Industry and team examples

• note that DOF in gripper does not include the rotation of the gripper, that is an arm dof

Team	Year	SAR Score	Extreme Retrival Score	Equipment Servicing Mission	Picture	Number of Fingers in gripper	DOF in end effector	Allen Key feature	Other comments

Team	Year	SAR Score	Extreme Retrival Score	Equipment Servicing Mission	Picture	Number of Fingers in gripper	DOF in end effector	Allen Key feature	Other comments
Ryerson Rams Robotics	2019		90	77	Open	4	1	Not apparent	4 fingers make it easy to grab rocks They are lacking strength in the wrist
IMPULS	2019		80	69	Open	2	1	Not apparent	Very rigid stiff
PCz Rover Team	2019		80	42	Open	2	1	Not apparent	Interchangeable end nubs
Stanford Student Robotics	2019		64	57	Open	2	1	Not apparent	rubber band in v grove for compliance.
Michigan Mars Rover Team	2019		32	54.5	Open	2 - one fixed	1	Not apparent	no compliance? - didn't score well for extreme retrieval. perhaps it is correlated Arm is very interesting, no fancy links just direct drive through a gearbox. Not very aesthetic though.
Michigan Mars Rover Team	2020	96			Open	2	2	Allen key has its own lead screw on the outside of the claw. Might be off center of rotation	No slip ring wires allow a certain number of twists Wire management is also kinda a mess on this bot.
Stanford Student Robotics	2020	94				2	1	Allen key coupled with the central lead screw that controls the jaws	Wrist looks like it has no slip ring. Jaws fold back, exposing the allen key, and the axis 6 screws in the screw. Looks like a coaxial axle is used to control both axis 6 and the jaws.   They have a very good design.
BRACU University Mongol-Tori	2020	93			Open	2 shovels	1	Not apparent	Chain driven axis 6 is interesting.  piston rod driven gripper is also interesting. Allows for axis six to 'wrap around' it without any issues. A sort of mechanical slip ring.
Missouri S&T Mars Rover Design team	2020	93			Open	2 spring loaded	1	Opposite side of the differential. Looks like it has multiple tooling bits!	gripper looks like it only half works, as one complies fully and the other does not. 2 cameras for each tool which doubles the expense there. Nice small cameras though.
Mars Rover Manipal	2020	92			Open	2	2	Differential wrist with isolated Allen key with its own motor.	Very simple and cheap good design. Very epic CAD render transitions
Team Anveshak	2020	91			Open	2	2	Allen Key is 90° from the claw and has its own motor	A nice compliant mechanism Very good claw. Love the Erasers.

Additional Notes:

From other teams it seems strength of gripper is the biggest contributor to performance. the great variation in grippers also suggests also that the performance in each mission is heavily dependent on the performance of the arm and control system. This can be seen from IMPULS' very simple digit claw that has no compliance. compared to Michigan though, they have a cup shape grove which may help slightly

A lot of good teams, also have solenoids to trigger keyboard keys. this way the alignment can be done before hand without relying on dynamic precision.

Also note that no one uses slip rings! Also note that no one uses coaxial transmission shafts. It might be too difficult to design/too difficult to manufacture or just decided to go direct with the motor. None of these designs look very aesthetic, except for maybe Stanford, but that's my opinion.

End Effector

This is the claw, tool bit and key stroke pusher rolled into one. It is used to grip items in retrieval missions, turn cap screws with a hex drive feature, and push keys on a keyboard. Previously, our team has used an square end Allen key to turn the cap screw as well as push the keys. Some teams use a solenoid to push keys.

Ball-nose tool tip for a looser accuracy requirement

List of Interact-able Items

Below is a list of items we may have to interact with at comp, sorted by mission. This will give us a better idea of what we need to grip:

Extreme Retrieval and Delivery

NOTE: ALL ITEMS WILL BE NO GREATER THAN 5CM IN DIAMETER

• screwdriver

• hammer

• wrench

• Toolbox

• Gasoline Can

• Pick up and transport rocks up to 5kg in mass

• Tow rope (15mm diameter max) with a 5kg weight

Equipment Servicing

• Cache container (< 3kg) with a 10cm handle (min) with a 5cm diameter (max)

• Handle drawer

• Socket head cap screw

• Undo a latch on hinged panel, and open panel

• Type on Keyboard

• Operate a joystick to direct an antenna while observing a guage

• Pick up and insert a rugged USB memory stick into a USB slot

• Push buttons, flip switches, turn knobs

• Water bottle and other cylindrical items