent huggable robot ANTY aspires social children-robot interactions relying on face-to-face communication. The anatomy of anan thropomorphic eye and its movements are presented and ,linked to ,the design of the artificial robot eye-system. Keywords: huggable robot, artificial eyes, complaint

Research paper thumbnail of Modular Architecture for Humanoid Walking Pattern Prototyping and Experiments

Advanced Robotics, 2008

In this paper we describe the use of design patterns as a basis for creating a Humanoid Walking P... more In this paper we describe the use of design patterns as a basis for creating a Humanoid Walking Pattern Generator Software having a modular architecture. This architecture made possible the rapid porting of several novel walking algorithms on a full size humanoid robot HRP-2. The body of work currently available allows extracting a general software architecture usable with inter-exchange between simulations and real experiments. The proposed architecture with the associated design patterns are described together with several applications: a pattern generator for a HRP-2 with passive toe-joints, a pattern for dynamically stepping over large obstacles, and a new quadratic problem (QP) formulation for the generation of the reference ZMP. Thanks to the versatility and the modularity of the proposed framework, the QP method has been implemented and experienced within four days only.

Research paper thumbnail of Motion Generation and Control for the Pneumatic Biped "Lucy

The current control architecture focuses on the trajectory generator and the tracking controller,... more The current control architecture focuses on the trajectory generator and the tracking controller, which is divided into a computed torque controller, a delta-p unit, a PI position controller and a pressure bang-bang controller. The trajectory generator provides polynomial joint ...

Research paper thumbnail of ANTY : The development of an intelligent huggable robot for hospitalized children

This paper reports on the concept for the development of an intelligent huggable robot named ANTY... more This paper reports on the concept for the development of an intelligent huggable robot named ANTY (Fig.1) that will interact with hospitalized children to distract and support them during their stay in hospital. This robot is subject of a multidisciplinary project covering research opportunities not only in mechanical design, vision, speech and AI, but also in sociology and psychology. The

Research paper thumbnail of Control of Pneumatic Artificial Muscles with Enhanced Speed Up Circuitry

The power to weight ratio of the actuators is an important design factor for running robots. Ther... more The power to weight ratio of the actuators is an important design factor for running robots. Therefore pleated pneumatic artificial muscles are optimal actuators. Obviously the weight of the pressure control valves has to be taken into consideration as well. For this application, standard pressure regulating valves are rather heavy and slow. An intelligent controlled number of fast switching on-off

Research paper thumbnail of Control architecture of LUCY, a Biped with Pneumatic Artiflcial Muscles

This paper describes the biped Lucy and it's control architecture that will be used. Lucy is actu... more This paper describes the biped Lucy and it's control architecture that will be used. Lucy is actuated by Pleated Pneumatic Artificial Muscles, which have a very high power to weight ratio and an inherent adaptable compliance. These characteristics will be used to let Lucy walk in a dynamically stable manner while exploiting the adaptable passive behaviour of these muscles. A quasi-static global control has been implemented while using adapted PID techniques for the local feedback joint control. These initial control techniques resulted in the first movements of Lucy. This paper will discuss a future control architecture of Lucy to induce faster and smoother motion. The proposed control scheme is a combination of a global trajectory planner and a local low-level joint controller. The trajectory planner generates motion patterns based on two specific concepts, being the use of objective locomotion parameters, and exploiting the natural upper body dynamics by manipulating the angular momentum equation. The low-level controller can be divided in four parts: a computed torque module, an inverse delta-p unit, a local PI controller and a bang-bang controller. In order to evaluate the proposed control structure a hybrid simulator was created. Both the pneumatics and mechanics are put together in this hybrid dynamic simulation.

Research paper thumbnail of Dynamic Control of a Bipedal Walking Robot actuated with Pneumatic Artificial Muscles

Proceedings of the 2005 IEEE International Conference on Robotics and Automation, 2005

Abstract—This paper reports on the control structure of the pneumatic biped Lucy. The robot is ac... more Abstract—This paper reports on the control structure of the pneumatic biped Lucy. The robot is actuated with pleated pneumatic artificial muscles, which have interesting characteristics that can be exploited for legged machines. They have a high power to weight ratio, an ...

