1. A method for simplifying a Viterbi decoder, comprising:
receiving a partial response, and determining an amount of redundant selector modules according to a tap number of the partial response;
analyzing an output signal of the redundant selector modules for determining an initial input signal; and
taking Viterbi decoding process to a sequence of data in the Viterbi decoder according to a forward trace status and the initial input signal.
2. The method of claim 1, wherein the amount of the redundant selector modules equals the value of subtracting a specific value from the tap number of the partial response.
3. The method of claim 2, wherein the specific value is greater than or equals to 2, but no more than the value of subtracting 1 from the tap number of the partial response.
4. The method of claim 1, wherein the initial input signal is the output signal of the redundant selector modules.
5. The method of claim 1, wherein the Viterbi decoder is set in a high-density digital-versatile-disc (HD-DVD) drive for taking Viterbi decoding process to the sequence of data.
6. The method of claim 5, wherein a path memory module of the Viterbi decoder comprises 17 selector modules.
7. The method of claim 5, wherein the initial input signal of the first-stage selector module of the path memory module in the Viterbi decoder is (0,0,0,0,0,1,1,1,1,1).
8. A method for simplifying a Viterbi decoder, comprising:
determining an amount of redundant selector modules (Nrs) according to a tap number of a partial response (Tap);
analyzing an output signal of the redundant selector modules for determining an initial input signal; and
taking Viterbi decoding process to a sequence of data in the Viterbi decoder according to a forward trace status and the initial input signal.
9. The method of claim 8, wherein the amount of redundant selector modules (Nrs) is determined by the following:
Nrs=Tap\u2212k
2\u2266k<Tap
where k is an integer, Nrs is the amount of redundant selector modules and Tap is the tap number of the partial response.
10. The method of claim 8, wherein the initial input signal is the output signal of the redundant selector modules.
11. The method of claim 8, wherein the Viterbi decoder is set in a high-density digital-versatile-disc (HD-DVD) drive for taking Viterbi decoding process to the sequence of data.
12. The method of claim 8, wherein the initial input signal of the first-stage selector module of the path memory module in the Viterbi decoder is (0,0,0,0,0,1,1,1,1,1).
13. A simplified viterbi decoder, comprising:
an add-compare-select unit for determining path metrics of a input signal; and
a path memory module for receiving a plurality of state values calculated by the add-compare-select unit;
wherein the path memory module includes a plurality of selector modules in a series connection, wherein an amount of the selector modules is determined by a tap number of a partial response and an initial input signal.
14. The simplified viterbi decoder of claim 13, wherein an amount of redundant selector modules (Nrs) is determined by the following:
Nrs=Tap\u2212k
2\u2266k<Tap
where k is an integer, Nrs is the amount of redundant selector modules and Tap is the tap number of the partial response.
15. The simplified viterbi decoder of claim 13, wherein an amount of registers which are removed in a first-stage of the selector modules is determined by the initial input signal.
16. The simplified viterbi decoder of claim 13, wherein the initial input signal is an output signal of the redundant selector modules.
17. The simplified viterbi decoder of claim 15, wherein the initial input signal of the first-stage of the selector modules is (0,0,0,0,0,1,1,1,1,1).
18. A simplified viterbi decoder in HD-DVD, comprising:
an add-compare-select unit for determining path metrics of a input signal; and
a path memory module for receiving a plurality of state values calculated by the add-compare-select unit;
wherein the path memory module includes a plurality of selector modules in a series connection, wherein an initial input signal of a first-stage of the selector modules is (0,0,0,0,0,1,1,1,1,1).
19. The simplified viterbi decoder of claim 18, wherein the path memory module includes at least 17 selector modules.
The claims below are in addition to those above.
All refrences to claim(s) which appear below refer to the numbering after this setence.
1. A medical instrument comprising:
a first clevis having a first body and a first pin, the first clevis being attached to a base so that the first clevis can rotate about a first axis, wherein the first body includes a plurality of guide channels;
a first jaw attached to the first clevis so that the first jaw can rotate about the first pin; and
a first cable and a second cable attached to the first jaw and routed through the guide channels in the first clevis, wherein pulling the first cable and relaxing the second cable causes a first torque that tends to rotate the first jaw about the first pin, pulling the first and second cables causes a second torque that tends to rotate the first clevis about the first axis, and contact of the first and second cables on surfaces of the guide channels determines a moment arm of the second torque.
