Prototype Motor Drive System for Autonomous Industrial Mobile Robots
Trademarks
C2000 and Launchpad are trademarks of Texas Instruments.
All trademarks are the property of their respective owners.
1 Introduction
The global autonomous guided vehicle (AGV) and autonomous mobile robot (AMR) market is expected to skyrocket as factory automation applications increasingly adopts mobile robots in day-to-day operational activities.
A new definition of mobile robots have also emerged which is the Industrial Mobile Robot, this definition is a consolidation of AMR and AGV robots and defines these now as Type A,B,C IMR robots and the traditional AGV robot, the details of this effort can be seen in the ANSI/RIA R15.08 standard.
Over the past few decades MCUs have been controlling motors which have evolved beyond simple commutation of the universal motor. Now there are many MCUs available to developers who seek to create low-cost, high-performance systems. Through complex control algorithms, systems have improved power efficiency, more accurate speed/position control and higher torque while doing so in the most cost-effective manner. Many of the motors controlled by MCUs are three-phase synchronous and are generally controlled using a method call field-oriented control (FOC) to maximize efficient torque production.
TI’s three-phase motor drive systems simplify designing motor control applications, where low-cost development boards provide a platform for engineers to quickly design a prototype motor drive system and bring to market their own motor control design. The C2000Ware MotorControl software development kit (SDK) unifies TI’s motor-control developments into a single product which supports the latest generation TMS320F280049C and TMS320F280025C series in the C2000™ platform. Real-time debug allows for the monitoring and changing of application variables in real time, making it easy to debug the complex control loop. Additionally, as these MCUs are code compatible across the C2000 platform so developers can make long-term code investments and reuse motor control designs for future cost savings.
Figure 1-1 Block Diagram of Typical 3-Phase
Motor Drive System2 Functional Safety
The TMS320F280025C are Functional safety compliant products developed using an ISO 26262/IEC 61508 compliant hardware development process that is independently assessed and certified to meet ASIL D/SIL 3 systematic capability. Design packages are available to assist with safety system development and certification.
3 Motor Shaft Position Through eQEP
A majority of the time, mechanical angular positional sensors obtain the rotor position. Incremental encoders are one of the popular solutions to determine rotor position because they provide high-angular resolution and an accurate derived speed feedback over the whole speed range. These features enable incremental encoders to be frequently used for speed/position control in motor control applications.
Today, many servo motors come with built-in incremental position encoders, commonly referred to as ABZ encoders by the names of their output signals, A, B and I, to feedback the motor-shaft angle once you know the index. Table 3-1 shows the data pins required by the QEP peripheral that should be wired to the corresponding pins on the encoder.
| Pin Type | Pin Name | Pin Usage Per Motor |
|---|---|---|
| Digital | EQEOxA | 3 |
| EQEPxB | ||
| EQEPxI |