In the period of reference (June 2011-July 2011) the following sub-tasks have been continued/initiated, according to the TESBE workplan:

T1.2: Implementation of the selected control approaches

T2.2: Implementation and test of the collaborative control

T3.2: Analysis and preliminary design of the under-actuated gripper mechanism

T3.3: Detailed development of the gripper

 In sub-task 1.2, the unified simulation framework, developed in the previous reporting period, has been tested, verifying the functionalities of all the composing modules.

This tool will be used in the next period to easily carry on a quantitative comparison of the system performances achievable with the different control approaches selected in T1.1.

In sub-task 2.2, the definition of a revised mathematical formulation of the collaborative control has been initiated, taking into account also the effect of the inertial forces on the position of the ZMP.

Through an in depth analysis of a simple 1 DoF system, it has been possible to quantitative define upper and lower limits for both the operator intended velocity and acceleration, ensuring that the ZMP always falls inside the support polygon and that the distortion of the operator intended motion is minimal.

These limits are dependent on the height of the system center of gravity from the support polygon and on the position of its projection on the support polygon.

In the next period the results achieved for the 1DoF system will be extended for a general n-DoF system.

In sub-task 3.2, the preliminary design of the gripper has been completed.

In sub-task 3.3, the detailed design of the gripper has been initiated.

In particular all the components of the mechanical transmission, located between the output of the actuator module and the input of the differential mechanism has been verified/dimensioned, the range of motion of the differential mechanism has been verified in function of the finger postures required to grasp the specified objects and the linkages and springs of the under-actuated fingers have been dimensioned.

The research activity in the TESBE experiment is organized in three complementary tasks, the first (task 1) devoted to the development of a new fast, accurate and robust force control to be used in a body extender for the tracking of the wearer’s limb motions and for force amplification,  the second (task 2) to the development of a newly conceived  collaborative postural control to prevent the overturning of the system under the action of gravity and iexternal interaction forces, and the third (task 3) to the development of an advanced haptically enhanced gripper able to stably grasp diverse typologies of objects, having different shapes, dimensions and consistencies.

In the first three months of the experiments all these tasks have been initiated according the TESBE work plan.

In particular, in sub-task 1.1 existing force control approaches based on both rigid and elastic mechanical transmission models have been identified, in sub-task 2.1 a preliminary control strategy aiming at preventing the overturning of the system has been formulated in the n-dimensional space of the BE’s DoFs, in sub-task 2.3 preliminary experimental investigation on the efficacy of artificially generated forces at the level the trunk have been carried out and in sub-task 3.1 a preliminary set of specifications for the gripper have been defined.