Monthly Archives: January 2017

Monitoring Batteries Wirelessly

Lithium-ion batteries, when used to drive automobiles, can operate reliably over long periods, but require considerable care. That means not operating them to the extreme ends of their state of charge or SOC. With passage of time and usage, the capacity of a lithium ion cell changes, and therefore, each cell in the system has to be managed so that it remains within its constrained SOC.

As vehicle operation requires generating as much as 1000 V or higher, tens or hundreds of cells are necessary, configured in series and parallel strings, to provide sufficient power for the vehicle. The battery electronics has to operate at these high voltages, while rejecting common mode voltage effects, and differentially measuring and controlling each cell in the strings. At the same time, the electronics has to transmit the information from each cell in the battery stack to a central point for processing.

High-power applications such as vehicles employing a high voltage battery stack impose tough conditions, including operation with wide operating temperatures and significant electrical noise. Therefore, the battery management electronics has to maximize its operating range, safety, lifetime, and reliability. At the same time, it has to minimize the weight, size, and cost.

Linear Technology has made steady advances in battery cell monitoring, increasing the life and reliability of battery packs in automobiles, and enabling high performance. For further improving the safety and reliability of full battery systems, Linear Technology is moving towards wireless Battery Management Systems or BMS.

Monitoring Batteries

Each LTC68xx IC from Linear Technology can monitor up to 12 Li-ion cells and they can be connected in series to enable simultaneous monitoring of every cell within a long, high voltage battery string. This enables precision battery management in hybrid/electric vehicles, electric vehicles, and other high power, high voltage battery stacks.

For instance, each LTC6811 has two built-in serial interfaces operating at 1 MHz each, one SPI interface for connecting to a local microprocessor, and the proprietary 2-wire isoSPI interface. Two communication options are possible with the isoSPI interface—you can connect and address multiple devices in parallel to the BMS master, or connect multiple devices in a daisy chain to the BMS master.

Wireless BMS

When employing a wireless BMS, a wireless connection interconnects each module rather than the twisted pair of the isoSPI. For instance, Linear Technology combines its SmartMesh wireless mesh networking with the LTC811 battery stack monitors to replace the traditional wired connections between the battery packs and the battery management system. This is a significant breakthrough offering a huge potential for lowering costs, reducing wiring complexity, thereby improving the reliability for large multicell battery stacks for electric and hybrid vehicles.

Automakers are ensuring the safety and reliability of their electric and hybrid vehicles by addressing the potential mechanical failure of connectors, cables, and wiring harness, as these have to operate in high-vibration automotive environments. Until now, automakers were under the impression that wireless systems would be unreliable in the metal and high-EMI surroundings within a vehicle. With SmartMesh networking, the interconnect system has proved to be truly redundant.

The Energy Efficient RRAMs

Engineers at Stanford are making 3-D memory chips that can offer faster and more energy efficient solutions for computer memory. These are the Resistive random Access Memory or RRAMs, which are based on a new semiconductor material. It stores data based on temperature and voltage. However, the actual workings of RRAMs continued to be a mystery until a team at Stanford used a new tool for their investigations. They found the optimal temperature range to be lower than they had expected. This could lead to memory that is more efficient.

Conventional computer chips operate on a two dimensional plane. Typically, the CPU and memory communicate with each other through the data bus. While both the CPU and memory components have advanced technically, the data bus has lagged, leading to a slowdown of the entire system when crunching large amounts of data.

The special semiconductor RRAMs can be stacked one on top of the other, creating a 3-D structure. This brings the memory and its logic components closer together. As conventional silicon devices cannot replicate this, the 3-D high-rise chips can work at much higher speeds and be more energy efficient. Not only is this a better solution for tacking the challenges of Big Data, it can also extend the battery life of mobile devices.

The RRAMs work more like a switch. As explained by the Stanford engineers, in their natural state, the RRAM materials behave just as insulators do—resist the flow of electrons. However, when zapped with an electric field, a filament-like path opens up in the material, and electrons can flow through it. A second jolt closes the filament, and the material returns to being the insulator it was. Alternating between the two states generates a binary code with no signal transfer representing a zero and the passage of electrons representing a one.

The temperature rise of the material when subjected to the electric field causes the filament to form, allowing electrons to pass through. So far, the engineers were unable to estimate the exact temperature of the material that caused the switch. They needed much more precise information about the fundamental behavior of the RRAM material before they could hope to produce reliable devices.

