Sunday, July 1, 2012

TBs TechTalk 08 - Designing the Power Functions System

Gaute Munch is Product Manager of LEGO Power Functions (LPF), the LEGO electric building system also referred as Power Functions System (PFS). He is also the responsible for Technology Innovation at LEGO, in this area of research and development.

TBs: Hi Gaute! Thank you for having accepted to answer this interview for the TechnicBRICKs readers.
We know you have been responsible for the LPF development. Can you tell us a bit more about your function and responsibilities at LEGO?

GM: I am heading up the team that works with technology platforms across the product areas of LEGO including LEGO Education. LEGO technology components are divided into the following platforms:

    All Technology components on the DUPLO platform (e.g. Light & Sound and DUPLO Train)
  • FX
    Simple self-contained functions like light, sound, wind-up, pull-back, fly-wheel and shooters

    Our pneumatic (air powered) system with pumps, pistons, air tank, hoses and valves

    Our electronic building system with battery boxes, motors, light, Remote Control, WeDo Hub and sensors

    Our Mindstorms robotics platform with Programmable Brick, motors and sensors

We work with these platforms to ensure that we deliver the right quality of functionality, building and play. The scope of the platform team is from early ideation to final design and functionality specification of a new LEGO technology component.

TBs: Does your scope of work also extend to the LEGO MINDSTORMS System (LMS) development and other somehow related products (e.g. WeDo and Energy elements from LEGO Education sets)?

GM: When we work with complex technology products such as LMS it is a cross competence teamwork. My team is involved in aspects of platform architecture, design and UI/BI. The WeDo and Renewable Energy products are done from the LPF platform.

TBs: Typically how much time does the development of a new system like LPF, takes from the initial concept till the market release into LEGO sets?

GM: When we are making a new technology platform like LPF or MINDSTORMS NXT it is important that we mature the platform architecture in good time before entering the process of making specific products on the platform. A platform architecture includes design guidelines, UI/BI, interface (like plug system, communication interface and - protocols) etc. When all this is done we can make specific components on the platform. The time it takes will depend on how complex the platform is.

TBs: Which was the main purpose and objectives to address when the PFS started to be developed (later released in 2007 with the LEGO Technic 8275 Motorized Bulldozer)?

GM: The 9V system was limited by the 2 wire architecture. In the LPF platform we implemented a 4 wire architecture with separate power supply and control line. The power supply runs unbroken throughout an LPF construction. This separation enables us to use the control line (C1/C2) in many different ways. It can be simple power drive of a motor, function control (like in the LPF Servo) or more advanced communication. The first new thing we introduced with the LPF platform was the modular Remote Control system.

This was the LEGO Technic set where the new PF elements were first introduced in 2007.

TBs: The PFS opened a wide range of possibilities via the several elements that comprise the system.
How do you choose and prioritize the new elements to develop and to integrate into the system?

GM: When we developed the LPF platform architecture we also did a mapping of all sorts of possible LPF components. Since then we have been filling in with new ideas and most of them are prototyped for further exploration. So…we have lots of goodies on the shelves. A new LPF component is launched when there are enough new products wanting to use it. The investment must be justified by the volume of use.

TBs: Does LPF comprise both active and passive elements? In other words, do passive elements like the Linear Actuators (61927c01, 92693c01) also belong to the LPF family of elements and consequently to its development?

GM: The Linear actuators do not belong to LPF but to the FX platform. We have decided to build a design relationship between LPF and a range of the FX components. This is done to emphasize the functional relationship.

TBs: Since new pneumatic elements have been developed for the 8110 Mercedes-Benz Unimog U400, are the pneumatic elements also actually scoped within the LPF development somehow?

GM: The Pneumatic platform is also part of our responsibility. It plays a key role for LEGO Technic and LEGO Education. Also here we have a range of functional possibilities in the platform roadmap.

TBs: Why does LEGO actual electric and robotic building systems like LPF, LMS and WeDo, differ so much? Why don't we have a better integration among all them in order to offer a more homogeneous active building system and better LEGO experience?

