AR4 support

[thijstriemstra]

The AR4 was released recently and I wonder if this is compatible with ar3_core?

[ongdexter]

Hi there! From my understanding, the main differences are in the encoders and Teensy 4. The software stack will not require any changes aside from updating the config file to account for the different encoders. I wouldn't expect significant changes to the sketch either since it isn't doing anything too complicated - just serial comms and I/O. You'd just need to make sure that the pins are correct.

[pitarasho]

@thijstriemstra
Have you managed to make the necessary adjustments to make it work on AR4?
Thanks

[thijstriemstra]

no i decided to go with a different robot arm for now.

[pitarasho]

@thijstriemstra
Thanks, which robot arm did u end up using for your project?

[flippybit]

@ongdexter
Hi dexter its me again i wrote you an email a long time ago about some issues with calibration,
you were right in both your asumtions the wiring and Teensy. 2/2
Now that this repo is getting the atention it deserves maybe this fix can help others.

I found up that im using Teensy 4.1 that has a significatlly faster PWM frequency than Teensy 3.5
https://www.pjrc.com/teensy/td_pulse.html
both of the drivers versions makes use of AccelStepper so if anyone is having problems moving the motors and uses Teensy 4.0 or above
adding stepperJoints[i].setMinPulseWidth(10);
when inicializing the AccelStepper instance may fix your troubles!

ar3_core/ar3_microcontrollers/teensy/baseline_dev/baseline_dev.ino

Lines 288 to 295 in cd43fed

	// initialise AccelStepper instance
	for (int i = 0; i < NUM_JOINTS; ++i)
	{
	stepperJoints[i] = AccelStepper(1, STEP_PINS[i], DIR_PINS[i]);
	stepperJoints[i].setPinsInverted(true, false, false); // DM542T CW
	stepperJoints[i].setAcceleration(MOTOR_MAX_ACCEL[i]);
	stepperJoints[i].setMaxSpeed(MOTOR_MAX_SPEED[i]);
	}

[ogland]

Hi! Is it possible we will see AR4 support in this repo? I just built one and the control software options are very limited as far as I can tell.

[flippybit]

Most of the hard work is already done by ongdexter he said he was too busy at the moment to continue support.
I dont see why we cant continue the effort that's the whole point of FOSS im currently working on some features

• Gripper and grasping code and 3d models here
• Object detection, segmentation using mask r-cnn
• Move group interface using python3
• Xbox controller support

But its all for AR3 (this is the version i own) i dont think much has changed on the AR4.
There is also some talk about upgrading to ROS2 which makes sense, if i manage to pull it off ill will make it available here.

Regarding AR4, to my knowledge the changes are mostly

• Encoders (now come preinstalled on the steppers)
• MCU (now uses Teensy 4.1)

These are not mayor changes, and relatively simple to upgrade.
thnx again to ongdexter for this great contribution.

Happy hacking to all !

[quinnliu]

Hi everyone. I plan to buy a AR4 in Austin, Texas & program it to make 3 Michelin star beef jerky in my robotics office near the Pennybacker bridge. I plan to make the AR4 programmable code here https://github.com/quinnliu/AR4

For anyone currently with an AR4 or planning to build a future AR4 I would be very interested in collaborating on making the AR4 easy to program with general 3D computer vision & a 3D memetic motion planning algorithm. My private e-mail is [email protected]

Please e-mail me if you are serious about making an extremely easy to program general purpose robotic arm. Especially if you are in Austin, Texas.

Also is anyone interested in designing a robotic arm based on the AR4 that is much more aesthetically pleasing to the eye?

@thijstriemstra @ongdexter @pitarasho @flippybit @ogland

[JudeL12]

@quinnliu

I have done a similar project, this is probably the best ROS repository. RoboDK also has good integration with projects like this though it is pricey.

[venkataprasad-git]

@ongdexter Hi dexter its me again i wrote you an email a long time ago about some issues with calibration, you were right in both your asumtions the wiring and Teensy. 2/2 Now that this repo is getting the atention it deserves maybe this fix can help others.

I found up that im using Teensy 4.1 that has a significatlly faster PWM frequency than Teensy 3.5 https://www.pjrc.com/teensy/td_pulse.html both of the drivers versions makes use of AccelStepper so if anyone is having problems moving the motors and uses Teensy 4.0 or above adding stepperJoints[i].setMinPulseWidth(10); when inicializing the AccelStepper instance may fix your troubles!

ar3_core/ar3_microcontrollers/teensy/baseline_dev/baseline_dev.ino

Lines 288 to 295 in cd43fed

	// initialise AccelStepper instance
	for (int i = 0; i < NUM_JOINTS; ++i)
	{
	stepperJoints[i] = AccelStepper(1, STEP_PINS[i], DIR_PINS[i]);
	stepperJoints[i].setPinsInverted(true, false, false); // DM542T CW
	stepperJoints[i].setAcceleration(MOTOR_MAX_ACCEL[i]);
	stepperJoints[i].setMaxSpeed(MOTOR_MAX_SPEED[i]);
	}

this method is not working for TEENSY 4.1 i have tried it

[nolan-kwok]

who is gonna adapt this ros ar3 project to my ar4 mk2 version? I would like to pay for your knowledge and time, thank you