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Embedded CANopen in ExoHand and CogniGame

At Hanover Fair Industry, Festo (Germany) introduced the results of some sponsored future technology projects using the company’s products. The ExoHand and the CogniGame projects implement embedded CANopen networks. The CANopen connected controllers and drives are commercially available state-of-the-art products. Coupling the ideas of both projects can help stroke patients with their recovery.

THE FESTO BOOTH COMPRISED A SIGNIFICANT AREA for the future concept presentations. Camera teams from all over the world filmed the ExoHand, the CogniGame, and the other project results. Festo’s investment into the projects paid back quite well. In many countries, the daily TV news reported about the research projects mentioning also the name of the sponsor, of course. This makes the company known as innovative industrial automation supplier.

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ExoHand: Remote control with force feedback

The ExoHand is an exoskeleton that can be worn like a glove. The finger’s can be actively moved and their strength amplified; the operator’s movements are transmitted to the remote robotic hand in real-time. This allows remote operations, for example when human beings are not able to access the working area (e.g. due to high radio-activity). When the ExoHand is used for remote manipulation of a robotic hand, the force feedback of the artificial hand helps the operator to feel the gripping as real.

The fingers can be actively moved. The exoskeleton is a structure that supports the human hand externally and simulates the physiological degrees of freedom of the hand. Eight pneumatic actuators move the exoskeleton. Sensors record the forces, angles and distances. Servo-pneumatic open- and closed-loop control algorithms allow precise movement of the individual finger joints. The ExoHand thus supports the various possibilities for gripping and touching, which a human hand has. The pneumatic components allow highly flexible and ergonomic control of the individual finger joints.
High forces can thus be transmitted precisely in a small space and with a low weight without the system becoming rigid and restrictive. This flexibility is crucial in human-machine interaction, as it minimizes the risk of injury.
The control system comprises an Ethernet network and an embedded CANopen network. It is based on the MPA-L valve terminal with an integrated CPX-CEC control unit and I/O modules. The controller implements the Codesys IEC 61131-3 compliant software. Festo uses CANopen in many of its products, for example in its CMXR multi-axis controllers.

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The ExoHand was developed in co-operation with the Centre for Integrative Neuroscience (University of Tuebingen) and experts from Robotics Technology (RT) Leaders.

When used for remote manipulation of a robotic hand in an industrial environment, the ExoHand allows complex activities in for example dangerous or hazardous environments to be carried out from some distance away. Because all joints and their actuators exist in the form of an exoskeleton outside of the actual hand, the ExoHand can be worn over a human hand or an artificial hand made from silicone. The ExoHand performs two functions here – acting firstly as an interface between the operator and the control system and secondly as a robotic hand. This allows the control of a complete artificial hand with virtually all of the relevant degrees of freedom.

With a single system it is thus possible to design an innovative scenario that combines robotics with orthotics. Forces can be transmitted to the hand as force feedback from another environment, creating an ability to feel shapes. This technology offers enormous potential not only for remote manipulation, but also for navigation in the virtual world. When the ExoHand is used in combination with a robot in domestic or medical environments, human-like characteristics are absolutely essential. The flexibility of pneumatic systems in particular ensures reliable human-machine interaction.

CogniGame: Interfacing the brain

This system is a reinterpretation of the table tennis simulation game, which was launched in the 1970s. As in table tennis the two players move a bar to hit a ball back to the other side. In CogniGame one player operates a joystick, while the other use a brain-computer interface. The real playing field inclines the field depending the position of the ball in order to move it to other side. This motion is controlled by means of an embedded CANopen network.

The brain-computer interface allows moving the bar just by the power of thoughts. As in EEG (electroencephalography), this interface measures voltage fluctuations on the player’s scalp by means of affixed electrodes. The CogniWare software needs to be trained and can then interpret the “thoughts”. But it is very difficult and requires a high concentration. “On the fair it is much more difficult to keep my eye on the ball,” said Nadine Kärcher playing against visitors just with her mind.

Combining the ExoHand and the CogniGame opens new possibilities in rehabilitation. In stroke therapy, for example, the hand orthosis can be used to help treat the first signs of paralysis in patients. It can be used together with a brain-computer interface to create a closed feedback loop. It can help stroke patients who are showing the first signs of paralysis to restore the missing connection between brain and hand. An EEG signal from the brain indicates the patient's desire to open or close the hand. The active hand orthosis then performs the movement. The result is a training effect, which over time helps patients to move their hand again without any technical assistance. Festo is working together with the Centre for Integrative Neuroscience on this subject.