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The Guide To DC Motor Drivers for Heavy-Duty Robots

There are many motor drivers for heavy-duty robots that can drive the high-torque brushed DC motors of your robot. Though, not many of them come cheaply and with high performances. In this post, I’m covering DC motor drivers for brushed DC motors that can help you focus on what’s important: building robots.

1. DimensionEngineering

The Dimension Engineering’s motor drivers have a good attraction to hobbyists who are building heavy-duty remote controlled robots. But not many hobbyists take all the advantages of these powerful motor drivers. Looking into any of the Dimension Engineering’s motor drivers, you can use them to control two DC motors via analog voltage, radio control, serial and packetized serial.

All of these motor drivers are overcurrent and thermal protection designed meaning you’ll never damage one of these with accidental stalls or by controlling two big motors. Also, there is a regenerative system which recharges the batteries of the robot whenever it receives a command to slow down or reverse the DC motors.

Any of these motor drivers are designed with a simple interface, just plug and play once you’ve set the switches as needed. Moreover, these require only a single pin for control.

The easier way is to use any microcontroller-compatible analog or digital sensor to send information to a Sabertooth motor driver. At the top of microcontrollers used to control them is Arduino. It is easy to understand why numerous hobbyists use the motor drivers with Arduino. You have great examples for inspiration, libraries, and Arduino code and instructions for a remote controlled robot.

The Dimension Engineering’s motor drivers – Sabertooth Dual 12A/25A/32A/60A – are suitable for mobile robots, electric vehicles, or scooters between 45Kg (100lbs) and 450 Kg (1000lbs).

These four are the ones capable to control high-torque brushed DC motors:

  1. Sabertooth Dual 12A (price $$)
    31ejb5hvjdl-001_opt-1

    • 12A continuous per channel;
    • 25A peak per channel;
    • up to 24V in;
  2. Sabertooth Dual 25A (price $$$)
    31ejb5hvjdl-002_opt

    • 25A continuous per channel;
    • 50A peak per channel;
    • 6-30V nominal;
    • 33.6V absolute maximum;
  3. Sabertooth Dual 32A (price $$$)
    31ejb5hvjdl-003_opt

    • 32A continuous per channel;
    • 64A peak per channel;
    • 6-30V nominal;
    • 33.6V absolute maximum;
  4. Sabertooth Dual 60A (price $$$)
    31ejb5hvjdl-004_opt

    • 60A continuous per channel;
    • 120A peak per channel;
    • 6-30V nominal;
    • 33.6V absolute maximum;

2. Pololu

Pololu was initially focused on designing and producing beacons for robots to detect each other. It has since been transformed into a powerful manufacturer for electronics and mechanical components used in robotics.

Pololu’s DC motor drivers had the reputation of being Sabertooth’s little brothers for amateurs and roboticists. One very useful feature is that these motor drivers let you build autonomous and remote controlled robots. Pololu’s G2 series and VNH5019 are by far the handiest way to control brushed DC motors if you are on a low budget.

None of the Pololu’s motor drivers do not include a heat sink and over-temperature protection. Three very useful features are the reverse-voltage protection, short circuit protection, and the undervoltage shutdown circuit that protects the batteries from over discharge.

These five are the Pololu’s motor drivers capable to control high-torque brushed DC motors:

  1. VNH5019 (price $$)
    001pllp_opt
    The concept around VNH5019 is to have a DC motor shield for Arduino.

    • 12A continuous per channel;
    • 30A peak per channel;
    • 5.5V – 24V nominal;
  2. G2 24v13 (price $$)
    002-pllp_opt

    • 12A continuous per channel;
    • 30A peak per channel;
    • 6.5 V to 40 V nominal;
  3. G2 18v17 (price $$)
    003-pllp_opt

    • 17A continuous per channel;
    • 40A peak per channel;
    • 6.5 V to 30 V nominal;
  4. G2 24v21(price $$)
    004-pllp_opt

    • 21A continuous per channel;
    • 50A peak per channel;
    • 6.5 V to 40 V nominal;
  5. G2 18v25(price $$)
    005-pllp_opt

    • 25A continuous per channel;
    • 60A peak per channel;
    • 6.5 V to 30 V nominal;

3. Cytron

Cytron has become more popular and been put to greater use in recent years. At least two DC motor drivers are used in building combat/sumo and all-terrain robots. SmartDrive160 and the 30A DC Motor Driver are two of the best ways to control the DC motors of your robot.