As the engineers had no way of measuring the heat produced by a jolt of electricity, they heated the RRAM chips using a hot plate, while not applying any voltage. They then monitored the flow of electrons as filaments began to form. This allowed the team to measure the exact temperature band necessary for the materials to form the filaments. The engineers found the filaments formed between 26.7 and 126.7°C. Therefore, future RRAM devices will require less electricity for generating these temperatures, and that would make them more energy efficient.

Although at this moment, RRAMs are not yet ready to be incorporated into consumer devices, the researchers are confident that the discovery of the temperature range will speed up development work.

According to Ziwen Wang, a member of the team, the voltage and temperature discovered can be the predictive design inputs for enabling the design of a better memory device. The researchers will be presenting their find at the IEEE International Electron Devices Meeting in San Francisco.

A Drone-Disabler with the Raspberry Pi

Drones or quad-copters are now affordable, and it is possible to record unique perspectives using their high quality video transmissions. The FAA calls them the unmanned aircraft systems, and these have started posing new challenges to security, safety, and privacy. Experts have started cautioning pilots to consider the implications of the increase in drone usage. Apart from constant surveillance concerns, it is possible for hackers using roving drones to collect location information from mobile devices.

The above has given rise to a cottage industry for anti-drone technology. You can find these devices in a variety of sizes, from handheld tools to plane-mounted types. It is possible to build one using the popular single board computer, the Raspberry Pi (RBPi). However, this rig will work against only Wi-Fi controlled network-based quad-copters. Please be careful to use this technique only on networks and devices that you own, or have permission to experiment, as otherwise, it may be considered illegal.

Many quad-copters use Wi-Fi as the key interface for communication between its controller and the tablet displaying mapping and telemetry data. Others use Wi-Fi as the sole means of control, and existing network-based attacks can be used against these devices. Since modern drones can be treated as flying computers, the attacks developed for use against traditional computer systems are also effective against drones. To illustrate the project, the AR.Drone 2.0 is selected, as it is a low-cost drone with impressive features and sensors.

Using a smartphone, a user can connect to the AR.Drone 2.0 via an access point named ardrone2. It is easy to connect, as the access point is open by default, does not require authentication, and there is no encryption involved. As soon as the user connects to the device through the access point, launching an app allows control of the drone. Although convenient for the user, the process also makes it easy for others to take control of the drone.

Therefore, using a laptop computer or on an RBPi along with a USB Wi-Fi card and a new antenna, it is possible to attack and take over the controls of the drone. For instance, if a friend is flying the AR.Drone 2.0 using the app, the access point will show up in your available wireless network.

The RBPi uses two executable scripts, one to connect to the access point, and the other to disable the drone. Use the first to connect to the network and start up your favorite terminal application. Usually, the default gateway address for this network is 192.168.1.1. As the access point is wide open on the drone system, it is possible to telnet to this address easily. Once you have access, you can proceed to explore the system, or to shut if off entirely.

This project needs a good antenna for effective connectivity. Connecting a good antenna to the wireless device can also extend its range. If you want a directional antenna, it is advisable to go for a cantenna, and you can easily make one from an available empty beer can. The cantenna will allow you control the selected drone without affecting any other device nearby.

Why not wear Digital Clothes?

We carry so much digital technology on our person all the time; it is quite natural to wonder about digital clothes. Technologists and manufacturers assure us that the field of printed electronics to produce digital clothes will be making significant advances in 2017. We have some indications as to what is to be expected.

For instance, there is the safety garment that Flex and MAS Holdings is planning on producing. The garment has LEDs embedded into the fabric. As of now, the manufacturers are working to identify the gaps in making fabrics and electronics work together. This includes materials, connectors, encapsulation techniques, antennas, and batteries (as power sources).

At another event exhibiting printed electronics, several manufacturers of medical and e-wear exhibited useful conductive yarns able to survive more than 100 wash cycles. However, manufacturers are facing a lack of benchmarks and standards for these yarns.

Project Jacquard, started by Google in early 2014 with a small team, has an aim to use smart fabrics for creating devices to recognize gestures. Google’s plan is to use standard, industrial looms to create fabrics with touch and gesture interactivity woven into the textile.

Along with conductive fabrics, there is also the need for flexible components such as batteries and substrates. At present, digital wearables need these to replace the rigid printed circuit boards that constitute them. Although there had been considerable talk of printed, flexible sensors in the annual Sensor Expo earlier, advances have been rather slow on these fronts.

For rapid prototyping, inkjet printers with conductive inks can allow creation of circuits printed within objects, including playing structural roles if necessary. Startup Nano Dimensions has demonstrated such a printer that prints circuit boards on plastic using conductive inks.

Very soon on the market, you can expect printable, solid-state batteries that can be formed. STMicroelectronics is already making these in a plant in Tours, France. However, at present, these have very low energy density, of the order of 20 mAh.

The US Department of Defense, along with a group of companies, universities, and research centers have funded the NextFlex center. According to Malcolm Thompson, executive director of NextFlex, the field of flexible, printed electronics is still in an embryonic state and flexible. Although some companies are manufacturing these devices and processes, there is no single large-scale manufacturing anywhere. Thompson expects things to change very soon.

For instance, NextFlex has a program to develop EDA tools for using conductive inks to print transistors and other discrete components on plastic. For this, they are partnering with Ansys and Hewlett Packard Enterprises. According to Jason Marsh, director of technology for NextFlex, although the printed transistors, diodes, and resistors at present are not substantial, the process is critical for reaching the NFC tag of below one cent—the ultimate target for printed electronics.

Over the last decade, along with the US, several regional and national centers in Europe have also invested substantial amounts in flexible, printed electronics.

China is also setting up its own research facility. According to analyst Raghu Das, the Chinese government is funding for equipment to the amount of $50 million for the facility.

The Next Generation Wireless Audio

We have been seeing wirelessly connected speakers for quite some time now, mainly using the Bluetooth technology. Although convenient, Bluetooth technology has its limitations because of bandwidth and range. The first to overcome this was Sonos who introduced Wi-Fi based wireless speaker system with their SonosNet mesh-networking technology. Several others followed, such as DTS’s Play-Fi, DLNA or Digital Living Network Alliance, and Apple AirPlay among the leading few. The most recent is the Google Cast protocols to allow sending audio over Wi-Fi in different ways. However, the lack of standardization gives consumers several choices.

Next few years will see key players taking the center stage in wireless audio. Among these will be Sony, Harman, Bose, Sonos, Google, and Amazon, among a few others. Amazon has already made its mark with the highly successful Amazon Echo, a voice-enabled speaker and virtual assistant. It is rivaled by the Google Home device, which works like a smart-home control center and a virtual assistance as well. By pivoting round the voice-enabled interactive products, the market is offering users a choice of looking away from the phone screens for some time of the day.

The key challenge for voice-enabled systems will be the design of the microphone-array, as these will be crucial to allow the device to accurately interpret the users voices both in the near- as well as far-field scenarios. Amazon’s product has an excellent voice-listening capability.

On the other end of the spectrum of products are the wireless headsets, headphones, and earbuds. Although most use Bluetooth and BLE or Bluetooth Low Energy, some will be using Wi-Fi in the near future. For instance, Apple has introduced its wireless AirPods. Therefore, such wireless hearables will be coming up strongly. These products will be governed by the requirements of super-low current consumption and long battery life.

For OEMs introducing multi-channel and multi-room audio systems such as 5.1, 7.1 and others, the key challenge will be delivering an audio stream synchronized to all the devices on the network. Systems will need time-stamped algorithms for all packets entering or leaving for ensuring perfect synchronizing of the audio output to the speakers. Different nodes on the network will have varying latency, and the OEMs will need to address these, to keep the system in synch for both over the air as well as through the system channels.

There is extensive fragmentation among Bluetooth audio standards. For instance, there are Miracast, DLNA, DTS Play-Fi, SonosNet, Spotify Connect, Google Cast, Apple’s AirPlay, A2DP, and others. All have their own differentiating features, with business leaders pushing their own ecosystems for their business and technological reasons. However, these remain popular as they cater to different segments of users.

Although Bluetooth is very popular, easy to use, low power, low-cost, and a wide range of devices has the technology built-in already, it is limited by range and the inability to handle more than one device at a time. AirPlay works only with Apple hardware and software. Google Cast, Play-Fi, and Spotify Connect work with Wi-Fi, and these enable streaming audio over longer distances and to multiple speakers at the same time.

