The Velvet Fingers

Built like a Human Hand, but Made for Industrial Unloading

Trend and Market Movement in Robotic Gripping

Versatility, adaptability and agility are the requirements for robotic gripping solutions as the automation market continues to refine itself. Speed and efficiency continue to rein in streamlining processes, specifically concerning the gripping of goods to increase throughput. Today, companies in an array of different fields are experiencing a reduction in the dimension of batches they produce; consequentially a “flexible” gripper able to grasp objects with different shape and properties is becoming more fundamental to optimize costs.
Progressively, robotic gripping units are needed for greater reliability and cycle-rate efficiencies.

The requirements for such units can range from very specific precision grasping to units with multiple functionalities. Altogether the units need to be robust, but in some sense also flexible to accommodate the demand(s). An inclining trend with simple grippers is occurring; they are being used in a variety of applications where various part sizes have to be handled quickly and processed reliably. Technologies that accommodate this speed along with tactile handling abilities – similar to the intricate functionalities of human grasping principals - are finding a niche for example in delicate part handling (think: vegetables, fruits, cakes, meat, but also lenses, mirrors, solar cells).

Fig 1. schematic of the Velvet Fingers

If You Build It, They Will Come

And, just in time, a solution to the gripping conundrum of speed and tactility has been developed. The Velvet Fingers, a simple tactile under-actuated gripper, is a prototype device developed for this niche with a grappling future ahead. This smart gripper designed with its dexterous technology, is a novel concept of the end-effector combining simple under-actuated mechanics with high manipulation possibilities. This is possible due to built-in conveyors in the finger pads. Contact surface engineering has been recently proposed as a possible means to introduce dexterity in simple grippers, for example with the purpose of on-the-fly reorienting, thus reducing the cost of two separate operations: grasping and handling+re-orienting. Such a solution could be a plus both in internal/external logistics and assembly lines where grasping, transporting, inserting and possibly screwing are requested.

How It Works

The specialties of the Velvet Fingers allow it to apply just the right amount of gripping pressure while also assuring a stable grasp during both simple grasping and in-hand manipulation (see figure 1). Moreover the gripper has the automatic ability to pass from a pinch-to-power grasping in just few seconds thus improving the reliability of the gripper itself. The active conveyors of the gripper are modeled and controlled by way of few servomotors, which are rendered able to emulate different levels of friction and to apply tangential thrusts to the contacted objects. This means that the unit is able to successfully grip in sequence without program reference, hence increasing the overall cycle time with more successful grips.

Why it will be Beneficial

Though still in the “prototype” stage, the Velvet Fingers have already proved to be a resourceful gripping device from its integration into the RobLog project’s advanced demonstrator (see figure 2). In real time, the Velvet Fingers have been challenged to grip a variety of goods ranging from various box sizes, to deformable items such as a cylindrical object, a sack and a plush teddy bear. In all encounters, the Velvet Fingers proved successful by nimbly applying just the right amount of pressure to grasp and retract the goods in a safe manner.
So the future looks bright for the Velvet Fingers and other such simple tactile grippers, in a variety of different industries. As this technology continues to evolve, more and more applications in a variety of complexities will be seen for its usage. And remember, never will circumstances prove too much for the resourceful Velvet Fingers.

Fig. 2 the Velvet Fingers

The Velvet Fingers integrated

The main gripping unit of the RobLog advanced demonstrator