Precision Assembly:
Controlled insertion for high tolerance assembly.
Assembly quality control for increased productivity.

UAV Inspection:
Provides constant force for reliable measurements.
Consistent and repetitive measurements.
Ability to generate diagnostic data.
Reduces exposure to hazardous environments.

Rehabilitation with Robotic Systems
Enhances haptic interaction between patient, therapist and robot.
Consistent and controlled rehabilitation.
Provides sense of security for patient and therapist.
Tracks patient progress quantitatively.
Generates accurate diagnostic reports.
Lowers physiotherapy costs.


Increases productivity.
Ensures high-quality production.
Safe for safety-critical operations.
Capable of manipulating fragile parts.

Robotic Assisted Surgery:
Reduces medical risks.
Enhances security for patient and surgeon.
Leads to less post-surgery scars.
Shorter recovery time.
Lowers costs per operation.

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Towards Dynamic Transparency: Robust Interaction Force Tracking Using Multi-Sensory Control


A high-quality free-motion rendering is one of the most vital traits to achieve an immersive human-robot interaction. Rendering free-motion is notably challenging for rehabilitation exoskeletons due to their relatively high weight and powerful actuators required for strength training and support. In the presence of dynamic human movements, accurate feedback linearization of the robot’s dynamics is necessary to allow for linear synthesis of interaction wrench controllers.


Hence, we introduce a virtual model controller that uses two 6-DoF force sensors to control the interaction wrenches of a multi-DoF torque-controlled exoskeleton over the joint accelerations and inverse dynamics. Furthermore, we propose a disturbance observer for controlling the joint acceleration to diminish the influence of modeling errors on inverse dynamics. To provide a high-bandwidth, low-bias estimation of the system’s acceleration, we introduce a bias-observer that fuses the information from joint encoders and seven low-priced IMUs.

We have validated the performance of our proposed control structure on the shoulder and arm exoskeleton ANYexo. The experimental comparison of the controllers shows a reduction of the felt inertia and maximum reflected joint torque by a factor of more than three compared to state-of-the-art. The controllers’ robustness w.r.t. a model mismatch is validated. The experiments show that the closed-loop acceleration control improves the tracking, particularly at joints with low inertia. The proposed controllers’ performance sets a new benchmark in haptic transparency for comparable devices and should be transferable to other applications.


"We chose to use three Rokubi EtherCAT sensors for our upper-limb exoskeleton due to the small volume and integrated electronics. These features make them easy to incorporate into the design of the exoskeleton. Further, the different connector locations help to integrate the sensor flush into the design. The drift resistance of the sensors is beneficial for use in longer exercises where the arm of the user is continuously connected to the sensor. The inbuilt electronics for EtherCAT communication enable adding sensors in a modular fashion to an existing framework of actuators and sensors. This keeps the flexibility of the system high."- Yves Zimmermann, Robotic Systems Lab and at Sensory-Motor Systems Lab of ETH Zurich