On the 17^th of March, Staro Process Control (SPC) had its Open Day at the Riviera on Vaal Country Club in Vereeniging. Together with our suppliers Rockwell Automation, Eaton UPS Systems and ADI Global Distribution, we had a wide range of products and services on display.

 Starobot

For the purpose of our Open Day, Staro’s engineering department designed the “STAROBOT” (derived from Staro and Robot) as an interactive demonstration unit to give our clients some hands on experience. We found from past similar “displays” that this method results in a much more memorable experience on the various products we offer. This ensures a fun and positive interaction for our clients at each of our open days.

Rockwell’s Motion Analyzer Software was used to determine what servo drive and motor would be needed, bearing in mind that our objective was to design a simple and compact unit for demonstration purposes. This software allows the user a simple and fast analysis with the full advantages of a mechatronic design approach, as well as being able to simulate, optimize and select motion controls systems. This powerful software can help solving many possible problems prior to the implementation and commissioning.

STAROBOT comprises of a ULTRA3000 Digital Servo Drive with sercos communication, MPL series servo motor, 5:1 ratio gearbox and a 1756-L60M03SE CPU with sercos communication.

Taking the gearbox ratio of 5:1 into consideration, our maximum speed on the gearbox output shaft would be the maximum rpm of the MPL servo motor divided by the ratio of the gearbox.

Gearbox Out = (6000 rpm / 5 ratio) = 1200rpm

The maximum torque i.e. the peak torque and the continuous torque on the shaft after the gearbox are shown below:

Peak Torque = (4.9 Nm X 5 ratio) = 24.5Nm

Continuous Torque = (1.61 Nm X 5 ratio) = 8.05Nm

For this design we focused on the peak torque as STAROBOT would only be required to do a motion after the FORCE and SPEED parameters were entered by the user every so often, thus giving the motion application rest periods in-between each motion and not needing to execute the motion continuously. 

The combination of these Allen-Bradley products was to show just how easy it is to setup and execute simple motion actions. Using RSLogix 5000 software, our STAROBOT was tuned with the golf club of choice. This was done so that the rotary load or torque/force percentage scaling and load inertia ratio of the golf club and fixtures can be automatically determined. 

Once the tuning was completed, we required a home position. This would preferably be the position we want the golf club to be at the start position, which we decided to be the position just behind the tee. A proximity sensor was used to detect a striker mounted to the back end of the gearbox to indicate the home position for the club. For the execution of the back swing and follow through, we wanted to simulate STAROBOT to behave in a similar fashion as that of a golfer. So we used two simple MAM (Motion Axis Move) commands allowing the user only to change the Acceleration and Speed on the follow through swing.

A PanelView Plus was used as an HMI (Human Machine Interface). The user could only let the motion execute once both values for Acceleration and Speed were entered. These values were automatically cleared after each motion was executed to prevent the next user to just fine tune his predecessor’s settings.

STAROBOT was capable of reaching an impressive 65 meters, depending on the type of golf club used.  This was magnificent for such a small servo motor.

Suppliers

Rockwell Automation was represented by most of their product specialists and had various products on display. Rockwell’s extensive product portfolio, services and support capabilities are designed to improve your process through every stage of your manufacturing cycle, from design and installation through operation and maintenance. One of the highlights was the new PowerFlex 75x range of AC drives which was released in South Africa this year and promises to live up to the expectations set by the PowerFlex 70/700 range. Another highlight was the new FactoryTalk VantagePoint which exposes FactoryTalk Metrics and Factory Talk Historian data via a Trend object and click and drag Excel reports.

EATON UPS Systems was also represented and this year they had an impressive array of products on display as can be seen from the picture below. We were glad to see that there was a lot of interest in this product which boasts with an impressive installed base at companies like ArcelorMittal, New Vaal Colliery and Sasol.

ADI is a leading one stop-solution provider in security and low voltage products, distributing to customers every day across South Africa and Africa. Highlights at our open day was the showcase of a thermal graphic camera which was pointed at Staro’s Scalextric track detecting different temperature levels on the cars as they passed. Their high speed dome camera was also a source of enjoyment as the attendees were able to control and focus it manually.

Apart from the “work” we also had some fun. The mashie course was opened for our event where clients and personnel got to know each other a bit differently.

Staro also had its Scalextric track on display, and as can be seen below attracted a lot of attention.

The course was modified where one of the lanes were controlled via an Allen-Bradley CompactLogix L35E PLC. Different recipes, to control different cars, could be selected via a PanelView Plus 1000.

Fiber optic diffused photoelectric sensors was used on DeviceNet to detect the position of the specially customized Staro car to brake and accelerate at specific positions to result in the “perfect run”. 

As can be seen from the results below, we were able to kick dust in even the most optimistic challenger’s eyes. The fastest lap time for our PLC was 3.074sec.

We would like to thank you, our valued customers for attending our Open Day. Thanks to you it was a huge success!

We ran a few competitions and the winners were as follows:

To you who won, congratulations and enjoy your prize.

We trust you enjoyed the day with us and that it was as informative as you expected it to be. If any further information is required regarding the products that were on display, please do not hesitate to contact us.

The working of our ‟spook circuit‟

Maybe it will not be a bad idea if I just quickly recap on the working of a diode before I explain how our “spook circuit” works.

A semiconductor diode consists of a PN junction and has two terminals, an anode (+) and a cathode (-). Current flows from the anode to the cathode within the diode. An ideal diode is like a light switch in your home. When the switch is closed, the circuit is completed; and the light turns on. When the switch is open, there is no current and the light is off. However, the diode has an additional property; it is unidirectional, i.e. current flows in one direction only (anode to cathode internally). In this direction, the diode is said to be “forward-biased” and the only effect on the signal is that there will be a voltage loss of around 0.3V for germanium and 0.7V for silicon diodes. In the opposite direction, the diode is said to be “reverse-biased” and no current will flow through it. When a forward voltage is applied (the anode voltage is more positive than the cathode voltage), the diode conducts; and when a reverse voltage is applied (the anode voltage is less positive than the cathode voltage), there is no conduction.

As can be seen from the circuit below, it is supplied with a 220VAC supply. The H3 LED is placed in parallel to the main circuit just as power indication.

Without the diodes (which were hidden within the casings of both the push buttons and the incandescent lamps) the circuit below is supposed to operate as follows:

• When push button S1 is pushed, H1 and H2 should be off as the circuit is interrupted by S2.
• When push button S2 is pushed, H1 and H2 should be off as the circuit is interrupted by S1.
• When both push buttons S1 and S2 are pushed, H1 and H2 should be on.

Now, within the positive cycle of the AC wave, when S1 is pushed, diode D3 will be forward-biased and the current will flow through it rather than through H1. Diode D2 will be reverse-biased and thus the current will be forced to flow through H2. Diode D4 will also be forward-biased and the current will bypass S2 through D4 which will complete the circuit wherein only H2 has lit up.

The inverse will be the case within the negative cycle of the AC wave. D1 and D2 will be forward-biased and D3 and D4 will be reverse-biased. Therefore if S2 is pressed, current will bypass S1 and flow through D1. It will then flow through H1, bypass H2 through D2 and complete the circuit through the energized S2 push button.

We at Staro would like to thank those who supplied us with so much entertainment through their inability to figure out something which seemed to defeat all logic.