Position Control by Joystick, Jg Vel Jp #B, DP0

The corresponding velocity for the motor is assigned to the VEL variable.

Instruction

JG0

BGX #B VIN=@AN[1] VEL=VIN*20000

JG VEL

JP #B

Position Control by Joystick

This system requires the position of the motor to be proportional to the joystick angle. Furthermore, the ratio between the two positions must be programmable. For example, if the control ratio is 5:1, it implies that when the joystick voltage is 5 Volts, corresponding to 1028 counts, the required motor position must be 5120 counts. The variable V3 changes the position ratio.

INSTRUCTION	FUNCTION
#A	Label
V3=5	Initial position ratio
DP0	Define the starting position
JG0	Set motor in jog mode as zero
BGX	Start
#B
VIN=@AN[1]	Read analog input
V2=V1*V3	Compute the desired position
V4=V2-_TPX-_TEX	Find the following error
V5=V4*20	Compute a proportional speed
JG V5	Change the speed
JP #B	Repeat the process
EN	End

Backlash Compensation by Sampled Dual-Loop

The continuous dual loop, enabled by the DV1 function is an effective way to compensate for backlash. In some cases, however, when the backlash magnitude is large, it may be difficult to stabilize the system. In those cases, it may be easier to use the sampled dual loop method described below.

This design example addresses the basic problems of backlash in motion control systems. The objective is to control the position of a linear slide precisely. The slide is to be controlled by a rotary motor, which is coupled to the slide by a leadscrew. Such a leadscrew has a backlash of 4 micron, and the required position accuracy is for 0.5 micron.

The basic dilemma is where to mount the sensor. If you use a rotary sensor, you get a 4 micron backlash error. On the other hand, if you use a linear encoder, the backlash in the feedback loop will cause oscillations due to instability.

An alternative approach is the dual-loop, where we use two sensors, rotary and linear. The rotary sensor assures stability (because the position loop is closed before the backlash) whereas the linear sensor provides accurate load position information. The operation principle is to drive the motor to a given rotary position near the final point.

174 • Chapter 7 Application Programming

DMC-1700/1800

DMC-1800, DMC-1700 specifications

The Galil DMC-1700 and DMC-1800 are advanced motion controllers widely recognized for their high performance and versatility in the automation and robotics industries. These controllers are designed to meet the demands of complex motion control applications, providing users with enhanced features and innovative technologies that optimize motion precision and efficiency.

One of the main features of the Galil DMC-1700 is its ability to handle up to 8 axes of motion control. This capability makes it suitable for a range of applications, from simple point-to-point movements to intricate trajectories in multi-axis systems. In contrast, the DMC-1800 extends this functionality, supporting up to 64 axes, making it ideal for large-scale automation environments.

Both models leverage Galil's powerful programming interface, which simplifies the development of motion control applications. The DMC-1700 and DMC-1800 controllers utilize a high-level programming language that supports advanced motion commands, including linear interpolation, circular interpolation, and complex motion profiles. This feature allows users to implement sophisticated motion sequences seamlessly.

In terms of connectivity, the Galil DMC series offers multiple communication options, including Ethernet, RS-232, and CAN bus, ensuring compatibility with various hardware and enabling easy integration into existing systems. The controllers also come equipped with digital and analog I/O ports, providing flexibility for sensor feedback and actuator control.

The advanced technology incorporated into both the DMC-1700 and DMC-1800 includes on-board PID control, which ensures precise motion control through closed-loop feedback. This results in improved stability and accuracy, particularly in high-speed applications. Additionally, the controllers offer extensive diagnostics and monitoring capabilities, allowing for real-time performance analysis and troubleshooting.

Another notable characteristic of these motion controllers is their compact design, which offers space-saving advantages while maintaining high processing power. Their robust construction and ability to operate in challenging environments make them suitable for a wide range of industrial applications, from CNC machining to assembly lines.

In conclusion, the Galil DMC-1700 and DMC-1800 motion controllers stand out due to their high-performance capabilities, advanced programming features, and flexibility in connectivity. With their ability to handle complex motion control tasks efficiently, these controllers are invaluable tools for engineers and manufacturers looking to enhance their automation processes. By integrating Galil's innovative motion control technology, industries can achieve greater precision, speed, and reliability in their operational workflows.

Galil DMC-1800 Position Control by Joystick, Backlash Compensation by Sampled Dual-Loop, DP0

Models: DMC-1800 DMC-1700