A model predictive fault-tolerant temperature control scheme for hot isostatic pressing furnaces

A fault-tolerant model predictive control (MPC) scheme for precise control of temperature in HIP furnaces was developed, implemented and tested on a production 6-zone HIP furnace at Bodycote IMT, Inc., in Andover, MA. A nonlinear state space representation of the dynamics of the temperature in a HIP furnace was developed and used to design the MPC. The MPC-based fault-tolerant control system was demonstrated to outperform the existing PID controller in the following aspects: (i) achievement of heating rate of at least twice more than the existing PID, which resulted in the reduction of the total cycle time and hence substantial increase in the production; (ii) automatic detection of loss of power to furnace zone (due to ground faults), and controller reconfiguration to achieve the desired process objectives, which with the PID system was impossible and required operator intervention