MIT LEG LAB BIPED JOURNAL. began on 04.99 and backdated some...
05.30.99 some picture here some picture here

A CAD model of the entire biped(minus a leg of course) and a close-up of the upper body without the shell. There are simplified actuators in the assembly. All degrees of freedom have fully defined actuation schemes with limit stops. The electronics are missing and the shell interferes a bit with the yaw actuators. As well, the exact mechanism for attaching the external frame to the internal frame is uncertain. This assembly is completely independant from the 10.98 assembly. The only pieces they share are carbon fiber tubes.
04.10.99 some picture here

A CAD model of the biped thigh and hip. There are two simplified FrAP's in the assembly which drive the hip pitch and knee pitch. The hip pitch is a cable system and the knee pitch is a direct attachment drive system with a rodend. The knee pitch actuator is mounted on a pivot and the hip pitch actuator is fixed to the thigh frame. The hip assembly includes limit stops for pitch and roll. It also includes an off-the-shelf double pack angular contact bearing mount which attaches the leg to the body.
01.25.99 some picture here

A CAD model of the biped shin and foot. As opposed to the Leg-uator design, these actuators are self contained and do not share structure with the robot leg. The actuators are mounted by a universal joint on the shin and attached to the foot below the ankle with a ball and socket(a rod-end) Driving the actuators together actuates ankle pitch and driving them in opposite direction creates ankle roll. The six axis force sensor has been replaced by four single axis load cells as mentioned in the previous foot prototype. A more detailed picture of the FrAP can be found on the main biped page.
11.98 some picture


Preliminary size and weight specifications used for early M2 computer simulations and for keeping designers in check. The specifications are based on preliminary actuator weight estimates. Each actuator is about 2.5 lbs. The link lengths are based on those of a 50th percentile US male. If the JPG is not readable, try this .tif.
11.07.98 some picture


A prototype of a foot design. The foot has a passive toe joint. The toe joint is constrained by a limit strap which defines the maximum flexion angle and a spring which returns it to flat when unloaded. It is sized after a 50th percentile human foot. It has four contact points. One at the heel and three points in the toe area. This might seem overconstrained but if the roll degree of freedom is force controlled the foot will flatten itself.
10.98 some picture here

A Preliminary CAD Assembly of the robot M2. Assmebly is missing many details but contains all the major elements of the robot design. The actuators in this assembly are an integral part of the leg design. The actuator and legs share common structural elements. There is a six axis loadcell in the foot just below the ankle. The hip is just short of one meter high. There are four actuators in the body(hip yaw & roll) and four actuators in each leg: hip pitch and knee pitch in the thigh, ankle pitch and roll in the shin.
09.10.98 some picture here

A possible hip actuation scheme. There are six linear series elastic actuators within the body of the robot. The blocks are meant to represent the thighs of the robot. The two vertical actuators in the foreground actuate the hip pitch(flex/extension). The two vertical actuators slightly in the background actuate the hip roll(ab/adduction). The two horizontal actuators actuate the hip yaw. The ordering of the axes is yaw, roll and then pitch. The yaw and roll axes are essentially a universal joint. The pitch axis is about 1" below the roll axis.
08.18.98 some picture here

The Leg-uator. A preliminary model of the shin and foot of the robot. The assembly is slightly incomplete so don't take it literally. There are two actuators side by side in the shin of the robot. The actuators share a frame with each other and the leg. The frame consists of three carbon fiber tubes. The actuators have a motor, belt drive, ballscrew, and springs on the axis of the ballscrew. The actuators drive cables on a offset axis universal joint(thru additional carbon fiber tubes, only shown on one side). Below the universal joint is a six force/torque load cell to measure the ground contact forces on the foot.
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