Quick Writer 5 | - Freelance Writer
Aug 17, 2018 | #1
Introduction
The automation of machine tools has been referred to as numerical control since the 1940s. These machines had motors, which were controlled by punched tape. An outcome of these servomechanisms is the machine tools of today, which are computer numerical controlled (CNC). There have been a number of improvements made to these machines which rely on adaptive controls. This type of control is done automatically and relies upon monitoring of the machine performance operation in response to variable conditions. This type of control can prevent damage to machines due to malfunctions. For example, a drill bit may become too dull and cause additional stress on the motor. As the motor overheats due to increased friction, it could be damaged. An adaptive machine would shut the motor down before any damage was done. A more sensitive type of machine would reduce the pressure placed on the drill bit according to its changing level of sharpness. Adaptive machines have reduced the cost of manufacturing. There are many types of manufacturing, which now require only one individual to monitor a computer screen (Tao). This same system may have previously required several individuals to constantly adjust the machines.
A closed loop adaptive control system uses a recursive identification algorithm in real time to compute the control parameters. These parameters are based on the current values received from appropriately placed sensors. The adjustments depend on the desired performance level of the machine. The controller can be tuned automatically by the appropriate computer software to react to variable conditions. This can be done each time the controller takes measurements or on a predetermined schedule. If a schedule is used it is important that the programmer be certain that the time-frame is appropriate.
It is critical that an adaptive control system using a closed loop have a supervision function. This function should monitor the measurement of operational conditions and the adaptive loop to ensure that the correct operation is being programmed. This prevents the adaptive system from giving inappropriate direction to the machine due to problems with monitoring. For example, a signal may be weak and indicate that the machine requires more power. This could result in the adaptive control sending an excess of power to the machine and causing it to damage the product (Landau & Zito).
There are two general types of adaptive control closed loop systems. The first is the self-tuning operation. This type of adaptation begins when there is degradation in performance. It stops when the performance has been restored. With the second type of operation, there is an algorithm which controls the machine operation at all times. Either of these methods can be useful and frequently depend on the type of machine and conditions in which it is being used.
With an open loop control system, the inputs which can be monitored and delivered to the program are specified ahead of time (Tao). This is done when it is assumed that there are no uncertainties in the system, and it will be operating under specific conditions. There is no output information from the system which must be used to generate the input signal used for control. The disadvantage of this type of system is that it cannot change appropriately regarding unanticipated conditions. This lack of adaptation makes it less effective when the tasks being controlled are more sophisticated. For this reason, the open loop system of adaptive control is used less frequently. However, there are instances when this type of system is warranted and works well.
Adaptive control open loop systems have been used successfully for over two decades. An example is provided by multi-locomotive trains. This type of control has the goal of maintaining a specific velocity. It can also be used to reduce noise caused by changes in grade and keep the coupler forces below a pre-specified limit. The controller is set to determine the appropriate throttling and braking necessary for the train to accelerate and decelerate appropriately. This allows the locomotives to act in a fashion, which causes the nonlinear rolling resistance to assume a linear force despite velocity and grade changes.
The open loop control system for multi-locomotive trains has been found to work appropriately even with a relatively primitive 16-bit microprocessor. Full-scale testing was done over a six-week period of time. There were side and crosswinds of up to 10 m/s which did not interfere with the train's smooth operation. In fact, the wind had almost no effect on the performance of the system. This was taken to indicate that the open loop control system was robust. The same microcomputer was used for monitoring engine temperature, alternator output, and oil pressure (Chalam). These types of systems are now more common.
Conclusion
The advent of computer numerical control machines have allowed for adaptive controls. These types of controls work automatically by monitoring the performance of a machine and adjusting its performance in relation to present conditions. This prevents machines from operating inefficiently or damaging themselves.
A closed loop adaptive control system uses an algorithm with recursive identification to provide real-time control of operational parameters (Landau & Zito). The parameters are based on information provided to the computer by sensors. These sensors can be set to act constantly or on a schedule. A closed loop which is self-tuning begins to operate when there is a reduction in performance. It adjusts the machine until performance has been restored. There are also systems, which work according to an algorithm which controls the machine at all times.
An open loop adaptive control system has inputs, which are predetermined. This type of system is less common but can be effective for certain applications. An example of an open loop control system developed more than 20 years ago is a multi-locomotive train. A 16-bit microprocessor was capable of analyzing changes in the rail grade as well as coupler forces. The train maintained appropriate throttling, reduced noise, and a reduction in coupler tension (Chalam). These systems are now more common.
References
Chalam, V. V. (1987), Research study on adaptive control systems: techniques and applications, Marcel Dekker, New York.
Landau, I. D. & Zito, G. (2006), Digital control systems: design, identification and implementation, Springer, London.
Tao, G. (2003), Adaptive control design and analysis, Wiley, Hoboken, New Jersey.