You can work with the 30A DC Motor Driver to control one DC brushed motor or use SmartDrive160 perfectly optimize to control two DC brushed motors.

If you’re a veteran designer, you probably want to work with SmartDrive160. It has multiple input modes: RC, Analog, PWM, Simplified Serial and Packetized Serial. In addition to LiPo battery low voltage warning, the motor driver features thermal protection and current limiting based on temperature sensing.

These two DC motor drivers should be what you needed from Cytron:

  1. SmartDrive160 (price $$$)
    smartdrive160-35132-800x800_opt

    • 160A continuous per channel;
    • 190A peak per channel;
    • 8V to 28V nominal;
  2. 30A DC Motor Driver (price $$)
    5124ojwyjflytry-try_opt

    • 30A continuous per channel;
    • 80A peak per channel;
    • 5V to 30V nominal;

4. SparkFun

Among all of the roboticists in the world, many of them probably heard of SparkFun. They produce the Monster Moto Shield. It is a small dual motor driver designed for extreme high-demand applications. It had issues trying to disperse the temperature generated when it is used at full capacity. Sparkfun claims to improve thermal efficiency using a heat-sink or fan.

Monster Moto Shield (price $$)
51weso7dqjldgfd-gfd_opt

  • 14A continuous per channel;
  • 30A peak per channel;
  • maxim 16V;

DFRobot

DFrobot produces one of the user-friendly, intuitive and Arduino compatible DC motor driver. If you are getting your feet wet with heavy-duty robots, this is one of the cheapest DC motor driver capable of controlling high-torque motors. Therefore, you can use it in 4WD mobile and combat robots, to driven pumps and more.

DC Motor Driver 2×15A – Lite (price $$)
dfrobot-motor-driver_opt

  • 15A continuous per channel;
  • 20A peak per channel;
  • 4.8 to 35V nominal;

20+ Christmas Gifts That Creates More A-Ha Moments for Smart Kids

The most powerful educational kits for learning robotics and electronics are the ones kids love to use.

Something magical happens when you give your little boy and girl one of these kits. They can create unique projects for personal learning at almost every age. The robotics and electronics applications become more immersed through the power of modular components and versatile platforms like these.

Explore twenty-one of the best kits able to create a-ha moments for smart kids.

  1. DFRobot Cherokey 4WD Mobile Robot
    • Recommended age: 12 years and up
    • Price: $$

    61zuasnah4l-_sl1024_

    With this mobile kit and a development board such as Arduino, sensors, and boards for wireless control, any kid can be initiated into robotics.

  2. Salt Water Powered Robot Kit DIY Mini Robot
    • Recommended age: 3 years and up
    • Price: $$

    02

    Do you want your child to experience clean energy? This robot kit works on electrical energy generated by salt water. Give your children the chance to learn about clean energy while playing with robots.

  3. 4M Doodling Robot
    • Recommended age: 9 years and up
    • Price: $$

    03

    Create works of art with this little robot able to vibrate and spin while draw lines on paper. It is easy to build and fun to play with!

  4. OWI 14-in-1 Solar Robot
    • Recommended age: 8-15 years
    • Price: $$

    04

    This little robot is powered by the sun and good for children with the ability to assemble.

  5. Pi-bot – The Ultimate Robotics Experience
    • Recommended age: 14 months and up
    • Price: $$

    05

    Introduce your children into the robotics world in a fun way using a programmable robot featured with sensors able to detect the surroundings.

  6. Mini Robot Rover Chassis Kit
    • Recommended age: 3 years and up
    • Price: $$

    06

    Less is more. This small two-wheeled robot is ready to keep your children busy for days.

  7. Makeblock mBot 1.0 Kit – STEM Education
    • Recommended age: 12 years and up
    • Price: $$

    07

    Infinite extensibility with only one kit. Makeblock mBot 1.0 is an all-in-one solution to introduce your children to graphical programming, electronics, and robotics.

  8. OWI Robotic Arm Edge
    • Recommended age: 10-15 years
    • Price: $$

    08

    Simple and intuitive. OWI is a plastic robotic arm gripper with multiple movements and functions.

  9. Smart Video Car Kit for Raspberry Pi with Android App
    • Recommended age: 12 years and up
    • Price: $$

    09

    Everyone can code Raspberry Pi and build Android applications. This smart video car is probably the best starting point to learn, write, and teach coding the Linux development board – Raspberry Pi.

