Centre for Automation and Robotics 

Spanish National Research Council

Field & Service Robotics Group

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Goals of the project







Spanish Ministry for Innovation and Science  (DPI2010-18702)


                 Goals of the project                          

In the last years a new generation of legged-locomotion robots is atracting the interest of researchers of a broad range of areas because of its potential impact in the society of the future. Lower-limb exoskeletons and active orthoses are robotic devices worn by an operator that fit closely and operate in parallel with the human legs, and are the best choice for augmenting human performance in urban, industrial, and natural scenarios. Exoskeletons and active orthoses are expected to help the user walk (and even run) while carrying the human’s weight and additional payload. The potential benefits of these robotic devices in assisting physically challenged persons are impressive. However, in spite of the research effort on the subject, there are very few prototypes having the envisaged performance. The major challenges that limit their performance are:
(1) The need for energetic autonomy for long periods,
(2) as portable devices they have to include all actuators and power source,
(3) The requirement of large actuation power,
(4) The requirement of being light-weight devices, and
(5) they have to safely interact with the human user.
These five
requirements cannot be met with conventional actuation technology

This builds up a new line of research aimed at designing energy efficient, large power-to-weight actuators and energy-efficient-locomotion control schemes for the new generation of legged robots. This project aims at establishing this new long-term research by reaching three main goals: The first goal is to research, design and develop novel actuators capable of delivering the large power to weight requirements of exoskeletons. The second goal of the project is to study how to achieve energy efficiency in the control of locomotion. The combination of passive dynamics (making use of elastic elements for storing energy along some phases of the gait cycle) with the use of controllable resistive actuators for achieving variable compliance along the gait cycle, should allow to provide active actuation only when it is needed to infer power to the system. This will be the means to optimize power consumption and enlarge the autonomy of the robot.

To show the benefits of the research on new actuators and control schemes, the ultimate goal of the project is to design, develop and test an active orthosis for a quadriplegic child. The device will produce her motions in everyday-life activities (stand up, sit down, walk stably). The DCA of the CAR (previously IAI-CSIC) exhibits extensive expertise in the design, development and control of legged-locomotion robots and it is leading the research since 20 years ago.

The ATLAS Lower-Limb Exoskeleton for Gait Assistance in Quadriplegia 

The ATLAS exoskeleton falls within the classification of active orthosis as it is devised for gait assistance, not for load-carrying augmentation. In orthotic terminology it can be considered as an active THKAFO (Trunk- Hip-Knee-Ankle-Foot Orthosis). ATLAS is intended to support a 25-kg girl and help her out with walking at a moderate speed (<1m/s). The particular pathology of ATLAS' user is quadriplegia: she is a 8 year-old girl affected by paralysis of both legs and arms (the girl can only move her left hand). This paralysis was caused by spinal cord injury, and therefore, she cannot move her extremities, and she cannot control the torso to keep balance. Besides, biological signals from the motor cortex do not reach the extremities in quadriplegic patients. Therefore, in order to command the motion of the exoskeleton, biosignals cannot even be acquired through typical non-invasive methods used in exoskeletons, such as Electro-miogram. With all this in mind, the ATLAS exoskeleton has been thought of as a lightweight, easy to handle and to put on robotic system composed of the following main components, sketched in Figure 1.

Figure 1. Conceptual sketch of the ATLAS exoskeleton

  1. Mechanical structure: As a lower limb orthosis, it must be simple, lightweight, strong, durable and cosmetically acceptable. It is a 6 DOF mechanism, having 3 DOF per leg: hip, knee and ankle. The structure is attached to the user body through comfortable belts. The exoskeleton will be worn by the user underneath her cloths, so it must not be bulky.
  2. Actuation system: The motion of the joints is driven by electrical motors at the hip, knee and ankle.
  3. Sensorial system: It is composed of goniometers at the hip, knee and ankle of the user to measure joint angles, an inertial measurement unit (IMU) at the torso, and an in-shoe plantar pressure measurement system at each foot.
  4. Gait controller: The controller is based on a National Instruments SingleBoard RIO, with a real time operating system and FPGA. An impedance controller is programmed to follow natural joint trajectories which have been obtained making use of Clinical Gait Analysis data (CGA), while reacting compliantly from small perturbations in the sagittal plane. The controller, related electronics, sensor amplifiers and batteries are placed inside a backpack. 

