Introduction to Mechatronics: Using Software to Operate Mechanical Systems
- A History of Increasing Complexity
- Mechatronic System Organization
- Amplifiers and Isolation
- Scope: The Unit Machine
- Real-Time Software
- Nasty Software Properties
- Engineering Design and Computational Performance
- Control System Organization
- Software Portability
- Operator Interface
- Multicomputer Systems: Communication
- The Design and Implementation Process
Mechanical system control is undergoing a revolution in which the primary determinant of system function is becoming the control software. This revolution is enabled by developments occurring in electronic and computer technology. The term mecha-tronics, attributed to Yasakawa Electric in the early 1970s, was coined to describe the new kind of mechanical system that could be created when electronics took on the decision-making function formerly performed by mechanical components. The phenomenal improvement in cost/performance of computers since that time has led to a shift from electronics to software as the primary decision-making medium. With that in mind, and with the understanding that decision-making media are likely to change again, the following definition broadens the concept of mechatronics while keeping the original spirit of the term:
Mechatronics: The application of complex decision-making to the operation of physical systems.
With this context, the compucentric nature of modern mechanical system design becomes clearer. Computational capabilities and limitations must be considered at all stages of the design and implementation process. In particular, the effectiveness of the final production system will depend very heavily on the quality of the real-time software that controls the machine.
By the mid-1990s, computers embedded in devices of all sorts had become so ubiquitous that the newspaper USA Today thought it important enough to show the following on the first page of the business section:
USA Today, May 1, 1995, page 1B
USA SNAPSHOTS - A look at statistics that shape your finances Micromanaging our Lives
Microcontrollers tiny computer chips are now running things from microwave ovens (one) to cars (up to 10) to jets (up to 1,000).
How many microcontrollers we encounter daily:
1985 less than 3 1990 10 1995 50
By 2000, "up to 10" microcontrollers in high-end cars had grown to 60. In the same vein, according to Embedded Systems Programming: "More than 99% of all microprocessors sold in 1998 were used in embedded systems".
1.1 A History of Increasing Complexity
Technological history shows that there has always been a striving for complexity in mechanical systems. The list in table 1.1 (which is not strictly chronological) contains some examples of machines that show the marvelous ingenuity of their inventors.
A diagram of the Watt steam engine speed control (governor) is shown in figure 1-1. As the engine speeds up, the flyballs spin outward, moving the linkage so as to close the steam valve and thus slow the engine. The entire control process is performed by mechanical hardware.
Figure 1-1. Watt governeor
Table 1.1. Some Historically Significant Machines
Mechanical adding machine
Pneumatic adding machine
Tape controlled NC machine tool