Tachometer +




Tachometer -


Toint 0
 variable:
 tachometer:
 output:
 drive ratio:
 filter gain:
Toint 1
 variable:
 tachometer:
 output:
 drive ratio:
 filter gain:
Toint 2
 variable:
 tachometer:
 output:
 drive ratio:
 filter gain:


V0
Servo-Tek SU-780D-1
45 volts per 1000 RPM
1:1
10

V1
Servo-Tek SU-780D-1
45 volts per 1000 RPM
1:1
10

V2
Servo-Tek SA-740A-2
7.0 volts per 1000 RPM
1:1
5


Figure 4.22. Circuit diagram of the tachometers.


 For joints 0 and 1, Servo-Tek D series tachometers were chosen (Figure 4.22). The shaft

of each tachometer was directly connected to the mounting shaft of the link so that any motion

of the link created a voltage across the tachometer. Using 12-bit A/D converters and a software

filter with a gain of 10, the resulting resolution of the tachometers was 30.7 bits per degree per

second (0.033 degrees per second per bit). The velocity of the sliding tube was determined by a

Servo-Tek model SA-740A-2 tachometer. The 740A tachometer was mounted on the back side of

the Hartmann motor but connected to the motor's shaft through the 1:1 miter gear. This

mounting arrangement allowed the linear velocity of the sliding joint to be measured by the

angular velocity of the tachometer. A 12-bit A/D converter and a software filter with a gain of

5 were used to quantify the tachometer voltage. The resolution of the velocity sensor for the