  10. Sphero 2.0: The App-Controlled Robot Ball
    • Recommended age: 8 years and up
    • Price: $$

    10

    This is the most intelligent ball. It is a smart toy gadget controllable via Apple or Android mobile devices. You want your child to play indoor, Sphero is ready to move anywhere in the house. You want your child to play outdoor, Sphero is waterproof, pet-proof, and ready for outdoor adventure.

  11. LEGO Mindstorms EV3 31313
    • Recommended age: 10 – 15 years
    • Price:$$$

    11

    LEGO Mindstorms EV3 is designed to inspire the engineers of tomorrow. The EV3 kit is an inevitable source of inspiration for any children with building abilities. With a wide range of components and an intelligent brick, anyone can build intelligent and interactive robots.

  12. HEXBUG VEX IQ Robotics Construction Set
    • Recommended age: 8 – 15 years
    • Price:$$$

    12

    Build anything you can imagine in terms of robots. HEXBUG is a modular kit mainly used in robotics competitions.

  13. ArcBotics Sparki Robot – Programmable Arduino STEM Robot Kit for Kids
    • Recommended age: 9 years and up
    • Price:$$$

    13

    Do you want to learn your children basic programming and a little engineering? Sparki is a low-cost way to get introduced to Arduino. You have all the code for free and lessons to learn.

  14. Makeblock Codeybot – STEM Education
    • Recommended age: 12 years and up
    • Price:$$$

    14

    Codeybot is an entertainment and educational robot who teaches basic programming through an array of interactive features.

  15. Wonder Workshop Dash Robot
    • Recommended age: 8 years and up
    • Price:$$$

    15

    These balls are magical. Is an exceptional way to teach kids programming through play.

  16. 11 in 1 Programmable Robot Kit
    • Recommended age: 9 years and up
    • Price:$$$

    16

    This robot kit on legs is designed for the beginners who are willing to learn robotics, electronics, and Arduino programming.

  17. Cubelets SIX robot blocks
    • Recommended age: 4 – 15 years
    • Price: $$$

    17

    Simple, intuitive and magic. Cubelets are modular robots that any kids can play with and have fun.

  18. UBTECH Jimu Inventor Level Robot Kit
    • Recommended age: 8 years and up
    • Price: $$$

    18

    Make any kids happy with this robotics kit able to transform into an elephant, humanoid robot, wolf, rhino, and more.

  19. littleBits Electronics Base Kit
    • Recommended age: 8 years and up
    • Price:$$

    19

    Create more a-ha moments for your children while playing with lights, sounds, sensing and buttons without wiring, soldering or programming.

  20. fischertechnik ROBO TX ElectroPneumatic Set
    • Recommended age: 10 years and up
    • Price:$$$

    20

    This electro-pneumatic kit contains 440 components for building 4 functional models.

  21. Piper Computer Kit | STEM and Coding through Minecraft
    • Recommended age: 7 – 13 years
    • Price:$$$

    21

    Wood, electronics, Minecraft, and excitement projects to introduce your children programming and electronics.

I Look Into The Best Motor Drivers For 24V Brushed DC Motors

The key to have a good experience with an all-terrain robot is the motor driver used to control the high-torque DC motors. In this article, I look into the best motor drivers for 24V brushed DC motors. This selection is made based on the robot specifications which began to take shape with the article about how to choose the 24V DC motor for an all-terrain robot.

What means the best for my robot? The best high current motor drivers must meet at least two conditions. The first condition is the compatibility with development boards such as Arduino and Raspberry Pi. The second one is more related to future plans. Because I have a limited budget, I have to use the same motor driver for both versions of the robot: remote control and autonomous.

Before listing the high current motor drivers, let’s start with important theoretical things.

The difference between a motor controller and a motor driver

To have a clear view of the difference between a motor controller and motor driver, I’ll make a short overview of both.

Whether you’re using a motor controller or a motor driver, both of them are capable to control the speed and direction of the DC motors. The difference consists of the on-board microcontroller or the lack of it.

A motor controller is a motor driver with a microcontroller on it. The motor driver comes without the microcontroller, so it has to be controlled by another device such as an Arduino or Raspberry Pi to control the speed of the motor and direction. Otherwise, you can use a motor controller designed to take care of generating the PWM and control the motor direction.

