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Events ■ ICRA 2014 Workshop on Hydraulic Robots

ICRA 2014 Workshop on Hydraulic Robots

Hydraulic Robots with Torque Control for Inverse
Dynamics and Active Compliance

2014 IEEE International Conference on Robotics and Automation (ICRA), Hong Kong, China
This full-day workshop takes place on Sunday, June 1st, 2014. (SuWT7, room S229)

3rd workshop in the series of Hydraulic Robots (ICRA 2013, IROS 2013)


  • Claudio Semini, Istituto Italiano di Tecnologia (IIT)
  • Michele Focchi, Istituto Italiano di Tecnologia (IIT)
  • Thiago Boaventura, Swiss Federal Institute of Technology (ETH)
  • Jonas Buchli, Swiss Federal Institute of Technology (ETH)

Call for extended abstracts closed.

Final Schedule (scroll down for the talk abstracts)

9:00 - 9:30 Introduction and talk by Claudio Semini (Istituto Italiano di Tecnologia, Italy)
9:30 - 10:00 Talk by Jonas Buchli (ETHZ Zurich, Switzerland)
10:00 - 10:30 Talk by Thiago Boaventura (ETHZ Zurich, Switzerland)
10:30 - 10:50 coffee break
10:50 - 11:20 Talk by Michele Focchi (Istituto Italiano di Tecnologia, Italy)
11:20 - 11:50
Talk by Scott Kuindersma (MIT, USA)
11:50 - 12:30 Poster/Interactive session with teasers in the first 15min
12:30 - 14:00 lunch break
14:00 - 14:30 Talk by Jouni Mattila (Tampere University of Technology, Finland)
14:30 - 15:00
Talk by Hyungpil Moon (SungKyunKwan University, South Korea)
15:00 - 15:30 Discussion round
15:30 - 15:50 coffee break
15:50 - 16:20 Talk by
Ian Whiting (MOOG Controls Ltd., UK)
16:20 - 16:30 Concluding remarks



This full-day workshop will bring together key researchers of academia and industry to discuss the implementation and limitations of high-performance torque control, inverse dynamics and active compliance control of robots with hydraulic actuation. Inverse dynamics control and active compliance are prime examples to illustrate the benefits of torque control. Inverse dynamics control uses rigid-body dynamics models to calculate the joint torques required to achieve desired contact forces or motion. Active compliance (or better: impedance) is the implementation of virtual springs-dampers in either joint space or between any two points on the robot structure (e.g. hip and foot). This impedance can be adjusted in real-time according to the desired interaction behavior. For these reasons, torque control is critical for legged locomotion and manipulation in unstructured environments where a proper control of contact forces is crucial. Torque control is therefore a key technology for versatile service and field robots. Several companies, mostly funded through US defense grants (e.g. Boston Dynamics and Sarcos Raytheon), are developing robots and exoskeletons with impressive performance. All of them have torque control and hydraulic actuation and impressively demonstrate the advantages of this technology combination. Recently, also academic groups developed robots based on this technology (e.g. the quadruped robot HyQ). Our workshop is part of an academic and civil use oriented program focusing on the research, dissemination and application of this critical technology.

List of topics:

- Torque control on hydraulic robots
- Leg/arm impedance control
- Limitations on achievable impedance parameters in real implementations
- Different torque measurement approaches (strain gages, pressure difference, SEA)
- Applications of active compliance
- Inverse dynamics model-based control
- Feedback linearisation for hydraulic actuators
- Balancing of hydraulic legged robots
- Highly dynamic motions of hydraulic robots
- Whole body control of hydraulic robots
- Torque control in rehabilitation devices

List of Speakers

ClaudioSemini Claudio Semini, Istituto Italiano di Tecnologia (IIT), Italy, confirmed

Talk: Torque Control for increased Performance and Versatility of Legged Robots
Abstract: This talk will focus on the benefits of torque control for versatile legged robots. To improve the performance and versatility of legged robots in real-world settings, it is crucial to properly control the interaction forces between the robot and the environment. We will focus on active impedance/compliance. Recent experiments on IIT’s fully torque-controlled hydraulic robot HyQ are used to illustrate the importance of torque control for legged robots. HyQ has recently demonstrated a large set of behaviors ranging from highly dynamic motions to planned navigation on rough terrain, e.g. flying trot, punch bag disturbance rejection, and walking over stepping stones.