The automation of machine tools has been referred to as numerical control since the 1940s. These machines had motors, which were controlled by punched tape. An outcome of these servomechanisms is the machine tools of today, which are computer numerical controlled (CNC). There have been a number of improvements made to these machines which rely on adaptive controls. This type of control is done automatically and relies upon monitoring of the machine performance operation in response to variable conditions. This type of control can prevent damage to machines due to malfunctions. For example, a drill bit may become too dull and cause additional stress on the motor. As the motor overheats due to increased friction, it could be damaged. An adaptive machine would shut the motor down before any damage was done. A more sensitive type of machine would reduce the pressure placed on the drill bit according to its changing level of sharpness. Adaptive machines have reduced the cost of manufacturing. There are many types of manufacturing, which now require only one individual to monitor a computer screen (Tao). This same system may have previously required several individuals to constantly adjust the machines.
Closed Loop Systems
A closed loop adaptive control system uses a recursive identification algorithm in real time to compute the control parameters. These parameters are based on the current values received from appropriately placed sensors. The adjustments depend on the desired performance level of the machine. The controller can be tuned automatically by the appropriate computer software to react to variable conditions. This can be done each time the controller takes measurements or on a predetermined schedule. If a schedule is used it is important that the programmer be certain that the time-frame is appropriate.It is critical that an adaptive control system using a closed loop have a supervision function. This function should monitor the measurement of operational conditions and the adaptive loop to ensure that the correct operation is being programmed. This prevents the adaptive system from giving inappropriate direction to the machine due to problems with monitoring. For example, a signal may be weak and indicate that the machine requires more power. This could result in the adaptive control sending an excess of power to the machine and causing it to damage the product (Landau & Zito).
There are two general types of adaptive control closed loop systems. The first is the self-tuning operation. This type of adaptation begins when there is degradation in performance. It stops when the performance has been restored. With the second type of operation, there is an algorithm which controls the machine operation at all times. Either of these methods can be useful and frequently depend on the type of machine and conditions in which it is being used.
Open Loop Systems
With an open loop control system, the inputs which can be monitored and delivered to the program are specified ahead of time (Tao). This is done when it is assumed that there are no uncertainties in the system, and it will be operating under specific conditions. There is no output information from the system which must be used to generate the input signal used for control. The disadvantage of this type of system is that it cannot change appropriately regarding unanticipated conditions. This lack of adaptation makes it less effective when the tasks being controlled are more sophisticated. For this reason, the open loop system of adaptive control is used less frequently. However, there are instances when this type of system is warranted and works well.
Adaptive control open loop systems have been used successfully for over two decades. An example is provided by multi-locomotive trains. This type of control has the goal of maintaining a specific velocity. It can also be used to reduce noise caused by changes in grade and keep the coupler forces below a pre-specified limit. The controller is set to determine the appropriate throttling and braking necessary for the train to accelerate and decelerate appropriately. This allows the locomotives to act in a fashion, which causes the nonlinear rolling resistance to assume a linear force despite velocity and grade changes.
The open loop control system for multi-locomotive trains has been found to work appropriately even with a relatively primitive 16-bit microprocessor. Full-scale testing was done over a six-week period of time. There were side and crosswinds of up to 10 m/s which did not interfere with the train's smooth operation. In fact, the wind had almost no effect on the performance of the system. This was taken to indicate that the open loop control system was robust. The same microcomputer was used for monitoring engine temperature, alternator output, and oil pressure (Chalam). These types of systems are now more common.
Conclusion
The advent of computer numerical control machines have allowed for adaptive controls. These types of controls work automatically by monitoring the performance of a machine and adjusting its performance in relation to present conditions. This prevents machines from operating inefficiently or damaging themselves.
A closed loop adaptive control system uses an algorithm with recursive identification to provide real-time control of operational parameters (Landau & Zito). The parameters are based on information provided to the computer by sensors. These sensors can be set to act constantly or on a schedule. A closed loop which is self-tuning begins to operate when there is a reduction in performance. It adjusts the machine until performance has been restored. There are also systems, which work according to an algorithm which controls the machine at all times.
An open loop adaptive control system has inputs, which are predetermined. This type of system is less common but can be effective for certain applications. An example of an open loop control system developed more than 20 years ago is a multi-locomotive train. A 16-bit microprocessor was capable of analyzing changes in the rail grade as well as coupler forces. The train maintained appropriate throttling, reduced noise, and a reduction in coupler tension (Chalam). These systems are now more common.
References
Chalam, V. V. (1987), Research study on adaptive control systems: techniques and applications, Marcel Dekker, New York.
Landau, I. D. & Zito, G. (2006), Digital control systems: design, identification and implementation, Springer, London.
Tao, G. (2003), Adaptive control design and analysis, Wiley, Hoboken, New Jersey.