Research paper thumbnail of A Control Strategy for a Dynamic Walking Biped with Articulated Legs

In this paper, a high-level real-time control strategy for a bipedal walking robot is presented. ... more In this paper, a high-level real-time control strategy for a bipedal walking robot is presented. The considered motion is a steady walking pattern with instantaneous double support phase. The presented algorithm introduces a number of objective locomotion parameters which char- acterize the steps, and at the same time controls the upper body motion. Polynomial trajectories are designed to be tracked by the different controllers of the leg links. These trajectories deal with the fact that the ankle torque is limited by the physical length of the foot. The motion of the upper body is quasi naturally steered by using the angular momentum equation in a convenient way. Only a small ankle torque has to be added to reach exactly the desired conditions for the upper body. Promising results of the simulations are shown.

Research paper thumbnail of Proxy-based Sliding Mode Control of a Planar Pneumatic Manipulator

The International Journal of Robotics Research, 2009

For a robotic system that shares its workspace with humans and physically interacts with them, sa... more For a robotic system that shares its workspace with humans and physically interacts with them, safety is of paramount importance. In order to build a safe system, safety has to be considered in both hardware and software (control). In this paper, we present the safe control of a two-degree-of-freedom planar manipulator actuated by Pleated Pneumatic Artificial Muscles. Owing to its low weight and inherent compliance, the system hardware has excellent safety characteristics. In traditional control methods, safety and good tracking are often impossible to combine. This is different in the case of Proxy-Based Sliding Mode Control (PSMC), a novel control method introduced by Kikuuwe and Fujimoto. PSMC combines responsive and accurate tracking during normal operation with smooth, slow and safe recovery from large position errors. It can also make the system behave compliantly to external disturbances. We present both task-and jointspace implementations of PSMC applied to the pneumatic manipulator, and compare their performance with PID control. Good tracking results are obtained, especially with the joint-space implementation. Safety is evaluated by means of the Head Injury Criterion and by the maximum interaction force in the case of collision. It is found that in spite of the hardware safety features, the system is unsafe when under PID control. PSMC, on the other hand, provides increased safety as well as good tracking.

Research paper thumbnail of Treadmill walking of the pneumatic biped Lucy: Walking at different speeds and step-lengths

International Applied Mechanics, 2008

Actuators with adaptable compliance are gaining interest in the field of legged robotics due to t... more Actuators with adaptable compliance are gaining interest in the field of legged robotics due to their capability to store motion energy and to exploit the natural dynamics of the system to reduce energy consumption while walking and running. To perform research on compliant actuators we have built the planar biped Lucy. The robot has six actuated joints, the ankle, knee and hip of both legs with each joint powered by two pleated pneumatic artificial muscles in an antagonistic setup. This makes it possible to control both the torque and the stiffness of the joint. Such compliant actuators are used in passive walkers to overcome friction when walking over level ground and to improve stability. Typically, this kind of robots is only designed to walk with a constant walking speed and step-length, determined by the mechanical design of the mechanism and the properties of the ground. In this paper, we show that by an appropriate control, the robot Lucy is able to walk at different speeds and step-lengths and that adding and releasing weights does not affect the stability of the robot. To perform these experiments, an automated treadmill was built Keywords: bipedal walking robot, pneumatic artificial muscle 1. Introduction. Bipedal robots are gaining interest because of their potential for higher mobility than that of wheeled vehicles. Although for an outsider in the field walking is very obvious, the fastest robot at the moment is Asimo with a top running speed of 6 km/h. A study on humanoid robots performed by FZI [1] forecasts that it will take about 10-20 years before bipeds can even with humans. The best-known humanoid robots are Asimo [2], Qrio [3], and HRP-2 [4], all actuated by classical electric drives. Nowadays, research is performed to develop soft or compliant actuators and implement them in bipeds. A study of the control system of robots in which soft actuators were used can be found in [5] for a sagittal hopping robot, [6, 7] for a 3D hopping robot, and [8] for a walking biped. Other publications can be noted, in which the problems of control of similar systems are considered. Main reason is to reduce the energy consumption of those robots by exploiting the natural dynamics of the system. The "Passive walkers" do not even need actuation at all to walk down a sloped surface or only use a limited amount of actuation when walking over level ground just enough to overcome friction. Examples are the Cornell biped, the Delft biped Denise, and MIT robot Toddler . Unfortunately, they are of little practical use. They have difficulties to start, cannot change their speed, and cannot stop, contrary to a completely actuated robot. Adding control while exploiting the natural dynamics of the system will be probably the optimal. The way we want to find this optimal is by using actuators with controllable compliance just like humans do.