MicheleFocchi Michele Focchi, Istituto Italiano di Tecnologia (IIT), Italy, confirmed

Talk: High-slope Terrain Locomotion for Torque-Controlled Quadruped Robots
Abstract: Research into legged robotics is primarily motivated by the prospects of building machines that are able to navigate in challenging and complex environments that are predominantly non-flat. In this context, control of contact forces is fundamental to ensure stable contacts and stability of the robot. In my talk I will propose a planning/control framework for quasi-static walking for quadrupedal robots, implemented for a demanding application (walking inside 50deg V-shaped walls) in which regulation of ground reaction forces is crucial for the success of the walking behaviour. To achieve this the robot is distributing its weight among the stance legs so as to optimize user-defined criteria (e.g. no foot slippage and minimization of the actuators effort).

JouniMattila Jouni Mattila, Tampere University of Technology, Finland, confirmed

Talk: High Performance and Energy-efficient Torque Based Control of Hydraulic Manipulators
Abstract: This talk gives an overview of our recent developments in high performance torque based control of hydraulic manipulators. Our industrially driven objective is to develop high performance motion and interaction control systems for hydraulic manipulators that are energy-efficient. We present ways to improve four quadrant force-velocity operating envelope of hydraulic servodrives utilizing joint torque control, and how to couple variable displacement pumps with electric load sensing into overall energy-efficiency enhanced design. Our developments are founded on advanced nonlinear modeling and parameter adaptation coupled together with control strategy called Virtual Decomposition Control (VDC), which rigorously guarantees the stability of entire complex system without imposing additional approximations.

IanWhiting Ian Whiting, Moog Controls Ltd, Tewkesbury, UK, confirmed

Talk: Analysis by Dynamic Modelling – The Key to Understanding Miniature Hydraulic Servo Performance
Abstract: Whilst today’s industrial servo valves benefit from on-board sensors and digital electronics; the original Moog nozzle/flapper/feedback wire design remains the technology of choice where miniaturisation or extreme environments are required. This is evident in the recently developed and constantly evolving E024 series servo valve used for motorsport and robotic applications. Affordable computer based analysis tools today play a key role. This is especially true in servo actuation where dynamic analysis has become the norm both for product design and application. This presentation outlines the experiences of Moog in our everyday pursuance of design excellence.

ThiagoBoaventuraThiago Boaventura, Swiss Federal Institute of Technology (ETHZ), Switzerland, confirmed

Talk: Model-based design and analysis of hydraulic compliant controllers
Abstract: In order to obtain a high-performance actively compliant robot, it is desirable to design an inner torque closed-loop controller with as high bandwidth as possible. In this talk, I'll describe some intrinsic physical characteristics that limit the performance in force/torque control, and how to use model-based controllers to compensate for them with hydraulic actuators. Furthermore, I'll show that the torque control loop performance has a big impact in the overall leg stability when interacting with the environment, and also that other mechanical issues such as inertia and friction can strongly influence the robot compliance performance.

JonasBuchliJonas Buchli, Swiss Federal Institute of Technology (ETHZ), Switzerland, confirmed

Talk: It is the law...
Abstract: I will review the motivation behind the classical impedance control scheme with an inner torque/force control loop an an outer position control loop. I will show why this control scheme easily succeeds in providing overall robust robot performance in contact tasks (e.g. locomotion and manipulation) where other approaches fail. Even though this is a long established and well worked argument, surprisingly to this day a large fraction of the robotics community is ignoring this fundamental physics lesson. I will attempt to dispel the myth that good torque control is necessarily complicated and difficult to implement. And, what hardware it takes to do so. Finally, I will sketch out the tremendous opportunities that active impedance control offers when combined with model based and learning control. By understanding that this combination is key to versatile and robust robot performance, we will understand why (active) impedance control has been a bit of a forgotten treasure to this date.

