Powerful Robot Controller Concept

Just two controllers for the entire range of robots - Application-optimized functions and compact dimensions - New "Tracking" function enables robot use on products in motion 

Excellent economy and a wealth of application-optimized functions are the main focuses of the powerful robot controller concept from Mitsubishi Electric. The company just needs two controllers - the established CR1 and the new CR2A for handling payloads between 3 and 10kg - for all its articulated-arm, SCARA and high-precision robot models. Just like the robots themselves the Mitsubishi controllers impress with a combination of outstanding performance and extremely compact design. The technological highlights include number-crunching power for demandingly complex three-dimensional movement and manipulation sequences, parallel execution of up to 32 separate programs and Compliance Control for gentle part placement. Additional functions for special applications can be added with four optional expansion cards. The most exciting of these options is the new Tracking function that enables the robots to work on components in motion, which Mitsubishi Electric is presenting for the first time at Motek 2002. The other expansion cards provide an Ethernet link with support for real-time robot control, facilities for controlling additional axes and a CC-Link interface for communication between multiple robots. 

Mitsubishi Electric's modular robot controllers form an integral part of the robot system and contain the CPU and power electronics for controlling and driving the robot. The control concept for all the company's robot models - which include articulated-arm, SCARA and high-precision robots with handling payloads of up to 10kg - is based on just two controllers, the CR1 and the CR2A, which differ only in their power stages. For the user this means that no matter which robot or combination of robots is being used, exactly the same functions and capabilities are always available, and the programming is always performed in the same language. The CR2A controller is designed for use with Mitsubishi's SCARA robots (the RH-5AH and RH-10AH85 models) and the Mitsubishi articulated-arm robots with six degrees of freedom and lifting capacities of three, four and five kilograms (the RV-3AL, RV-4A and RV?5AJ models). All Mitsubishi robots with lower handling payloads are controlled by the more compact CR1 controller. 

The extremely compact design of Mitsubishi Electric's robot controllers makes it very easy to integrate them in your applications and systems. The outside dimensions of the larger CR2A controller are just 430 x 200 x 400mm (WxHxD). The CR1 is even smaller - measuring in at just 212 x 166 x 290mm (WxHxD) it could fit on an A4 format sheet of paper. In their standard configurations the CR2A controller has 32 digital inputs and 32 outputs, the CR1 has 16 digital inputs and 16 outputs. The number of inputs and outputs can be increased to 256 each for complex applications with the help of optional remote I/O expansion boxes. 

Powerful processor and large program memory 
The heart of both Mitsubishi robot controllers is a powerful 64-bit RISC microprocessor. Together with an integrated digital signal processor (DSP) this unit provides the number-crunching power you need for fast processing of mathematical functions and demanding 3?D circular and linear interpolations. This enables the robots to perform very complex movement and manipulation sequences in 3-dimensional space quickly and reliably. The controller's memory can store up to 88 independent programs that can call each other as required. Up to 32 programs can be executed simultaneously by the controller's multitasking operating system. Mitsubishi Electric robots are programmed in MELFA BASIC IV, a powerful, high-level language developed specifically for robot control applications at Mitsubishi. In addition to controlling movement sequences the MELFA BASIC IV instruction set also includes everything you need to perform complex calculations in the robot controller, without having to make use of a connected PC. 

Compliance Control 
Compliance Control enables very gentle manipulation and placement of components. When this function is activated the robot registers resistance and varies the force it applies accordingly with adjustable sensitivity. This prevents unnecessary stresses on the components and prevents robot shutdowns when resistance is encountered. Instead, the robot responds gently and flexibly to changing conditions, making it much more versatile. Compliance Control can be activated and deactivated as required by the robot control program. 

Optional expansion cards for more flexibility 
Mitsubishi Electric's controller concept includes a large number of application-optimised functions that bring solid economic benefits in daily operation. In addition to this the following four optional cards are available for adding advanced functions to the CR1 and CR2A controllers for special applications: 

Serial expansion with Tracking function 

• Ethernet link with real-time access function 
• Control for up to eight additional robot axes 
• CC-Link interface for communication between several robots, connection of a PLC etc. 

You simply plug the cards into the controller's expansion slots, just like expansion cards in a PC. They are compatible with all the robots in the Mitsubishi Electric range. 

Optimising production time with the new Tracking function 
The new Tracking function is one of the top highlights of the new generation of Mitsubishi robot controllers. This function is being presented for the first time at Motek 2002, where it is demonstrated in an application with a high-precision robot. Tracking allows a robot to "synchronise" with components or products on a conveyor belt so that it can manipulate or process them while they are in motion. This eliminates the need to step the conveyor, which brings economic benefits in the form of shorter cycle periods and faster production. The Tracking function can be used on belts travelling at up to 20 metres per minute and can even synchronise with varying belt speeds. The position of the components is registered either with a simple photoelectric barrier synch signal for parts placed with the correct orientation, or with a combination of a synch pulse and a camera imaging system for position identification. The optional Tracking expansion card has two encoder inputs for belt speed registration and several serial communications ports (RS?232, RS?422/485) for connection of peripheral equipment. 

Real-time access via Ethernet 
Mitsubishi Electric's robot controller concept is also highly competitive when it comes to communications. The Ethernet card with real-time access supports genuine real-time data acquisition and processing. This means immediate access to all sensor data, and immediate adjustment of all robot movements on the basis of the data for genuine real-time response. For example, normally one would use the Teaching Box to "show" the robot how to move to each end position in a movement sequence. This is not necessary with a Mitsubishi robot with real-time access. Here the optimum end position is registered with a proximity sensor and the data is transmitted to the PC via the Ethernet link. The PC responds immediately, sending new movement control data to the robot and enabling the robot to respond appropriately in real time. A traditionally-controlled robot faced with an unexpected obstacle would damage the component or shut down the production line; with real-time access the robot responds interactively and production can continue normally. 

Source Mitsubishi Electric