151H0653H00L Bio-Inspired Motor Control

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1 Lecture H0653H00L Bio-Inspired Motor Control Fumiya Iida, Jonas Buchli Luzius Brodbeck, Derek Leach, Xiaoxiang Yu, Amir Jafari, Hugo Marques, Liyu Wang, Surya Nurzaman 11/20/2012 1

2 Lecture 10 Today Lecture: Bio-Inspired Actuators 1 Definition and Classification of Actuators 2 Why Do We Need Bio-Inspired Actuators? 3 4 Different Ways of Realizing Softness Unconventional Actuators 11/20/2012 2

3 Lecture 10 Today Lecture: Bio-Inspired Actuators 1 Definition and Classification of Actuators 2 Why Do We Need Bio-Inspired Actuators? 3 4 Different Ways of Realizing Softness Unconventional Actuators 11/20/2012 3

4 Lecture 10 Actuator Definition Actuator is system able to provide the mechanical action within a certain time Energy Source Motion converter Transducer 11/20/2012 4

5 Lecture 10 Actuator Definition Actuator is system able to provide the mechanical action within a certain time Energy Source 11/20/2012 5

6 Lecture 10 Actuator Definition Actuator is system able to provide the mechanical action within a certain time Motion converter 11/20/2012 6

7 Lecture 10 Actuator Definition Electrical Chemical high torque / low velocity Thermal Transducer Mechanical Motion Converter Nuclear low torque / high velocity Sound 11/20/2012 7

Lecture 10 Actuator Characteristics Fundamental characteristics in the evaluation of an actuator are: Force per unit of area that the transducer can give (N/m^2) Stroke that the transducer can

8 Lecture 10 Actuator Characteristics Fundamental characteristics in the evaluation of an actuator are: Force per unit of area that the transducer can give (N/m^2) Stroke that the transducer can provide with respect to its dimensions (%) Frequency of actuation (cycles per second, Hz) Efficiency of the transducer Bulk of the motion converter Efficiency of the motion converter Type of battery / energy source 11/20/2012 8

9 Lecture 10 1 Definition and Classification of Actuators 2 Why Do We Need Bio-Inspired Actuators? 3 4 Different Ways of Realizing Softness Unconventional Actuators 11/20/2012 9

10 Lecture 10 Inspiration Performances of robotic systems are still far from those characterizing animals and, in general, living systems. Major limitations are due to actuation systems, where traditional concepts have been improved through the years, without really changing core solutions. 11/20/

11 Inspiration Industrial actuators Accurate Rigid Bulky, heavy Fast Position control Unsafe DLR 11/20/

12 Inspiration How can we control the robot s behavior in an unknown environment?! 11/20/

13 Lecture 10 Soft Actuators The specifications of Nature's designs consist of general features rather than making exact duplicates Shape Functionality Performance 11/20/

14 Lecture 10 1 Definition and Classification of Actuators 2 Why Do We Need Bio-Inspired Actuators? 3 4 Different Ways of Realizing Softness Unconventional Actuators 11/20/

15 Different Ways of Realizing Softness Covering robot with soft and compliant material Adding large inertia to the system Cooling the electronics Affecting maneuverability of the robot Humanoid robot Macra 11/20/

16 Different Ways of Realizing Softness (active compliance) Sense the force Facilitate the robot with force/torque sensors and feedback control to detect collisions and avoid them DLR 11/20/

17 Different Ways of Realizing Softness (active compliance) Calculate the force Alessandro De Luca and Raffaella Mattone. 2005, Sensorless Robot Collision Detection and Hybrid Force/Motion Control, IEEE International Conference on Robotics and Automation 11/20/

18 Different Ways of Realizing Softness (passive compliance) Traditional actuators Motor GB Link I r N 2 +I l : apparent Inertia 11/20/

19 Different Ways of Realizing Softness (passive compliance) Series Elastic Actuator (SEA) Motor GB Link Robust Perturbations and uncertainties 11/20/

20 Different Ways of Realizing Softness Compliant Humanoid: CoMan Li Zhibin and Nikos Tsagarakis from Italian Institute of Technology 11/20/

21 Different Ways of Realizing Softness (passive compliance) Series Elastic Actuator (SEA) x l Motor GB Link Energy 11/20/

22 Different Ways of Realizing Softness (passive compliance) Series Elastic Actuator (SEA) Motor GB Link Motor GB Link 11/20/

23 Varaible Compliance Why do we need variable compliance actuators?! 11/20/

24 Lecture 10 11/20/

25 Variable Stiffness Actuators Safety and Performance Giovanni Tonietti et al. 2003, Design and Control of a Variable Stiffness Actuator for Safe and Fast Physical Human/Robot Interaction, IEEE International Conference on Robotics and Automation 11/20/

26 Variable Stiffness Actuators Minimizing Energy Consumption Motor GB 11/20/

27 Variable Stiffness Actuators Maximizing output power Motor GB Link Motor GB Link Motor GB Link 11/20/

28 HDAU Korea University 11/20/

29 Variable Stiffness Actuators Motor Motor GB GB Link Two actuation units Stiffness adjusting mechanism 11/20/

30 Variable Stiffness Actuators Mot Actuation GB Mot or Units GB or Link 11/20/

Variable Stiffness Actuators Approaches Classes Table 1. Classification of different VSAs Examples Schemes C1: Simple antagonistic Biologically inspired joint stiffness control [Migliore et al.

