Tack and deformation based sensorised gripping using conductive hot melt adhesive

The development of a universal method for grasping objects of varying morphology, material and size in unstructured environments remains an unsolved challenge. There is no one ‘universal’ solution which can function with low positional precision, can grasp a variety of objects and materials and has easily inter-gratable sensing to allow simple feedback mechanisms to be implemented. This paper works towards this goal, detailing a grasping method utilising the tack force of thermoplastics to enable grasping using a conductive hot melt adhesive (CHMA). CHMA is developed to be conductive and pressure sensitive by including conductive carbon black particles. The material has controllable tackiness and deformation; this combined effect enables high tack forces to be achieved enabling successful grasping of a wide range of objects. Temperature and indentation force primarily control the tack force generated; a theoretical model relating these is given in this paper. This integrated pressure sensing ability enables a feedback system to be implemented to optimise the time taken to grasp and minimise the force required to grasp the object. This feedback system has been integrated to enable a variety of objects to be picked — ranging from highly soft fabric, to PTFE and a soft ball, all of which were tested and analysed for single point pick and place.