Automated Trucks 2022
The attempt use Kineysys Motors to move 'Merrily We Roll Along' Set pieces across the stage...
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General Info
The director requested that all props and set movements be done by cast. No crew were to be seen on stage at any point. This left lots to ssort out as the downstage truck was only 600mm high and needed to travel both US and DS. The plan is for the truck to be made out of 4 bits of steel deck, double layered, this roughly puts it at 0.5 Tonne. The original idea for this truck was to use a manual Flints truck winch and operate it from the wing off stage.
Upon drawing up the plans for this, we wondered if programmed correctly we could use one kinesys motor for US pull and one motor for DS pull. We knew the risks that two motors pulling against each other could have and ensured the cues for the show were Pre Programmed in advance. We then ran the cues with the motors in position without connecting them, ensuring the cues were programmed correctly. This became the sole showfile with one backup identical copy made
Our biggest challenge was overcoming the pulling force of the motor on the floor. The motor was rigged normally, onto the I beam under the fly floor. This is where angle factor played a huge part.
Angular vector forces occur when ropes/wires are passed through a directional pulley. Dependent on the angle created, this can have a multiplying effect on the forces that are felt at the deviation or directional pulley components and the associated anchor points. For example, if you attatch a stage weight to a line with a pulley directly above it, and you pull on the line, that would be an Angle of 0 degrees and an angle factor of 2.
As the table below states, an angle of 90 degrees, which is the angle our steel wire ropes path took to connect to the truck, would = an angle factor of 1.41
Our largest truck was expected to be 1200Kg and in testing the force needed to move the truck from stationary with the kinesys motor this - at its peak- was 80Kg. To do this we used a Load Cell.
Now that we have our Load (80Kg), we can use L x A = S, Load X Angle Factor = Stress, this was (80Kg X 1.41 = 112Kg). This was more force than we were comfortable pulling on the floor.
We figured out the best solution was to add in an additional divert pulley to decrease the size of the 90 degree angle to two 135 degree angles.
This reduced our calculation to (80 X 0.76 = 60.8Kg), a number we were much happier with after numerous tests with the load cell
Force is an influence that has both magnitude and direction, it is usually given in the dynamic unit of Newtons (N). For ease of explanation, we have used kilograms on this page.