The ankle joint range of motion and homing

Support & Troubleshooting Hardware
1

Hi. After running homing_joint.py in either direction for the ankle joint in either direction and then reading_sensor_data.py to read the encoder position, I get,

Dorsiflexion: 36.4 degs

Plantarflexion: -7.6 degs

The RoM of is 44 degs. This is different from the current specs on the website specify a range of 60 degs (-30 to 30 degs). Is this normal?

I should note that during homing, if I command the position to the middle of this range (14.4 deg), it does appear that foot is flat (so the range would be -22 to 22).

Thanks!

2

Hi malizade, This is not normal you should get 60 deg ROM.

First check if there is nothing that could block the joint and reduce the ROM. Otherwise pay attention, that the motor_position attribute is expressed in the motor frame and not joint frame.

If possible, check your ROM with your joint encoder.

Best regards, Louis

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3

Thanks! From the outside, there does not seem to be anything constraining the joint’s movement.

@senthur Can you confirm the [-30, 30] RoM? We bought the OSL in 2022, so maybe the design has been updated?

4

Never mind, when I was calculating the RoM, there was a mix up with output_position, motor_position, and their units, as @ldevillez helpfully suggested.

5

Hey Mohsen, the hard stops are built into the housing. There is a slot on the housing that limits the ROM of the ankle output pulley to [-30, 30].

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