Beefing up the Hip Suspension

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dsc03364Once I started to traverse over obstacles with a fully loaded torso and the robot was being shaken I noticed that the gas shocks were not keeping the torso/hip level. At first I thought I had sheared the cross bolt to the hip motor cam on the Dewert motor but upon careful examination that was not the case. The gas shocks were not strong enough so I  replaced the 4420 gas shocks (which were only giving approximately 25lbs of lift support each) with the Mightly lift model numbers E 95859 (4048)  which yielded approximately 60 lbs of lift for each shock. (remember there are 2 shocks used for the hip)However this was too much for the dewert motor to move but it did flex the aluminum sub waist plate! So I tried 40 lbs shocks. Those work good but they are not the best. I need to review the physics books to figure out the optimal strut strength for a 100 lb load.  There has to be a math equation to figure this out. In the mean time I lengthened the long arm of the hip rotation assembly and shortened the cam to decrease the fulcrum effect on the motor so the downward weight of the torso would not have as great of an affect on the motor (so the motor would be more effective as a brake when not in use). It still may be necessary to find a motor that has a brake but time will tell……

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B9 Electronics: The Inside Story Part 3 – Leg, Hip & Waist

OK, fair warning now… the further we go up, the more complicated the electronics become… sort of…Again, this is what I did. There are several ways to “skin a cat” and this is one of them……
My hip section moves up and down to simulate a power failure from a power pack pull out as well as to bow to pick things up, address royalty, etc. The motor to rotate the torso is also located in the hip section. This is a departure from Mike Joyce’s replica robot where the waist rotation motor is actualy inside the torso. The motors used for both the hip and waist rotation is the Dewert 24v motors. Each one is controlled by a Vantec RET 411P single motor controller. These plug in to the RC receiver. I fused each RET 411p to protect it from any overload or spike from the batteries, etc. The manual for the RET 411P is located on the Vantec web site at http://www.vantec.com/retman98d.pdf. It is a very straight forward wiring procedure where the positive and negative leads of the motor are connected to the white and gray wires of the vantec controller. The black and orange wires go to the positive and negative leads of the battery. Note where the switch goes. I will use one of the switches inside of the programming bay to control hip and waist rotation. By switching them off I could save on battery power consumption and also serve as a safety control mechanism if I wanted to limit movement of my robot.

Hip Rotation Drive unit

I have had a few inquiries on how I was able to make my torso “whip” around as Bob May did in the Lost in Space series. What I did was first ask Andy Schwartz (an approved B9 vendor) to make a supersized waist gear so I could get an increase in RPM from the 24v Dewert motor to accomplish this. Thinking of the consequences of such a design I had to ensure safety for the visitors as well as for my robot. So I had James build in a spring loaded retaining mechanism to allow the gear to “skip” or “break away” if the robot were to meet any resistance (presumably from striking any object in the robots rotational path). It is tricky getting the right tension for the “break away” mechanism to function reliably because you also have to overcome the force to actually whip the torso around while “stalling” when hitting a stationary object. Added to that; the tension relief needed to install the torso gear to the leg section can be a challenge. One way I thought of overcoming the install issue is to have a special tool made to pull the gear out of position. I will work more on that later on in the build .

B9 going on a diet!

After I had the realization that my B9 was becoming a porker I decided to put him on a diet. A drastic diet!! I had James (my machinist) lighten the entire endoskeleton. Every rail, plate and bar was lightened. Every nut that could be removed was removed and threaded into the structure that could support it. Below are the before and after pictures of my “aluminum liposuction procedures”. It is beautiful isnt it?! Too bad it will be covered up with silicon rubber.


Mods R US

I did some additional changes to the articulating hip and leg assembly. I made the back area narrower as well and I did a re-orientation of the base plate for better wire feeding throughout the endoskeleton. In addition, standoffs were drilled and tapped for controller placements and wire feeding. I used patterns for an insulated standoff for the Vantec Controllers I will be using. I also made some changes to the torso rotation motor and mount. I will be using the RDFR23 for the foot drives and 1 RET411P for the hip motor and 1 RET411H for the Torso rotation motor. Instead of the friction wheel rotation method used by Mike, I will be re-orienting the motor and installing a hub and extra large gear for a very fast rotation direct drive so I can more precisely control the speed and whip around as seen in the series when Bob May would spin the torso around quickly. Speaking of Torso’s……. I also received the Replica Torso from Mike Joyce. I had purchased the club standard torso and had it professionally prepared by Richie. It was awesome but when I took it to be professionally painted the shop that did it used the wrong paint and solvent. The Torso started to melt. In their haste they tried to fix it but made it even worse so it was a total loss. A 2500 loss. Ouch!
So I am starting over again with a new torso and donut. As you can see to the left there is a side by side comparison of the club vs. the replica torso. This will present some new and additional challenges in that the replica torso is smaller so other items like the collar, vents, donut and neon base plate may require additional fitment. Only time will tell if I will need to make new components or if the smaller torso size will even be noticeable with existing parts. The Replica torso is the black one. The club standard is the gray one.
Also, here is the drive section that I created. This baby hauls a lot of weight (over 330 lbs) at parade speed with ease. It is smooth on acceleration and deceleration. For those who don’t know what that blue thing is on top of it, that is the infamous Mike Joyce Replica Soil Sampler (no longer available). All of this stuff fits inside of the tread sections. I will be redesigning the soil sampler so members will have an option later on.