Put on paper what you need

If you’re using high-torque DC motors, you absolutely need a high current motor driver. But before buying the motor driver(s) of your project, you have to put on paper the functional requirements of the robot and calculate the output of the DC motors. I already have done this for my project, and you can do it also. Here is the example of how I calculate the theoretical power of the DC motors able to push my robot.

What I need for my project, may differ from what you need for your project. My project should be considered only as an example. As a reference for a heavy-duty robot.

I need one/two/four motor drivers able to feed four high-torque DC motors with the motor voltage per channel of 24V and support a full load current of no more than 19A per motor. If I’ll use only one motor driver with two channels, it should support a maximum current of 38A per channel. For two motor drivers with one channel, each of them should support a maximum current of 38A per channel. If I choose four motor drivers, each of them should support the stall current of the DC motors. In my case, 19A maximum current per motor.

The list

Since I want to use the motor driver for the same robot in autonomous and manually operated mode, I have to avoid some of the most popular motor drivers used by hobbyists to build remote controlled robots. Why? I already had a not very pleasant experience with a Sabertooth motor driver used to control four DC motors of an autonomous robot. Any of the Sabertooth motor drivers does a great job when you manually control a robot. For autonomous robots, I’ll never use again a motor driver designed mainly for remote controlled robots.

With so many online shops and interesting offers, choosing a motor driver seems simple. It’s not. I have spent hours finding a high current motor driver that fits with my robot specifications.

Below, I look into the best motor drivers for 24V brushed DC motors with 10A/20A continuous and support more than 19A/38A stall current per channel.

high-current-dc-motor-drivers

  1. 30A Bi-directional DC Motor Driver
    • Price: $$
    • Maximum current: 80A peak (1 second), 30A continuously
    • Motor voltage: 5V – 30V
    • 3.3V and 5V logic level inputs

    I need two of these high current motor drivers to feed my high-powered brushed DC motors. It’s compatible with both Arduino and Raspberry Pi, which means that it meets both conditions to be the best motor driver. Also, the board doesn’t require a fan for cooling and incorporates some friendly features for protection and efficiency.

    The documentation makes things clear for anyone who uses the motor driver. Here is the manual of the MD30C 30A DC Motor Driver.

  2. VNH5019
    • Price: $$
    • Maximum current: 30A maximum per motor, 12A continuous
    • Motor voltage: 5.5V – 30V
    • 3.3V and 5V logic level inputs

    I need two of these high current DC motor drivers to drive my 24V DC motors. It is a component compatible with Arduino. The Arduino library makes things easier to control the speed and direction of the electric motors. The board is designed to draw heat out of the motor driver chips, but for a better performance I can add heat sinks.

  3. Pololu G2
    • Price: $$
    • Maximum current: ? maximum per motor (probably a higher current than 40A), 21A continuous
    • Motor voltage: 6.5V – 40V
    • 1.8 V, 3.3 V, and 5 V logic level inputs

    I need two of these high-current motor drivers since it can output a continuous current of 21A. The MOSFET H-bridge is designed to drive large brushed DC motors and deliver a continuous 21A without a heat sink.

  4. DC Motor Driver 2x15A
    • Price: $$
    • Maximum current: ? maximum per motor (probably a higher current than 30A), 15A continuous
    • Motor voltage: 4.8V – 35V
    • Directly compatible with Arduino

    I need two of these motor drivers to control four brushed 24V DC motors. The board is Arduino compatible and use a BTS7960 H-bridge driver circuit to control the two channels. The driver circuit offers protection over temperature and high voltage.

How To Choose the Batteries for an All-Terrain Robot When the DC Motors Require 24V to Run

This is one of the questions that comes up when I was planning a 4WD mobile robot able to deal with difficult terrains. And because without electrical energy my robot is just a simple piece of furniture, in this article I have to find the best report between technology and price for the batteries that will keep my robot up and running for 1.5 hours.

Furthermore, to simplify the power system of the robot I will use two 12V batteries. I will not use multiple batteries with different nominal voltage for each type of components just because the voltage range may differ. I’ll keep everything as simple as possible.

I know that there are advantages and disadvantages in using only one nominal voltage. One of the advantages is that I can recharge the batteries in the same time with only one battery charger. The second advantage is the low weight of the platform. A light weight would likely be an advantage to traction given that the robot will work outside. A lighter robot requires less power so I need smaller batteries to get more run time.

