Proceedings 2001 IEEE/RSJ International Conference on Intelligent Robots and Systems. Expanding the Societal Role of Robotics in the the Next Millennium (Cat. No.01CH37180), 2001
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
In situations where robots share their workspace with humans, and where physical human-robot inte... more In situations where robots share their workspace with humans, and where physical human-robot interaction is possible or even necessary, safety is of paramount importance. This paper presents a study of the safety of a lightweight robot actuated by pneumatic muscles. Due to its low weight, it has excellent hardware safety characteristics. In spite of this, it is shown that the system can be unsafe when under PID control. It is also shown that safety can be greatly increased by using Proxy-Based Sliding Mode Control (PSMC). The role of passive compliance in safety is also investigated. It is argued that passive compliance can have positive as well as negative effects on robot safety, depending on the situation.
2009 IEEE International Conference on Rehabilitation Robotics, 2009
In this paper, we present the results of walking experiments with a below-knee amputee fitted wit... more In this paper, we present the results of walking experiments with a below-knee amputee fitted with a biologically-inspired prosthesis. The design of the prosthesis is described together with the characteristics and working principle of its actuators. First experimental results with an amputee are presented that demonstrate the encouraging performance of the prosthesis in restoring ankle torque to the user during level walking.
This paper describes the biped Lucy and it's control architecture that will be used. Lucy is ... more This paper describes the biped Lucy and it's control architecture that will be used. Lucy is actuated by Pleated Pneumatic Artiflcial Muscles, which have a very high power to weight ratio and an inherent adaptable com- pliance. These characteristics will be used to make Lucy walk in a dynamically stable manner while exploiting the adaptable passive behavior of these muscles.
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.
The International Journal of Robotics Research, 2009
... Van Ham (2006) showed that a linearization is justified for angles smaller than 45 2 if B8C 5... more ... Van Ham (2006) showed that a linearization is justified for angles smaller than 45 2 if B8C 5, due to the quasi-linear torque characteristic. ... the compliance is dependent on the joint angle as can be seen in (5). The relationship between energy consumption and stiff-ness is a ...
This paper presents a sliding mode controller for a "Soft" 2-DOF Planar Pneumatic Manipulator act... more This paper presents a sliding mode controller for a "Soft" 2-DOF Planar Pneumatic Manipulator actuated by pleated pneumatic artificial muscle actuators. Since actuator dynamics is not negligible, an approximate model for pressure dynamics was taken into account, which made it necessary to perform full input-output feedback linearization in order to design a sliding mode controller. The design of the controller is presented in detail, and experimental results obtained by implementing the controller are discussed
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.
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.
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 ...
... 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 ...
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
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 ...
Proceedings 2001 IEEE/RSJ International Conference on Intelligent Robots and Systems. Expanding the Societal Role of Robotics in the the Next Millennium (Cat. No.01CH37180), 2001
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
In situations where robots share their workspace with humans, and where physical human-robot inte... more In situations where robots share their workspace with humans, and where physical human-robot interaction is possible or even necessary, safety is of paramount importance. This paper presents a study of the safety of a lightweight robot actuated by pneumatic muscles. Due to its low weight, it has excellent hardware safety characteristics. In spite of this, it is shown that the system can be unsafe when under PID control. It is also shown that safety can be greatly increased by using Proxy-Based Sliding Mode Control (PSMC). The role of passive compliance in safety is also investigated. It is argued that passive compliance can have positive as well as negative effects on robot safety, depending on the situation.
2009 IEEE International Conference on Rehabilitation Robotics, 2009
In this paper, we present the results of walking experiments with a below-knee amputee fitted wit... more In this paper, we present the results of walking experiments with a below-knee amputee fitted with a biologically-inspired prosthesis. The design of the prosthesis is described together with the characteristics and working principle of its actuators. First experimental results with an amputee are presented that demonstrate the encouraging performance of the prosthesis in restoring ankle torque to the user during level walking.
This paper describes the biped Lucy and it's control architecture that will be used. Lucy is ... more This paper describes the biped Lucy and it's control architecture that will be used. Lucy is actuated by Pleated Pneumatic Artiflcial Muscles, which have a very high power to weight ratio and an inherent adaptable com- pliance. These characteristics will be used to make Lucy walk in a dynamically stable manner while exploiting the adaptable passive behavior of these muscles.
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.
The International Journal of Robotics Research, 2009
... Van Ham (2006) showed that a linearization is justified for angles smaller than 45 2 if B8C 5... more ... Van Ham (2006) showed that a linearization is justified for angles smaller than 45 2 if B8C 5, due to the quasi-linear torque characteristic. ... the compliance is dependent on the joint angle as can be seen in (5). The relationship between energy consumption and stiff-ness is a ...
This paper presents a sliding mode controller for a "Soft" 2-DOF Planar Pneumatic Manipulator act... more This paper presents a sliding mode controller for a "Soft" 2-DOF Planar Pneumatic Manipulator actuated by pleated pneumatic artificial muscle actuators. Since actuator dynamics is not negligible, an approximate model for pressure dynamics was taken into account, which made it necessary to perform full input-output feedback linearization in order to design a sliding mode controller. The design of the controller is presented in detail, and experimental results obtained by implementing the controller are discussed
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.
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.
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 ...
... 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 ...
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
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 ...
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Papers by R. Van Ham