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Using Thrusters With Analogue Controler


(stephendueck) #1

This is a great product. I was introduced to it at our regional MATE ROV competition last weekend. I work with two ROV teams. One Ranger class and one Scout class (MATE). We are a small school so we don’t have students with the programming skills to use the ESC controllers. I am using the new Triggerfish control box from MATE with both my teams. It uses an analogue speed controller connected to joysticks that have a built in potentiometer in them. This is a great setup for my students who are non programmers

My question is this. Can these thrusters be configured to be used with the MATE analogue controllers (sabertooth controller). For anyone who can help me with this question, the specs for this are found here.

https://www.dimensionengineering.com/products/sabertooth2x5



(Harold Scadden) #2

Rusty will be better at answering this since the Thrusters are his companies design, but I would say after a real quick look at the specifications … NO.

This is a link that Rusty provided in a thread for a guy wanting control of his Kayak without the use of a microcontroller. Check out this link.

http://www.hobbyking.com/hobbyking/store/__8296__Turnigy_Servo_Tester.html

You would have to use the ESC’s to provide the three phase power to the thrusters etc. The card that you are looking at appears to be for a standard DC motor … this won’t work with the T100/200’s.

 


(stephendueck) #3

I kind of figured that the short answer would be no seeing as the sabertooth is for brushed DC moters…but in this day and age of being able to hack anything…I figured I would ask. I am really impressed with these thrusters and am looking for a way to incorporate onto both our Ranger and Scout class ROV’s. The learning curve for the students is the big hurdle here…great product guys…just sorry I didn’t get in on the kickstarter when it first went up…:frowning:


(Harold Scadden) #4

Well what are you control requirements. There are people on this site that can help out. Do you have a website with any technical information on your ROV’s?

 


(Rusty) #5

Hi Stephen,

Harold is correct, the thrusters won’t work with the Sabertooth controller. There are a few options however!

We have some example code for Arduino that is meant for controlling three thrusters with analog joysticks. You can check that out here: https://github.com/bluerobotics/br-esc-examples/tree/master/arduino/AnalogJoystickControl

It’s designed for the analog joysticks from Parallax but could definitely be adapted to your joysticks. We’d be happy to help you out with that if you are interested.

Best,

Rusty


(stephendueck) #6

The arduino route would work…there is one small problem. Our ROV has four thrusters…two vertical, two horizontal…and I would like to upgrade to six. Here is a video from last years competition that shows what my students are working with.

https://www.youtube.com/watch?v=jKqAxntrZrE This years video has yet to be edited and posted to youtube…hopefully in the next couple of days I will get around to that…

Rusty…thanks for the offer. Any ideas on how to use the BR thrusters would be great.


(Ed) #7

This controller from ebay works well with brushless 3 phase motors. It can be easily interfaced to microprocessors.

I have done a few experiments and found it quite robust and easy to control.

http://www.ebay.com.au/itm/like/331257392856?limghlpsr=true&hlpv=2&ops=true&viphx=1&hlpht=true&lpid=107&chn=ps


(stephendueck) #8

Looks interesting…do you have any pics of the setup with the ESC controller. It looks like it has only a 5V output…do I read that right? Not sure how I would connect the three wires for the joystick potentiometer. As you can see…learning curve for me…


(Ed) #9

Stephen,

Firstly, the ebay 3 phase inverter controller; The SET control bus has the following connections;

5v; Control voltage, connect to one terminal of your pot

Signal; 0-5v pulsed output indicating speed of driver

Z/F; Direction. 5V=clockwise, 0V=anticlockwise

VR; Input voltage 0 - 5v. Connect this to the variable wiper of your pot

GND; 0v, connect this to the the other terminal of your pot.

I have experimented with it - it gives quite good control.

Secondly; I looked at your Sabretooth motor controllers. They are all for brushed motors. They cannot be used for 3 phase brushless motors.

Thirdly; I have recently gone through a learning curve of 3 phase brushless motors, so I thought I would give a summary of my lessons learnt. My apologies if this is trivial;

Small brushless motors are in the R/C hobby universe. They have incredible power density and efficiency and have grown from hobby model plane, boat and copter demands.

The brushless motor controllers (or ESC) are also hobby R/C orientated. They are driven by the R/C servo signal protocol. This protocol is a 0-5v pulse strobed every 20mS. the pulse varies from 0.6mS (0% travel) to 2.4mS (100% travel).

If you want to convert from 0(0%)-5v(100%) potentiometer to R/C servo signal (pulsed as above) you will need to do some programming (any microprocessor, but the PICAXE controller can achieve this with a just a few commands) or buy a convertor.

An alternative to a hobby R/C ESC with pulsed control is to use an 3 phase inverter controller with an alternative control signal like the ebay one above.

The hobby R/C ESC controllers are always your best bet. They are a mature technology, compact, efficient and cheap. However, if you buy them off ebay or an online hobby shop you will be faced with poor documentation and a horrible programming methods. You have to match the ESC to your motor, and only a few ESC’s are forward and reverse.

Your real best bet is to buy the hobby R/C ESC off a reputable supplier who has filtered the quality, documentation, programming and matched it to your motor. So, unless you want a lot of hassle, I suggest you buy the BlueRobotics Basic ESC.

 

 

 


(Rusty) #10

@Ed,

Very nice explanation of the signal to the ESC. I’ve never seen the brushless controller you linked to - it’s really interesting and cool that it has an analog input.

@Stephen,

The Arduino code that I linked to could be changed pretty easily to support the four thruster configuration that you are using. We’d be happy to add that in if you are interested. It looks like your configuration allows forward/reverse, up/down, turning (yaw), and rolling motions. How do the joysticks currently control the thrusters? Are they mixed together or is each thruster separate?

-Rusty


(stephendueck) #11

@Ed.

Thanks for the detailed explanation. It certainly sheds some light on some of the questions that I had. Where I have not been involved with RC stuff a lot of it is all new to me.

@Rusty

Thank you for the offer. If it gets me one step closer to using your thrusters with our ROV that would be great. Our control box is set up so that one controller/joystick looks after forward/back/left/right and the other controller/joystick controls vertical and roll. Arduino is new to me and I am not a programmer that is why our students had switched to the sabertooth controller. simple to wire and simple to use