Raspberry Pi Goes Binocular

This project uses the popular single board computer, the Raspberry Pi (RBPi) and a spare pair of binoculars to view and take pictures. The LCD on the RBPi is touch enabled to make it easy to capture the images.

To start with, you will need the appropriate Operating System for the RBPi. Download the Wheezy Raspbian OS from the Adafruit site, which will make it easy to interface the 2.8” TFT LCD with a capacitive touchscreen from Adafruit. Once download is complete, unzip the image and install it on the SD card. For the RBPi, you will need the Pi camera with its cable.

Make a suitable arrangement to mount the RBPi and LCD securely on the binoculars and place the camera on one of the eyepieces. This will tell you if the default cable that came with the camera is enough for the purpose or you need to order a longer one. A Wi-Fi dongle (USB type) makes the entire arrangement suitable for transmitting images over the net. In the absence of a Wi-Fi dongle, connect the RBPi to your network using an Ethernet cable.

To configure the RBPi, initially you may have to start with the Raspberry Pi Software Configuration Tool, by logging in and running the command “sudo raspi-config.” This will allow you to set the language, time zone, and keyboard layout according to preference. Additionally, you will also be able to enable the camera, set up the IP address, and the Wi-Fi credentials, which the RBPi will use to communicate.

You can mount the RBPi over the camera in a number of ways, depending on the material available. It is possible to do this with stiff cardboard, thin plywood, and tape. Measure the binoculars and the RBPi to make a suitable cutout in the cardboard. This may require using jigsaw, drill, or laser cutters. If you have access to a 3-D printer, take more accurate measurements, make a suitable image using engineering software, and print a template. Whatever the method of mounting, make sure the RBPi is secure and does not fall over.

Power up the RBPi and the camera and you should be able to see the image on the LCD screen. Place the camera on one of the eyepieces so that light passes through the binoculars and falls on the camera lens. Adjust the position of the camera until you see a well-defined circle on the screen. Now secure the camera to the eyepiece with tape.

For transportability, use a rechargeable battery pack to power the RBPi. For instance, a 2300 mAh battery pack will allow around two hours of operation. To prevent corruption of the SD card, program the RBPi for safe shutdown well before the two hours is over. If the battery pack is also mounted on the binoculars, the total weight may increase, making it difficult to hold and adjust. It might help to have the battery pack on a long enough USB cable, to allow the pack to be kept in the pocket.

It is necessary to connect the RBPi to the Internet if you want the images properly time-stamped. As the RBPi does not have an internal clock, it has to synchronize the date and time with the Internet connection.

Annoy-Pi: Using the Raspberry PI to Annoy Others

Most of us, as children, have made several attempts at annoying our neighbors. The electronically inclined have attempted circuits producing random chirps, which when hidden in cupboards, produced the most annoying effects. Another was a tiny coin-cell battery operated beeper that produced a beep every minute or so, designed to make people go crazy. Now, you can use the Raspberry Pi (RBPi), the popular single board computer, and try different programs to see which of them can produce the most annoying effect on people nearby.

The Annoy-Pi, as this project has been named, pseudo-randomizes both the duration of the beep, and the delay between them. Unlike the coin-battery operated beeper, where the beep could be anticipated every minute or so, the Annoy-Pi prevents the ability to expect the beep at definite intervals. The random pitch, lasting for a random period, also prevents the ability to identify the actual source of the sound.

As the beeps are noticeably different, the victim is unable to immediately identify that the sound comes from the same source, and instead chalks it up to something else entirely. Changing the pitch of the sound randomly queers the situation further. For instance, when the beeps are extremely short and high-pitched, a person might wonder if they just heard something, rather than long enough to really hear something and register it. Neighbors find this to be far more annoying and aggravating rather than regular tones and intervals.

Electronic circuits produce random chirps in different ways. One of the methods is to use two unsynchronized timers—one running at a much higher frequency than the other does. The timer running at a lower frequency uses a lossy capacitor, making its frequency unpredictable. The low frequency timer also triggers its companion, and as they are not synchronized, the triggering occurs at random intervals. You can use the same technique for programming Annoy-Pi.

In programming Annoy-Pi, the principle of threading helps the concept of generating random beeps to a large extent. The operating system keeps track of the threads, which allows the program to switch from one thread to another when necessary, and to come back to its original thread once again.

One way to do this would be to have a cron job running at boot time, with the script waiting for a random 2-5 minutes before actually beeping. The next part of the code may be involved in deciding whether to continue beeping or to stop. If the two are not related to one another, the effect will be random one.

However, with all the threads running simultaneously, you must be careful to not let the script pause or stop suddenly with the threads still running. The threads need to be closed first and only then should the script stop.

As the entire exercise is based on a program, you can try creating random threads to generate various types of beeps to annoy people. Apart from being a prank exercise, the project has a deeper purpose—of stimulating the thought process of the programmer towards generating innovative ideas.

How Do You Count People Using Wi-Fi?

Other than providing wireless communication facilities, Wi-Fi can have other uses as well. Researchers at the UCSB are now experimenting with a common wireless signal to tell them the number of people present in a designated space. Astonishingly, these people need not be carrying any personal devices on them.

At Professor Yasamin Mostofi’s lab in the UC, Santa Barbara, researchers are demonstrating that wireless signals have more uses than simply providing access to the Internet. With a Wi-Fi signal, they are counting the number of people in a given space. According to the researchers, this technology can lead to diverse applications, such as search-and-rescue operations and energy efficiency.

Mostofi explains the process as estimating the number of people walking about in an area, based on the scattering and received power measurements of a Wi-Fi link. Moreover, it is unnecessary for the people being counted to carry any Wi-Fi enabled telecommunications devices.

In the demonstration, the researchers placed two Wi-Fi cards at the opposite sides of a target area measuring roughly 70-square-meters. They measured the received power of the link between the two cards, and this approach allowed them to estimate the number of people walking about in that area. So far, they have been successful in detecting up to nine people in both outdoor and indoor settings. Mostofi’s research group will be publishing their findings in the special issue on location-awareness for radios and networks in the Selected Areas in Communication of the publication of the Institute of Electrical and Electronics Engineers Journal.

According to Mostofi, the main motivation for this work comes from counting several continuously walking people in a small area by measuring only the power of one link of the Wi-Fi signal.

The researchers count people relying to a large extent on the changes in the received wireless signal. Human bodies scatter wireless signal, and when a person crosses the direct wireless link between the two cards, there is a distinct attenuation of the signal—both effects combining to form multi-path fading. Based on these two key phenomena, and a probabilistic mathematical framework, the researchers have proposed a method of estimating the number of people walking in the space.

With Wi-Fi abounding in most urban settings, the researchers estimate a huge potential for their findings for many diverse applications. For instance, smart homes and buildings can estimate the heating and air-conditioning requirements based on occupancy or the number of people present in a given space at the time. Stores can go for better business planning based on the number of shoppers on specific days of the week.

Occupancy estimation could also help in security and rescue operations. Remote estimation of the number of people stranded at a place can help with the organization and logistics involved in arrangement of the transportation required to rescue them. Mostofi and his team have also done extensive research work in their lab involving estimation of stationary objects and humans through walls using Wi-Fi signals. They ultimately plan to bring the two projects together in the future, so that security and rescue operations can commence with better preparation.

What Active Safety Systems do Cars Use?

As cars move towards independence from drivers, and become more self-reliant, they are also becoming smarter and safer. Manufacturers are using newer systems every year for the assistance of drivers with the systems increasingly employing advanced technology and data processing. Among such advanced technology range from automatic high-bean control to pre-collision braking systems, and these are now becoming the norm in practically all kinds of cars.At present, the active safety systems manufacturers use in cars are mainly in the form of three major sensors – LIDAR, radar, and cameras. While assisting drivers in cars, these sensors offer benefits in different ways. Manufacturers also combine these with other sensors for achieving better solutions.

Light Detection and Ranging – LIDAR

This technology relies on lasers to measure distance. When used for automotive applications, the LIDAR system uses infrared lasers firing hundreds of pulses every second. The system measures the time of flight for the reflected light to return to the sensor. The distance to the object is then half of the time of flight times the speed of light.

LIDAR systems are in use by major car manufacturers, including Toyota, Volvo, Continental, and Infinity. These and other manufacturers often combine LIDAR sensors with other technologies such as radar and cameras to provide additional information. For instance, the MFL system from Continental combines LIDAR with a multifunctional camera that Toyota uses for providing automatic high-beam control, lane departure alert and a pre-collision system.

