Parallel gripper on the way. FWIW, the Solarbotics gripper only uses the servo through ~90 degrees. I'm after more like 180, which gives twice the gripping power.
That's a nice improvement. The good part about connecting the linkages forward on the finger is the mechanical advantage you get versus moving them from the joint. But the servo mounting looks harder to do. Do you think it is possible to turn the servo 90 degrees and mount it back on the base where the fingers are attached? That would angle the linkages and reduce the jaw movement a bit.
Anything's possible. For me, it's a quest for minimalism and keeping the weight low. IMHO, to make an efficient arm with a decent payload, you must start at the gripper and work backwards, keeping everything as light as possible.
There's a balancing act to match the servo's power & torque abilities to the geometry & strength of the (UGH!) plastic gripper linkage. Different pivots will change the speed, opening range & max grip force of the arm.
I've been wrestling with what Duane has brought up. It seems to me that it is hard to have a generic gripper that will work well in many different scenarios. The grippers I have studied all seem to be specific to a need. So it got me to thinking would it be possible/worthwhile to build a robotic arm that had the ability to change its grippers like a CNC mill can with a tool changer? If the arm detects it is to move a soda can it changes to that gripper. If a wooden block it switches to a gripper like Erco's. If stackable wooden robots another. Sure would make our robotic arms more useful to a broader range of uses.
I believe industrial robot arms do have interchangeable grippers. I think the technical term is "end effector" or something like that.
Have you seen the balloon with coffee grounds gripper? I've wondered about having the normal gripper pick up a coffee grounds gripper when it's needed.
Another thought I've had is to use different shaped pads to attach to the inner gripper surface to aid the gripper in getting a good "grip". For example, to pick up a soda can (hopefully full), I'd use a curved pad to match the contours of the can.
I know this (end effector design) is a huge area of robot research.
I hadn't come across the interchangeable grippers in my research, but I knew I had a great idea.
I have seen the coffee gripper. I believe it was in Nuts&Volts that I read a really good article about how to build one and use it. I haven't come across it yet in my past issues. I wonder how stable the release nature of the coffee gripper is? In other words, can I pick-up plastic army men and set them back down and they remain standing.
I have thought about using inflatable pads on a parallel gripper like Erco's to let it conform to the object but seemed like to much overhead and weight to use them.
I'm going to take your advice and work from the gripper down. So I need to design a light weight gripper that can pick-up plastic army men and then set them down and they remain standing. Give me a couple of hours.
Comments
The Solarbotics claw brings the contact points together closer to parallel than your claw.
How do the two compare in the ability to pick things up?
Duane
Parallel gripper on the way. FWIW, the Solarbotics gripper only uses the servo through ~90 degrees. I'm after more like 180, which gives twice the gripping power.
It has a shorter "arm," and no rubber tips for the fingers, but otherwise it's basically the same as they've always been.
-- Gordon
Version 2.0 has parallel-closing jaws and weighs in at 20.6 grams.
There's a balancing act to match the servo's power & torque abilities to the geometry & strength of the (UGH!) plastic gripper linkage. Different pivots will change the speed, opening range & max grip force of the arm.
I like you parallel gripper. Very nice.
I agree, the gripper seems like a good place to begin building an arm. But what are you going to grip?
I've been amazed how difficult it is to pick things up with a robotic arm.
I have one of these beasts.
I was amazed how hard it was to pick up an empty soda can with it.
It's a good thing I have a mini-frig next to my computer because I'm afraid my Dr. Pepper fetching robot is a ways off.
I do think the arm would have a better chance of success at picking up soda cans if the gripper was modified to curve around the can.
I bring this up because I think your arm will more likely be successful if you build it with the items you wish it to manipulate in mind.
Have you decided what type of items you plan to manipulate with your robot arm? (Other than human fingers.)
Duane
Tony
I believe industrial robot arms do have interchangeable grippers. I think the technical term is "end effector" or something like that.
Have you seen the balloon with coffee grounds gripper? I've wondered about having the normal gripper pick up a coffee grounds gripper when it's needed.
Another thought I've had is to use different shaped pads to attach to the inner gripper surface to aid the gripper in getting a good "grip". For example, to pick up a soda can (hopefully full), I'd use a curved pad to match the contours of the can.
I know this (end effector design) is a huge area of robot research.
Duane
I hadn't come across the interchangeable grippers in my research, but I knew I had a great idea.
I have seen the coffee gripper. I believe it was in Nuts&Volts that I read a really good article about how to build one and use it. I haven't come across it yet in my past issues. I wonder how stable the release nature of the coffee gripper is? In other words, can I pick-up plastic army men and set them back down and they remain standing.
I have thought about using inflatable pads on a parallel gripper like Erco's to let it conform to the object but seemed like to much overhead and weight to use them.
I'm going to take your advice and work from the gripper down. So I need to design a light weight gripper that can pick-up plastic army men and then set them down and they remain standing. Give me a couple of hours.
Tony
All will become frighteningly clear, but it will be too late.
Mwah-ha-ha...