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The design of human assistive systems requires actuators that are capable of producing compliant motions. One key technological development for this compliant actuation is series elastic actuation, which is a challenging design problem, as the load side dynamics of the actuator changes during operation. In this paper, a novel series elastic actuator (SEA) structure using composite beams as series elastic elements and its torque control strategy are presented. We proposed a two-stage controller, a novel adaptive state feedback controller for transient dynamics and a PI controller for eliminating steady-state error. The effect of disturbance torque is studied, together with load dynamics, which is estimated online by a recursive least square method. The performance of the actuator was evaluated in case studies in which the actuator was controlled with various knee torque profiles. The experimental results showed that desired dynamic behaviour of the designed SEA can be obtained with the proposed control algorithm despite the unknown load dynamics.

The freezer system on ships involves provisions where meat, fish, vegetables etc. are cooled down. Provision room is one of the essential features on ships for the preservation of food. The size of the cooling chamber varies according to the length of the ship and the number of personnel. Under the scope of the study, a room with volume of 15 m 3 (H x L x W, 2.5 x 3 x 2 m.) has been designed for the preservation of the meat. Boundary conditions which are determined for numerical and theoretical analysis in provision room have been chosen considering existing ship conditions. Refrigeration load, temperature distribution and flow streamline to keep the meat at the desired temperature in the provision room have been analyzed for one hour working period. Within this time interval, average meat domain and air temperature drop have been found as 4.33 K and 13 K, respectively. CFD analysis and theoretical calculation results have been compared. The results have found to be in agreement with acceptable errors less than 10%. The outputs from analysis show that refrigeration unit provides suitable temperature decrease within determined time interval.

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