Video 1: Testing ATLAS Exoskeleton on a dummy

Video 2: Testing ATLAS on a healthy subject: Irene 9 years old. Standing up, walking and sitting down

Video 3: Testing ATLAS on a Quadriplegic (C4-C7 Spinal Cord Injuried) subject: Daniela 9 years old. Standing up, walking and sitting down


1.- Sanz-Merodio, D., Cestari, M., Arevalo, J. and Garcia, E., "Exploiting joint synergy for actuation in a lower-limb active orthosis"     Industrial Robot, An International Journal, Vol. 40 No. 3, 2013

2.- D. Sanz-Merodio, M. Cestari, J. C. Arevalo and E. Garcia, "Gait parameter adaptation for lower-limb exoskeletons" In Proceedings of the International Work-Conference on Bioinformatics and Biomedical Engineering, March 18-20, 2013, Granada, Spain.

3.- D. Sanz-Merodio, M. Cestari, J.C. Arevalo, and E.Garcia, “A lower-limb exoskeleton for gait assistance in quadriplegia” Best Paper in Robotics Finalist”, Proceedings of IEEE International Conference on Robotics and Biomimetics, Guangzhou, China, 2012 ISBN:  978-1-4673-2127-3

4.- J.C. Arevalo, D. Sanz-Merodio, M. Cestari and E. Garcia, “Parameterized Inverted and Double Pendulum Model for Controlling Lower-limb Active Orthosis”, Proceedings of IEEE International Conference on Robotics and Biomimetics, Guangzhou, China, 2012 ISBN:  978-1-4673-2127-3

5.- M. Cestari, D. Sanz-Merodio, J.C. Arevalo, and E.Garcia, “Development of Synergic Multiarticular Actuation in a Lower-Limb Active Orthosis”, Proceedings MECHATRONICS 2012, Linz, Austria, 2012

6.- D. Sanz-Merodio, M. Cestari, J.C. Arevalo, and E.Garcia, "Control Motion Approach of a Lower Limb Orthosis to Reduce Energy Consumption", International Journal of Advanced Robotic Systems, Vol. 9, 2012.

7.-D. Sanz-Merodio, M. Cestari, J.C. Arevalo, and E.Garcia, "Strategies to reduce energy expenditure in the development of
lower-limb orthoses", Proceedings of the 15th Int. Conf. Climbing and Walking Robots and the Support Technologies for Mobile Machines, Adaptive Mobile Robotics ISBN: 13 978-981-4415-94-1 Baltimore, USA, 2012

8.- D. Sanz-Merodio, M. Cestari, J.C. Arevalo, and E.Garcia, "Taking advantage of the joint synergy for the actuation in a lower-limb active orthosis", Proceedings of the 15th Int. Conf. Climbing and Walking Robots and the Support Technologies for Mobile Machines, Adaptive Mobile Robotics ISBN: 13 978-981-4415-94-1 Baltimore, USA, 2012. Innovation Award 2012 – For practical innovation in the field of robotics, Awarded by Industrial Robot, Emerald Group Publishing Limited.

9.- J.C. Arevalo, M. Cestari, D. Sanz-Merodio, and E.Garcia, “Impedance control for a bioinspired underactuated leg”, Best Technical Paper Award 2012 –Highly Commended paper, Awarded by CLAWAR Association, Proceedings of the 15th Int. Conf. Climbing and Walking Robots and the Support Technologies for Mobile Machines, Baltimore, USA, 2012. ISBN:  13 978-981-4415-94-1

10.-Arevalo, J.C and Garcia, E. "Impedance Control for Legged Robots: An insight into the Concepts Involved" IEEE Transactions on Systems Man and Cybernetics - Part C: Applications and Reviews, Vol. 42, No. 6, pp. 1400-1411, 2012, (DOI:

11.- E. Garcia, D. Sanz-Merodio, F. Sanchez, J.C. Arevalo and P. Gonzalez de Santos, Development of the ATLAS lower-limb active orthosis, 14th Int. Conf. Climbing and Walking Robots and the Support Technologies for Mobile Machines, Field Robotics ISBN: 13 978-981-4374-27-9 Paris, France, 2011

ATLAS in the Media

             elena.garcia AT csic.es              

Field and Service Robotics Group :: Applied Robotics Department :: Centre for Automation and Robotics :: CSIC-UPM