Linear actuator using ClearPath Integrated Servo System @ 72V DC

The larger servo uses a full size USB connector

Dan

Low torque, low speed hard stoping works very well with those. You just have to mount it beyond the kinematic range ;-)

No power supply, no servo controller, no sensors, nothing but 19pins from @Thanos board to feed all 6 motors.

I can’t believe how simple this setup is!

It comes at a price though. I ordered the 5 other motors today. Came in around $4400 with cables and shipping.

I'll start a separate thread once everything starts going together. Pertaining to this post though, the MCPV models seem to be a solid option at this point. Definitely makes it less intimidating

Dan

That’s maybe the price for convince and quality.
With those you have enough torque for a small dual cockpit with a decent speed.

Those gearboxes do they have a limit for nominal, max, and ultimate torque ?

What’s the price of those?

I don't see why it wouldn't work with SMC3 also with minor modifications. Instead of PWM outputting speeds (power) to h-bridges instead it can be made to output positions. Furthermore since PID calculations are no longer required all 6 motors (or more) can run off of one Arduino Mega.

Upon further thought need to ditch SMC3 altogether since its main function is not needed here and then go with a more powerful microcontroller that can easily output higher resolution PWM like an ESP32. Its so simple all that's needed is to convert each actuator position into a 12 or 16 bit PWM signal.

Since in follow mode an actuators resolution can only be as large as the PWM input resolution did you check what the servos firmwares maximum possible resolution is?

Spoiler alert... you would need atleast 12bit resolution PWM on follow digital mode, and older models do not even have this. Plus another mode that was supported is pulse burst mode and these are not using PWM... they are using Bursts of pulses... like real servosmotors do...

Almost same code (made back in 2015) worked for generic servomotors using just pulses and direction... the only difference is that generic servos do not have automated homing function with hard stop like clearpath servos.




And here is another video that shows a little more details about the range and frequencies used:

The max resolution would be 4096 positions... with 2ms latency.

Could you make me a favor plz. ?

As the pulse-burst code has changed on the AMC controller, and your motor is already geared and not attached yet, could you please test this mode, if it is still going out of sync putting the ClearPath motor in the error state ?

Thanks a lot

Can't test with my clearpath motor, its the MC model that doesn't have pulse burst mode like the PV model ones you have.

I could provably give you an improved beta version to try on your motors... I'm sure its not going to give out any errors now. @Nisch PM me for contact information...

Just small precision:

- You have the follow velocity one MCVC

- I have the old MCPV with follow velocity and pulse-burst

- Nisch have new MCPV with follow velocity, pulse-burst, and follow position.

Am I wrong?

@Thanos , I perfectly understand that it’s hard to interface something you can’t put your hands on.

I was just thinking the modification of your pulse-burst code for AC could maybe work out of the box for ClearPath. That’s the reason I was asking @Nisch for a quick test.

Good idea ?

Yes, asked @Nisch to contact me for the improved firmware

I will check it soon. I have been stuck at the office with server problems. I'll post back as soon as I can perform this test.

Dan

Hi @Hexapod,

Great question about firmware changes for the Pulse Burst Operational mode!

Teknic has a feature request database, to which we’ve added your request. We absolutely do take customer requests into consideration both when designing new products, and when adding new features to existing products. For example, the development of the ClearPath product itself, and the Follow Digital Position mode were based, in part, on customer feedback.

A number of people have questions about why Pulse Burst Positioning functions as it does. This mode was designed to meet specific application needs which may make some of the design decisions seem unclear without a little more background information:

Pulse Burst Positioning was designed as a value option for simple, point-to-point positioning applications where the user wants to avoid the cost of an external "trajectory generator", indexer, or controller, and is fine with all moves executing at the same speed and acceleration (technically there are two speeds available).

• You only need a simple source of pulses to use Pulse Burst Positioning mode (many Arduinos work very well for this)
• For example, to initiate a move of 20,000 counts, you would send a burst of 20,000 pulses to the ClearPath input.
• Most users send a fixed frequency burst, but pulse timing is not critical in this mode (as it is in Step & Dir mode).
• The ClearPath motor's internal controller then translates the pulses into a properly-formed, profiled move based on the speed and acceleration setting you specified in the MSP Setup Program.
• For more details on this mode, please see the ClearPath User Manual.

As a general recommendation for dynamic positioning (changing position commands on the fly), we typically suggest ClearPath MCPV's “Follow Digital Position or ClearPath SD’s “Step and Direction” or “Quadrature Input” mode (See my other post for additional info).

If anyone has more technical questions about ClearPath operational modes, please give us a call at 585-784-4754 or email support@teknic.com

Aaron B. – Teknic Servo Systems Engineer

Your precisions arę highly valuable.

I understand better now. As it was designed for point to point application, there is no wonder we had issues with the interface.

Shall I understand that the dynamic positioning needed for our application could be also possible using pulse-burst mode through an eventual internal code modification on your or our side ?

Thank you very much

@Nisch
Any progress on your project using Clearpath Servo with the "follow position" feature ?
I am looking forward to getting some info

The conclusion is that it does work, but it's ultimately more expensive at about $900 per motor after the cost of the motor, cable and shipping. @Thanos has been making a lot of progress with servo control which presents a much more affordable and more simple setup without the need for the potentiometers for position feedback. Out of the box, the Teknic servos are super simple and that was what I was going for. It worked with a stock firmware AMC base board, leaving the only setup required to be in the Teknic software to set start, end, max RPM, acceleration, etc.

I purchased the additional motors and am making my frame. Waiting on a little more metal.

If cost is not a factor, then they look like a great solution. Look forward to seeing them in action.

Those motors are huge... Great to know that it is working alright with no need for external positionnning sensor and no power supply if I get correctly. 900$ / motor is a high price indeed, but I guess it is the price to pay for "relative" simplicity. And to be fair, adding the costs of servo drives, power supplies and sensors, it is not that much more expensive I guess. Only the gearbox is still needed. Can you share more info regarding it by the way ? Model, price, supplier, etc...
Thanks in advance.