In the period of reference (April 2011-May 2011) the following sub-tasks have been initiated/continued, 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

In Task 1.2, for the implementation of the different control approaches, it has been decided to develop a unified simulation framework, allowing an easy evaluation of their performances in the scope of predefined range of variability of the parameters, defining the load/environment and human impedances (variability of the plant). The simulation framework is composed by 6 main modules, modeling the BE mechanics, the load/environment and human impedances, the desired BE admittance, the primary motion control law, the stabilizing contributions and one evaluating the performances of the different control approaches according to the method proposed by Hogan.

In sub-task 2.2, simulations carried on a simplified dynamic model of the BE demonstrated that the algorithm defined in T2.1 can effectively guarantee the fulfillment of the system equilibrium conditions only for relatively low velocity of the operator intended motion, while for higher velocity the accelerations produced by the distortion of the user intended motion could displace the zero moment point of the system outside the support polygon. A new more accurate formulation of the control is  now under development, taking into account the inertial forces, previously neglected.

In sub-task 3.2 the preliminary design of the under-actuated gripper mechanism has been continued.

In particular, the differential mechanism, having one input and three output, has been preliminary designed as well as the mechanical transmission from the motor to the input of the differential mechanism.