As a disadvantage, I have to use a lot of voltage regulators since some of the electronics usually operate at different voltages than the actuators and sensors.

Define the needs

These are the theoretical values of the DC motors that I’ll use to build the robot. Here is how I choose the 24V DC motors for the all-terrain robot that I have to build.

  • RPM: 148
  • Torque: 2 X 6.12Nm = 12.24Nm

Moreover, I’ll take as the example a DC motor closer to the above specifications. This is a 350W at 24V with 10.7Nm that pulls no more than 18.7A at the stall.

I consider that an average of 1.5 working hours on a charge is more than enough for this robot.

I did some calculations here:

  • The DC motors: 4 X 24V nominal, 18.7A at stall
  • The time between recharges: 1.5 hours

The formula to calculate the capacity of the batteries is:

  • 4 motors x 18.7 A/motor x 1.5 hours = 112.2 Ah capacity of the battery

Well, let’s take a deep breath to try cutting some numbers. The stall current is the maximum current drawn when the motor is applying its maximum torque. But the motors will generally run at the maximum torque for a limited time of period. Of course, I have sensors and electronics that will eat my batteries, but these components consume a negligible amount of current compared to the DC motors. So, the capacity of the batteries needed to run for 1.5 hours is less than 112.2 Ah.

Therefore, I’ll consider an average current drawn by each motor of 9A.

Recalculate the battery capacity:

  • 4 motors x 9 A/motor x 1.5 hours = 54 Ah capacity of the battery

Therefore, two 12V 54 Ah batteries will last around 1.5 hours.

The best report between technology and price

Below I explore all the chemistry used in batteries that come into my mind.

NiMH

These batteries are in use in hybrid vehicles like the Toyota Prius and do a great job. The NiMH batteries are not affected by memory, meaning every charge should bring the battery up to full capacity. In general, these batteries have a good price and weights less than other batteries which can save me some torque for slopes and uneven terrain.

But I have a problem with these batteries. I didn’t find a battery that fits my needs. So, I have to go on to the next batteries.

NiCd

If you’re using cordless power tools such as a cordless drill, you’ve probably used a NiCd battery. One great thing about these batteries is that they can be charged rapidly without damaging them. But there are also disadvantages in using NiCd batteries. These batteries lose part of the capacity each time after the charge/discharge cycle.

In addition, since my robot will work in really cold weather (in Romania, the winter can reach temperatures below -20 degrees) I can damage the batteries at recharge. Yes, I can damage the batteries because the gas absorption reaction is not adequate when the temperature is below 0 degrees. Next.

LiFePO4

These batteries are extremely lightweight than standard batteries and have a faster charging rate. But the price is so… $690 for a 12V 50Ah, and $1,246 for a 12V 100Ah Lithium Ion battery. Since I’m not a millionaire, I have to jump quickly to a new category.

Sealed Lead Acid

The SLA batteries are still the cheapest option for high capacity and, like any old rusty trucks, these are widely available. They require almost no maintenance for several years and a thousand of charge/discharge cycles if the discharge is no more than 30% of capacity. In addition, the SLA batteries can output tons of current and are easy to charge.

But these batteries are like heavy boulders for mobile robots. For example, a 12V car battery store a few dozen amp hours at a weighing of around 15Kg. A considerable weight even for a heavy-duty robot. Moreover, I need two of these.

During the mid-1970s, researchers developed what is called a maintenance-free lead-acid battery. These batteries can operate in any position since the liquid electrolyte is gelled into moistened separators and the enclosure is sealed. So, I can mount the batteries without taking too much into account their position.

Using powerful DC motors, I need batteries with deeper discharges at higher current and for a higher number of cycles. These batteries are only good for power supply high-torque DC motors.

I know that the electric vehicles use lithium batteries, but they’re more concerned with the weight for a high travel range. Also, the drones use lithium as well, for their low weight and high capacity.

For me, keeping the robot light-weight is not the primary concern, but money is.

As a conclusion, I have to find two 12V SLA batteries with a capacity higher than 50Ah to run my robot.