2. The instrument of claim 1, further comprising:
a second jaw attached to the first clevis so that the second jaw can rotate about the first pin; and
a third cable and a fourth cable attached to the second jaw and routed through the guide channels in the first clevis, wherein pulling the third cable and relaxing the fourth cable causes a third torque that tends to rotate the second jaw about the first pin, pulling the third and fourth cables causes a fourth torque that tends to rotate the first clevis about the first axis, and contact of the third and fourth cables on surfaces of the guide channels determines a moment arm of the fourth torque.
3. The instrument of claim 2, wherein the first and second cables are opposite ends of a first loop of cable, and the third and fourth cables are opposite ends of a second loop of cable.
4. The instrument of claim 2, wherein the base comprises a second clevis having a second pin, wherein the first clevis is attached to the second clevis so that the first clevis can rotate about the second pin and thereby rotate about the first axis.
5. The instrument of claim 4, further comprising:
a tube having a first end attached to the second clevis, wherein the first, second, third, and fourth cables extend through the tube; and
a backend mechanism attached to a second end of the tube, wherein the backend mechanism mechanically couples the first, second, third, and fourth cables to three rotational axes.
6. The instrument of claim 2, wherein the first torque and the third torque cause the first and second jaws to close on each other, the first cable has a portion that is stiffer than a corresponding portion of the second cable, and the third cable has a portion that is stiffer than a corresponding portion of the fourth cable.
7. The instrument of claim 1, wherein the cables follow path from the first jaw to the base, in which the cables contact the surface of the first clevis without contacting a pulley.
8. The instrument of claim 1, wherein the guide channels includes a first guide channel through which the first drive cable runs, wherein the first guide channel has a solid surface shaped as a circular arc, and the first drive cable rides on the solid surface.
9. The instrument of claim 1, wherein the first and second cables are opposite ends of a loop of cable.
10. A medical instrument comprising:
a first clevis having a first pin;
a second clevis rotatably mounted on the first pin, the second clevis includes a second pin, a first guide channel, a second guide channel, a third guide channel and a fourth guide channel;
a first jaw rotatably mounted on the second pin;
a first cable that extends through the first clevis, rides on a first solid surface that is part of the first guide channel, and attaches to the first jaw;
a second cable that extends through the first clevis, rides on a second solid surface that is part of the second guide channel, and attaches to the first jaw;
a second jaw rotatably mounted on the second pin;
a third cable that extends through the first clevis, rides on a third solid surface that is part of the third guide channel, and attaches to the second jaw; and
a fourth cable that extends through the first clevis, rides on a fourth solid surface that is part of the fourth guide channel, and attaches to the second jaw.
11. The instrument of claim 10, wherein each of the first, second, third, and fourth solid surfaces is shaped as a circular arc centered about the first pin;
12. The instrument of claim 10, wherein pulling on the first cable and the second cable while releasing the third cable and the fourth cable, causes a torque that tends to rotate the second clevis about the first pin, and contact of the first and second cables on the first and second solid surfaces determines a moment arm of the torque.
13. The instrument of claim 10, wherein pulling in a length of the first cable while releasing the length of the second cable, causes the first jaw to rotate, the first cable to slide on the first solid surface, and the second cable to slide on the second solid surface.
14. The instrument of claim 10, wherein the first and second cables are opposite ends of a first loop of cable, and the third and fourth cables are opposite ends of a second loop of cable.
15. A method for operating a wrist mechanism, comprising:
pulling on a first cable and a second cable that are attached to a first jaw that is rotatably mounted on a first pin in a clevis, the first and second cables respectively resting on first and second guide channels that pass through the clevis, wherein pulling on the first and second cables causes a first torque on the clevis, the first torque causing the clevis to rotate about a second pin and having a moment arm that depends on a distance from the first and second guide channels to the second pin; and
pulling on the first cable while releasing the second cable, wherein pulling on the first cable and releasing the second cables causes a second torque on the first jaw, the second torque causing the first jaw to rotate about a first pin.
16. The method of claim 15, further comprising pulling on a third cable and a fourth cable that are attached to a second jaw that is rotatably mounted on the first pin in the clevis, the third and fourth cables respectively resting on guide channels that pass through the clevis, wherein pulling on the third and fourth cables causes a third torque on the clevis, the third torque being opposite to the first torque and causing the clevis to rotate about the second pin and having a moment arm that depends on a distance from the third and fourth guide channels to the second pin.
17. The method of claim 16, further comprising changing a grip of the first jaw relative to the second jaw by pulling one of the first and second cables while releasing another of the first and second cables and pulling one of the third and fourth cables while releasing another of the third and fourth cables.
18. The method of claim 16, further comprising changing a yaw of an effector including the first and second jaws by pulling one of the first and second cables while releasing another of the first and second cables and pulling one of the third and fourth cables while releasing another of the third and fourth cables.