Description:
Background
While implementation of a forward kinematics in a machine, it is difficult to follow a task using sensors and actuators, which are usually considered imperfect. Controlling heavy machines with the help of hydraulic adds another difficulty to the efficiency of the actuators. To avoid such difficulty and also for energy loss reduction, mobile hydraulics systems generally employ simplified control loops which have higher energy efficiencies than some other control loops, for example hydraulic robots. Manual control of such mobile machines with imperfect hydraulic circuits work really well. Control methods and systems can attempt to provide great flexibility in the adaptability of the control system parameters to allow for unknown, possibly unlimited and arbitrary ranges of variation in such factors.
Description
Our researchers at University of Nevada, Reno have created a new method and system for controlling a hydraulically actuated mechanical arm to perform a task. The method included determining a dynamic model of the motion of the hydraulic arm for each hydraulic arm link by relating the input signal vector for each link to the output signal vector for that same link. It also includes determining an error signal for each link as the weighted sum of the differences between a measured position and a reference position & between the time derivatives of the measured position and the time derivatives of the reference position for each respective link. The weights used in the determination of the error signal are determine by the constant coefficients of the dynamic model. The error signal in a closed negative feedback control loop to diminish or eliminate the error signal for each respective link.
Advantages
- The method helps to measure the actual positions of each link for the respective time steps and provides an output signal vector from the measured actual positions.
- This method helps to determine a motion model of the hydraulic arm for each link by relating the input signal vector for each respective link to the output signal vector for the same link.
- These methods and systems can help to provide great flexibility in the adaptability of control system parameters to allow for unknown, possibly unlimited and arbitrary ranges of variation in such factors.
Patent: US8065037B2
UNR08-006