Radio Detection and Ranging – RADAR

One of the oldest and predominant sensor technologies, radar is used for advanced driver safety systems in automotive applications. These safety systems measure the time of flight, frequency shift, and the amplitude of the return signal for determining the relevant information. Automotive applications use radar systems for monitoring blind spots and provide warning for forward collision.

Similar to the LIDAR sensors, other technologies are used in conjunction with radar to obtain better information. By combining a camera and radar into a single package system, mounted in front of the rearview mirror inside the car, it offers multiple functionality such as traffic sign recognition, headlight control, object detection, pedestrian detection, full autonomous braking, pre-crash collision mitigation, forward collision warning, headway alert, lane departure warning/lane keeping, and full-speed adaptive cruise control.

Daylight and Night Vision Cameras

Driver assistance systems majorly rely on cameras, either on their own or by augmenting other systems using computer vision algorithms. Powerful processors extract valuable data using sophisticated image processing in real time. Some cars contain multiple cameras for providing different forms of data to the driver.

Cameras are also useful in assisting the driver to remain attentive when driving. For instance, the Driver Status Monitor from DENSO uses a system of cameras for detecting the driver’s head position, drowsiness level, long-duration eye closure, and the face angle to determine if the driver is distracted of drowsy. IR LEDs provide illumination for nighttime detection. The system then produces a suitable warning for the driver.

In the Future

A decade ago, such systems would be part of science fiction and even five years earlier, these safety systems were part only of luxury vehicles. However, these are commonplace now. Maybe, within the next five to ten years, self-driving cars will be the norm and people will take these and other safety systems for granted.

Brixo, Toaster & Jet Pack: Crowdfunded Hardware Designs

New Crowdfunded Hardware Designs

If you possess an inventive streak, there are various places from where you can draw inspiration for your next big idea. Hardware designs on sites such as the Crowd Supply, Indiegogo, and Kickstarter can provide a spark to fire up your imagination and trigger a series of thoughts to lead you to your next discovery. Some inexpensive favorites are given below.

Legos on Steroids – Brixo

Brixo presents blocks similar to and compatible with those made by Lego, and the difference may not be apparent at first glance. A closer look reveals that Brixo has chrome plated many of their blocks. The special chrome plating conducts electricity and there are three unique connector blocks that Brixo has designed especially for performing specific functions. The three special blocks are the Connector, Trigger, and Action blocks. While the Connector blocks transmit power to the others, the Trigger blocks contain Bluetooth controller and other sensors such as sound, light, and proximity. The Action blocks have motors and lights within them.

The Starter kit comprises one battery case with BLE, one motor block, 20 4×1 blocks, two 2×2 blocks, 10 2×1 blocks, one light switch, and one LED. They offer other kits of increasing numbers of blocks – Standard kit, Makers’ kit, Expert kit, and The Mad Scientist kit. Brixo also offers a Classroom kit for 40 students.

The battery block with its 9 V internal battery powers your entire assembly. The built-in Bluetooth controller allows controlling actions with Brixo’s mobile application. Therefore, you can set the Action blocks to light up, spin, move, and take action using your smartphone. Brixo’s kits are great for learning about IoT and IFTTT.

Dual Output with Toaster

While testing electronic projects, there is usually a requirement for different supplies. For instance, digital circuits need 5 or 3.3 VDC, while analog circuits may require anything between 5-16 Volts. It is cumbersome having to plug in and operate several power supply units to get all the voltages necessary – hence the Toaster.

The Toaster is a single 50 x 25 mm board, and you can plug it into your breadboard. It powers up with either a single USB cable or a wall charger with 5 Volts. Once powered up, one rail on the breadboard will have a variable voltage that can be preset to anywhere between 3.3 and 5 Volts. The other rail can be preset to any voltage between 5 and 16 Volts. The input is protected with a 1.1 A resettable fuse.

Drive Motors with the Jet Pack

The Jet Pack is a motor shield for Arduino wireless programming. As the name implies, its wireless features eliminate the need to hook up the board physically to a computer for programming. That makes Arduino programming and development much easier and quicker. Bluetooth takes care of the data transfer and wireless programmability.

Depending on how you use it, the Jet Pack allows you to drive one stepper motor or two DC motors simultaneously. The creators of the Jet Pack also offer a Rover kit that makes the Jet Pack more robotics-friendly. With the Rover kit, you get all the parts necessary to build a basic remote controlled rover.