Identification and Torque/Force Control of Hydraulic Actuator
The technology provides a system for torque control in rotary hydraulic (and linear hydraulic) actuators, thus making the actuators more accurate. The control system allows rotary (and linear) hydraulic actuators to precisely generate the desired torque, irrespective of the motion of the actuator. This system employs sensors to measure selected physical parameters of the in-situ operating hydraulic actuator, and these parameters are incorporated into a controller that drives a controller for the hydraulic actuator.
The technology is comprised of a combined scheme of identification and torque control for rotary hydraulic actuators (or force control for linear hydraulic actuators). The composite controller consists of a dynamic feedback-linearizing inner loop cascaded with an optimal robust linear feedback outer loop. The proposed controller allows the actuator to generate desired torque, irrespective of the actuator motion. In fact, the controller reduces significantly the impedance of the actuator as seen by its external load, making the system an ideal source of torque suitable for many robotics and automation applications. Also included is an identification method to extract the parameters of a non-linear model of actuator dynamics and to estimate a boundary for modelling uncertainty, used for synthesis of the outer optimal controller.
The identification and control scheme does not rely on an a priori knowledge of load dynamics or on external torques, and makes the controlled actuator a source of torque with low impedance, i.e., acting virtually like an electro-motor. Moreover, no a priori assumption is made in regard to a boundary for actuator unmodelled dynamics: the boundary is estimated through use of an identification procedure.
The invention provides an identification and control strategy that will enable a licensee to engineer robust torque/force control for hydraulic actuators in the company's own products. The commercial product that would be derived from this invention consists of a hydraulic actuator with additional sensors (i.e., pressure transducer and motion sensors to capture position and velocity) and a controller with embedded proprietary software. The actuator would be part of an industrial system with sufficient on-board processing hardware to accommodate the controller. The resulting product would have a comparative competitive advantage over existing hydraulic actuators in the marketplace in industrial applications where high torque/force and precision are required, such as in industrial robotics and automation.
The Business Opportunity
The invention has direct application to hydraulic systems and particularly to hydraulic manipulators. The proposed control methodology can enhance accuracy in these devices. The technology will be of interest to manufacturers of hydraulic actuators and ancillary equipment for the robotics industry. Hydraulic actuators are widely used in a variety of industrial applications outside the robotics industry, and may represent an additional opportunity for this technology.
Technology Transfer Details
The technology is available for licensing.
The business opportunity may be referred to by its CSA case ID: 50719
- Aghili, F. and K. Parsa, "A Reconfigurable Robot with Lockable Cylindrical Joints," Institute of Electrical and Electronics Engineers (IEEE), Transactions on Robotics, Vol. 25, No. 4, pp. 785–797, August 2009.
- Namvar, M. and F. Aghili, "Failure Detection and Isolation in Robotic Manipulators Using Joint Torque Sensors," Robotica, Vol. 27, pp. 1–13, June 2009.
- Aghili, F., "Optimal Control of a Space Manipulator for Detumbling of a Target Satellite," Institute of Electrical and Electronics Engineers (IEEE), International Conference on Robotics & Automation, Kobe, Japan, pp. 3019–3024, May 2009.
- Number: 2,489,181 Note: Abandoned patent application
- Source: Canadian Intellectual Property Office (CIPO)
- Number: 7,403,826 Note: Abandoned patent
- Source: United States Patent and Trademark Office (USPTO)
- Date modified: