# Trigonometry in robotics

In an inspired use of their geometry, the Greeks did what no earlier people seems to have done: they geometrized the heavens by supposing that the Sun, Moon, and planets move around a stationary Earth on a rotating circle or set of circles, and they calculated the speed of rotation of these supposititious circles from observed motions.

Thus they assigned to the Sun a circle eccentric to the Earth to account for the unequal lengths of the seasons. Ptolemy flourished — ce in Alexandria, Egypt worked out complete sets of circles for all the planets. Contrary to the Elementshowever, the Almagest deploys geometry for the purpose of calculation. Among the items Ptolemy calculated was a table of chords, which correspond to the trigonometric sine function later introduced by Indian and Islamic mathematicians.

The table of chords assisted the calculation of distances from angular measurements as a modern astronomer might do with the law of sines. The application of geometry to astronomy reframed the perennial Greek pursuit of the nature of truth. That gave two observationally equivalent solar theories based on two quite different mechanisms. Geometry was too prolific of alternatives to disclose the true principles of nature.

The Greeks, who had raised a sublime science from a pile of practical recipes, discovered that in reversing the process, in reapplying their mathematics to the world, they had no securer claims to truth than the Egyptian rope pullers. Since the ancients recognized four or five elements at most, Plato sought a small set of uniquely defined geometrical objects to serve as elementary constituents.

He found them in the only three-dimensional structures whose faces are equal regular polygons that meet one another at equal solid angles: the tetrahedron, or pyramid with 4 triangular faces ; the cube with 6 square faces ; the octahedron with 8 equilateral triangular faces ; the dodecahedron with 12 pentagonal faces ; and the icosahedron with 20 equilateral triangular faces.

See animation. The cosmology of the Timaeus had a consequence of the first importance for the development of mathematical astronomy. It guided Johannes Kepler — to his discovery of the laws of planetary motion.

Kepler deployed the five regular Platonic solids not as indicators of the nature and number of the elements but as a model of the structure of the heavens. Geometry offered Greek cosmologists not only a way to speculate about the structure of the universe but also the means to measure it. Aristarchus of Samos c. Ptolemy equated the maximum distance of the Moon in its eccentric orbit with the closest approach of Mercury riding on its epicycle; the farthest distance of Mercury with the closest of Venus; and the farthest of Venus with the closest of the Sun.

Thus he could compute the solar distance in terms of the lunar distance and thence the terrestrial radius. His answer agreed with that of Aristarchus. The Ptolemaic conception of the order and machinery of the planets, the most powerful application of Greek geometry to the physical world, thus corroborated the result of direct measurement and established the dimensions of the cosmos for over a thousand years.

As the ancient philosophers said, there is no truth in astronomy. Geometry Article Media Additional Info. Article Contents.Engineering is an extremely mathematics-intensive career, with necessary skills in both trigonometry and calculus to describe mechanical designs and to make aesthetic designs practical. The understanding of angles and planes is the most common skill used by engineers. Trigonometry also contains an understanding on natural laws and mathematical expressions that can be used to assist in engineering.

Engineers must have an understanding of angles and planes, as this is one of the most common applications in their job. Both mechanical and civil engineers make use of the mathematical understanding of planes to break down curvatures, patterns or electrical fields into mathematical terms. Mechanical systems can be imagined and drawn in mechanical terms, and problems in these systems can be solved with geometric understanding. Structural engineers are tasked with creating structurally sound buildings while making aesthetic additions from a designer possible.

Structural engineers can also map light and sound patterns through a room using expressions from trigonometry. Electrical engineers design and test electrical layouts, mapping out requirements and flows of electricity throughout a building.

Almost any type of engineer is able to combine their knowledge of trigonometry with computer expertise to create or debug computer programs to simulate and design things in their respective fields.

How Do Engineers Use Trigonometry? More From Reference.Where possible, this document tries to stick to general mathematical guidelines on notation, so those familiar with it can probably skip this section.

However, since most of this isn't taught in the United States Public Education Curriculum until the Calculus level, this is put in here for sake of completeness.

Trigonometry is the study of the mathematics involved with angles related to triangles. It is used very heavily in algebra, geometry, and calculus. The basic trigonometric functions are the basic parts of how we use trigonometry in mathematics in every day use. It does this, by wrapping the values around to fit in the real domain. It does this by subtracting or adding degrees until it is in range. Inverse functions are functions that provide a translation from the result of a function back into a value that was passed in to it.

In mathematics, inverse functions are usually represented as above by inserting a -1 super-script between the function name and its parenthesis. But in computer programming it is often difficult to represent a super-script in a quick and efficiently typed manner, so computer scientists usually use the classical naming, 'Arc' Trigonometric functions, which comes from the classical Greek word for 'inverse.