Research paper thumbnail of MACCEPA, The mechanically adjustable compliance and controllable equilibrium position actuator: A 3DOF joint with two independent compliances

International Applied Mechanics, 2007

In this paper a novel rotational actuator with adaptable compliance is presented. First the impor... more In this paper a novel rotational actuator with adaptable compliance is presented. First the importance of adaptable compliance for bipedal walking is explained, and then a number of comparable designs are given with their possible drawbacks.

Research paper thumbnail of Concept of combining adaptable passive behaviour with an active control structure using Pleated Pneumatic Artificial Muscles for the bipedal robot LUCY

Proceedings of the …, 2003

Research paper thumbnail of The Pneumatic Biped ?Lucy? Actuated with Pleated Pneumatic Artificial Muscles

Autonomous Robots, 2005

Abstract. This paper reports on the bipedal robot Lucy which is actuated by pleated pneumatic art... more Abstract. This paper reports on the bipedal robot Lucy which is actuated by pleated pneumatic artificial muscles. This novel actuator is very suitable to be used in machines which move by means of legs. Besides its high power to weight ratio the actuator has an adaptable ...

Research paper thumbnail of Development of a compliance controller to reduce energy consumption for bipedal robots

Autonomous Robots, 2008

... The biped Lucy, powered by pleated pneumatic artificial mus-cles, has been built and controll... more ... The biped Lucy, powered by pleated pneumatic artificial mus-cles, has been built and controlled and is able to walk up to a speed of 0.15 m/s. The pressures inside the muscles are controlled by a joint trajectory tracking controller to track the desired joint trajectories calculated ...

Research paper thumbnail of The Development of the Eye-Systemfor the Intelligent Huggable Robot ANTY

Abstract: Thepur poseof this studyis to design and develop an anthropomorphic based eye-system, u... more Abstract: Thepur poseof this studyis to design and develop an anthropomorphic based eye-system, used in the intelligent huggable robot ANTY. The intelligent huggable robot ANTY aspires social children-robot interactions relying on face-to-face communication. The anatomy of anan thropomorphic eye and its movements are presented and ,linked to ,the design of the artificial robot eye-system. Keywords: huggable robot, artificial eyes, complaint

Research paper thumbnail of Modular Architecture for Humanoid Walking Pattern Prototyping and Experiments

Advanced Robotics, 2008

In this paper we describe the use of design patterns as a basis for creating a Humanoid Walking P... more In this paper we describe the use of design patterns as a basis for creating a Humanoid Walking Pattern Generator Software having a modular architecture. This architecture made possible the rapid porting of several novel walking algorithms on a full size humanoid robot HRP-2. The body of work currently available allows extracting a general software architecture usable with inter-exchange between simulations and real experiments. The proposed architecture with the associated design patterns are described together with several applications: a pattern generator for a HRP-2 with passive toe-joints, a pattern for dynamically stepping over large obstacles, and a new quadratic problem (QP) formulation for the generation of the reference ZMP. Thanks to the versatility and the modularity of the proposed framework, the QP method has been implemented and experienced within four days only.

Research paper thumbnail of Motion Generation and Control for the Pneumatic Biped "Lucy

The current control architecture focuses on the trajectory generator and the tracking controller,... more The current control architecture focuses on the trajectory generator and the tracking controller, which is divided into a computed torque controller, a delta-p unit, a PI position controller and a pressure bang-bang controller. The trajectory generator provides polynomial joint ...