GM: Earlier we had one electric platform: The 9V System. This gave a lot of great electronic functionality and this was where Mindstorms started with the RCX.
Working with the 2006 platform upgrade for Mindstorms made us realize that the 9V System would not be able to give us the functionality we wanted for Mindstorms – this resulted in the MS-NXT platform we know today.
Also, as I mentioned earlier, the 9V System would not deliver the electric building system we wanted in the future – this was leading to the LPF platform with the 4-wire plug.
The MS-NXT and LPF platforms have a range of conflicting demands on functionality. All those taken into account the best solution was to make 2 separate platforms each with their own design expression and connection interface. Where it makes sense we have consistency between the 2 platforms e.g. on motor control.
WeDo is made on the LPF platform and if expansions are made in the future it will still be within the LPF platform.

TBs: As Product Manager don't you see a benefit in such approach and optimization? Are these differences made on purpose (why?), or either it would have meant a much higher development cost to design a common control system, rather than a different one for every single platform?
Was it ever considered such common approach?

GM: See above.

TBs: As you know, there are many other elements that LEGO Technic fans would like to see developed and officially added to the PFS. Hopefully some of them are already on your drawing board…
In between we're now going to assist the release of two new motors to the LPF line-up, with the 9398 4x4 Crawler, which might be serving new and demanding requirements - The L-Motor and the PF Servo Motor.
How does the L-Motor positions among the rest of the PF motors (E, M and XL)? Which are the characteristics and main applications for this new motor?

GM: The LPF Large motor is taking over where the LPF Medium motor is not strong enough. The size and BI makes it very usable where space is too tight for the XL motor. It has a compact 3x3 BI in the front and back. At the body it is 3x4 modules.

Overall unit size is (3+0,5+0,5)x3x7 modules.

TBs: And what about the PF Servo motor? Is it designed to offer proportional control or is it a full left/right with return-to-center motor?

GM: The LPF Servo motor has front and back outputs giving an easy build of e.g. 4-wheel steering.
The output can, from its center position, turn up to 90 degrees clockwise and counter-clockwise with 7 steps in each direction. In total you have 15 positions:

  • 1 center position
  • 7 positions clockwise
  • 7 positions counter-clockwise
When the Servo Motor is controlled with full power in either direction it will turn to the full 90 degrees position (for example with the IR Remote Control).
When it is controlled with power steps in either direction it will turn through the 7 positions corresponding to the 7 power levels (for example with the LPF Speed Remote Control or the LPF Rechargeable Battery box).

From the explanation above, new PF Servo motor does feature proportional turn, with PWM control devices like 8879 Speed Remote or 8878 Rechargeable Battery Box.
If controlled via the 8885 bang-bang IR Remote Control, it also features return to center when the remote is not actuated.

Overall unit size is 5x3x7 modules.

TBs: Do you think we have now a suitable and complete range of LPF motors to satisfy the builders’ needs and applications, or do you identify still some gaps in the LPF motors range? Which?

GM: For the Technic area we have a lot of possibilities with the current range. It will be exciting to see future MOC’s with the LPF Servo motor. We could imagine a smaller LEGO System motor. Maybe we should ask your readers what they think?

TBs: The LPF Rechargeable Battery Box has a security but quite inconvenient feature for the AFOLs use at exhibition displays, which turns OFF the battery after running continuously for about two hours, regardless of the charge level still remaining in it.
Have you considered including some "hidden" override mechanism (e.g. a key sequence) for the power users? Why not?
Wasn't it a safe and added value feature for this element?

GM: You are completely right: This would be a good feature and it is on our list when we update it. This power down override was implemented in the LPF AAA Battery box after launch of the rechargeable.
When the charger is on it will not power down.

From left to right we have the LPF Battery Boxes per release order (8881, 8878 and 88000). Like with NXT brick, the last two batteries implement auto turn OFF feature, after approx. 2 hours of continuous operation.
Only with the 88000 PF AAA Battery Box, the user can override this function - If you press and hold down the green button for more than 3 seconds the green light will blink to indicate that auto turn OFF is disabled. This means that a motor will run until the batteries are empty. To enable again turn the AAA Battery Box OFF and ON again.