ScottKuindersmaScott Kuindersma, MIT CSAIL, Cambridge, USA, confirmed

Talk: Achieving Stable Dynamic Locomotion with an Atlas Humanoid Robot
Abstract: What does it take to make a 155kg, 188cm tall hydraulic humanoid move dynamically? In this talk, I will describe our approach to achieving dynamic balancing, walking, and compliant upper body control with Atlas. Starting with an efficient optimization-based controller for whole-body locomotion, I will share our process of moving from simulation to the real robot, including system identification, state estimation, and joint-level control. Along the way l will highlight several properties of the system that make precise force control difficult and describe how we are coping with these limitations.

HyungpilMoonHyungpil Moon, SungKyunKwan University, Suwon, Korea

Talk: Limitations on force tracking control in hydraulic robot systems with servo-valves
Abstract: Robot control technologies have been developed mainly for electrical motor driven robot systems. As opposed to velocity control of robot joints, force control can performs better in situations where manipulators make contact with handling objects or environments. In case of robots with electric motors, we may directly measure joint torques from various joint torque sensors or directly measure the contact force from force/torque sensor at the tip of end effector. Current control is also applicable to realize force control for mechanically well-designed robotic systems. Because of dynamically fast responses of electric motors, many force control methodologies have been applied to robotic systems without too much attention to the electric responses of the motor itself. Although the electric-hydraulic analogy is generally accepted in many analysis problems of both, the force control of hydraulic robot system with servo-valve is not the case. In this workshop, we will discuss the issue of force tracking in a simply hydraulic system. The fundamental limitations of the hydraulic system with servo-valves require advanced control algorithms as a necessity tool. We will revisit the more-than-a-decade-old issue and remind ourselves of what limitations we are dealing with.

Poster Presentations

Feng Gao, Chenkun Qi, Qiao Sun, Xianbao Chen and Xinghua Tian:
 "Hydraulic system design for the quadruped robot 'Baby Elephant'"

Sven Hubacher, Thiago Boaventura, Farbod Farshidian, Michele Focchi, Claudio Semini, and Jonas Buchli:
 "Optimization of the Low-Level Torque Controller of the Quadruped Robot HyQ"

J. Meng, Y. Li, H. Zhang, H. Chai and G. Zhang:
 "Stair Climbing and Person Tracking of SCalf-II"

Alexander Winkler, Ioannis Havoutis and Claudio Semini:
 "Combining Active Compliance with on-the-fly Motion Replanning using Haptic Information"

P. Beeson, J. James, J. Kramer, F. Weng, K. Khokar, M. Chu, S. Gee, M. Rynderman, E. Huber, D. Kortenkamp and R. Burridge:
"Development on Atlas Humanoid Robot for Remote Execution of Disaster Relief Tasks under Human Supervisory Control"

Open Call for 1-page abstracts (closed)
We invite researchers that are working on the control and/or design of high-performance hydraulic robots, components and robotic devices to submit a 1-page abstract. Authors of accepted abstracts will be given the opportunity to present their work during the poster session, preceded by a short poster teaser presentation.

Important Dates

1-page abstracts submission deadline: April 25th, 2014 (23:59 PST)
Notification of acceptance: April 30th, 2014

Submission Instructions 

Please prepare a 1-page extended abstract PDF using the IEEE template (US-letter!).
The template can be downloaded here:
Before submitting check your pdf with the IEEE compliance test for ICRA 2014. Then submit your extended abstract to Michele Focchi (michele.focchi{a} ) with the tag [ICRA2014] in the subject line.
Abstracts will be checked by the organizers for suitability for this workshop and completeness, but will not be fully peer-reviewed.

Motorsport applications of the Moog E024 Servo valve – High performance, precision miniaturization and extreme environmental robustnessHyQ Robotmoon data

Last Updated on Friday, 30 May 2014 06:51


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