### Astronomy and trigonometry

The inverse functions for trigonometry don't have simple relationships to the actual lengths and angles that the basic functions do, and were only formally defined after the definition of Calculus. Thankfully, most calculators and computers actually implement the underlying calculus into a simple way to do it.

Technically, atan will only return angles in the first and forth quadrants if you don't know what that means: up and to the right, or down and to the left. Because of the division, the signs positive or negative of both X and Y are lost, and only their total sign is left.

For this reason, it is complex and often error prone to convert the result of atan into a real usable value. For this reason, Robot Battle 1. This function does the heavy lifting for you, and returns the proper angle.

Unless you really know what you're doing, and have a really good reason, you should always use atan2 instead of atan. It should be pointed out that this document in no way is meant as a replacement for a real education. Don't try to use it as an excuse to sleep through your High School trig class.

Sign In Don't have an account? Start a Wiki. This tutorial is in progress It may be incomplete. Please help by editing it. Contents [ show ]. Categories :.Last Updated: March 18, References. This article was co-authored by our trained team of editors and researchers who validated it for accuracy and comprehensiveness.

## How Do Engineers Use Trigonometry?

There are 12 references cited in this article, which can be found at the bottom of the page. This article has been viewed 65, times. Learn more Robotics is a hobby that, as you program and build your own robots, can bring lasting enjoyment and even become a future career. If you want to learn robotics, the best way to do so is developing proficiency in computer science, coding, physics, and linear algebra. From there, you can take robotics classes, participate in clubs and competitions, and build on your basic robotics abilities to strengthen your skills over time.

Robotics - Part 5 - Direct and Inverse Kinematics of 2 dof and 3 dof

By using our site, you agree to our cookie policy. Cookie Settings. Learn why people trust wikiHow. Explore this Article parts. Tips and Warnings. Related Articles. Part 1 of Practice basic coding so you can program your robots. Coding is a foundational element of robotics, and you will need to know how to use variables, create conditional statements, use functions, and other basic coding skills.

Choose a coding language and study it on your own or take coding classes to improve your skills. Learn linear algebra to prepare you for building robots. Basic algebra is essential for both programming a robot and tweaking its code. Take plenty of algebra courses in high school or college, or study algebra on your own to strengthen your mathematical skills. Many pre- and post-secondary schools also have math help labs to teach struggling students key concepts. Study physics as a background for learning robotics.

Building robots involves an understanding of how your robot moves and interacts with the outside world. If you haven't taken a physics course before, enroll in an online program or learn basic physics on your own. Study computer science to strengthen your robotics skill.

Robotics is strongly connected to computer science, and a strong understanding of the latter is key for learning the former. Practice or study basic computer skills and try to keep up-to-date on articles or websites about computer science. Part 2 of Build your own robot using a kit or on your own to build your first robot.

Once you've learned the basic skills for robotics, purchase a robot building kit and build your robot using coding, mathematics, and manual tinkering based on the kit's instructions. Alternatively, you can also build your own using parts and tools you can purchase from most hardware stores. Start with simple robots and, as you gain experience, move on to complex models over time.Unfortunately, they both require tuning that is difficult to do and is part science, art form and luck.

Fortunately, for one of the main problems that we need to solve with mobile robots, there is a clever trick of trigonometry that creates a controller that works fairly well and is not difficult to tune. This controller may be used to provide Go To Angle behavior for a mobile robot using Differential Drive. The Go To Angle behavior is one of the most basic mobile robot behaviors. It is a major component the Go To Goal behavior, but is useful for other objectives also.

If the pose of the robot is oriented atbut the The Unicycle Model calls for the robot to turn to anglethe Go To Angle controller will move the robot forward while rotating it in the direction of. The rotation needed is. The trick of this controller is that it considers a new point on the robot to calculate the needed Jacobian, and thus the needed wheel velocities. Because the robot can not move perpendicular to its wheels, the second term of The Jacobian is always zero. The robot moves in the direction of its orientation,but The Unicycle Model requires movement in the direction of.

This constraint limits our ability to directly apply The Unicycle Model in our control algorithm. We would like to take the derivative of with respect to time and set it equal to the velocity vector from The Unicycle Modelbut no and can satisfy such an equation.

However, such is not the case for a new pointwhich is positioned a small distance,directly in front of. The point can simultaneously move forward, perpendicular and rotate. Thus, as a close approximation to the ideal, we will design a controller to satisfy. For now, do not worry about the value of. After we complete the analysis, reasonable ranges for will be obvious and computer simulations, can help us tune.

