Skip to main content

NXT Motor Grader: Part 2: Steering and wheel lean

Yesterday I started a new series of posts on creating a NXT motor Grader. In part 2 today I like to continue where I left off: designing the steering and wheel lean.
The wheel lean is an important feature of the motor grader that sets it apart from other construction vehicles:
Unlike some vehicle that uses wheel-lean to steer the vehicle (e.g. the Dodge Tomahawk), the wheel lean is used to aid the operator achieve a perfect grading finish: when the blade is at an angle, it helps keeping the grader pulling in a straight line. The top of the front wheels are normally leaned in the direction that material comes off the moldboard. You can find out more from this site [Thanks to John Brost for the link].

video:

[And please remember to press the new HQ button on the YouTube video to watch the video in high definition.]

The Design process:
My first attempt at creating the wheel lean used two PF motors and linear actuators and a single NXT servo motor in the middle for steering:
The PF motors were powered by a separate PF supply and contolled from the NXT by an IR-Link. An array of 4 IR receivers were placed infront of the IR-Link which commanded the motors based on the signal sent by the IR-Link for each of the four channels. The IR-Link and the remote receivers were then covered to stop the interfereence from sun light.

Two additional PF motors provided power to the two front wheels. With the new PF block for the IR-Lik, one can vary the power between left and right during steering - giving excellent control over the turning circle.
And although it looked elegant, I had got the pivot point wrong - so instead of leaning just the wheel it raised and lowered the vehicle instead! (see video above). I also made the wheels powered - just like the top of the range graders. However, the powered front wheels made accurate steering very hard.

My second attempt used some of the new components that shipped with some of the new 2009 TECHNIC models - namely the wheel braces. However, I removed the front wheel drive motors as it impacted the steering accuracy. And talking of accuracy - I replaced the PF motors + clutch with NXT servo motor (with built in rotation sensors) - so I have fine control over the lean of the two wheels:


The finished design worked beautifully achieving 45 degrees lean either way. The leaning had an impact on the turning circle - making it smaller (see video above):

BlueToothKiwi

Popular posts from this blog

MINDSTORMS Retires!

2023 is the 25th Anniversary of the MINDSTORMS brand. For 25 years, MINDSTORMS has educated and inspired a generation of robot builders, both children and adults. Unfortunately, the LEGO Group decided to end the line on December 2022. Many ROBOTMAK3RS have been passionately involved with the development of MINDSTORMS through the MUP and MCP programs. Even with the newest Robot Inventor line, several ROBOTMAK3RS were invited to submit additional bonus models that were included in the official app. Regardless of the retirement of a major LEGO robotics product line, ROBOTMAK3RS continue to MAKE-SHARE-INSPIRE using all LEGO robotics platforms available to us. Here is the official statement from LEGO. Since its launch in September 1998, LEGO MINDSTORMS has been one of the core ‘Build & Code’ experiences in the company’s portfolio, carrying with it significant brand equity and becoming a stand-out experience for the early days of consumer robotics and leading to current Build & Code

Celebrating MINDSTORMS with a Remix Part 1

In honor of the 25th Anniversary of MINDSTORMS, we asked ROBOTMAK3RS to combine a LEGO set of their choice with a MINDSTORMS set. Here is what these five ROBOTMAK3RS came up with.  MINDSTORMS Chess Assistant by Arvind Seshan Overview: When you are new to chess, it can be a challenge to remember which pieces go where. Now, you can use machine learning and LEGO MINDSTORMS Robot Inventor to build a tool to help you learn where all the chess pieces go on the chess board. Sets used: LEGO® Iconic Chess Set (40174) and MINDSTORMS Robot Inventor (51515) Review: I really like how the chess set base can store all the pieces underneath and that the board neatly splits in half for handy storage. The chess pieces themselves are very sturdy and well built. My only criticism is the building of the box itself. It was quite difficult to see what pieces to use and since the entire box is made mostly of thin plates, it took a lot of time and patience. I would have liked the storage area to be sliding dra

Celebrating 25 Years of MINDSTORMS

In celebration of the 25th Anniversary of MINDSTORMS, we take a trip through history. Please also visit ROBOTMAK3RS Community every week as we highlight different projects all through 2023 in celebration of the anniversary. Some of the early history is based on the content shared by  Coder Shah  in our  MINDSTORMS EV3 Community Group . Some of the text and links may have been edited from his original posts for consistency and clarity.  1984 - Kjeld Kirk Kristiansen watched a TV program called "Talking Turtle," where MIT professor Seymour Papert demonstrated how children could control robot "turtles" using LOGO, a programming language he developed. 1988 - The collaboration between MIT and LEGO resulted in LEGO TC Logo in 1988, which allowed students to control LEGO models using computer commands. The video shows Papert demonstrating TC Logo. 1990 - LEGO TC Logo was hampered since the robots you built had to be tethered to a personal computer. LEGO and MIT