A low-cost compliant 7-DOF robotic manipulator

Abstract

Abstract-We present the design of a new low-cost serieselastic robotic arm. The arm is unique in that it achieves reasonable performance for the envisioned tasks (backlash-free, sub-3mm repeatability, moves at 1.5m/s, 2kg payload) but with a significantly lower parts cost than comparable manipulators. The paper explores the design decisions and tradeoffs made in achieving this combination of price and performance. A new, human-safe design is also described: the arm uses stepper motors with a series-elastic transmission for the proximal four degrees of freedom (DOF), and non-series-elastic robotics servos for the distal three DOF. Tradeoffs of the design are discussed, especially in the areas of human safety and control bandwidth. The arm is used to demonstrate pancake cooking (pouring batter, flipping pancakes), using the intrinsic compliance of the arm to aid in interaction with objects.

Design of a low cost PC interface Six DOF robotic arm utilizing recycled materials

“…The basement section has produced 216 Nm torque for this operation. The operation result shows a satisfactory agreement with other designed robotic system [6] [9][17]. This main purpose of this design is to make the system affordable for the third world country where budget is a big issue but necessity is there.…”

“…For the design of the manipulator, mostly spur gears of different radius have been utilized to control the speed of the motors. For controlling the speed and position of the wrist, a bevel and worm gear have been used [7][8][9]. Using a spring system connected between top of the fore arm to shoulder to increase the lifting weight capacity.…”

Low-cost robot arm with 3-DOF counterbalance mechanism

“…However, the robot arm market is still limited because of the high prices of robot arms. Therefore, much research has been done to develop low-cost, high performance robot arms [4][5][6].…”

Hybrid Operational Space Control for Compliant Legged Systems

“…Since the achievable controller fidelity (in terms of bandwidth and feedback gains) is lowered within every additional loop of the cascaded structure, this setup can greatly limit performance in practice. For a mechanically stiff system (such as for example the DLR robot arm [6]) or 'soft' tasks (such as interacting with the environment) this is not too much of a problem, but for mechanically compliant systems (such as the Meka Arm or similar robots with a torque bandwidth of below 5Hz [20]) and precise positioning tasks (such as foot placement) this can quickly become critical. Consequently, for purely kinematic tasks, a low level joint position controller that compensates for the known series elasticity (e.g., a LQG (Linear-QuadraticGaussian) structure presented in [10]) will always perform better than an inverse dynamics framework in a cascaded setup as depicted in Fig.…”