1999] Antagonistic C2: Cross coupled Variable Stiffness Actuator (VSA) [Tonietti et al. 2005] C3: Bidirectional Variable Stiffness Actuator-II (VSA-II) [Schiavi et al. 2008] VSA-HD [Castalano et al.

31 Variable Stiffness Actuators Approaches Classes Table 1. Classification of different VSAs Examples Schemes C1: Simple antagonistic Biologically inspired joint stiffness control [Migliore et al.2005] Actuator with Mechanically Adjustable Series Compliance (AMASC) [Hurst et al. 2010] Plated Pneumatic Artificial Muscles (PPAM) [Darden, et al. 1999] Antagonistic C2: Cross coupled Variable Stiffness Actuator (VSA) [Tonietti et al. 2005] C3: Bidirectional Variable Stiffness Actuator-II (VSA-II) [Schiavi et al. 2008] VSA-HD [Castalano et al. 2010] VSA-CUBE [castalano et al. 2011] Bidirectional Antagonism with Variable Stiffness (BAVS) [Petit et al. 2010] Floating Spring Joint (FSJ)[Wolf et al. 2011] Quasi-Antagonistic joint (QA-joint)[Eiberger et al. 2010] C4: Changing the spring's deflection Mechanically Adjustable and Controllable Compliance Equilibrium Position Actuator (MACCEPA) [Van Ham et al. 2006] and (MACCEPA 2.0) [vanderborght et al. 2011] Varaible Stiffness Joint (VS-joint) [Wolf et al. 2008] Safe Joint Mechanism (SJM I) [Park et al. 2010] and (SJM II) [Park et al. 2011] Series C5: Changing the lever ratio Actuator with Adjustable Stiffness (AwAS-I) [Jafari et al. 2010] and (AwAS-II) [Jafari et al. 2012] Compact Variable Stiffness Actuator (ComPact-VSA) [Tsagarakis et al. 2011] Energy Efficient Variable Stiffness Actuator [Visser et al. 2011] Variable Stiffness Actuator University of Twente [Carloni et al. 2012] Hybrid Dual Actuation Unit (HDAU) [Park et al. 2011] C6: Changing the transmission angle Mechanism for Varying Stiffness via Changing Transmission Angle (MESTRAN) [Quy et al. 2011] C7: Changing the inertia Structure Controlled Stiffness (SCS) [Sugar et al. 2004] 11/20/2012

32 Bio-Inspired Approach Two muscles actuate one joint Force to deflection profile is nonlinear Muscles are unidirectional actuators Position and stiffness can be controlled independently 11/20/

33 Penumatic Artificial Muscles (PAM) as artificial muscles

34 Plated Pneumatic Artificial Muscles (PPAM) Vrije Universiteit Brussel Daerden, et al.(2001) 11/20/

35 Plated Pneumatic Artificial Muscles (PPAM) Vrije Universiteit Brussel Stiff Soft 11/20/

36 Plated Pneumatic Artificial Muscles (PPAM) Vrije Universiteit Brussel Biped Lucy: Vanderborght, et al.(2006) Vrije Universiteit Brussel 11/20/

37 Introduction What is Pneumatic Artificial Muscle PAM: A contractile and linear motion engine operated by gas pressure [Daerden and Lefeben, 2000]

38 Introduction The Operation Principle (1) Operation at constant load M is constant p=0 < p 1 < p 2 V min < V 1 < V 2 l max > l 1 > l 2 [Kelasidi et al. 2012, Daerden and Lefeben 2000]

39 Introduction The Operation Principle (2) Operation at constant pressure p is constant M 1 > M 2 V 1 < V 2 < V max l 1 > l 2 > l max [Kelasidi et al. 2012, Daerden and Lefeben 2000]

40 Introduction Why PAM? PAM enables a resemblance of skeletal muscle system: - Lightweight and strong - Direct connection - Ready replacement [Daerden and Lefeben 2000, Yamada et al. 2011]

41 General Properties Similarities with biological muscles (1) 1. Force versus Length relationship* F = muscle load L = length instantaneous value: m value at the resting length: m,o [Klute et al. 1999]

42 General Properties Similarities with biological muscles (2) 2. Compliance characteristic C = compliance, K = stiffness 3. Antagonist characteristic [Daerden and Lefeben 2000]

