This paper presents a 7-DOF partially statically balanced robot that has been developed for physical human robot interaction. The gravity compensation technique uses remote counterweights connected to the robot via a low-pressure hydraulic transmission. Low-friction diaphragm cylinders are used in order to provide very low residual friction. A two-stage balancing bench allows using a unique moving counterweight to adapt the balancing to a payload of up to 10 kg, that is the maximal payload of the gripper. The robot can be easily moved passively while being capable of physically assisting humans in the performance of tasks.

Providing robots with the capability of sensing their surrounding environment is an important feature that would lead to a more intuitive and safe physical human-robot interaction. This paper proposes a new design of homogeneous flexible and stretchable robot skin based on carbon-black-filled (CBF) silicone and conductive fabric that can sense multiple contact locations as well as applied pressure. CBF silicone has been already used in sensing technology but its piezoresistivity is still largely misunderstood. This particular behavior is investigated in this paper through a set of experiments conducted on isolated sensing cells. Using the results of these experiments, a model describing the variation of the resistivity in the CBF silicone as a function of the applied pressure is proposed. Based on this model, a simple way to accurately estimate the applied pressure in real time is demonstrated. Finally, using this improved knowledge of the behaviour of the CBF silicone, the fabrication of a fully functional sensor array is presented. The proposed design has the particularity of circumventing the well-known problem of cross-talk between sensing cells.

Providing contact sensing on the whole body of a robot is a key feature to increase the safety level of physical human-robot interaction. In this paper, a new robot skin capable of sensing multiple contact locations is presented. The motivation behind the proposed design is to produce a relatively inexpensive skin having the capability to provide the spatial location of collisions and also to add compliance to the robot's external cover. The resulting device is a thin flexible sensor sheet made of polyimide films with electrically conductive ink and a pressure sensitive conductive rubber sheet. The problem of internal wire routing is circumvented by the use of conductive ink and a circuit is proposed to minimize the number of output wires. To provide collision absorption and mechanical robustness, the sensor is embedded in different layers of polyurethane using shape deposition manufacturing (SDM). The paper presents the design and the fabrication process of the skin but also some experimental results on the determination of the mechanical properties of the resulting sensor as well as its potential for increasing human safety during human robot interaction.