# Pololu Blog (Page 8)

Welcome to the Pololu Blog, where we provide updates about what we and our customers are doing and thinking about. This blog used to be Pololu president Jan Malášek’s Engage Your Brain blog; you can view just those posts here.

# New Product: TB9051FTG Motor Driver Carrier

Posted by Jan on 14 May 2018

This is the second new motor driver product in less than a week, and I’m really excited about this one: the TB9051FTG from Toshiba. The TB67H420FTG I posted about the other day has this new part beat for higher voltages, but its one shortcoming for our purposes is that it doesn’t work at lower voltages. This new TB9051 doesn’t go up into those voltages where it starts getting dangerous, but it covers a great operating range of 4.5 V to 28 V, with transient operation to 40 V, which means you can use this driver with everything from 6 V lead-acid batteries and 2-cell LiPo packs all the way up to 24 V systems and 6-cell LiPo packs, maybe even 7-cell packs. The operating voltage range is similar to another recent favorite of mine, Maxim’s MAX14870, but this new Toshiba part delivers almost double the current.

With its excellent operating voltage range and great current ability for an integrated package, I expect the TB9051 to be an ideal all-around DC brushed motor driver for most indoor robots and other projects that do not involve moving frighteningly large objects at potentially catastrophic speeds. The chip seems positioned to compete performance-wise with my previous almost-favorite chip, the Motorola Freescale NXP MC33926. That chip would have been my favorite if it had been easier to work with Freescale, and things have only gotten worse since NXP acquired them and then got distracted by yet another merger, this time with Qualcomm, which seems to have been in limbo forever. Maybe their sales are actually doing great, and we just have a hard time with them because they are busy with bigger customers. In any case, a part with great performance is not so great overall if it’s difficult to get it, so you can expect us to be updating some of those products that use the NXP part to use the Toshiba part instead.

One pretty obvious feature the TB9051 has over the MC33926 is its smaller size, from 8 mm x 8 mm down to 6 mm x 6 mm, which is great for getting these onto smaller boards in smaller spaces, but it might also have some ramifications for how it tolerates pushing the limits of the specs. We liked how the MC33926 was able to endure lots of abuse from customers who were pushing it because it was our highest-voltage integrated driver. The TB9051 is, like the MC33926, an automotive-rated part, so it is intended to last a long time in harsh conditions. It’s interesting to see how thick the packages for these chips are, and I like their thickness (similar to how I like the proportions on 737 airplanes):

This video makes it seem like Toshiba is quite proud of their packaging accomplishment with the TB9051FTG:

Update: It looks like the above video might no longer be available on youtube, but it is still available on the Toshiba website.

Is the “competitor” in this video the MC33926? Sure seems like it to me. I know of no other part like that, and I keep looking.

Toshiba has not publicly posted a complete datasheet for the TB9051FTG yet, so the product page for our carrier only has a preliminary summary document. Our product page has more information about how to use the device, and we are working on getting a complete datasheet that we can post.

Since I expect this driver to hit a nice sweet spot for many of our customers’ general-purpose motor control needs, it’s a good candidate for using in some higher channel count products. We have not gone much beyond two motors (the TReX motor controllers have a third, unidirectional channel), and I would like to know what kind of interest there is in single boards that can control three or more motors. If you would like to see such products, please let me know.

# New product: TB67H420FTG Dual/Single Motor Driver Carrier

Posted by Jan on 9 May 2018
Tags: new products

Hey! We have a new dual motor driver carrier for Toshiba’s exciting TB67H420FTG that offers quite the power jump from the TB6612FNG we popularized over a decade ago. This chip has a recommended operating range of 10-47 V and can deliver peaks of 4.5 A per channel. In our tests on this carrier, without additional heat sinking or airflow, the maximum continuous current is about 1.7 A per channel.

One of the most common questions we get about our motor drivers is whether the outputs can be paralleled to drive a single bigger motor. The TB67H420FTG specifically has that feature built-in so that you can safely do that while only requiring control signal connections for one channel. This brings the available current for single-motor operation to 9 A peak and about 3.4 A continuous.

