A grapple device for grasping, holding and releasing an object having a deformable cover material such as sacks and bags, has a mounting bracket and two rollers. The rollers are pushed toward each other by the force of at least one spring. When the rollers are powered to spin, the inward spinning of the rollers causes the sack material to be dragged in between the rollers due to friction between the surfaces of the rollers and the sack material. The spring pushes the rollers toward each other with sufficient force to hold the sack material in place between the rollers. The grapple device also includes a holding mechanism to engage at least one of the rollers and prevent rotation of the roller when engaged, so that when sack material is located in the inter-roller region and the holding mechanism is engaged, the contact between the sack material and rollers causes the sack to be held by the grapple device. When the rollers are powered to spin outwardly, the sack material passes out of inter-roller region causing the sack to be released. Using the invention described here, in conjunction with a robot or a material handling device, a sack can be lifted by grasping any point on the sack. The device includes a control system for operating the device in three phases to: grasp, hold and release sacks.

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Pre-strained electroactive polymers are described that improve conversion from electrical to mechanical energy. When a voltage is applied to electrodes contacting a pre-strained polymer, the polymer deflects. This deflection may be used to do mechanical work. The pre-strain improves the mechanical response of an electroactive polymer. Also described herein are actuators that include an electroactive polymer and mechanical coupling to convert deflection of the polymer into mechanical work. Further described are compliant electrodes that conform to the shape of a polymer. Methods for fabricating electromechanical devices including one or more electroactive polymers are also described.

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The present invention relates to transducers, their use and fabrication. The transducers convert between mechanical and electrical energy. Some transducers of the present invention include a pre-strained polymer. The pre-strain improves the conversion between electrical and mechanical energy. The present invention also relates to devices including an electroactive polymer to convert between electrical and mechanical energy. The present invention further relates to compliant electrodes that conform to the shape of a polymer included in a transducer. The present invention provides methods for fabricating electromechanical devices including one or more electroactive polymers.

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In this paper we present a framework that allows the haptic rendering of interactions between the human hand and a virtual environment consisting of polygonal objects. The proposed solution creates a representation of the human hand through simple geometric primitives (spheres, cylinders etc.) and allows the fast collision detection and calculation of forces of interaction. Theforces are calculated with precision and smoothness, especially at the fingertips, where the human haptic perception is more sensitive. The area of each contacted region is taken into account to correctly weigh the importance of each force we calculate.The objective is to give a simulation tool that will allow the use of exoskeletons for the human hand with an improved level ofprecision, which is necessary for the correct evaluation of these haptic devices and their efficient use.

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