TBs: Because fans are always eager to give their contribution and suggestions, I'll ask you if the LEGO CUUSOO platform is the most appropriate to raise ideas for potential new LPF elements?
Is a widely supported and technically viable new idea for a new LPF element, something that LEGO would consider producing if proposed this way, or is it CUUSOO exclusively targeted for ideas regarding new LEGO sets?

GM: The investment into making a new LPF component is quite high and we are living with the product responsibility for a long period. Therefore there has to be LEGO products using the component in high volumes over a range of years before we will decide to launch it.
The best way of promoting ideas for new LPF components is to make a good component description with model and product ideas and send it through the LEGO Ambassadors. I would actually encourage you to do so. If the idea is good it will become part of our internal “goodies on the shelf” and might find its way to the shelf in the stores.

TBs: The proportional control allowed by the LPF RC protocol is an addition of great value! However the relative and low precise control delivered with the 8879 Power Functions IR Speed Remote Control dials, doesn't ease to take advantage from a full play experience, rather than absolute control dials or sticks would do.
Did you realize or gathered similar feedback on your tests? Was it on purpose or which are the advantages of using this solution? Why did you have not taken the absolute control way?

GM: A lot of generic control has been build into the LPF Remote Control protocol. When we make a specific LPF Remote Control handset we must make a lot of choices directed by the purpose of this handset. The main purpose of the LPF Speed Remote Control is to enable kids down to the age of 6 to control trains. At the same time of course it is a general purpose power level Remote Control in the LPF platform. Using absolute power control with a speed dial works very well when you have a hardwired solution like the 9V train. In a Remote Control system with multiple channels it becomes inconsistent:
I have a train on channel 1, I turn the speed dial to +5. I change to another train on channel 2. The speed dial says +5, but the train is not moving!? Well, I just want the train to back up slowly. I turn the speed dial back…to +4 – now the train runs fast forward! I turn back to channel 1. This train is still running at +5 but the dial says +4.
By using Increment/Decrement and forced STOP the train itself will always be the reference and that works very well for the younger kids controlling trains. In the future we might launch other types of controls. As you know, the LPF Remote Control protocol is open source, so you always have the option of making your own AFOL community super controller.

TBs: BTW, we are still waiting for a few goodies from you…
  • A PF Programmable Sound Brick
  • A PF Programmable Light Brick
  • A PF Electric Linear Solenoid Actuator (compact size)
  • A PF Electric Pneumatic Valve (3/4-way) (compact size)
  • A PF Integrated Electrical Pump
  • A PF BT Receiver to integrate with the NXT brick, smartphones, tablets, or any other dedicated remote to develop.
  • Last but not the least, the still missing PF S-Motor or u-Motor, to fill the gap and replace the old and beloved 9V Micromotor
  • And alike…

GM: As I said: We have a lot of goodies on the shelves and things in the pipeline for launch. Of course I cannot disclose any of that, but keep the good ideas coming.

TBs: Many thanks for your time and having accepted to answer our questions!

GM: Thanks to you as well Fernando. It was great talking to you!

Now I leave you with some additional information obtained after the original interview questions.

  • The new 9398 4x4 Crawler is released with a new version of the RC Receiver (6020086), which got a "V2" label printed.
    The newest RC Receiver was upgraded with a CMOS motor driver giving less power loss.
    This upgrade with a new CMOS motor driver is not directly connected with the release of the new LPF L-motor, but LEGO has been looking for this opportunity for a while and now the right driver is available.
    The timing is however  connected with the launch of the 9398 4x4 Crawler, and the new RC Receiver enables two PF L-motors to be connected to the same output on the RC Receiver. This is not possible with the earlier RC Receiver versions released! (4506085, 4566756)

    RC Receiver was first modified in 2009, when support to 'access to extra address space' was implemented and a minor fix related with a 'single pin mode' design flaw. By that time the LPF RC Protocol was also updated and new documentation was released (version 1.10).
    This documentation was later found to be incorrect and a new document with the protocol description was then released in 2010 (version 1.20).

    The current hardware change to the RC Receiver is released with no further modifications to the LPF RC Protocol.

    The new receiver got a "V2" label just because the first upgrade in 2009, was purely a firmware change.

    So we have now the following list of LPF RC Receivers released:

    • Element ID 4506085 - Original hardware, with RC Protocol firmware version 1.00 (released in 2007).