Note that this controller has only one variable to tune, which makes it easier to use than other controllers. Angles can be tricky because they are linear between andyet they are circular in that and are in fact the same angle. Another issue with angles is that the atan function arctangent requires divisionwhich is not defined when. The solution is this is to use atan2 to compute angles and to wrap any linear angle calculations to the range.

Angle wrapping may be performed in either of two methods in traditional programming languages. This is what it would look like in Python:.

Let us use to define the location of. Then we can take the derivative of and set it equal to the desired velocity vector from the unicycle model. We will use rectangular coordinates for the initial calculations.He made a substitute appearance versus Vancouver in the Western Conference semifinals but has otherwise been sidelined throughout the playoff push. UEFA announced on Thursday that Real Madrid defender Dani Carvajal will miss the holder's Champions League last-16 first leg tie after issuing a two game ban for appearing to deliberately pick up a booking.

Carvajal was shown a yellow card in the 90th minute for time wasting in the 6-0 win over APOEL. As it was his third, it ruled him out of Wednesday's victory over Dortmund, but in theory would have meant he was available for the round of 16 next February.

However, UEFA Control, Ethics and Disciplinary Body found that Carvajal had breached Article 15 of the Disciplinary Regulations. Stoke manager Mark Hughes says Bruno Martins Indi will be out for up to eight weeks as he recovers from a groin injury.

The Netherlands international had to be substituted during last weekend's 2-1 triumph over Swansea. He has started his treatment already, but it will be a long process. Goalkeeper Gianlugi Buffon did not even feature against the Greek side as he continues to recover from a calf injury. Stephan Lichtsteiner has also missed the past two games with a muscle injury and is doubtful.

Mehdi Benatia returned to training and is no longer a doubt while Mario Mandzukic is now fully recovered from his injury and highly likely to feature against Inter. Giorgio Chiellini is also likely to return after the flu kept him out of the Olympiacos game. Louis Blues placed goaltender Carter Hutton on injured reserve Friday with a lower-body injury. Hutton, 31, has appeared in eight games for the Blues this season, posting a 4-2-0 record with a 1. The New York Rangers signed free agent goaltender Marek Mazanec on Wednesday.

Mazanec, 26, was assigned to the Hartford Wolf Pack of the American Hockey League. Mazanec has appeared in 31 career NHL games over parts of three seasons, all with the Nashville Predators, recording an 8-13-4 record with a 2.

Dallas Mavericks backup center Nerlens Noel underwent surgery on his left thumb and will be sidelined indefinitely. The operation was performed to repair a torn ligament in the thumb. Coach Rick Carlisle told the team website that Noel will be sidelined at least several weeks. The 23-year-old Noel is averaging just 4.

The Phoenix Suns announced guard Devin Booker will be out of action for two to three weeks following his left adductor strain he suffered in Tuesday's contest against the Toronto Raptors.Also, explain that drugs from the doctor help the person the doctor gives them to but that they can harm someone else. Help your child understand the difference between make-believe and real life. Ask your child what he thinks about a TV program or story.

Let your child know about your likes and dislikes. Discuss how violence or bad decisions can hurt people. Turn frustration into a learning opportunity. If a tower of blocks keeps collapsing during a play session, work with your child to find possible solutions to the problem. Tips for Conversations with Your Early Elementary School Child Talk to your kids about the drug-related messages they receive through advertisements, the news media and entertainment sources.

Keep your discussions about substances focused on the present long-term consequences are too distant to have any meaning. Talk about the differences between the medicinal uses and illegal uses of drugs, and how drugs can negatively impact the families and friends of people who use them. Set clear rules and explain the reasons for your rules. If you use tobacco or alcohol, be mindful of the message you are sending to your children.

Work on problem solving: Help them find long-lasting solutions to homework trouble, a fight with a friend, or in dealing with a bully.

Be sure to point out that quick fixes are not long-term solutions. Give your kids the power to escape from situations that make them feel bad. Check in once in awhile to make sure they are giving their children the same kinds of messages you give your children. The following scripts will help you get conversations going with your 9- to 12-year-old: Scenario Your child is just starting middle school and you know that eventually, he will be offered drugs and alcohol.

Research shows that kids are less likely to use tobacco, alcohol, and other drugs if their parents have established a pattern of setting clear rules and consequences for breaking those rules. Offset those feelings with a lot of positive comments about who he is as an individual and not just when he brings home an A. Tell them about the smelly hair and ashtray breath caused by cigarettes. Check in by phone or a visit once in awhile to make sure they are on the same page with prohibiting drug or alcohol use, particularly when their home is to be used for a party or sleepover.