The TB67H420FTG has a maximum supply voltage of 50 V, making it one of the highest-voltage drivers we have available. Please note that we populated with 50 V capacitors on the supply line, so there is less margin there than on our usual products if you want to push the upper voltage limits of this chip. As with most of our carriers, we also added reverse voltage protection. The MOSFET we use for that is a 40 V max MOSFET, so the maximum reverse voltage that it protects you from is that same 40 V. If you’re wondering why we didn’t use higher-voltage parts, it’s because the next standard voltages are much higher, 100 V in the case of the capacitors. Getting the same capacitance at that rating would require bulkier, more expensive capacitors for almost no benefit. I’m telling you here in case you are one of those people who like to put 55 V on a 50 V max part just to see what will happen.

# Video: Overview of the Jrk G2 Motor Controllers with Feedback

Posted by Emily on 27 April 2018

In our last blog post, we announced the release of our second generation of Jrk Motor Controllers with Feedback. If that announcement wasn’t enough to get you excited about the Jrks, here’s a short video to give you a taste of what the Jrks can do:

You totally want one now, right? Well lucky for you, our special introductory coupon is still valid. The first 100 customers to use coupon code JRKG2INTRO can get 40% off up to three units. (Click to add the coupon code to your cart.)

# New products: Jrk G2 USB Motor Controllers with Feedback

Posted by Jan on 19 April 2018

After many months or years of work (depending on how you look at it), I am happy to introduce our newest motor controllers, the Jrk G2 USB Motor Controllers with Feedback, which we are releasing today in four power variants:

Jrk G218v19 Jrk G224v13 Jrk G218v27 Jrk G224v21 24 V(1) 34 V(2) 24 V(1) 34 V(2) 18 V 28 V 18 V 28 V 19 A 13 A 27 A 21 A 1.4″ × 1.2″ 1.7″ × 1.2″

1 30 V absolute max.
2 40 V absolute max.

The main purpose of the Jrk G2 family is to enable feedback-based control of DC brushed motors, simplifying closed-loop control of things like the position of an actuator. An example that is probably familiar to most of us is the common hobby servo that has an output shaft that can rotate to various positions as commanded over a simple interface. The Jrk motor controllers can be used for giant versions of those servos, and they can also be used in many other systems as long as you can somehow get feedback in the form of an analog voltage or a frequency. Analog voltage feedback is often easy to get from potentiometers that can serve as angle or position sensors.

The frequency feedback feature is handy for maintaining a speed of a motor independent of your supply voltage and motor load. You might use that kind of feature to run a treadmill at some set speed independent of the weight of the lab rats on it or to stir some jar of goop at a constant rate as the goop gradually thickens. With mobile robot applications, it can be handy to have a motor controller that will make your wheel go at the speed you set independent of whether the robot is on a hard floor or a carpet. (The Jrks do not support quadrature encoders, but you can use one channel of a quadrature encoder as the tachometer for the Jrk. In some applications, keeping track of absolute position is not necessary, or the quadrature encoder can be monitored directly by a main controller that could still benefit from the closed-loop speed control being taken care of by the motor controller.)

To control a wide range of motors in a variety of applications, it’s important to be able to configure a lot of parameters, which makes the Jrk’s USB connection and free configuration utility software extremely important. Even if you ultimately want to use your Jrk in a radio control installation or command it over I²C from your favorite embedded controller, it’s very convenient to be able to set everything up from your computer.

That screenshot is actually of the utility for the original Jrks, which we released almost 9 years ago (I announced those on the forum because we did not have this blog back then). You might notice on some older web pages that we referred to the original Jrks as our second-generation feedback controllers. The really original ancestor to today’s new motor controllers is this product we called simply Pololu 3A Motor Controller with Feedback, which we released at the beginning of 2005. Here are a picture and block diagram of that controller:

Candice and I were probably still running Pololu out of our house back when we started work on that controller, and it’s probably the last product of ours for which Candice wrote some of the firmware. That controller led to the development of a larger, customized controller (similar to our SMC04 High-Power Motor Controller with Feedback) and an even higher-power version that was used on control cables of large autonomous parachutes for the military.

Back to the new Jrk G2 family: these new controllers are in many ways a refinement of the original Jrks, which have been used all over the world in applications from animatronic displays to motion simulators and even full-sized airplanes. The most noticeable improvement on the four Jrk G2 controllers we are releasing today is the increased power available from their discrete MOSFET H-bridges. The G2 high-power motor driver design is part of the reason for the “G2” in the new Jrk family name, though we plan on releasing lower-power, smaller Jrk G2 products later this year. The new driver technology, along with going to double-sided PCB assembly and four-layer PCBs, allowed us to make much higher-power controllers that are smaller than the old Jrk 12v12, which used to be our highest-power version.

The Jrk G2 24v13 and 24v21 in particular open up new application opportunities because they can operate off of 24 V power rails, making them appropriate for huge linear actuators (note that we only carry 12 V versions right now, partly because we did not have controllers that we could recommend for 24 V use). It’s exciting that these tiny boards can control such huge actuators, and the size difference is so big it’s difficult to convey in a picture:

Other features new to the G2 Jrks are an I²C interface option and an improved tachometer/frequency feedback mode that now offers pulse width measuring rather than only frequency counting to allow for better control of low-speed motors with lower-resolution encoders or tachometers. Here is a summary of the main features of the Jrk G2 motor controllers:

• Easy open-loop or closed-loop control of one brushed DC motor
• A variety of control interfaces:
• USB for direct connection to a computer
• TTL serial operating at 5 V for use with a microcontroller
• I²C for use with a microcontroller
• RC hobby servo pulses for use in an RC system
• Analog voltage for use with a potentiometer or analog joystick
• Feedback options:
• Analog voltage (0 V to 5 V), for making a closed-loop servo system
• Frequency pulse counting (for higher-frequency feedback) or pulse timing (for lower-frequency feedback), for closed-loop speed control
• None, for open-loop speed control
• Note: the Jrk does not support using quadrature encoders for position control
• Ultrasonic 20 kHz PWM for quieter operation (can be configured to use 5 kHz instead)
• Simple configuration and calibration over USB with free configuration software utility
• Configurable parameters include:
• PID period and PID constants (feedback tuning parameters)
• Maximum current
• Maximum duty cycle
• Maximum acceleration and deceleration
• Error response
• Input calibration (learning) for analog and RC control
• Optional CRC error detection eliminates communication errors caused by noise or software faults
• Reversed-power protection
• Optional feedback potentiometer disconnect detection

As with all of our new product releases this year, we are offering an extra introductory discount: the first 100 customers to use coupon code JRKG2INTRO can get 40% off up to three units. (Click to add the coupon code to your cart.)

# Performance graphs for our Micro Metal Gearmotors

Posted by Ben on 5 April 2018
Tags: motors

After spending many months conducting thousands of motor tests, we are excited to finally publish performance graphs for our micro metal gearmotors (2MB pdf). In some sense, this datasheet is the culmination of a decade of work to improve our processes and better characterize our gearmotors, and we have come a long way since those early tests clamping motors in vises and making them lift ever heavier bags of steel bearings. Here is one of the setups we are using now:

The key thing is to be able to apply a measurable, variable load while the motor is spinning, which we do via an electromagnetic brake coupled to a torque meter. A combination of programs running on an A-Star 32U4 Prime test controller and a PC automatically sweep the load through a sequence of points while measuring parameters such as speed, current, and torque (plus internal test rig currents, voltages, etc).

These performance characterizations are the latest example of our continued commitment to being the best source for this popular form factor of gearmotor. You might see similar-looking motors elsewhere, but no one comes close to our offering, from the quality of the gears to our exclusive long-life carbon brush options to the overall breadth of our selection (over 100 versions!), all in stock for shipment the day you order.

Please note that we are still in the process of updating the specifications on our website to match new, more accurate data from the performance graphs, so if you notice discrepancies between what is in the datasheet and what is on the product page, go with the datasheet.

If you have any questions or feedback about these graphs or if there is additional information you would like to see available for our motors, please feel free to contact us (or just leave a comment below). And if you are wondering about graphs for our larger gearmotors, don’t worry, those are coming! (If you need something before those datasheets are done, just let us know and we might be able to get you preliminary data for a particular gearmotor.)

# UNLV wins 1st place in Student Design Competition at ASME E-Fest West

Posted by Patrick on 30 March 2018

At Pololu, I have spent the recent weeks developing new products, like the motor driver I announced on Wednesday, but at school (I am a mechanical engineering student at the University of Nevada, Las Vegas, UNLV) I have been managing an American Society of Mechanical Engineers (ASME) Student Design Competition (SDC) team. SDC teams create robotic devices to fulfill a problem statement that changes every year. They compete with their devices at one of ASME’s regional student conferences called E-Fests. Last year, I managed a three-member team that built The Rebel WIP and earned third place in the Robot Pentathalon at the E-Fest West. This year, my ten-member team made a squad of robots called The Rebel Bandits for the new SDC challenge, Robot Football. We overcame many technical challenges and 14 other teams to win first place at this year’s E-Fest West that competed this past Saturday!