    • Element ID 4566756 - Original hardware, with RC Protocol firmware version 1.20 (released in 2010).
      Distinguishes by: LED double blink on startup.
      4566735 is the element ID for the corresponding set (8884-1) sold separately.

    • Element ID 6020086 - Second hardware, with RC Protocol firmware version 1.20 (released in 2012).
      Hardware modifications: New CMOS motor driver with lower power loss.
      Distinguishes by: LED also blinks twice on startup and "V2" printed label on the front.

  • Regarding concerns about eventual center drift of LPF Servo motor - This motor has a fixed zero detection point and there will always be a certain tolerance and hysteresis. These will in most cases be below the slip of practical Technic gearings.

For any other questions you might have about LPF, you may also want to read the FAQ published at LEGO website.

Later I'll publish here at TBs a table with comprehensive information and characteristics of all the LPF RC Receivers and Battery Boxes.


TechnicBRICKs said...

The Linear Actuators and Pneumatic Pump images used in this post, were prepared from images kindly provided by iLe90s store on eBay.

Many thanks, Mauricio!

Allanp said...

Good read, thanks for posting. Nice to see the reciever has been given an upgrade to handle more power.

santi said...

The positive thing I get from the interview is that he mentioned a S-motor himself before you asked :)

The negative is that he doesn't think CUUSOO is the right way to propose new PF elements, and so that wonderful project for the XS-motor in CUUSOo has no chances :(

Dave said...

What a great article! It answers a lot of questions. Thanks, Fernando!

Ian said...

I'd like to see clutch gears in the bevelled format (so I can actually fit one in a 3 stud gap!), and also a new gear selection system that is not an even numbered amount of studs. A gear toggle arrangement that fits in the current "odd" numbered system would be heaven!

Alex Campos said...

That's a truly great and informative interview! I love knowing these details and the general feeling of "this is an open system, the possibilities are limitless".

Regarding the smaller motor, I definitely think it is a good idea! The old 9V micromotor, even though small and underpowered, is very handy for applications that require small size and/or weight, and currently there is nothing like it on the LPF platform.

Still going small, one thing I liked about the old 9V system was its seamless integration with standard LEGO System elements. I think a new LPF version of the Light & Sound system (with small battery box (possibly containing three 3V lithium batteries), lights with flashing effects and sound elements), would greatly benefit small Technic models and System models in general. A great example of the kind of stuff that is possible with the 9V system but not yet with LPF is the 6484 F1 Hauler, with cleverly hidden power, light and motor functions in a small model.

Like others, I would also welcome a more integrated approach to the integration between the Pneumatic and LPF platforms: a compact PF pump, a switch (possibly using a simplified version of the new PF Servo), and a safety cutoff valve (working like the current Pole Reverser, but with a pneumatic input that triggers beyond a certain pressure instead of a manual lever).

Finally, and given the surfacing of the new Servo I wouldn't be surprised if it were already under development, a new remote control would be nice. It could be a cross between the two existing remotes: based on sticks with return-to-neutral, but with proportional control instead of either full off or full on. Indeed, it could be expanded into something with dual X-Y sticks like RC helicopter controllers, each one configurable for one LPF channel. Or it could be modular, with a central module containing the transmitter and the batteries, and several types of add-on controls (sticks, knobs, etc.) that connect to it and receive human input. Or, going in the opposite direction of more centralisation, it could be given more "intelligence" and be able to record/playback sequences of controller inputs, to automate models: a bit like a Power Functions version of the old Control Centre...

Like I wrote at the beginning of this comment, the possibilities are limitless! :)

santi said...

Every time I check this page I can't help but grow more eager to get my hands on these new motors. Can anyone remind me when is the new Crawler set going to be generally available for purchase worldwide? (I keep checking BrickLink, but these new motors havent't shown up yet!! :))

TechnicBRICKs said...


I believe it will be available from in August.

BrickLink shouldn't help for now. The way it is now, not even new LEGO elements are being added to the database. So even if anyone had them to sell the won't ba able to.
Hopefully it will be fixed soon.

santi said...

Thanks! I guess I can wait a month... :)

DanielM said...

Great interview! I would love to see a small "s" motor.

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