Here are four of them:
Ritar 12V 60Ah 12V 75Ah Sealed Lead Acid Battery
24v-battery-001

UB12550 12V 55Ah Scooter Wheelchair Mobility Deep Cycle SLA AGM Battery
12v-battery-002

12V 55Ah SLA Sealed Lead Acid AGM Rechargeable Replacement Battery
12v-battery-003

UB12500 12V 50Ah Toy Car Play Mobile Scooter Rechargeable SLA
12v-battery-004

Disclaimer:
This article is written to help the robot hobbyist gain some understanding for the batteries used to power up the robots. The author assumes that you have sufficient knowledge about electricity and the basic operation of batteries. Please consult manufacturer’s data sheets in order to use batteries. The author will not be held responsible for accidents or injuries resulting from use of the information herein.

References:

How I Choose the 24V DC Motors For An All-Terrain Robot Platform

I want to build a 4W robot platform able to deal with difficult terrains. The first step is to make a list of possible DC motors able to push the robot on sand, mud, over rocks, in a forest, in lawns or anywhere else I would like to drive it.

In this article, my objective is to find the theoretical values of torque and RPM for the DC motors. Also, I did a list of DC motors that I can use for this project. I know that matching a motor for a specific application is not easily accomplished through trials and errors. Moreover, the necessity of purchasing and testing many DC motors are inefficient and brings me additional costs. So, I have to determine the optimal DC motor specifications for the functional requirements.

DC Motors (image source)

DC Motors (image source)

Let’s move a little bit to the functional requirements of the mobile platform. This robot should be able to climb slopes up to 20 degrees, driven by four DC motors connected through belts or shafts to the wheels, supplied voltage = 24 Volts, the diameter of the wheel = 0.35m, and able to reach a maximum speed of 10km/h (6.2 mph). Broadly speaking, these are the functional requirements of the robot.

The key: 24V.

Why 24V? Because the motors are happy at 24V. I know that a 12V DC motor is cheaper than a 24V DC motor. The second advantage is the weight of these electric motors that are lighter than the 24V DC motors. But it is clear to me. I’ll use 24V DC motors.

It does not seem complicated, but it would be a challenge to choose the right DC motors since I have to take into account the weight of the robot as well the minimum working time that I have in mind. I consider that an average of 1.5 working hours on a charge is more than enough for this all-terrain robot.

The batteries, the chassis, and the motors are the biggest problem for the total weight of the robot.

For example, a 12V 55Ah SLA battery weights 17Kg (37 pounds). This battery has a good price in Romania – Europe. It costs around 76EUR. With 12V and 55Ah per battery, I need two of them to have energy for at least one and a half working hour. So, only the batteries will weigh around 35Kg (75 pounds).

I need a strong chassis to carry all the weight and resist to shocks and other external factors. I can estimate that this would have a weight of 15 Kg (33 pounds) without the wheels.

The wheels will have around 0.35m (13.7 inches) in diameters. I found that such a heavy duty wheel could have a weight of 4Kg (9 pounds). Adding the weight of the wheels, there will be a plus of 16Kg (36 pounds).

Four 24V DC motors can cost me another 8 to 10Kg (13 to 22 pounds).

Considering other components, the DC motors will drive a total weight of about 70Kg (154 pounds).

So, I need four powerful DC motors able to drive a weight of 70Kg (154 pounds). Well, I’m not so glad by these numbers, but I have to take this challenge and find the right electric motors for this robot.

First step: I calculate the required wheel torque

What I know is:

  • Mass = 70Kg
  • Acceleration = 2meter/square second

Force(Newtons) = Mass (Kg) x Acceleration (meter/square second)

F= 70Kg x 2meter/square second=140N

The total force required to meet the functional requirement is 140 Newtons. However, the robot has 4 motors and wheels. Therefore, each motor/wheel combination needs only supply quarter the required force or 35 Newtons.

Torque (Nm)= Force(Newtons) x Distance (meters)

In this case, the distance is the wheel diameter/2 (0.35m/2).

Torque = 35N x 0.175m = 6.12Nm

The required torque at each wheel is 6.12 Newton meters.

Second step: calculate the required wheel RPM

What I know is:

  • Wheel Diameter = 0.35m
  • Wheel Circumference = Pi x Diameter = 1.09 meters
  • Required Speed = 2.7 meters/second (10km/h)

Speed (meters/second) = RPS (revolutions per second) x Circumference (meters)

RPS= Speed / Circumference = 2.7 / 1.09 = 2.47

RPM = 2.47 x 60 seconds = 148 revolutions per minute

A very long conclusion

The required torque at each wheel is 6.12 Newton meters. The DC motors should have at least 148 revolutions per minute.

