While readers are interested in knowing what the state of the art is, there is no need for authors to exploit the opportunity to advertise free for their organization or products. Clearly, these articles could be written in a commercialism-free format. The close-up pictures and the detailed explanations were very informative. While reading the article, I found myself drawing simple sketches to understand and verify the concepts he was explaining regarding the traction at the wheels. I have a few constructive criticisms for future articles.
Engineers are, by training, very visual in their intake of ideas.
It is a lot easier to understand simple or complex ideas if visual cues are present. Your readers would have been much better served if, instead of the long paragraphs describing the tractive and resisting forces and their moments, the author had substituted simple sketches and a much shorter verbal explanation. Apart from this minor irritant, the article was really enjoyable. During operations, the sim enabled us to test critical operations here on Earth before sending commands to Sojourner on Mars. Respect for Engineers Charles H. Marks, p.e.