Elbow controller

The idea of controlling the whole arm and assist manipulation in humans lacking shoulder and elbow control is getting more attention recently by the research team at the Case Western Reserve University (CWRU) in Cleveland, OH [36-39]. The system was designed to combine a fuUy implantable grasping system with some additional channels to control elbow extension, flexion, and shoulder movements. The control of reaching, unlike the control in the BGS NP, measures the position of the arm in space and for certain arm positions automatically triggers stimulation of the triceps brachii m. 

For prosthetic arms to be more than just position controllers for portable vices, multifunctional mechanisms that have the ability to have multiple degrees of freedom controlled simultaneously (in parallel) in a subconscious manner need to be developed. Current commercially available multifunctional controllers are generally sequential in nature and take the form of two site, three state multifunctional controllers. Motion Control, Inc., in the ProControl hand-wrist controller, uses rapid cocontraction of the forearm extensors and flexors to switch control between hand opening and closing to wrist rotation. Otto Bock uses a similar control strategy in its wrist-hand controller. Motion Control, Inc., in its elbow controller, uses dwell time (parking) to switch from elbow flexion and extension to hand opening and closure and cocontraction of biceps and triceps to switch control from the hand back to elbow. 

The Advanced Inspection Robot - AIR-1 is a portable (weight approx. 25 kg.) 6-axis articulated elbow type robot manipulator with 6 degrees of freedom. It is build from standard motor and control module components from FORCE Institutes Modular Scanner System and is controlled from within the UltraSlM/UlScan graphical generic robot control application. 

If the regulatoiy control system were perfect, the target could be set exactly equal to the constraint (that is, the target for the pressure controller could be set at the vessel rehef pressure). However, no regulatory control svstem is perfect. Therefore, the value specified for the target must te on the safe side of the constraint, thus giving the control system some elbow room. How much depends on the following ... 

Current designs for venturi scrubbers generally use the vertical downflow of gas through the venturi contactor and incorporate three features (I) a wet-approach or flooded-waU entry sec tion, to avoid dust buildup at a wet-dry pmction (2) an adjustable throat for the venturi (or orifice), to provide for adjustment of the pressure drop and (3) a flooded elbow located below the venturi and ahead of the entrainment separator, to reduce wear by abrasive particles. The venturi throat is sometimes fitted with a refractoiy fining to resist abrasion by dust particles. The entrainment separator is commonly, but not invariably, of the cyclone type. An example of the standard form of venturi scrubber is shown in Fig. 17-48. The wet-approach entiy section has made practical the recirculation of slurries. Various forms of adjustable throats, which may be under manual or automatic control. 

Example The maximum flare load of a system is 1,000,000 Ibs/hr of vapor. The pressure at the base of the flare stack is 2 psig, the average molecular weight of the vapor is 50, at a temperature of 200°F at the combined header to the flare stack. The distance from the drum to the stack is 500 ft. The line consists of two 90° welding elbows and an orifice for a flow controller. The total pressure drop at the knock-out drum is 0.5 psi. Determine the pressure at the inlet of the knock-out drum. 

Assume the reboiler -will have a full shell diameter top outlet elbow vapor nozzle. Thus, a flux of (104,000) (0.90) or 93,600 Btu/hr (fP) is possible if steam temperature is adequate. At the latter flux, the fouled AT = 204°F. This -will require a steam temperature of 298 + 204 or 498°F equivalent to 693 psia steam. Because only 200 psig steam is available do-wnstream of the control valve at the chest, a lower flux must be used. 

The downstream pressure-sensing pipe of each valve is connected to a straight section of pipe 10 diameters or 1 meter downstream of the nearest tee, elbow or valve. This sensing line should be pitched down, to drain into the low-pressure line. If it cannot drain when connected to the top of this line it can often be connected instead to the side of the pipe. The pipe between the two control valves must be drained through a steam trap, just as would the foot of any riser downstream of the pressure-reducing station. 

The distillation column operates at a pressure of 500 mmHg (500 mm of mercury, absolute). The feed point to the column is 12 m above the base of the tank. The tank and column are connected by a 50 mm internal diameter commercial steel pipe, 200 m long. The pipe run from the tank to the column contains the following valves and fittings 20 standard radius 90° elbows two gate valves to isolate the pump (operated fully open) an orifice plate and a flow-control valve. 

You want to control the flow rate of a liquid in a transfer line at 350 gpm. The pump in the line has the characteristics shown in Fig. 8-2, with an 5 in. impeller. The line contains 150 ft of 3 in. sch 40 pipe, 10 flanged elbows, four gate valves, and a 3 x 3 control valve. The pressure and elevation at the entrance and exit of the line are the same. The valve has an equal percentage trim with the characteristics given in Table 10-3. What should the valve opening be to achieve the desired flow rate (in terms of percent of total stem travel) The fluid has a viscosity of 5cP and a SG of 0.85. 

A liquid with a viscosity of 25 cP and an SG of 0.87 is pumped from an open tank to another tank in which the pressure is 15 psig. The line is 2 in. sch 40 diameter, 200 ft long, and contains eight flanged elbows, two gate valves, a control valve, and an orifice meter. 

When a flow sensor is installed for accurate accounting measurements of the absolute flow rate, many precautions must be taken, such as providing a long section of straight pipe before the orifice plate. For control purposes, however, one may not need to know the absolute value of the flow but only the changes in flow rate. Therefore pressure drops over pieces of equipment, around elbows or over sections of pipe can sometimes be used to get a rough indication of flow rate changes. 

The solids flow rate can be controlled by nonmechanical valves such as the L-valve, as noted in Chapter 8. The L-valve has a long horizontal leg. Thus, it is convenient to characterize the pressure drop across an L-valve by two terms. One term is the pressure drop through the elbow (A/ V). This term can be described by the equations developed for the mechanical valve because the solids flow patterns between the two are similar... 

The elbow test involves applying products to the inside of the elbow up to six times per day for three weeks. This is a sensitive area of skin, and easily defined, which is important since this is a selfapplication test. This test is useful for products such as body lotions, etc., and also as a preliminary to a face test, where the skin is more sensitive. Each panellist serves as their own control the test material is applied to one elbow and the control material applied to the other. The panel is balanced according to sex, hand dominance, and initial skin grades of reaction. One half of the panel has the dominant hand allocated to the test material, and the other half has their dominant hand allocated to the control material. The levels of irritation elicited by the test and control treatments are compared. Subjective comments are also taken into consideration. At intervals throughout the treatment period, each site is assessed for visible signs of irritation, for example, erythema and dryness. 

For control valves and other areas of high-turbulence (velocity 8 ft/s [2.5 m/s]) (I e, downstream of control valves, rich carbonate inlet of carbonate regenerator, reboiler tube sheet, and baffles), use type 304 SS plus i/32 in, (1 mm) CA Do not use miters long radius elbows are preferred. See piping specifications for other limitations on miters. 

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