Taking into consideration the additional losses mainly due to the friction and inefficiency in the power transmission mechanisms and considering that the robot should be able to climb slopes up to 20 degrees, normally I have to take a large margin for torque. For this robot, a fairly large margin is the Newton meters x 2.

I have to find four DC motors with values closer to:

  • RPM: 148
  • Torque: 2 X 6.12Nm = 12.24Nm

Here is a list of potential DC motors that I can use for this project:

Disclaimer: The values are only rough approximations. You bear the risk of anything unexpected and trying it. So, please don’t blame me!

Resources:

New opportunities presented by cloud robotics (AD)

An emerging sub-genre within the larger field of robotics, cloud robotics is the perfect intersection of cloud-based technologies and artificial intelligence. Building robots using cloud storage and computing gives designers a number of benefits, whether it’s in a faster rate of data transfer or in the use of open-source hardware and software. Here’s a closer look at this emerging field, and how we can expect it to accelerate robot development.

cloud-robotic

Robots and Big Data
One of the barriers that robots currently are facing is their ability to deal with the random nature of a human environment. Robots can be programmed for just about any usual eventuality, but when they face the unusual they falter. For example, a house robot that’s built to tidy the house could do so easily provided it is picking up objects it recognizes. However, what will it do if it encounters an unknown object? With cloud robotics, robotic devices can access all of the knowledge of the cloud, essentially asking the internet for answers. By turning to the cloud, robots can overcome the barrier of the unknown. At the same time, they can communicate with one another to solve problems via big data and the cloud, giving constant, real-time feedback to one another.

Giving Robots a Cloud-based Brain
With the development of the telco cloud from Nokia Networks and other major tech companies, cloud robotics allows robots to access remote servers. In the past, robots have had to be self-contained, with their own clunky computers and batteries for operation. Using the cloud means that their “brain” can be outsourced, as they offload more burdensome tasks to their remote servers. The robot can use its built-in sensors to interact with the world around it, and then find answers in the cloud to improve its speech, language, and planning abilities via an external computer. A robot could even turn to a call centre staffed by humans if it needs answers.

Apps for Robots
Cloud computing could also help with the development of apps specifically built for robots. Task-specific apps could build on the robot’s knowledge, expanding it into the cloud. Downloading and running mobile, cloud-based apps gives robotics a new dimension. Robots can access information far beyond what’s immediately programmed into them, using apps much in the same way that people currently do.

Challenges to Overcome
Naturally, as an emerging field there are still numerous challenges that must be addressed. The sensors and feedback that provide data can’t be placed in the cloud, so some degree of onboard processing is still required. Robots will need to be able to react in real-time to a variety of situations, which requires powerful networks. The arrival of the next generation 5G network may be the technology that’s needed to bridge this gap and push robotics to the next level. With unlimited processing power and extra cloud-based storage space, robotic systems could be enhanced by the big data stored in the cloud. It could be retrieved almost instantaneously for a quickly reacting robot. Yet at the moment work still must be done to get to this point.

What Makes Roboticists Buy The RoboClaw 2x30A? Five Reasons Why.

Several months ago I worked for the first time with an expensive and advanced motor controller. It is about the Sabertooth 2x25A. It has a price of $299.98 on Amazon.

The Sabertooth motor controller does his job correctly, but was hard to setup and it took me some time to write the final version of an Arduino sketch that controls four brushed DC motors.

For my next project, I want to try something new. This time, something that I’ll use to build an all-terrain robot with big wheels, large DC motors and heavy weight. I already had the idea of the DC motors, battery, and chassis.

RoboClaw 2x30A Motor Controller (image source amazon.com)

RoboClaw 2x30A Motor Controller (image source amazon.com)

The RoboClaw 2x30A by Ion Motion Control can supply two brushed DC motors with 30A continuous (60A peak), or four brushed DC motors with 15A continuous. For my project, I have in plan to use four DC brushed motors with a maximum consumption of 13A each in 24V.

And because I’m quite convinced that this motor controller is best for my project, below are five of the reasons why I chose it over other motor controllers.

  1. Inputs
    I work with Arduino and Raspberry Pi. These two development boards fulfill all the conditions for what I have in plans to do next. For these two boards, I need a motor controller compatible with both Linux PC and microcontroller.

