myCobot 320: Review A Medical Student's Robotics Journey

This article is republished and edited with permission from the author, Harunashi. We thank Harunashi for contributing this excellent unboxing article.

link: https://harunaishina.hatenablog.com/entry/2022/08/04/183158

Introduction

Hi, my name is Harunashi. I'm a medical student with a passion for building robots and artificial intelligence. This time, I've purchased the myCobot 320, and I wanted to write a review article about my unboxing experience. While there are many articles about the myCobot 280, information on the 320 is scarce, and I was very hesitant to buy it myself. I believe those who own the myCobot 280 might consider purchasing the 320, so I wrote this article as a reference.

I'm not an expert, so there may be some doubts regarding my writing. Please understand and feel free to point out any incorrect methods of verification. I have not made this action or decision for any other interest, nor have I been influenced by any other parties.

This article is written for those who own the myCobot 280 and are considering buying the myCobot 320. It will describe the appearance and performance of the myCobot 320, along with my personal impressions and thoughts.

I will also introduce some information about direct teaching and ROS control, but will not explain the methods in detail. The purpose of this article is to provide a review of the myCobot 320, not to serve as an implementation guide.

Overview

● Overall Impression: Compared to the myCobot 280, the myCobot 320 is significantly larger.

● Power: The myCobot 320 is much more powerful than the myCobot 280; the two are hardly comparable.

● Backlash: There is some degree of backlash (looseness in the joints).

● Positional Accuracy: The positional accuracy of the myCobot 320 is very satisfactory.

● Environment Transition: If you have already set up an environment on the 280, it can be immediately transferred to the 320 (ROS).

Personally, I am very satisfied with the price.

Background Information

I purchased the myCobot 320 M5Stack, which used to be known as the myCobot pro. I bought it through Switch Science.

The myCobot 320 weighs 3 kg, has an effective payload of 1 kg, a working radius of 320 mm, and was priced at about 370, 000 Japanese Yen (as of August 2022). From my research, this price and specification are very affordable in the robot market.

The reason I wanted to buy the 320 is that the tasks I wanted to perform had exceeded the capabilities of the myCobot 280, which was quite frustrating for me. Especially when weight was applied, the position control performance was poor, and there was significant "looseness" (backlash) when reactive forces were applied, which was bothersome.

Personally, my biggest concern was whether the 320 truly had enough power and how severe its "looseness" would be.

Unboxing

I placed an order through Switch Science and made the payment on the same day; the package arrived the next morning. The delivery was very fast. It's said that if payment is made before 2 PM, the shipment will be dispatched the same day (August 2022).

Upon opening the box, my first impression of the myCobot 320 M5Stack was, "It's big, it's heavy."

Unlike the myCobot 280, it comes equipped with suction cups for securing it to a desk and an emergency stop button to halt the arm's movement to prevent collisions.

In summary, the myCobot 320 is significantly larger. I compared it directly with the 280, and the difference was starkly apparent.

Regarding installation, I referred to a video by Switch Science. Without this video, I might have been somewhat confused. Initially, I was worried about using the suction cups for mounting, but they turned out to be very secure once in place. There was no feeling of looseness at all.

Trial Operation

Surprisingly, the official instructions for the myCobot 320 were very easy to understand and not much different from those for the myCobot 280.

gitbook

My first impression was its size; it wasn't as compact and cute as the myCobot 280, but it felt very robust.

Simple Operation

Let's directly operate the myCobot 320 to see how it performs.

It feels very smooth, which is amazing, and it's quite quiet too.

Using Slider Control

Operating the robotic arm with slider control in ROS is very much like the operation with the myCobot 280, and it was successful.

Using MoveIt and sync_plan.py for Operation

I used MoveIt in ROS for path planning of the robotic arm and the official sync_plan feature to establish communication with the myCobot 320, which went very smoothly and was quite effortless.

Load Verification

Next, we verified the load capacity of the myCobot 320's end-effector. It effortlessly handled installing parts weighing about 250g. Ideally, I should test loads up to 1 kg (as the myCobot 320 is rated for a maximum end-effector load of 1kg), but considering the risk of damage, I decided to be cautious.

Amazing!! Effortless and enjoyable! So powerful! With the high-performance myCobot 320, anything is possible! There are so many experiments I want to redo!!!

Backlash

This is a concern I had: whether the robotic arm's joints would be loose. I confirmed this after adjusting the positions using slider control.

Compared to the myCobot 280, all the joints are quite sturdy, but there is still some looseness. After conducting some tests, I found that the looseness is particularly noticeable in the lowest joint (joint1). When force is applied in the direction of rotation of joint1, it seems to move quite a bit. The other joints have almost no looseness.

Precautions

It's worth noting that, unlike the myCobot 280, the myCobot 320 is not compatible with LEGO Technic parts. However, it's possible to manage a fit by using the screws included to reduce the size of the parts. When installing something on its end, it's necessary to consider securing it with screws.

Summary

In summary, this has been my review of the myCobot 320. I will continuously update this article with further impressions as I use it more.

Since I've already begun using it in my primary research, this review might not be exceptionally comprehensive, and there could be omissions. However, if this review is helpful to you, I would be very pleased.

Personally, I am very satisfied with it. Although it's not cheap, the performance of the myCobot 320 justifies its price. The seamless transition from the environment created for the myCobot 280 to ROS left a very good impression on me.

If you have any suggestions or specific verifications you'd like me to conduct, please feel free to ask.

Thank you for reading.