Practical and Experimental Robotics

Ferat Sahin, Pushkin Kachroo

• Publisher: CRC Press
• Year: 2017
• Print ISBN: 9781420059090
• eBook ISBN: 9781351835008
• Topic: Technology & Engineering
• Subtopic: Mechanics
• Index: Technology & Engineering

Taking a completely hands-on approach, using cheap and easily available robotics kits, Practical and Experimental Robotics provides a detailed exploration of the construction, theory, and experiments for different types of robots. With topics ranging from basic stamp microcontrollers to biped and propeller based robots, the text contains laboratory experiments, examples with solutions, and case studies. The authors begin with a review of the essential elements of electronics and mechanics. They describe the basic mechanical construction and electrical control of the robot, then give at least one example of how to operate the robot using microcontrollers or software. The book includes a reference chapter on Basic Stamp Microcontollers with example code pieces and a chapter completely devoted to PC interfacing. Each chapter begins with the fundamentals, then moves on to advanced topics, thus building a foundation for learning from the ground up. Building a bridge between technicians who have hands-on experience and engineers with a deeper insight into the workings, the book covers a range of machines, from arm, wheel, and leg robots to flying robots and robotic submarines and boats. Unlike most books in this field, this one offers a complete set of topics from electronics, mechanics, and computer interface and programming, making it an independent source for knowledge and understanding of robotics.

1
Fundamentals of Electronics and Mechanics

In this chapter we will explore the fundamentals of Electronics and Mechanics. The example applications related to electrical and mechanical components are also presented.

1.1 Fundamentals of Electronics

In this section, we explore electrical components, semiconductor devices, Operational Amplifiers (OPAMPs) and their applications, and digital systems components. There are some very good books that cover analysis of electric circuits such as [10] and [2]. There are also some good books on hands on robotics such as [7].

1.1.1 Electrical Components

Resistors, capacitors, and inductors are basic electrical components used in electronic circuits. Some of the electrical components and their symbols are given in Figure 1.1.

1.1.1.1 Resistors

Resistors are components which resist the flow of electronic current. The resistors are mainly used to reduce the voltage applied to other components and to limit the current flowing through other components. The higher the value of the resistance, the lower the current will be. Resistance of a resistor is measured in terms of Ohms (Ω) since the relationship between voltage (V, volts), current (I, Ampere), and resistance (R) is explained by Ohm’s law given in 1.1.

V=IR⁢(1.1)

The most common resistors are made using a carbon rod core with end caps and wire leads. We can categorize resistors into two basic types: fixed and variable resistors (or potentiometers). A fixed resistor is the one which has a fixed resistance value. Variable resistors have variable resistance values. The value of the resistor is often changed by a user by turning a knob or a dial. There are some special resistors designed to change in resistance when heated. They are called Thermistors and are used in temperature measuring circuits. The same idea is also used to design pressure sensors where a membrane is designed to be a resistor. The membrane resistance changes when it is deformed by the pressure in a chamber.

FIGURE 1.1

Common electrical components and their symbols

Resistors generate heat and have a wattage rating relating the power level they can handle. The higher the wattage rating the more heat they can dissipate. There are standard wattage ratings such as 1/8, 1/4, 1/2, 1, more watts. In addition to the value and wattage, each resistor has a tolerance regarding their resistance. Standard resistors have 10-20% tolerance but special resistors can have tolerances around 1%. Depending on the application, the proper tolerance rate is chosen. These properties are often marked on the resistors using a color code. Sometimes, they are written on the resistor.

1.1.1.1.1 Resistor Color Code and Standard Resistor Values

Fixed value resistors are color coded to indicate their value and tolerance. Some have their value written on them. There are three color coding systems: a 4 Band code, a 5 Band code, and 6 Band code.

The standard color coding method for resistors has 10 colors to represent numbers from 0 to 9: black, brown, red, orange, yellow, green, blue, purple, grey, and white. The first two bands always represent the significant digits on a 4 band resistor. On a 5 and 6 band, the significant digits are the first three bands. The third band is the multiplier or decade which is multiplied by the resulting value of the significant digit color bands. For example, if the first two bands are brown (1) and orange (3) and the third band is red (2), this means 10² or 100. Then, this gives a value of 13 × 100, or 1300 Ohms.

For the decade band, the gold and silver colors are used to divide by a power of 10 and 100 respectively, allowing for values below 10 Ohms. The tolerance of the resistor is represented by the next band. Four colors are used for the tolerance band: brown (+/-1%), red (+/-2%), gold (+/-5%), and silver (+/-10%). For example, if the tolerance band is silver, the true value of the resistor can be 10% more or less than 1300 Ohms. Thus, the actual value of the resistor can be from 1170 to 1430 Ohms. The sixth band on a 6 band resistor reveals the temperature coefficient of the resistor, measured parts per million per degree Centigrade (PPM/C). Seven colors are used for the temperature coefficient: white (1), purple (5), blue (10), orange (15), yellow (25), red (50), and brown (100). The most popular color is brown (100 PPM/C) and will work for normal temperature conditions. The other colors are used for temperature critical applications. Table 1.1 represents all the colors and their meaning depending on their location on resistors.

Figure 1.2 is a 6 band resistor with 27 KOhms, 10% tolerance, and the temperature coefficient of 50 PPM/C.

Since the sizes of the electronic components are shrinking or changing in shape, it becomes very difficult to put color bands on a resistor. Instead, a simpler alphanumeric coding system is used. This coding system uses three numbers, sometimes followed by a single letter. The numbers play the same role as the first three bands on a 4 band resistor. First two numbers is the significant digits. The thir...

Table of contents

• Cover Page
• Title Page
• Copyright Page
• Contents
• 1 Fundamentals of Electronics and Mechanics
• 2 BASIC Stamp Microcontroller
• 3 PC Interfacing
• 4 Robotic Arm
• 5 Robotic Arm Control
• 6 Differential Drive Robot
• 7 Four Wheel Drive Robot
• 8 Hexapod Robot
• 9 Biped Robots
• 10 Propeller Based Robots
• References
• Index