    The RoboClaw 2x30A supports a wide range of inputs. This is good for me since I have to work with a mini-computer and a microcontroller. The motor controller supports analog voltage, USB serial, I2C, PWM, RC input, UART (serial).

    I can use the RoboClaw controller via USB interface from Raspberry Pi or controlled via UART with Arduino.

  2. Built-in over current and thermal protection
    The final project will be a 50Kg robot able to climb slopes. At the maximum load, the DC motors will draw more power from the batteries.

    To protect the electronics, batteries, and other components I need to choose a motor controller with built-in over current and thermal protection. And the RoboClaw 2x30A has these protections.

  3. Regenerative
    RoboClaw’s will charge my batteries during slow down or breaking. This makes me happy and increases the time between battery recharging.
  4. Libraries
    The RoboClaw 2x30A is smart. A library helps me to have quick access to all controller functions. With few lines of code I can control the robot, use the built-in PID routine for closed-loop speed control to maintain motor speeds even if the load varies, and more.
  5. Documentation
    A comprehensive documentation makes thing clear for anyone who is working with the motor controller. Again, this motor controller comes with good documentation, including datasheets, manual and examples.

These five reasons make me buy the RoboClaw 2x30A. I’m sure that it worth the price of $124.95 + $14.99 shipping.

I Built This Autonomous Robot to Detect and Avoid Obstacles. The Code is Included.

This is a simple autonomous robot able to detect and avoid obstacles. I use a cheap 4WD robot platform (You can use any of these platforms), an Arduino UNO($18.59 on Amazon), and a cheap HC-SR04 sensor (2 pieces at $2.83 on Amazon).

The robot is programmed to drive forward till an obstacle is detected. Then it turns the sensor left and right. Compare the values returned by the ultrasonic sensor and take a decision.

This is the Arduino code:

And this is how the robot navigates autonomously in my kitchen:

How did you check the robot on an LCD screen when most of the time is sunny?

When you have a remote controlled robot that sends real-time images to an LCD screen, one of the problems is to check the robot “on spot” when most of the time is sunny.

An LCD display becomes less viewable in a bright ambient light. No LCD screen will be bright enough to compete with the sun and the glare off the front of the screen. The simple solution is to keep the hands around the screen. But, how you’ll control the robot if the hands are around the screen?

  1. The first solution is to set the brightness of the LCD screen accordingly. If you use a smartphone or a tablet to remote control a robot, this could be easy. But what if you have attached an LCD screen attached to a development board such as Arduino and Raspberry Pi?
  2. Polarized sunglasses: A pair of polarized sunglasses is one handy solution because they reduce the glare or reflected light.
  3. Another solution is to use a monitor sunshade sun hood like this one. This accessory is designed to keep out hot sun glare of your phone or tablet screen when controlling the robot. But it could also work if the LCD screen is attached to a Pi or Arduino. You just attach it inside the sunshade sun hood and control the robot.
  4. Another way is to use a virtual reality headset. This remote controlled robot with Oculus Rift is a good example. The disadvantage is that you have to stand still while using the virtual reality headset.

Can We Do For Under $100 A Cheap 360 Degree Camera for Outdoor Navigation?

Dyson 360 Eye Robot Vacuum has a 360-degree lens so it knows where it is located in a room and where it has already cleaned. The indoor navigation system uses a panoramic camera lens on top of the machine to map its way around the house.

So, now the question is that we can also build at home with less money a 360-degree vision system that can work outside in sunlight.

I search on the Internet and I found two solutions for DIY projects. A cheap one and an expensive one. The second solution is an Eye Mirror at a price of $453. So, it’s too expensive for me and probably for many other makers. Also, the price is miles away from the range of $100.

The cheapest solution is a Kogeto Panoramic Accessory for iPhone 4. It has a price of $14 on Amazon. And someone already uses it to build a 360 video camera system.

You can mount this panoramic lens on a 3d printed mount and connect it to a Raspberry Pi. The SimpleCV framework provides the algorithms to unwrap the frames and process the images.

For a good reason, the camera with the panoramic lens should be mounted on top of the robot.

Don’t expect to have high-quality 360-degree images with this panoramic lens, but at least you can try something new in robotics navigation for under $100.

What do you think? How big is the impact of sunlight on the images since the panoramic lens is aimed directly at the sun?

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