43 General Properties Differences with biological muscles (1) 1. Force versus Velocity relationship F = muscle load V = velocity of contraction instantaneous value: m value at the resting length: m,o [Klute et al. 1999]

44 General Properties Differences with biological muscles (2) 2. Biological muscles: - do not change volume during contraction - in fact have a modular structure - have integrated force and strain sensors - have energy stored in them - comestible [Daerden and Lefeben 2000]

45 McKibben PAM Different Type of PAMs Braided PAM Pleated PAM Netted PAM Embedded PAM [Kelasidi et al. 2012, Daerden and Lefeben 2000]

46 McKibben PAM Model of McKibben PAM F = muscle load p = pressure D max = muscle's diameter at θ=90 ε = contraction l = muscle length value at resting: o [Daerden and Lefeben 2000]

47 Applications Human like robot Exoskeleton

48 Lecture 10 1 Definition and Classification of Actuators 2 Why Do We Need Bio-Inspired Actuators? 3 4 Different Ways of Realizing Softness Unconventional Actuators 11/20/

49 Electroactive polymers (EAPs) as artificial muscles

50 Why do EAPs resemble muscles? Full & Meijer (2004) in Bar-Cohen (ed.) Electroactive Polymer Actuators as Artificial Muscles, ch. 3

51 Armwrestling Match of EAP Robotic Arm Against Human (2005) Environmental Robots Incorporated USA EMPA Switzerland Virginia Tech USA

52 EAPs as actuators in robots

53 EAPs as actuators in robots

54 EAPs as actuators in robots

55 A list of major EAP materials Electrorheological fluids (ERF) Bar-Cohen (2004) in Electrochemistry Encyclopedia: Samatham et al. (2007) in Kim & Tadokoro (ed.) Electroactive Polymers for Robotic Applications, ch. 1

56 A list of major EAP materials Electrorheological fluids (ERF) Bar-Cohen (2004) in Electrochemistry Encyclopedia: Samatham et al. (2007) in Kim & Tadokoro (ed.) Electroactive Polymers for Robotic Applications, ch. 1

Dielectric elastomers (DEs) Dielectric elastomers are essentially elastic parallel-plate capacitors Electrostatic forces generate significant actuation strains and

57 Dielectric elastomers (DEs) Dielectric elastomers are essentially elastic parallel-plate capacitors Electrostatic forces generate significant actuation strains and high energy densities Changes in resistance and capacitance can be using to self-sense Slide adapted from Conn (2012) at ETH Robotics Summer School on Soft Robotics

58 Dielectric elastomers (DEs) Slide modified from Conn (2012) at ETH Robotics Summer School on Soft Robotics

59 DE actuator configurations Kornbluh et al. (2004) in Bar-Cohen (ed.) Electroactive Polymer Actuators as Artificial Muscles, ch. 16

60 A list of major EAP materials Electrorheological fluids (ERF) Bar-Cohen (2004) in Electrochemistry Encyclopedia: Samatham et al. (2007) in Kim & Tadokoro (ed.) Electroactive Polymers for Robotic Applications, ch. 1

When a voltage is applied the IPMC bends in response to internal ion migration.

61 Ionic polymer-metal composites IPMCs consist of a polymer membrane coated with flexible gold electrodes. The polymer membrane provides channels for mobility of positive ions in a fixed network of negative ions. When a voltage is applied the IPMC bends in response to internal ion migration. The polymer membrane needs to be hydrated for operation. Voltage OFF Uniform cation distribution Voltage ON Cation migration Slide adapted from Conn (2012) at ETH Robotics Summer School on Soft Robotics

62 Ionic polymer-metal composites Slide modified from Conn (2012) at ETH Robotics Summer School on Soft Robotics

63 Potential applications Bio-inspired robots Biomedical devices Haptic interfaces Kornbluh et al. (2004) in Bar-Cohen (ed.) Electroactive Polymer Actuators as Artificial Muscles, ch. 16

64 Shape Memory Alloys

65 Lecture 10 11/20/

66 Shape-memory alloy (SMA) A material that can remember its shape A class of smart materials SMA also exhibits superelastic (pseudoelastic) behavior

67 STRESS Shape Memory Effect: Shape Recovery Under Stress Detwinned Martensite (stressed) Austenite M f M s A s A f TEMPERATURE

68 SMA Demonstrations and Applications Floral Arrangement SMA Actuated Butterfly: SMA Linear Actuator Thermobile Demonstrator: SMA Properties/Thermodynamics

69 Lecture 10 Do you want to make your own soft robot/actuator? 11/20/

Coupling between the Output Force and Stiffness in Different Variable Stiffness Actuators

Actuators 014, 3, 70-84; doi:10.3390/act303070 Article OPEN ACCESS actuators ISSN 076-085 www.mdpi.com/journal/actuators Coupling between the Output Force and Stiffness in Different Variable Stiffness