Robotic Arms

Date: Thu, 2 Nov 1995 12:34:16 +0200 (EET)
From: Lahtinen Antti Jussi <al76188@cs.tut.fi>
Subject: Robotic Arms

	Robotic arms

	I was not satisfied with the rules for robotic arms that were 
	presented in Vampire Fleets. The main reason for this is that 
	according to these rules the robotic arms do not improve with 
	higher TL, while vehicle suspension and transmission values 
	improve. Even though robotic arm is more complex device than 
	walker legs, they should have many similar problems and 
	solutions.

	One additional requirement for robotic arms is the Cybernetics 
	rules in FFS. According to the Peripheral Options table (FFS 
	page 86) prosthetic replacement limbs "Utility Arm" appears at 
	TL-10, and pseudobiologic "slick" versions appear at TL-12. I 
	think that it should be possible to build these prosthetic 
	limbs with normal robotic rules.

	According to human taxometry, the average displacement of man's 
	arm is approximately 7 liters. This means that TL-12 prosthetic 
	arm for the average man should displece 7 litres, and should 
	have at least AGL-6 and STR-6.

	Quick-and-dirty design fix:

	TL	AGL	STR	Price
	8	10%	1	100
	10	9%	1.5	150
	12	8%	2	200
	14	7%	2.5	250
	16	6%	3	300

	AGL:	The percentage of total volume used per point of AGL.
	STR:	The amount of STR gained per liter devoted to strength.
	Price:	The price of one liter of robotic arm. Pseudobiological 
		versions will have the price multiplied by 8. 
		Prostethic replacements will also have extra price for 
		surgery, calibration and rehabilation.
	Mass:	The mass of an arm in kilograms is its volume in liters
		multiplied by 2 (as stated in VF, page 74).
	Power:	The power requirement for robotic arms is its volume in
		liters multiplied by 0.4 kW.

	According to this table, TL-10 AGL-6, STR-6 robotic arm would 
	displace 8.7 liters, and similar TL-12 arm would displace 5.8 
	liters. 


	Powering Robots

	Thought VF has ignored the power usage of robotic arm, the arm 
	must be somehow powered (this is major problem in modren 
	prosthetic technology, and different power sources and 
	transmissions are beign developed). However the required input 
	power shown above is only the peak power usage, required only 
	when the arm is used to move its maximum load at full speed. 
	Full input power could be required for cargo loading arms, but 
	it is highly unlikely that other machines would need this much 
	power.

	In my designs I usually build robots with PNF power plant, and 
	allocate the robotic arms only 20-50% of the their maximum 
	input power. Additionally I install an suitable battery that 
	can power the arms for a short time at full power. This means
	that the robot will use its arms with full power only when
	needed, and in other times the surplus power is loaded into the
	battery.

	I have noticed that battery-powered robots can be quite tricky 
	to use. A re-designed TL-14 Zhodani WarBot will exhaust its 
	batteries in few days if it is fully powering all its 
	components at the same time, but the same WarBot can be in 
	sentry mode for a few months (that is, powering only its brain 
	and passive sensors).

-- 
        Antti Lahtinen    :     Justice is Only a Wish of a Weak
        al76188@cs.tut.fi :