The SDC’s Robot Football was loosely based on soccer, but with four robot teams competing to shoot eight tennis balls into four goals on a 5 m x 5 m field. Each team was assigned a goal to defend, and eight tennis balls were set in a square pattern at the center of the field for robots to score into the other goals. For this competition, teams could build multiple remote controlled robots, but the robots and controllers had to be able to fit inside a single 50 cm cube. Some teams built soccer squads with only two or three big robots, while other teams used up to six little robots for their squad (which made the matches super chaotic), but each team could only control one ball at a time. Robots controlling a ball needed to keep the ball on the ground when they moved around, but they could stop and lift the ball to shoot on a goal.

I am really proud of the robots my team designed and built for this competition, so I want to share how my team made a first place robot squad! However, since we won the competition at E-Fest West, we were invited to compete again in the SDC Finals at ASME’s International Mechanical Engineering Congress and Exposition in Pittsburgh, Pennsylvania this November. We will be competing against the first and second place winners from the other student conferences: E-Fest East, E-Fest Asia Pacific, and E-Fest South America, as well as the SDC team from California State University, Northridge, who came in second place at E-Fest West. The teams will be more competitive, and the prize money increases significantly! So that makes me a little bit nervous about showing all the technical details for our robots right now, but I would still like to give a basic rundown.

Our strategy was to build three large robots: one defender, and two offensive robots. We call the defender robot The Outlaw. It is built on a U-shaped frame with 19 in (48.3 cm) long sides and has tall walls. Even though it cannot block from inside our penalty box and is not particularly fast, it can seriously impede the efforts of other teams to score on our goal just by being big and tall. The Outlaw uses three DC motors for its drive train at the base of the U-frame, and Pololu ball casters help support the far ends of the U-frame. One DC motor is driven by a G2 High-Power Motor Driver, and since we use an A-Star 32U4 SV for the Outlaw’s microcontroller, the other two DC motors are driven by a Dual G2 High-Power Motor Driver Shield for Arduino.

The two offensive robots are named The Renegade and The Desperado (you should notice the Wild West theme by now). Other than the color schemes, these robots are almost complete duplicates. We decided to build only two offensive robots because it gave us sufficient space to build robust robots with high quality shooting mechanisms.

Each offensive robot uses four DC motors for the drive train. A standard size servo extends an arm with an intake belt, and a DC motor runs the intake belt to pull a ball into the robot’s reservoir. Another servo opens and closes a gate that keeps the ball in the reservoir or pushes the ball into the shooting mechanism. The reservoir allows the ball to roll on the ground as the robot moves without the intake belt constantly pushing down on the ball and impeding driving. The shooting device is a ramp and flywheel. When taking a shot on the goal, the operator stops the robot and the flywheel revs up to high speed. Then the gate servo pushes the ball into the ramp. The velocity of the wheel pulls the ball along the ramp structure and throws the ball at high velocity. Just beyond the outlet for the ball, a plate on a pivot controlled by a servo lets us control the ball’s trajectory. This allows us to shoot across long distances or over defender robots.

The offensive robots each use an Arduino Mega as their primary microcontroller. Most of the DC motors on The Renegade and The Desperado are controlled by either a Dual G2 High-Power Motor Driver Shield connected to the Arduino Mega or are driven by individual G2 High-Power Motor Drivers. On each robot, a Maestro servo controller is used as a slave controller that powers and controls the standard servos. Additionally we use the Maestros’ functionality as general I/O controllers to send logic signals to the individual 18v17 Motor Drivers. In our setups, we want the servos and the Maestros to be powered from 6 V, so we use a step-down voltage regulator to connect the Maestro power rails to main power supply on each robot, a 12 V lead-acid battery.

I am very fortunate to have worked with an awesome team this year for the SDC, and I am grateful for the parts and support we obtained from both Pololu and UNLV! It was also exciting to see different teams at the competition using other Pololu parts like our wheels, metal gearmotors, regulators, and brushed DC motor drivers. After our SDC Finals competition in November, I plan to write another blog post about more of the technical details of our robot. (Hopefully I will be able to brag a little about another first place trophy too!)

Until then, I want to know more about some of your projects! I hope you will share a little about your cool projects in the blog comments, or you can make a Pololu forum account and post in the Share Your Projects category!

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