Abstract: An innovative oil observer for estimating oil concentration and oil amount in a refrigerant compressor in a vapor compression cycle is described. The invention ensures the safe operation of the compressor by ensuring that adequate lubricant is present in the compressor. This oil observer is based on oil models for components of air conditioning and refrigeration systems. Oil models for HVAC components estimate oil mass and refrigerant mass in each component. With all component oil models and heat exchanger observers which provide the estimation of inner geometric lengths of two-phase flow heat exchangers, a system-level oil observer is established by integrating all component models. Experimental testing has been conducted to verify the performance of this oil observer for steady state operation and dynamic processes. The invention has direct applications in residential and commercial air conditioning and refrigeration systems.

Abstract: An apparatus and method for providing controlled heating, cooling and motion, in a device such as an active robotic automobile seat, are disclosed. A shape memory alloy (SMA) element, which changes shape upon application of a temperature change to the SMA element, is coupled to a thermoelectric device. Heat flows through the TED upon application of an electrical current through the TED. The apparatus is operable in one of a plurality of modes. In a first mode, a current is applied through the TED to cause a temperature change in the SMA element to change the shape of the SMA element. In a second mode, a current is applied to the TED to cause heat flow in a space adjacent to the apparatus. By controlling application of current to the TED, controlled motion, heating and cooling are achieved in the seat.

Abstract: An innovative oil observer for estimating oil concentration and oil amount in a refrigerant compressor in a vapor compression cycle is described. The invention ensures the safe operation of the compressor by ensuring that adequate lubricant is present in the compressor. This oil observer is based on oil models for components of air conditioning and refrigeration systems. Oil models for HVAC components estimate oil mass and refrigerant mass in each component. With all component oil models and heat exchanger observers which provide the estimation of inner geometric lengths of two-phase flow heat exchangers, a system-level oil observer is established by integrating all component models. Experimental testing has been conducted to verify the performance of this oil observer for steady state operation and dynamic processes. The invention has direct applications in residential and commercial air conditioning and refrigeration systems.

Abstract: A new feedback linearization approach to advanced control of single-unit and multi-unit HVAC systems is described. In accordance with the approach of the invention, this new nonlinear control includes a model-based feedback linearization part to compensate for the nonlinearity in the system dynamics. Therefore, the evaporating temperature and superheat values can be controlled by linear PI control designs to achieve desired system performance and reliability. The main advantages of the new nonlinear control approach include (1) better performance even with large model errors, (2) being able to adapt to indoor unit turn on/off operation, (3) much smaller PI control gains compared to that of current feedback PI controls, (4) much easier design procedures since there is no need for tuning the PI control gains over wide range operation.

Abstract: The invention proposes a design and deployment scheme for a hyper-articulated manipulator for assembly operations inside an aircraft wing box. The manipulator comprises nested C-channel structures connected by 1 degree of freedom rotary joints. The wing box has a large span, but is only accessible through multiple small portholes along its length. The manipulator is compact enough to enter the wing-box through the portholes, yet capable of subsequent reconfiguration so as to access multiple assembly points inside the wing-box. Traditional electromechanical actuators powering the rotary joints are unsuitable for this purpose, because of limited space and large payload requirements. The manipulator is an underactuated system which uses a single actuator at the base for the deployment of the C-channel serial linkage structure. The deployment scheme modulates gravitational torques in the system dynamics to rapidly deploy the system to a desired final configuration starting from any initial configuration.

Abstract: A new feedback linearization approach to advanced control of single-unit and multi-unit HVAC systems is described. In accordance with the approach of the invention, this new nonlinear control includes a model-based feedback linearization part to compensate for the nonlinearity in the system dynamics. Therefore, the evaporating temperature and superheat values can be controlled by linear PI control designs to achieve desired system performance and reliability. The main advantages of the new nonlinear control approach include (1) better performance even with large model errors, (2) being able to adapt to indoor unit turn on/off operation, (3) much smaller PI control gains compared to that of current feedback PI controls, (4) much easier design procedures since there is no need for tuning the PI control gains over wide range operation.

Abstract: A new feedback linearization approach to advanced control of single-unit and multi-unit HVAC systems is described. In accordance with the approach of the invention, this new nonlinear control includes a model-based feedback linearization part to compensate for the nonlinearity in the system dynamics. Therefore, the evaporating temperature and superheat values can be controlled by linear PI control designs to achieve desired system performance and reliability. The main advantages of the new nonlinear control approach include (1) better performance even with large model errors, (2) being able to adapt to indoor unit turn on/off operation, (3) much smaller PI control gains compared to that of current feedback PI controls, (4) much easier design procedures since there is no need for tuning the PI control gains over wide range operation.